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S.No. CONTENTS Page
1. Introduction 51
2. Respiratory organs 51
3. Human respiratory system 51
4. Mechanism of breathing 56
5. Respiratory volumes and capacities 57
6. Exchange of gases 59
7. Transport of oxygen 61
8. Oxyhaemoglobin dissociation curve 61
9. Transport of CO2 62
10. Regulation of respiration 64
11. Respiratory disorders 65
12. Exercise-I (Conceptual Questions) 67
13. Exercise-II (Previous Years Questions) 72
14. Exercise-III (Analytical Questions) 76
15. Exercise-IV (Assertion & Reason) 82
BR
EA
TH
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AN
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EX
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OF
GA
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S
ENEET SYLLABUSRespiratory organs in animals (recall only); Respiratory system in humans; Mechanism of breathing and its regulationin humans-Exchange of gases, transport of gases and regulation of respiration, Respiratory volumes; Disordersrelated to respiration-Asthma, Emphysema, Occupational respiratory disorders.
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DR. ANSUMAN MUKHOPADHYAY is a renowned Senior ConsultantPulmonologist with over 20 years of experience in Respiratory Medicine.
After finishing his DTCD training where he topped the university, Dr.Mukhopadhyay went on to finish his MD in Tuberculosis and RespiratoryDisease, and DNB in Respiratory Medicine. He has also been apostgraduate teacher and trained quite a few respiratory professionals whoare also established names in the speciality.
Completed training interventional bronchoscopy especially endobronchialultrasonography by the American College of Chest Physicians.
He is a Professional Member of:
• Indian Chest Society
• Associayion of Physiacians of India
• Indian Society of Critical Care Medicine
• European Respiratory Society
• Association of Chest Physicians of West Bengal
DR. MOHANKUMAR THEKKINKATTIL, MD., AB., DSc., DPPR.,FCCP., FAARC., FNCCP., FIAB, FIASM Present Position: HOD & ChiefConsultant, Institute Of Pulmonary Medicine And Research, SriRamakrishna Hospital, Coimbatore. First Indian to get MD and DPPR fromNancy University, Francez o Published & Written Articles in Indian / ForeignJou
Experience:
• Worked as Assistant Professor & Research Fellow, Nancy University(France)- till 1984
• Assistant Surgeon, Kerala Government Service-till 1987
• Chief, Pulmonology Department, Kovai Medical Center, Coimbatore-till 1992
• Chief, Institute of Pulmonary Medicine and Research, Sri RamakrishnaHospital, Coimbatore- till date
• Visiting consultant to various hospitals in Coimbatore.
• Visiting Professor, School of Medicine, West Verginia University, Morgantown, USA.
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Pre-Medical : BiologyALLEN
* Oxygen (O2) is utilised by the organisms to indirectly break down of nutrient molecules like glucose and to deriveenergy for performing various activities. Carbon dioxide (CO2) which is harmful is also released during the abovecatabolic reactions. It is, therefore, evident that O2 has to be continuously provided to the cells and CO2 producedby the cells have to be released out. This process of exchange of O2 from the atmosphere with CO2 producedby the cells is called breathing, commonly known as Respiration.
* Respiration is for energy liberation.
Respiration involves the following steps :-
(i) Breathing or pulmonary ventilation by which atmospheric air is drawn in and CO2 rich alveolar air is released out.
(ii) Diffusion of gases (O2 and CO2) across alveolar membrane.
(iii) Transport of gases by blood.
(iv) Diffusion of O2 and CO2 between blood and tissues.
(v) Utilisation of O2 by the cells for catabolic reactions and resultant release of CO2.
RESPIRATORY ORGANS
Respiratoryorgans
General bodysurface
Moist cuticle (skin) Tracheal tubes Gills Lungs
Examples Sponges,Coelenterates,Flatworms
Earthworm,Frogs
Insects Aquaticarthropods- Molluscs- Fishes
- Reptiles- Birds- Mammals
HUMAN RESPIRATORY SYSTEM(1) Respiratory tract.
(2) Lungs
Respiratory tract – A passage by which air enters into lungs
External nostrils Nasal Chamber Internal nares Naso pharynx
Pharynx GlottisLarynxTrachea
Bronchial Tree
Respiratory Tree
1. Nose and Nasal- passage -
Human have a pair of external nostrils opening out above the upper lip.
External nares open in vestibule region present in anterior part of nasal passage.
Vestibule posteriorly connected with nasal chambers.
Nasal passage is functionaly divided into 3 regions :
(i) Vestibular region : Skin, hair, sebaceous glands.
(ii) Respiratory region : Lined by PSCCGE.
(iii) Olfactory region : Lined by Neuro sensory epithelium (Olfactory epithelium/Schneidarian membrane)
BREATHING AND EXCHANGE OF GASES
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Pre-Medical : Biology ALLEN2. Bucco-pharyngeal cavity -
* It is divided into two parts. Anterior part is called the Buccal-cavity and the posterior part is called Pharyngeal-
cavity. Between the buccal and the Nasal cavity, hard palate followed by soft palate is present. The terminal
part of soft plate is called Uvula. This divides the pharyngeal-cavity incompletely into two chambers. Upper
chamber is the Nasopharyngeal chamber and the Lower chamber is Oropharyngeal chamber.
* At the time of swallowing of food, the Uvula lifts up and covers the internal-nares and so prevents the food from
entering the nasal-passage. In the oro pharyngeal chamber, 2 slit like apertures are present. Dorsal-pore is
called the gullet which opens into the oesophagus, so this is the path of food. Ventral-pore is called the glottis;
and it opens into the Larynx ; and so this is the respiratory-passage.
* Near the glottis, a flat elastic cartilage called the Epiglottis is present. At the time of swallowing of food, this
cartilagenous flap covers the glottis. During swallowing breathing stops.
* Pharynx is the only part where food and air passage mix together. (Pharynx is the common passage for food and
air)
3. Larynx (voice producing organ) :- Larynx is a cartilagenous box which helps in sound production and hence
called the sound box.
Larynx is made up of following cartilages :
1. Thyroid cartilage : Single, Largest, C-shaped, Dorsally incomplete, hyaline cartilage.
2. Cricoid cartilage : Single, Signet ring shaped, below thyroid cartilage, hyaline cartilage.
3. Arytenoid cartilage : One pair, pyramid shape cartilage, hyaline cartilage.
4. Cartilage of Santorini : One pair, node like cartilage, present at the end of arytenoid cartilage,
Elastic cartilage
In larynx two pair of vocal cords are present for sound production :-
(i) Anterior pair is called as false vocal cord. These are composed of membranes. They are pink in
colours & they don't help in phonation. They provide moisture to true vocal cords.
(ii) Posterior pair :- It is true vocal cords. They are composed of sheath of yellow fibrous connective tissue.
4. TRACHEA :
* It is a 10-12 cm long straight tube extending upto the mid thoracic cavity.
* In the trachea 16-20 'C' shaped cartilagenous rings are present which prevent trachea from collapsing. These
rings are incomplete on dorsal surface of trachea.
5. Bronchial tree (B. T.) & Respiratory Tree (R. T.)
l When trachea enter into thoracic cavity, it divides into two branches called as primary bronchus at the level of
fifth thoracic vertebra. Branches of primary bronchus upto terminal bronchioles makes bronchial tree.
l Terminal bronchioles divide to form respiratory bronchioles & branches of respiratory bronchioles makes
respiratory tree.
l In bronchial tree, cartilage rings are present, while these are absent in respiratory tree.
l Gaseous exchange occurs in respiratory tree while it is absent in bronchial tree.
l Volume of air which is filled in B.T. is dead space volume, which doesn't take a part in gaseous exchange.
(150 ml)
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Pre-Medical : BiologyALLENThere are two zones. (i) Conducting zones (ii) Exchange zone
External nostrils
Vestibules
Nasal Chambers
Internal nares
Naso pharynx
Pharynx Glottis
Larynx
Trachea
Primary Bronchi
Secondary Bronchi
Tertiary/Segmental Bronchi
Total Pulmonary Bronchioles
Terminal Bronchiole
Respiratory Bronchiole
Alveolar Duct
ATRIA
Alveolar Sac
Alveoli
Conducting Zone
Exchange Zone/Respiratory Zone
Respiratory tree
Bronchial tree
Incomplete C-shaped hyaline cartilagenous rings
Simple squamous epithelium
l Exchange zone is the actual site of diffusion of O2 and CO2 between blood and atmospheric air.
l The conducting zone transports the atmospheric air to the alveoli, clears it from foreign particles, humidifies
and also brings the air to body temperature.
Lungs : A pair of lungs are present in the thoracic-cavity. Lungs are covered by a double-membrane which are called
the Pleural-membranes. Outer membrane is the Parietal Pleura and inner-membrane is the
Visceral-pleura. Both these membranes are derived from the mesoderm. The outer pleural membrane is
in close contact with the thoracic lining whereas the inner pleural membrane is in contact with the lung
surface. In between both the membranes a very narrow cavity called Pleural-cavity is present. In this cavity,
a very thin layer of Pleural fluid is present. Pleural fluid reduces friction on the lung surface. Sometimes due
to bacterial infection the amount of this fluid increases. So, the organism feels a difficulty in breathing and
sever chest pain (dyspnoea). This is termed as pleuricy or pleural effusion disease.
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Pre-Medical : Biology ALLEN* In human right lung made up of 3 lobes & left lung made up of 2 lobes.
Trachea
ApexUpper lobeOblique fissure
Upper lobe
Horizontal fissure
Oblique fissure
Lower lobe
Cardiac notchMiddle lobe
Lower lobeHuman
Right lung Left lung
Respiratory bronchiole
Terminal bronchiole
Atria
Air saccules
Alveoli
Alveolar ducts
Human
Epiglottis
Larynx
Trachea
Pleural membranes
AlveoliPleural fluidBronchiole
Diaphragm
Lung
Cut end of rib
Bronchus
Diagram of the human lungs
HUMAN
Right lung (625 gm) Left lung (575 gm)
3 lobes– anterior lobe– middle lobe– posterior lobe
2 lobes– left anterior– left posterior
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Pre-Medical : BiologyALLENl Structural & functional unit of lungs is called alveoli
l Approximately 300 million alveoli are present in both lungs in total.
l Inner (alveolar) surface area of both lungs is approximately 70-100 m2 in total.
l Wall of alveoli consist of two layers, outer layer is composed of yellow fibrous C.T., inner layer is composed of
simple squamous epithelium
l Squamous cells of alveoli are called as Pneumocytes.
l Most of these pneumocytes are type-I which help in gaseous exchange while few pneumocytes are type-II which
are larger in size, secrete LECITHIN (Phospholipid) and this acts as surfactant which prevents collapsing of
alveoli by reducing its surface tension.
* Internal surface of alveoli is termed as the Respiratory surface. It is derived from the endoderm of the
embryo.
* Phagocyctic cells in alveoli are called dust cells.
* Mammalian lungs are solid and spongy. There is no central cavity.
* Muscles are absent in the lungs of mammals. So the power of self-contraction and self-expansion is absent in
these lungs. (Sucken lungs)
Thoracic cage :- Coverings of thoracic cavity makes thoracic cage.
Anterior surface : Clavicle bones, Neck
Posterior surface : Diaphragm.
Dorsal surface : Vertebral column & ribs
Ventral surface : Sternum & ribs.
Lateral surface : Ribs
Diaphragm :- A muscular septum which is found only in mammals and crocodile. Normal shape of diaphragm
is dome like which divides body cavity in two parts upper thoracic cavity & lower abdominal cavity.
Radial muscles are present in diaphragm. By the contraction in these muscles, diaphragm become flattened in
shape, so, volume of thoracic cavity increases in anterior posterier axis.
Intercostal muscles (ICM) :-
Space between two ribs is called intercostal space in which 2 types of muscles are present
– External ICM. (EICM) – Internal ICM. (IICM)
EICM :- By the contraction in this muscles, rib & sternum shifts upward and outward so thoracic volume
increase in dorso-ventral axis. So they help in inspiration.
InspirationSternum
Ribs
Vertebralcolumn
Expiration
Position of ribs(Thoracic respiration)
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Pre-Medical : Biology ALLENBEGINNER'S BOX-1
1. Larynx is a modified portion of(1) Pharynx (2) Trachea (3) Bronchus (4) Lungs
2. Cartilaginous rings in trachea are incomplete at which surface.(1) Dorsal (2) Ventral (3) Lateral (4) Ventrolateral
3. Wall of alveoli is composed of(1) Simple squamous epithelium (2) Simple cuboidal epithelium(3) Pseudostratified epithelium (4) Simple columnar epithelium
4. The structure which prevents the entry of food into respiratory tract is(1) pharynx (2) Larynx (3) Glottis (4) Epiglottis
5. In which part of lungs gaseous exchange takes place in human :–(1) Trachea & alveolar duct (2) Trachea & bronchi(3) Alveolar duct & alveoli (4) Alveoli & Trachea
6. Respiratory organ of insects are :-(1) General Body surface (2) Book lungs(3) Lungs (4) Tracheal tubes
7. In human lungs are divided into lobes(1) 3 right & 2 left lobes (2) 2 right & 3 left lobes(3) 2 right & 2 left lobes (4) 3 right & 3 left lobes
8. Arytenoid cartilage in larynx are(1) Elastic (2) Hyaline (3) Calcified (4) All of these
MECHANISM OF BREATHING
• Breathing involves two stages : inspiration during which atmospheric air is drawn in and expiration by which
the alveolar air is relased out.
• Inspiration can occur if the pressure within the lungs (intra pulmonary pressure) is less then the atmospheric
pressure so there is a negative pressure in the lungs than the atmospheric pressure. Similarly, expiration takes
place when the intra-pulmonary pressure is higher than the atmospheric pressure.
INSPIRATION Air entering lungs
Ribs and sternum raised
Rib cage
Volume of thorax increased
Diaphragmcontracted
Mechanism of Breathing showing Inspiration
• Inspiration is an active process.• Normally it takes around 2 seconds.• At the time of inspiration, contraction in diaphragm
and external intercostal muscles takes place.
• Diaphragm becomes flat and is pushed towards abdominal
cavity.
• Sternum moves towards ventral and anterior direction.
• Ribs move towards outside and ventral side. As a result of
all these reactions, the volume of thoracic cavity is
increased. So the pressure of pleural fluid over lungs is
decreased. Due to the spongy nature, lungs expand. As a result of this, air pressure in the lungs is decreased as
compared to atmospheric pressure. Now air rushes from outside, through respiratory track and fills the lungs.
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Pre-Medical : BiologyALLEN EXPIRATION
Volume of thoraxdecreases
Air expelled from lungs
Ribs and sternum
returned to original position
Diaphragmrelaxed
and arched
upwardsMechanism of Breathing showing Expiration
• Normal expiration is a passive activity. It takes
around 3 seconds. During expiration, contraction
(in any muscle) does not take place. During
expiration, relaxation in diaphragm andexternal intercostal muscles takes place. As
a result of this relaxation, diaphragm, sternum
and ribs attain their actual (normal) position. Due
to which the volume of thoracic cavity is
decreased, and pressure of thoracic cage on
lungs is increased. Thus air which was filled in
lungs goes outside through respiratory tract.
Normal breathing is also called Abdominal breathing.
• We have the ability to increase the strength of inspiration and expiration with the help of additional muscles.
This is called forceful breathing.
RESPIRATORY VOLUME AND CAPACITIES
The volume of air involved in breathing movements can be estimated by using a spirometer which helps in
clinical assessment of pulmonary functions.
1. Tidal volume [T.V.] - It is amount of air inspired or expired during normal breathing. Its value for man is
500 ml. Whole inspired air does not reach up to lungs. The portion of air which remains in the respiratory tract
is called Anatomical dead-space volume. Its value for man is 150 ml.
A healthy man can inspire or expire approximately 6000 to 8000 ml of air per minute.
2. Inspiratory Reserve Volume [I.R.V.] - Volume of air a person can inspire by forcible inspiration over tidal
volume. It's value is 2500 to 3000 ml
3. Expiratory reserve volume [E.R.V.]- It is the amount of air expired over tidal volume by most forceful expiration.
Its value is 1000-1100 ml.
4. Residual volume - [R.V.]- It is the amount of air that remains inside lungs after forceful expiration. Residual
volume can not be given out of lungs. Its value is 1100-1200 ml.
INSPIRATORY CAPACITY
3500 ml.
VITAL CAPACITY4800 ml.
TOTALLUNG
CAPACITY6000 ml.
FUNCTIONAL RESIDUALCAPACITY2300 ml.
INSPIRATORY RESERVE VOLUME 3000 ml.
EXPIRATORY RESERVE VOLUME 1100 ml.
RESIDUAL VOLUME 1200 ml.
TIDAL VOLUME 500 ml.
6,000 ml 6,000 ml
5,000 ml 5,000 ml
4,000 ml 4,000 ml
3,000 ml 3,000 ml
2,000 ml 2,000 ml
1,000 ml 1,000 ml
EC
Spirogram of pulmonary volumes and capacities
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Pre-Medical : Biology ALLENPULMONARY CAPACITIES
1. Inspiratory capacity - [I.C.] - Total volume of air a person can inspire after a normal expiration.
I.C. = I.R.V. + T.V.
= 3000 ml + 500 ml
I.C. = 3500 ml
2. Expiratory capacity (EC) : Total volume of air a person can expire after a normal inspiration.
E.C. = TV + ERV
3. Functional Residual capacity [FRC] - It is the amount of air that normally remains inside lungs afternormal expiration. In it expiratory reserve volume and residual volume are included
FRC = ERV + RV
= 1000 ml + 1200 ml
FRC = 2200 to 2500 ml
4. Vital capacity - [V.C.] - It is the amount of air that can be expired by most forceful expiration after a deepestinspiration. Inspiratory reserve volume, expiratory reserve volume and tidal volume are included in it.
V.C. = IRV + ERV + TV
= 3000 ml + 1000 ml + 500 ml
= 4500 ml (4300 to 4800 ml)
5. Total lung capacity - Total volume of air that can accomodated in the lungs at the end of forcedinspiration.
TLC = IRV + TV + ERV + RV
= 3000 + 500 + 1000 + 1200
TLC = 6000 ml (approx) (5700 to 6000 ml)
BEGINNER'S BOX-21. If expiratory reserve volume is 1100 ml residual volume is 1200 ml and tidal volume is 500 ml, what shall be
the functional residual capacity(1) 1600 ml (2) 2800 ml (3) 2300 ml (4) 1200 ml
2. Air filled in dead space is(1) 150 cc (2) 350 cc (3) 500 cc (4) 1500 cc
3. Very high number of alveoli present in a lung is meant for(1) More space for increasing volume of inspired air(2) More area for diffusion(3) Making the organ spongy(4) Increasing nerve supply
4. Expiration involves(1) Relaxation of diaphragm and intercostal muscles(2) Contraction of diaphragm and intercostal muscles(3) Contraction of diaphragm muscles(4) Contraction of intercostal muscles
5. Abdominal breathing refers to(1) Normal breathing (2) Slow breathing (3) Fast breathing (4) Forceful breathing
6. Residual volume is :(1) lesser than tidal volume (2) greater than inspiratory volume(3) greater than vital capacity (4) greater than tidal volume
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Pre-Medical : BiologyALLEN7. Vital capacity of lungs is
(1) TV + IRV + ERV (2) TV + IRV + RV
(3) TV + ERV (4) IRV + ERV
8. Match the items in column I with column II and choose the correct option
Column I Column II
(A) Tidal volume (i) 2500 to 3000 mL of air
(B) Inspiratory reserve volume (ii) 1000 mL of air
(C) Expiratory reserve volume (iii) 500 mL of air
(D) Residual volume (iv) 3400 to 4800 mL air
(E) Vital capacity (v) 1200 mL of air
A B C D E
(1) (iii) (iv) (ii) (i) (v)
(2) (iii) (i) (ii) (v) (iv)
(3) (iii) (i) (iv) (v) (iv)
(4) (iv) (iii) (ii) (i) (v)
EXCHANGE OF GASES
* Alveoli are the primary sites of exchange of gases. Exchange of gases also occur between blood and tissues.
Exchange of gases in the lungs is done between alveolar air and deoxygenated blood.
* Gaseous exchange is a passive activity. It is done by simple diffusion.
* Diffusion pressure for every gas (in blood or in air) is called partial pressure. At the time of diffusion, gases
move from high partial pressure to low partial pressure.
Table of partial pressure (in mm Hg) of oxygen and carbon dioxide :-
RespiratoryGas
AtmosphericAir Alveoli Deoxygenat-
ed BloodOxygenated
Blood Tissues Insidethe cell
ExpiredAir
O2 159 104 40 95 40 20 120
CO2 0.3 40 45 40 45 50 27
The partial pressure of O2 in alveolar air [2OP ] is 104 mm Hg, its value in arterial blood is 40 mm Hg. So oxygen
goes from alveolar air to arterial air
* In alveolar air, partial pressure of CO2 [ 2COP ] is 40 mm Hg and its value in deoxygenated blood is 45-46 mm
Hg. So CO2 moves from arterial blood to alveoli. In this way, according to partial pressure exchange of gases
takes place in the lungs.
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Pre-Medical : Biology ALLENExpired airInspired air
Alveolus
Alveolar air
PO =104 mmHg
PCO =40 mmHg
CO O
2
2
2 2
Pulmonary arteryCO2 O2
Pulmonary vein
Systemic arteries(carrying oxygenated blood)
Systemic veins(carrying deoxygenated blood)
CO2 O2
PO = 40 mm Hg
PCO = 45 mm Hg2
2
PO = 95 mm Hg
PCO = 40 mm Hg2
2
Diagrammatic representation of exchange of gases at the alveolus and the body tissues with blood and transport of oxygen and carbon dioxide
• Diffusing capacity depends on solubility of gases, thickess of the respiratory membrane and partial pressure difference.• As the solubility of CO2 is 20-25 times higher than that of O2, the amount of CO2 that can diffuse through the
diffusion membrane per unit difference in partial pressure is much higher compared to that of O2.• Diffusion membrane is made up of three major layers :-
(i) Thin squamous epithelium of Alveoli. (ii) Endothelium of Blood capillaries.
(iii) Basement substances in between them.
Capillary basement membrane
Capillary endotheliumInterstitialspace
Epithelialbasementmembrane
Alveolarepithelial wall
Alveolus Capillary
Diffusion of O2
Diffusion of CO2
Basementsubstance
Air
Alveolar wall(one-celled thick)
Blood capillary
Red blood cells
Alveolar cavityCapillaryendothelium
Fig : A diagram of a section of analveolus with a pulmonary capillary
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Pre-Medical : BiologyALLEN
TRANSPORT OF GASES
* Blood is the medium of transport for O2 and CO2. About 97 per cent of O2 is transported by RBCs in the blood.
The remaining 3 per cent of O2 is carried in a dissolved state through the plasma. Nearly 20-25 per cent of CO2
is transported by RBCs whereas 70 per cent of it is carried as bicarbonate. About 7 per cent of CO2 is carried
in a dissolved state through plasma.
Transport of oxygen
in Alveoli4 2 4 8inTissues
Hb 4O Hb O+ ����������������
* As much oxygen comes in the blood from air, it is approximately 3% dissolves in the blood plasma. Remaining
97% oxygen combines with haemoglobin to form oxyhaemoglobin. O2 can bind with Hb in a reversible
manner to form oxyhaemoglobin.
* Haemoglobin is a red coloured iron containing pigment present in the RBC.
* Haemoglobin is made up of 4 units. Each unit has 1 Fe in +2 state. Each haemoglobin molecule can carry a
maximum of four molecules of O2.
* 1 gm of haemoglobin transports 1.34 ml of oxygen. 100 ml (1 dL) of blood contains normally 15 gm of
haemoglobin, so 100 ml blood transports approximately 20 ml of oxygen.
* In a conducting cycle blood gives its 25% O2 to tissues. So every 100 ml of oxygenated blood can deliver
around 5 ml of O2 to tissue under normal physiological condition.
* Binding of oxygen with haemoglobin is primarly related to partial pressure of O2. But PCO2, hydrogen ion
concentration and temperature are the other factors which can interfere with this binding.
* Oxygen does not oxidise haemoglobin. Formation of oxyhaemoglobin is a process of oxygenation. The
valency of iron is 2 in oxyhaemoglobin. Some gases (e.g. Ozone) oxidise haemoglobin. This oxidised haemoglobin
is called Methamoglobin. This type of gases are environmental pollutant.
* At the time, oxyhaemoglobin reaches upto the tissues it dissociates. O2 freed from it goes into the tissue fluid
from blood. In place of it, CO2 from tissue fluid comes into blood. Gaseous exchange between blood and tissue
is called internal respiration or tissue respiration. It is also done by simple diffusion.
OXYGEN DISSOCIATION CURVE1. A graph is plotted between O2 concentration and
Per
cent
age
satu
ratio
n of
ha
emog
lobi
n w
ith o
xyge
n
Partial pressure of oxygen (mm Hg)0 20 40 60 80 100
20
40
60
80
100
Oxyhaemoglobin dissociation curve
percentage saturation of haemoglobin with this
curve is called Dissociation curve.
2. Dissociation curve is sigmoid shape.3. This curve is highly useful in studying the effect of
factors like 2COP , H+ concentration, temperature
on binding of O2 with Haemoglobin.
* Shift to left Means that increase in affinity between
O2 and Hb.
* Shift to Right Means that decrease in affinity
between O2 and Hb and dissociation of
oxyhaemoglobin.
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Pre-Medical : Biology ALLEN
* In tissue following conditions are favourable for dissociation of oxygen from oxyhaemoglobin :-
(i) Low PO2
(ii) High PCO2
(iii) High H+ concentration
(iv) Low pH
(v) Higher temperature.
* In the alveoli high PO2, low PCO2, Lesser H+ concentration and lower temperature factors are favourable for
the formation of oxyhaemoglobin.
GOLDEN KEY POINTS
* P50 value – 2OP at which the Hb is 50% saturated with O2. Higher the P50 , lower is the affinity of Hb for O2. A
rise in 2COP , H
Å conc. increases the value of P50.
* 2, 3 diphosphoglycreate (2, 3 DPG) – a susbtance formed during glycolysis.
2, 3 DPG will cause dissociation of oxyhaemoglobin .
* Bohr's effect : Dissociation of oxyhaemoglobin due to high CO2 concentration in tissue is called Bohr's effect.
* During heavy exercise 100 ml blood delivered 15 ml O2 to muscle.
* Hb cannot take up O2 beyond a saturation level of 97%.
TRANSPORT OF CARBON DIOXIDE* The blood transports carbon dioxide comparatively easily because of its higher solubility.
* There are three ways of transport of carbon dioxide.
(a) In dissolved state : Approximately 5-7 per cent of carbon dioxide is transported, being dissolved in theplasma of blood.
(b) As Carbamino haemoglobin : About 20-25% CO2 react with the amine group of Haemoglobin andform carbamino-haemoglobin.
(c) In the form of bicarbonate : Bulk of CO2 is transported by plasma as bicarbonate.
* Carbon dioxide produced by the tissues, diffuses into the RBCs, where it reacts with water to form carbonic acid
(H2CO3). This reaction is catalysed by the enzyme, Carbonic anhydrase. RBCs contain a very high concentrationof this enzyme & minute quantity is present in plasma too.
* Now carbonic acid dissociates into Hydrogen (H+) and bicarbonate (HCO3–) ions.
* The hydrogen ions (H+) released from carbonic acid combine with haemoglobin and form haemoglobinic acid
(H.Hb)
* The majority of bicarbonate ions (HCO3–) formed within the erythrocytes diffuse out into the plasma along a
concentration gradient. In the plasma HCO3– combine with Na+ and form Sodium bicarbonate (NaHCO3).
Nearly 70% CO2 transported by plasma as NaHCO3 form.
* In response of HCO3– chloride ions (Cl–) diffuse from plasma into the erythrocytes to maintain the ionic balance.
Thus, electrochemical neutrality is maintained. This is called Chloride shift or Hamburger Phenomenon.
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Pre-Medical : BiologyALLEN
77% CO2CO2
7% CO is carried dissolved in Plasma
2
23% CO2
Tissue Level
70% diffuses inside RBC
CO + H O2 2 H CO2 3
C.A.
H CO2 3 H + HCO+ –3
KHbO2 KHb + O2
KHb K + Hb+
H + Hb+ H.Hb
CO + HHb, NH2 2 H.Hb.NHCOOH
K + Cl+ – KCl
HCO3
Cl– NaCl Na + Cl+ –
HCO + Na3– + NaHCO3
C.A.
RBC
CA-carbonic anhydrase
–
* When the deoxygenated blood reaches the alveoli of the lung, then carbaminohaemoglobin, and sodium
bicarbonate dissociated because PCO2 is low and PO2 is high in the alveoli.
* This dissociation is stimulated by oxyhaemoglobin. This CO2 freed from blood goes into atmosphere. The effect
of oxyhaemoglobin on the dissociation of these compounds is known as Haldane effect. In this reaction
oxyhaemoglobin acts like a strong acid i.e, it frees H+ in the medium.
* Every 100 ml deoxygenated blood delivers around 4 ml CO2 to alveoli.
BEGINNER'S BOX-31. Oxygen haemoglobin dissociation curve will shift to right on decrease of
(1) Acidity (2) Carbon dioxide concentration
(3) Temperature (4) pH
2. Body tissues obtain O2 from oxyhaemoglobin because of its dissociation in tissues caused by
(1) Low oxygen concentration and high CO2 concentration
(2) High O2 concentration
(3) Low CO2 concentration
(4) High CO2 concentration
3. Partial pressure of carbon dioxide in Alveoli, atmospheric air and tissues will be :-
(1) (0.3, 40, 45) mmHg (2) (40, 0.3, 45) mmHg
(3) (0.3, 104, 28) mmHg (4) (104, 159, 40) mmHg
4. One haemoglobin carries how many molecules of O2 ?
(1) 4 (2) 2 (3) 6 (4) 8
5. Haemoglobin-oxygen dissociation curve is –
(1) Hyperbolic (2) Sigmoid (3) Straight (4) Constant
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Pre-Medical : Biology ALLEN6. CO2 is transported mainly as :-
(1) Carbaminohaemoglobin (2) Oxyhaemoglobin
(3) Bicarbonate (4) carboxyhaemoglobin
7. Every 100 ml deoxygenated blood delivers around ______ CO2 to alveoli :-
(1) 20 ml (2) 4 ml (3) 5 ml (4) 25 ml
8. How much oxygen, blood supplies to tissues in one circulation in normal condition :-
(1) 75% (2) 4% (3) 25% (4) 20%
REGULATION OF RESPIRATION
* Human beings have a significant ability to maintain and moderate the respiratory rhythm to suit the demand of
the body tissues. This is done by neural system.
* The respiratory rhythm centre in the Medulla is primarily responsible for this regulation.
Following respiratory groups regulate respiration :-
(i) The dorsal respiratory group (DRG) is present in the dorsal portion of medulla oblongata. The signals
from these neurons generate the basic respiratory rhythm. The nervous signal released from this group
is transmited to the diaphragm & EICM.
(ii) The ventral respiratory group (VRG) of neurons are located anterolateral to the dorsal respiratory
group. During normal respiration, this remains inactive.
In the enhanced respiratory drive, the respiratory signal of this group contributes to fulfil the demand by
regulating both inspiration and expiration. Few of the neurons of this group control inspiration, while few
other control expiration, thus regulating both.
(iii) The pneumotaxic centre is located on pons. It is called switch off point of inspiration. Neural
signal from this centre can reduce the duration of inspiration and thereby alter the respiratory
rate. When this center send strong signal then lungs are filled partially.
* Hering Breuer reflex arch :
In the walls of terminal bronchioles and atria stretch receptors are present, Which are normally inactive but they
become active when alveoli are fiiled with maximum air. The Heiring Breuer reflex arch now becomes acti-
vated and sends inhibitory signals to the inspiratory centre to switch off inspiration. This prevents the alveoli
from over stretching and bursting. Thus Hering Breuer reflex arch is a protective reflex which works only when
normal mechanism of switch off of inspiration does not work timely due to any reason.
* A chemosensitive area is situated adjacent to the rhythm centre which is highly sensitive to CO2 and
hydrogen ions. Increase in these substances can activate this centre which in turn can signal the rhythm centre
and increase breating rate. The role of oxygen in the regulation of respiratory rhythm is quite insignificant.
* Aortic body and carotid body are chemoreceptors associated with aortic arch and carotid artery. They also
can recognise changes in CO2 and H+-concentration.
* The activity of respiratory centre is also affected by body temperature and blood pressure. Whenever body
temperature is increased or blood pressure goes high, respiratory centre becomes more activated and this
increases the respiration rate.
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Pre-Medical : BiologyALLEN
Respiratory Disorders1. Asthma is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles.
2. Bronchitis is a disorder of bronchi in which there is regular swelling and itching of bronchi and is characterised
by rugular coughing.
3. Emphysema is a chronic disorder in which alveolar walls are damaged due to which respiratory surface is
decreased. One of the major causes of this is cigarette smoking.
4. Occupational Respiratory Disorders: In certain industries, especially those involving grinding or stone-
breaking, so much dust is produced that the defense mechanism of the body cannot fully cope with the situation.
Long exposure can give rise to inflammation leading to fibrosis (proliferation of fibrous tissues) and thus causing
serious lung damage. Workers in such industries should wear protective masks.
GOLDEN KEY POINTS
* Hypoxia - Low O2 supply to tissues.
* Asphyxia - It is the state of suffocation due to high CO2 concn or low O2 concentration.
* Physiological shunt :- Not entire amount of blood which enters the lungs via pulmonary arteries actually
reaches in the walls of alveoli. 2% of the total blood actually never passes through the walls of alveoli, instead
it enters the venule side from arteriole side via the conduction zone in lungs. So this blood never gets oxygenated.
This is shunted blood (2% of total) This means that only 98% of the blood which enters the lungs actually
gets oxygenated. This phenomenon of By pass of alveoli by 2% of total blood is called as physiological shunt.
It is normally present in all human beings.
* One molecule of haemoglobin combine with four molecules of carbon monoxide gas to form
carboxyhaemoglobin. Its colour is cherry red. Due to this it reduces.
* One molecule of myoglobin has 1Fe++ ions metal.
* Foetal haemoglobin differs from adult haemoglobin in structure. Foetal haemoglobin has higher affinity for O2
than adult haemoglobin. When PO2 is low. Foetal Hb can carry up to 30% more O2 than maternal Hb. So
dissociation curve for foetal Hb will appear on the left side.
* Bowman's glands are present in human naral cavity.
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Pre-Medical : Biology ALLEN
BEGINNER'S BOX-4
1. The impulse for voluntary muscles for forced breathing starts in
(1) Medulla oblongata (2) Vagus nerve (3) Cerebellum (4) Cerebrum
2. Respiratory centre of brain is stimulated by
(1) Carbon dioxide content in venous blood (2) Carbon dioxide content in arterial blood
(3) Oxygen content in venous blood (4) Oxygen content in arterial blood
3. Respiratory rhythm centre is present in :-
(1) cerebellum (2) Cerebrum
(3) Medulla oblongata (4) Pons
4. Hiccough (hiccup) is due to activity of
(1) Intercostal muscle (2) Food in air tract
(3) Diapharagm (4) Inadequate oxygne in environment
5. Pneumotaxic centre is present on
(1) Pons (2) Medulla (3) Cerebrum (4) Cerebellum
6. Asthma is a respiratory disease caused due to
(1) Infection of trachea (2) Infection of lungs
(3) Bleeding into pleural cavity (4) Spasm in bronchial muscles
7. When CO2 concentration in blood increases, breathing becomes –
(1) There is no effect on breathing (2) Slow and deep
(3) Faster (4) Shallower and slow
8. Haemoglobin shows maximum affinity with:-
(1) Carbon monoxide (2) Carbon dioxide
(3) Oxygen (4) Ammonia
ANSWER KEY
Que. 1 2 3 4 5 6 7 8
Ans. 2 1 1 4 3 4 1 2BEGINNER'S BOX-1
Que. 1 2 3 4 5 6 7 8
Ans. 3 1 2 1 1 4 1 2BEGINNER'S BOX-2
Que. 1 2 3 4 5 6 7 8
Ans. 4 1 2 1 2 3 2 3BEGINNER'S BOX-3
Que. 1 2 3 4 5 6 7 8
Ans. 4 2 3 3 1 4 3 1BEGINNER'S BOX-4
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Pre-Medical : BiologyALLENEXERCISE-I (Conceptual Questions) Build Up Your Understanding
ANATOMY
1. The function of tracheal cilia is to
(1) Pass mucus out (2) Pass mucus in
(3) Pass air out (4) Pass air in
2. Which of the following prevents collapsing of
Trachea
(1) Muscles
(2) Diaphragm
(3) Ribs
(4) Cartilaginuous rings
3. Simplest respiratory organ is :
(1) gills (2) contractile vacuole
(3) skin (4) lungs
4. Tracheal rings are :–
(1) Complete
(2) Incomplete
(3) Dorsally incomplete
(4) Lateral incomplete
5. Which one of the following has the smallest
diameter ?
(1) Right primary bronchus
(2) Secondary bronchi
(3) Trachea
(4) Respiratory bronchioles
6. Match the columns
Column I Column II
(a) Larynx (p) Lid of glottis
(b) Trachea (q) Air Sac
(c) Alveoli (r) Voice Box
(d) Epiglottis (s) Wind Pipe
(t) Common Passage
(1) a—r, b—s, c—q, d—p
(2) a—t, b—s, c—p, d—q
(3) a—r, b—s, c—q, d—t
(4) a—r, b—t, c—q, d—p
7. Adam's Apple represents
(1) Arytenoid cartilage of larynx
(2) Cricoid cartilage of larynx
(3) Thyroid cartilage of larynx
(4) All the above
8. During hibernation period, frog's respiration is :-
(1) cutaneous (2) pulmonary
(3) pharyngeal (4) buccopharyngeal
9. Which part of thyroid cartilage in larynx is closed
(1) Dorsal (2) Ventral
(3) Anterior (4) Posterior
10. Inflammation of the lung covering causing severe
chest pain is
(1) Emphysema (2) Pleurisy
(3) Asphyxia (4) Hypoxia
11. Which of the following is not a part of respiratory
tract
(1) Nasal chamber (2) Oesophagus
(3) Pharynx (4) Trachea
12. Residual air mostly occurs in
(1) Alveoli (2) Bronchus
(3) Nostrils (4) Trachea
13. The epithelium of respiratory bronchioles is :-
(1) Pseudostratified colummar
(2) Simple squamous
(3) Pseudostratified and sensory
(4) Cuboidal and columnar
14. '' Epiglottis '' is made up by :-
(1) Elastic cartilage
(2) Fibrous cartilage
(3) Hyaline cartilage
(4) Bony structure
15. Air is breathed through
(1) Trachea ® lungs ® larynx ® pharynx ®alveoli
(2) Nose ® larynx ® pharynx ® bronchus ®alveoli ® bronchioles
(3) Nostrils ® pharynx ® larynx ® trachea ®bronchi ® bronchioles ® alveoli
(4) Nose ® trachea ® larynx ® bronchi ®pharynx ® alveoli
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Pre-Medical : Biology ALLEN16. Lungs are covered by
(1) Perichondrium
(2) Pleural sac
(3) Pericardium
(4) Peristomium
17. Which of the following structure is not the part of
Respiratory tree ?
(1) Alveolar duct
(2) Atria
(3) Segmental bronchi
(4) Respiratory bronchiole
BREATHING AND PULMONARY VOLUMES
18. The most important muscular structure in
respiratory system of human is
(1) External intercostal muscles
(2) Internal intercostal muscles
(3) Diaphgram
(4) Vertebral column
19. Which one of the following statement is correct?
(1) Chest expands because air enters into the lungs
(2) Air enters into the lungs because chest expands
(3) The muscles of the diaphragm contracts because
air enters into the lungs
(4) All of the above statements are correct
20. Among mammals, the efficiency of ventilation of
lungs as compared to reptiles and birds is better
developed by the presence of
(1) Ribs & costal muscles
(2) Only ribs
(3) Only costal muscles
(4) Diaphragm
21. After deep inspiration, capacity of maximum
expiration of lung is called :-
(1) Total lung capacity
(2) Functional residual capacity
(3) Vital capacity
(4) Inspiratory capacity
22. Which statement is correct ?
(1) Pulmonary ventilation is equal to alveolar
ventilation.
(2) Pulmonary ventilation is less than alveolar
ventilation.
(3) Alveolar ventilation is more than Pulmonary
ventilation.
(4) Alveolar ventilation is less than Pulmonary
ventilation.
23. About 1500 ml of air left in lungs is called
(1) Tidal volume
(2) Inspiratory reserve volume
(3) Residual volume
(4) Vital capacity
24. At high altitude, RBC of human blood will
(1) increase in number
(2) Decrease in number
(3) Decrease in size
(4) Increase in size
25. Which one has the lowest value
(1) Tidal volume
(2) Vital capacity
(3) Inspiratory reserve volume
(4) Expiratory reserve volume
26. Volume of air inspired or expired with each normal
breath is known as
(1) Inspiratory capacity
(2) Total lung capacity
(3) Tidal volume
(4) Residual volume
27. Total lung capacity is
(1) One lit (2) 3 lit
(3) 6 lit (4) 8 lit
28. Air that remains in lung after most powerful
expiration is
(1) Inspiratory air (2) Dead space air
(3) Tidal air (4) Residual air
29. During normal respiration without any effort the
volume of air inspired or expired is called –
(1) Tidal volume
(2) Reserve volume
(3) Residual volume
(4) None of these
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Pre-Medical : BiologyALLEN30. Total lung capacity is :-
(1) total volume of air accommodated in lungs at
the end of forced inspiration
(2) RV + ERV + TV + IRV
(3) vital capacity + residual volume
(4) All of the above
31. Which instrument helps in clinical assessment of
pulmonary Volumes ?
(1) Sphygmomanometer
(2) Stethoscope
(3) Spirometer
(4) Electrocardiograph
32. Volume of air remains in the lungs after normal
expiration is
(1) ERV + RV (2) IRV + RV
(3) RV + IRV + ERV (4) TV
33. Which of the following volume is not included in vital
capacity
(1) ERV (2) TV
(3) IRV (4) RV
GASEOUS EXCHANGE
34. In lungs, air is separated from venous blood by
(1) Squamous epithelium + tunica externa of blood
vessel
(2) Squamous epithelium + endothelium of blood
vessel
(3) Transitional epithelium + tunica media of blood
vessel
(4) Columnar epithelium + 3 layered wall of blood
vessel.
35. In lung, gaseous exchange is done by :-
(1) Simple diffusion
(2) Active transport
(3) Passive transport
(4) fascilitated diffusion
36. Which of the following statements is not true ?
(1) The partial pressure of O2 in deoxygenated blood
is 40 mm Hg.
(2) The partial pressure of O2 in oxygenated blood
is 95 mm Hg
(3) The partial pressure of O2 in alveolar air is
104 mm Hg
(4) The partial pressure of CO2 in alveolar air
is 45 mm Hg
37. Partial pressure of oxygen in alveoli, atmospheric
air and tissue will be
(1) 40, 159, 45 (2) 40, 0.3, 45
(3) 104, 159, 40 (4) 104, 0.3, 45
38. What will be the PO2 and PCO2 in the atmospheric
air compared to those in the alveolar air ?
(1) PO2 lesser, PCO2
higher
(2) PO2 higher, PCO2
lesser
(3) PO2 higher, PCO2
higher
(4) PO2 lesser, PCO2
lesser
39. Partial pressure of CO2 is higher :-
(1) At alveolar level
(2) At tissue level
(3) In atmosphere
(4) In oxygenated blood
TRANSPORT OF GAS
40. "Methemoglobin" refers to
(1) A colourless respiratory pigment
(2) Oxidized haemoglobin
(3) Oxygenated haemoglobin
(4) Deoxygeneted haemoglobin
41. Under normal condition 100 ml blood deliver _____
to tissue.
(1) 4 ml O2 (2) 10 ml O2
(3) 5 ml O2 (4) 25 ml O2
42. Haldane effect is due to
(1) CO2
(2) Lactic acid
(3) pH
(4) Oxyheamoglobin
43. What percentage of CO2 flows in blood in form of
bicarbonates
(1) 7% (2) 23%
(3) 50% (4) 70%
44. Effect of CO2 concentration on dissociation of
oxyhaemoglobin is called
(1) Bohr's effect (2) Haldane effect
(3) Hamburger effect (4) Root effect
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Pre-Medical : Biology ALLEN45. Chloride shift for the transport of
(1) O2 (2) CO2
(3) CO (4) O3
46. Ratio of oxyhaemoglobin and haemoglobin in blood
is based upon
(1) Oxygen tension
(2) Carbon-di-oxide tension
(3) Carbonate tension
(4) Bicarbonate tension
47. Exchange of bicarbonates and chloride ions
between RBC and plasma is called:-
(1) Chloride shift.
(2) Bohr's effect.
(3) Haldane's effect.
(4) Intra cellular respiration.
48. Determination of oxygen carried by haemoglobin
is done by
(1) pH
(2) Partial pressure of oxygen
(3) Partial pressure of carbon dioxide
(4) All the above
49. For proper transport of O2 and CO2 blood should be
(1) Slightly acidic
(2) Strongly acidic
(3) Strongly alkaline
(4) Slightly alkaline
50. What would happen when blood is acidic
(1) Binding of oxygen with haemoglobin increases
(2) Red blood corpuscles are formed in higher number
(3) Binding of oxygen with haemoglobin decreases
(4) There is no change in oxygen binding nor
number of RBC
51. The chloride shift is movement of Cl–
(1) From plasma to RBC
(2) From WBC to plasma
(3) From RBC to plasma
(4) From plasm to WBC
52. Chloride shift occurs in respond to :
(1) H+ (2) K+
(3) –HCO3 (4) Na+
53. What happen to the O2 dissociation curve of Hb if
pH is decreased ?
(1) shift to left
(2) shift to right
(3) remain unchanged
(4) will oscillate erratically
54. Dissociation curve shifts to the right when :-
(1) CO2 concentration decreases
(2) CO2 concentration increases
(3) O2 concentration increases
(4) H+ concentration decreases
55. Concentration of carbonic acid does not increase in
blood due to presence of
(1) Na+ (2) Mg2+
(3) Ca2+ (4) K+
56. Oxyhaemoglobin acts as
(1) Alkali (2) Acid
(3) Neutral (4) Buffer
57. The oxygen- Haemoglobin dissociation curve will
show a right shift in case of :-
(1) Less H+ concentration
(2) High partial pressure of O2
(3) Low partial pressure of CO2
(4) High 2,3,D.P.G.
58. Statements
A- Carbonic anhydrase is present in the
erythrocytes.
B- In erythrocytes the carbondioxide combine with
water and is transported.
(1) Statement A is correct and is responsible for
statement B
(2) Statement A is not correct but Statement B is
correct
(3) Both Statement A and B are wrong
(4) Statement A is correct and statement B is wrong
REGULATION AND DISEASES
59. "Emphysema" is a condition in which -
(1) Repiratoy centre inhibited
(2) Lot of fluid in the lungs
(3) The walls seperating the alveoli break
(4) Lungs have more O2
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Pre-Medical : BiologyALLEN60. Rate of respiration is directly affected by
(1) CO2 concentration
(2) O2 in trachea
(3) Concentration of O2
(4) Diaphragm expansion
61. If a man from sea coast goes to Everest peak then
(1) His breathing and heart beat will increase
(2) His breathing and heart beat will decrease
(3) His respiratory rate will decrease
(4) His heart beat will decrease
62. CO is more toxic than CO2 because it :
(1) Damages lungs
(2) It destryos haemoglobin
(3) Affects the nervous system
(4) reduces the oxygen carrying capacity of
haemoglobin
63. Carbon monoxide has greater affinity for
Haemoglobin as compare to oxygen :-
(1) 1000 Times (2) 200 Times
(3) 20 Times (4) 2 Times
64. About 97% of oxygen is transported by RBC
remaining 3% is :-
(1) Dissolved in plasma & transported
(2) Retained in lungs
(3) Attached to cell membranes
(4) Found inside mitochondria
EXERCISE-I (Conceptual Questions) ANSWER KEYQue. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ans. 1 4 3 3 4 1 3 1 2 2 2 1 2 1 3Que. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Ans. 2 3 3 2 4 3 4 3 1 1 3 3 4 1 4Que. 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
Ans. 3 1 4 2 1 4 3 2 2 2 3 4 4 1 2Que. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Ans. 1 1 4 4 3 1 3 2 2 1 2 4 1 3 1Que. 61 62 63 64
Ans. 1 4 2 1
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Pre-Medical : Biology ALLEN
AIPMT 2006
1. Which one of the following statements is incorrect(1) The residual air in lungs slightly decreases the
efficiency of respiration in mammals
(2) The presence of non–respiratory air sacs,
increases the efficiency of respiration in birds
(3) In insects, circulating body fluids serve to
distribute oxygen to tissues
(4) The principle of countercurrent flow facilitates
efficient respiration in gills of fishes
2. The majority of carbon dioxide produced by our
body cells is transported to the lungs –
(1) Dissolved in the blood
(2) As bicarbonates
(3) As carbonates
(4) Attached to hemoglobin
3. Bowman's glands are found in –
(1) Olfactory epithelium
(2) External auditory canal
(3) Cortical nephrons only
(4) Juxtamedullary nephrons
AIPMT 2007
4. Bowman's glands are located in the :-
(1) Olfactory epithelium of our nose
(2) Proximal end of uriniferous tubules
(3) Anterior pituitary
(4) Female reproductive system of cockroach
AIIMS 2007
5. Arrange the following in the order of increasing
volume :
(A) Tidal volume
(B) Residual volume
(C) Inspiratory reserve volume
(D) Vital capacity
(1) A < B < C < D
(2) A < C < B < D
(3) A < D < C < B
(4) A < D < B < C
AIPMT 2008
6. What is vital capacity of our lungs ?
(1) inspiratory reserve volume plus expiratory
reserve volume
(2) total lung capacity minus residual volume
(3) inspiratory reserve volume plus tidal volume
(4) total lung capacity minus expiratory reserve
volume
AIPMT-Pre 2010
7. Listed below are four respiratory capacities (a-d)
and four jumbled respiratory volumes of a normal
human adult :
Respiratory capacities Respiratory volumes(a) Residual volume 2500 mL
(b) Vital capacity 3500 mL
(c) Inspiratory reserve 1200 mL
volume
(d) Inspiratory capacity 4500 mL
Which one of the following is the correct matching
of two capacities and volumes ?
(1) (a) 4500 mL, (b) 3500 mL
(2) (b) 2500 mL, (c) 4500 mL
(3) (c) 1200 mL, (d) 2500 mL
(4) (d) 3500 mL, (a) 1200 mL
8. What is true about RBCs in humans ?
(1) They do not carry CO2 at all
(2) They carry about 20-25 per cent of CO2
(3) They transport 99.5 per cent of O2
(4) They transport about 80 percent oxygen only
and the rest 20 per cent of it is transported in
dissolved state in blood plasma.
AIPMT-Pre 2011
9. Two friends are eating together on a dining table.
One of them suddenly starts coughing while
swallowing some food. This coughing would have
been due to improper movement of :-
(1) Epiglottis
(2) Diaphragm
(3) Neck
(4) Tongue
EXERCISE-II (Previous Year Questions) AIPMT/NEET & AIIMS (2006-2018)
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Pre-Medical : BiologyALLEN10. The figure given below shows a small part of human
lung where exchange of gases takes place. In whichone of the options given below, the one part, A, B,C or D is correctly identified along with its function
Options :(1) C : arterial capillary-passes oxygen to tissues(2) A : alveolar cavity-main site of exchange of
respiratory gases(3) D : Capillary wall-exchange of O2 and CO2
takes place here(4) B : red blood cell-transport of CO2 mainly
11. A large proportion of oxygen is left unused in thehuman blood even after its uptake by the bodytissues. This O2 :(1) Acts as a reserve during muscular exercise(2) Raises the pCO2 of blood to 75 mm of Hg.(3) Is enough to keep oxyhaemoglobin sturation at
96%(4) Helps in releasing more O2 to the epithelial
tissues
AIPMT-Mains 2011
12. Bulk of carbon dioxide (CO2) released from bodytissues into the blood is present as :(1) Carbamino-haemoglobin in RBCs(2) Bicarbonate in blood plasma and RBCs(3) Free CO2 in blood plasma(4) 70% carbamino-haemoglobin and 30% as
bicarbonate
AIPMT-Pre 2012
13. Which one of the following is the correct statementfor respiration in humans ?(1) Workers in grinding and stone-breaking industries
may suffer, from lung fibrosis(2) Abut 90% of carbon dioxide (CO2) is carried by
haemoglobin as carbamino haemoglobin(3) Cigarette smoking may lead to inflammation of
bronchi(4) Neural signals from pneumotoxic centre in pons
region of brain can increase the duration ofinspiration
14. People who have migrated from the planes to an
area adjoining Rohtang pass about six months back:
(1) suffer from altitude sickness with symptoms like
nausea, fatigue, etc.
(2) have the usual RBC count but their haemoglobin
has very high binding affinity to O2
(3) have more RBCs and their haemoglobin has
a lower binding affinity to O2
(4) are not physically fit to play games like football.
AIIMS 201215. During swallowing of food which of the following
structures prevent the entering of food into the
glottis?
(1) Semilunar Valve
(2) Circular Muscular flap
(3) Cartilaginous flap
(4) Circular sphincter
NEET-UG 201316. The figure shows a diagrammatic view of human
respiratory system with labels A, B, C and D. Select
the option which gives correct identification and
main function and/or characteristic :-
D
CB
A
Lung
Cut end of rib
Bronchus
heart
(1) D – Lower end of lungs – diaphragm pulls it
down during inspiration
(2) A – trachea - long tube supported by complete
cartilaginous rings for conducting inspired air
(3) B – pleural membrane - surround ribs on both
sides to provide cushion against rubbing
(4) C – Alveoli - thin walled vascular bag like
structures for exchange of gases
AIPMT 201417. Approximately seventy percent of carbon-dioxide
absorbed by the blood will be transported to the
lungs:
(1) as bicarbonate ions
(2) in the form of dissolved gas molecules
(3) by binding to R.B.C.
(4) as carbamino - haemoglobin
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Pre-Medical : Biology ALLENAIPMT 2015
18. When you hold your breath, which of the following
gas changes in blood would first lead to the urge to
breathe?
(1) rising CO2 concentration
(2) falling CO2 concentration
(3) rising CO2 and falling O2 concentration
(4) falling O2 concentration
AIIMS 201519. Given figure is showing spirogram of pulmonary
volumes and capacities
6,000 ml
5,000 ml
4,000 ml
3,000 ml
2,000 ml
1,000 ml
A
B
C
D
Which represent expiratory reserve volume :-
(1) A (2) B (3) C (4) D
20. Oxygen dissociation curve shifts to right when:-
(1) 2OP decreases
(2) 2CoP decreases
(3) pH increases
(4) Temperature decreases
NEET-I 2016
21. Asthma may be attributed to :
(1) bacterial infection of the lungs
(2) allergic reaction of the mast cells in the lungs
(3) inflammation of the trachea
(4) accumulation of fluid in the lungs
NEET-II 2016
22. The partial pressure of oxygen in the alveoli of the
lungs is :-
(1) Less than that in the blood
(2) Less than that of carbon dioxide
(3) Equal to that in the blood
(4) More than that in the blood
23. Lungs do not collapse between breaths and someair always remains in the lungs which can never beexpelled because :-
(1) There is a positive intrapleural pressure
(2) Pressure in the lungs is higher than theatomospheric pressure.
(3) There is a negative pressure in the lungs.
(4) There is a negative intrapleural pressure pullingat the lung walls
AIIMS 2016
24. Respiratory rhythm centre is regulated by :-(1) Difference between solubility of gases(2) Chemosensitive area present in medulla
oblongata for 2COP and pH
(3) Diencephalon and Brain stem(4) Chemosensitive area present in the wall of lungs
NEET(UG) 201725. Lungs are made up of air-filled sacs, the alveoli.
They do not collapse even after forceful expiration,
because of:
(1) Inspiratory Reserve Volume
(2) Tidal Volume
(3) Expiratory Reserve Volume
(4) Residual Volume
AIIMS 201726. 'CO' poisoning causes the decrease in oxygen
availability to the tissues because :-
(1) It binds the haemoglobin and to form stable
compound carboxyhaemoglobin
(2) It increases CO2 concentration in our body.
(3) It is a toxic gas so main body organs like brain,
failure occured.
(4) 'CO' impedes the CO2 transportation.
NEET(UG) 2018
27. Which of the following options correctly representsthe lung conditions in asthma and emphysema,respectively ?(1) Inflammation of bronchioles; Decreased
respiratory surface(2) Increased number of bronchioles; Increased
respiratory surface(3) Increased respiratory surface; Inflammation of
bronchioles(4) Decreased respiratory surface; Inflammation of
bronchioles
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Pre-Medical : BiologyALLEN28. Match the items given Column I with those in Column
II and select the correct option given below :
Column I Column IIa. Tidal volume i. 2500-3000 mL
b. Inspiratory Reserve ii. 1100-1200 mL
volume
c. Expiratory Reserve iii. 500-550 mL
volume
d. Residual volume iv. 1000-1100 mL
a b c d(1) iii ii i iv
(2) iii i iv ii
(3) iii iv ii iii
(4) iv iii ii i
EXERCISE-II (Previous Year Questions) ANSWER KEY
Que. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Ans. 3 2 1 1 1 2 4 2 1 2 1 2 1 3 3Que. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Ans. 4 1 1 3 1 2 4 4 2 4 1 1 2 2 1Que. 31Ans. 1
29. Which of the following is an occupational respiratory
disorder ? :
(1) Anthracis (2) Silicosis
(3) Botulism (4) Emphysema
AIIMS 201830. Oxygen dissociation curve represents :-
(1) percent saturation of Hb with oxygen
(2) partial pressure of oxygen
(3) partial pressure of carbondioxide
(4) percent saturation of Hb with carbondioxide31. CO2 binds to a, b chain of haemoglobin to form:-
(1) carbaminohaemoglobin(2) oxyhaemoglobin(3) deoxyhaemoglobin(4) carboxyhaemoglobin
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Pre-Medical : Biology ALLENEXERCISE-III (Analytical Questions) Check Your Understanding
EXERCISE-III(A) (NCERT BASED QUESTIONS)
1. Which is a common passage for food and air :-
(1) Trachea
(2) Oesophagus
(3) Pharynx
(4) Glottis
2. The function of conducting part in respiratory system
of human is :-
(1) Clears foreign particles.
(2) Humidifies atmospheric air
(3) Brings the air to body temperature
(4) All of the above
3. When there is no air in initial bronchioles, they does
not collapse. it is due to :-
(1) Presence of Lecithin
(2) Presence of incomplete cartilagenous rings
(3) Presence of complete cartilagenous rings
(4) Presence of mucous
4. Which of the following steps not involved in
respiration:-
(1) Diffusion of gases across alveolar membrane
(2) Transport of gases by the blood
(3) Provide nutrients to all the living cells of body
(4) Utilisation of O2 by the cells for catabolic
reactions and resultant release of CO2.
5. Inspiration can occur, when –
(1) Pressure within the lungs is less than the
atmospheric pressure.
(2) Pressure within the lungs is more than the
atmospheric pressure.
(3) Pressure within the lungs and atmospheric air
is same.
(4) No effect of pressure on inspiration.
6. By the contraction in diaphragm volume of thoracic
chamber increases in the :-
(1) Dorso-ventral axis
(2) Antero-posterior axis
(3) Dorso-posterior axis
(4) Antero-ventral axis
7. The primary muscle of inspiration is :-
(1) Diaphragm
(2) Intercostal muscle
(3) Abdominal muscle
(4) Oblique muscle
8. Total volume of air a person can expire after normal
inspiration is :-
(1) Vital capacity
(2) Functional residual capacity
(3) Inspiratory capacity
(4) Expiratory capacity
9. Which of the following factor can affect the rate of
diffusion of gases?
(1) Thickness of the membrances involved in diffusion
(2) Solubility of the gases
(3) Pressure of the gases
(4) All of these
10. Which of the following is correct?
Alveoli Deoxy genated Tissue
blood
(1) PO2=159mmHg PCO2=40mmHg PCO2=20 mmHg
(2) PCO2=40mmHg PO2=95mmHg PO2=40mmHg
(3) PO2=104mmHg PCO2=45mmHg PCO2=45mmHg
(4) PO2=40mmHg PO2=40mmHg PCO2=45mmHg
11. What is true about diffusion capacity.
(1) Diffusion capacity of CO2 is much higher than O2
(2) Diffusion capacity of O2 is much higher than CO2
(3) Diffusion capacity of O2 and CO2 is same
(4) None of the above
12. Which of the following statement is true :
(1) 20-25 percent CO2 is transported by RBCs.
(2) 97 percent O2 is transported by RBCs.
(3) 70 percent CO2 is carried as bicarbonate.
(4) All of these are true.
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Pre-Medical : BiologyALLEN13. Binding of oxygen with haemoglobin is primarily
related to :-
(1) Partial pressure of O2
(2) Partial pressure of CO2
(3) H+ ion concentration
(4) Temperature
14. In which the following factors can interfere in binding
of O2 with haemoglobin.
A-2COP
B-H+ ion concentration
C-Temperature
(1) Only A (2) B, C
(3) A and C (4) A, B, C
15. The conditions which are favourable for the
formation of oxyhaemoglobin :-
(1) PO2, PCO2, H+conc.¯, Temperature¯
(2) PO2¯, PCO2¯, H+conc., Temperature
(3) PO2, PCO2¯, H+conc.¯, Temperature¯
(4) PO2, PCO2, H+conc.¯, Temperature
16. Which of the following statement/s is/are correct?
A- A high concentration of carbonic anhydrase is
present in RBC.
B- Minute quantities of carbonic anhydrase is
present in plasma.
C- Every 100 ml blood delivers approximately
4 ml of CO2 to the alveoli.
D- 20-25% CO2 is carried by haemoglobin as
carbaminohaemoglobin.
(1) A, C and D
(2) A and D
(3) A, B, C and D
(4) Only A
17. Which of the following centre can moderate the
functions of the respiratory rhythm centre.
(1) Dorsal respiratory centre
(2) Ventral respiratory centre
(3) Pneumotaxic centre
(4) Chemosensitive centre
18. A chemosentive area is situated adjacent to
respiratory rhythm centre. Which is highly sensitive
to_____ and ________ions.
(1) O2, H+ (2) CO2, OH–
(3) CO2, H+ (4) CO2, O2
19. Respiratory rhythm centre is present in :-
(1) Pons region
(2) Aortic arch
(3) Medulla region
(4) Carotid artery
20. Chronic disorder in which alveolar wall are damged
due to which respiratory surface is decreased. One
of the major causes of this is cigarette smoking :-
(1) Asthma
(2) Emphysema
(3) Bronchitis
(4) Fibrosis
21. Regarding the functions of our conduction
respiratory system, mark the wrong entry.
(1) Humidifies the air
(2) Warms up the air
(3) Diffusion of gases
(4) Cleans up the air
22. Total volume of air accomodate in the lungs at the
end of forced inspiration :-
(1) TV + IRV
(2) TV + IRV + ERV
(3) TV + ERV
(4) TV + IRV + ERV + RV
23. Mark the true statement among the following with
reference to normal breathing
(1) Inspiration is a passive process where as
expiration is active
(2) Inspiration is a active process where as
expiration is passive
(3) Inspiration and expiration are active processes
(4) Inspiration and expiration are passive processes
24. A person breathes in some volume of air by forced
inspiration after having a forced expiration. This
quantity of air taken in is
(1) Total lung capacity
(2) Tidal volume
(3) Vital capacity
(4) Inspiratory capacity
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Pre-Medical : Biology ALLEN25. The oxygen - haemoglobin dissociation curve will
show a right shift in case of
(1) High pCO2 (2) High pO2
(3) Low pCO2 (4) Less H+ concentration
26. Match the following and mark the correct options
Animal Respiratory Organ
A. Earthworm i. Moist cuticle
B. Arthropods ii. Gills
C. Fishes iii. Lungs
D. Birds/Reptiles iv. Trachea
Options:
(1) A-ii, B-i, C-iv, D-iii (2) A-i, B-iv, C-ii, D-iii
(3) A-i, B-iii, C-ii, D-iv (4) A-i, B-ii, C-i.v, D-iii
27. Mark the correct pair of muscles involved in the
normal breathing in humans :-
(1) External and internal intercostal muscles
(2) Diaphragm and abdominal muscles
(3) Diaphragm and external intercostal muscles
(4) Diaphragm and internal intercostal muscles
28. A person suffers punctures in his chest cavity in an
accident, without any damage to the lungs its effect
could be :-
(1) Reduced breathing rate
(2) Rapid increase in breathing rate
(3) No change in respiration
(4) Cessation of breathing
29. Which of the following group of animals, is used
Lungs for respiration ?
(1) Fishes, Frog, Tadpole larva
(2) Fish, Mollusca, aquatic arthropods
(3) Reptiles, Birds, Mammals
(4) Insects, Earthworm, Mollusca
30. At which level of vertebrae of the vertebral column,
trachea divides and forms bronchus?
(1) 4th thorasic vertebrae
(2) 5th thorasic vertebrae
(3) 7th thorasic vertebrae
(4) 3rd thorasic vertebrae
EXERCISE-III(B) (ANALYTICAL QUESTIONS)
31. Whether a child died after normal birth or died
before birth can be confirmed by measuring –
(1) tidal volume of air
(2) residual volume of air
(3) the weight of the child
(4) the dead space air
32. Heiring-Breuer reflex related to :-
(1) Effect of pH on respiratory centre
(2) Effect of CO2 on respiratory centre
(3) Effect of nerves on respiratory centre
(4) Effect of temp. on respiratory center
33. Presence of large number of alveoli around alveolar
ducts opening into bronchioles in mammalian lungs
is :-
(1) Inefficient system of ventilation with litle of
residual air
(2) Inefficient system of ventilation with high
percentage of residual air
(3) An efficient system of ventilation with no residual
air
(4) An efficient system of ventilation with little residual
air
34. The maximum volume of air a person can
breathe in after a forced expiration is :-
(1) TV + ERV
(2) TV + IRV
(3) TV + ERV + IRV
(4) ERV + RV
35. How many animals in the given list have gills for
respiration ?
Earthworm, Frog, Fish, Insects, Reptiles, Aquatic
arthropods, Flatworm, Molluscs, Birds
(1) Six (2) Four
(3) Three (4) Five
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Pre-Medical : BiologyALLEN36. In Lungs there is definite exchange of ions between
RBC and Plasma. Removal of CO2 from bloodinvolves –
(1) efflux of Cls ions from RBC
(2) influx of Cls ions into RBC.
(3) influx of 3HCOs ions into Plasma.
(4) efflux of 3HCOs ions from RBC.
37. The chloride content of RBC will be higher thanthat of plasma in :-(1) Systemic arteries and pulmonary veins(2) Systemic veins and pulmonary arteries(3) Systemic arteries and pulmonary arteries(4) Systemic veins and pulmonary veins
38. Which of the following lung volumes or capacitiescan be measured by spirometer :(1) Functional residual capacity [FRC](2) Residual volume(3) Total lung capacity [TLC]
(4) Vital capacity
39. What happens in Hamburger shift ?(1) HCO3
– ions move out from the RBC andCl– ions enters into RBC
(2) Cl– ions move out f rom the RBC andHCO3
– ions enters into RBC(3) H+ ions move out from the plasma and Cl– ions
enters into RBC(4) HCO3
– ions move out from the plasma andCl– ions enters into plasma
40. The respiratory membranes facilitates the exchangeof respiratory gases through diffusion. Oxygenenters the deoxygenated blood through diffusionbecause :-(1) Partial pressure of oxygen in alveolar air and
capillaries is 40 mm Hg and 100 mm Hgrespectively
(2) Partial pressure of oxygen in alveolar air andcapillaries is 100 mm Hg and 40 mm Hgrespectively
(3) Partial pressure of oxygen in alveolar air andcapillaries is 46 mm Hg and 40mm Hgrespectively
(4) Partial pressure of oxygen in alveolar air andcapillaries it 40 mm Hg and 46 mm Hgrespectively
41. Blood do not become acidic although it carries CO2
because :-
(1) CO2 is continuously diffused through tissues
(2) CO2 combines with H2O to form HCO3
(3) In CO2 transport, buffers plays an important role
(4) CO2 is absorbed by WBC
42. Effect of 2,3–DPG on the human blood is that :-
(1) It increases the affinity of O2 for haemoglobin
(2) It decreases the affinity of O2 for haemoglobin
(3) It increases association of Hb and O2.
(4) It decreases the value of P50
43. Match the following columns.
Column I Column II
A Inspiratorycapacity (IC)
1 Total air, a person caninspire after normalexpiration
B Expiratorycapacity (EC)
2 Maximal volume of theair, a person can breathin after a forcedexpiration
C Functionalresidual capacity(FRC)
3 Volume of the air thatwill remain in lungsafter a normalexpiration
D Vital capacity(VC)
4 Total volume of air aperson can expire aftera normal inspiration
Codes :-
A B C D
(1) 1 2 3 4
(2) 1 4 3 2
(3) 1 4 2 3
(4) 4 1 3 2
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Pre-Medical : Biology ALLEN44. Find out the correct match from the following table:-
Column I Column II Column III
(i) At tissue level Po2 = 40 mm Hg Pco2 = 45 mm Hg
(ii) In pulmonary
vein
Po2 = 95 mm Hg Pco2 = 50 mm Hg
(iii) In systemic
artery
Po2 = 40 mm Hg Pco
2 = 40 mm Hg
(iv) In alveoli Po2 = 104 mm Hg Pco2 = 40 mm Hg
(1) Both (i) and (ii)
(2) Both (iii) and (iv)
(3) (i), (ii) and (iii)
(4) Both (i) and (iv)
45. Considering the following labels for mentioned
structures and select the correct sequence of their
arrangement :-
A = Terminal bronchiole
B = Respiratory bronchiole
C = Tertiary bronchi
D = Primary bronchi
E = Secondary bronchi
F = Total pulmonary bronchioles
(1) D ¾® E ¾® C ¾® F ¾® A ¾® B
(2) A ¾® B ¾® D ¾® E ¾® C ¾® F
(3) C ¾® F ¾® A ¾® B ¾® D ¾® E
(4) D ¾® E ¾® F ¾® C ¾® B ¾® A
46. Which of the following option gives correct
information about the coverings of thoracic cage
on various surfaces :-
Anteriorsurface
Posteriorsurface
Dorsalsurface
(1) Sternum andRibs
Ribs Diaphragm
(2) Sternum andRibs
Diaphragm Clavicle bonesand neck
(3) Sternum andRibs
Vertebralcolumn
Clavicle bonesand neck
(4) Clavicle bonesand neck
Diaphragm Vertebralcolumn
47. Consdider the following four statements (a-d) and
select the option which includes all the correct ones
only :-
(a) All the time of inspiration, contraction in
diaphragm and external intercostal muscles
take place.
(b) Normal breathing is also called as abdominal
breathing.
(c) Expiration during sneezing, coughing, yoga is
normal expiration during which IICM and
abdominal muscles relax.
(d) Inspiration can occur if the pressure within lungs
(intra pulmonary pressure) is more then the
atmospheric pressure.
(1) Statements (a), (b), (c), (d)
(2) Statements (a) only
(3) Statements (a), (b), (c)
(4) Statements (a) and (b)
48. Find out the correct match from the following table:-
Column I Column II Column III
(i) Tidal volume(TV)
(EC – ERV) 500 ml
(ii) Expiratoryreserve volume(ERV)
(VC – IRV – TV) 3000 ml
(iii) Vital capacity(VC)
IRV + ERV + RV 4500 ml
(iv) Residualvolume (RV)
FRC – ERV 1200 ml
(1) (i) and (ii) (2) (i), (iii) and (iv)
(3) (i), (ii) and (iii) (4) (i) and (iv)
49. Which of the following statement is not correct:-(1) Formation of oxyhaemoglobin is a process of
oxidation.
(2) Every 100 ml of oxygenated blood can deliver
aroun 5 ml of O2 to tissue under physiological
condition.
(3) Dissociation curve is curve between percentage
saturation of Hb with oxygen and partial
pressure of oxygen.
(4) High concentration of CO2 activates dissociation
of oxyhaemoglobin is called Bohr's effect.
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Pre-Medical : BiologyALLEN
EXERCISE-III (Analytical Questions) ANSWER KEYQue. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ans. 3 4 2 3 1 2 1 4 4 3 1 4 1 4 3Que. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Ans. 3 3 3 3 2 3 4 2 3 1 2 3 4 3 2Que. 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
Ans. 2 3 2 3 3 1 2 4 1 2 3 2 2 4 1Que. 46 47 48 49 50 51Ans. 4 4 4 1 2 3
50. Find out the correct match from the following :-
(i) Larynx – sound box
(ii) Trachea – complete cartilagenous rigns
(iii) Epiglottis – elastic cartilagenous flap
(iv) Alveoli – very thin, irregular wal led,
vascularised bag like structures
(v) Pleural fluid – reduces friction on the lung
surface
(1) (i), (ii), (iii), (iv), (v)
(2) (i), (iii), (iv), (v)
(3) (i), (iii), (v)
(4) (i) and (v)
51. Given below graph shows an oxygen dissociation
curve :-
X
Y
Z
0 80 100Partial pressure of oxygen (mm Hg)20 40 60
20
Perc
enta
ge sa
tura
tion
of h
aem
oglo
bin
with
oxy
gen
100
80
60
40
Where in the body will haemoglobin be saturationat the percentage shown at points X, Y and Z.(1) X - Pulmonary artery, Y - Pulmonary vein,
Z - Carotid artery(2) X - Systemic artery, Y - Pulmonary artery,
Z - Pulmonary vein(3) X - Pulmonary vein, Y - Systemic vein,
Z - Systemic vein during exercise(4) X - Left ventricle, Y - Right ventricle,
Z - Systemic artery
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Pre-Medical : Biology ALLEN
1. Assertion :- Larynx is a cartilaginous box whichhelps in sound production.Reason :- Epiglottis flap covers the glottis duringswallowing and prevents the entry of food into thelarynx.(1) A (2) B (3) C (4) D
2. Assertion :-The anatomical setup of lungs in thoraxis such that any change in the volume of the thoraciccavity will be reflected in the lung cavity. (Pulmonarycavity)Reason :- Lungs have no muscles so we cannotdirectly alter the pulmonary volume.(1) A (2) B (3) C (4) D
3. Assertion :-Inspiration can occur if intra pulmonarypressure is less than the atmospheric pressure.Reason :- Inspiration is initiated by the relaxationof diaphragm and external intercostal muscle.(1) A (2) B (3) C (4) D
4. Assertion :-The volume of air a person can expireafter normal inspiration is TV + ERV.Reason :- Volume of air that will remain in the lungsafter a normal expiration is ERV + RV.(1) A (2) B (3) C (4) D
5. Assertion :-The amount of CO2 that can diffusethrough the diffusion membrane per unit differencein partial pressure is much higher compared to thatof O2.Reason :- The solubility of CO2 is 20-25 timeshigher than that of O2 solubility.(1) A (2) B (3) C (4) D
6. Assertion :-In the tissue high 2OP , low
2COP ,
higher HÅ concentration conditions are favourablefor dissociation of oxygen from the oxyhaemoglobin.Reason :- Every 100ml of oxygenated blood candeliver around 5ml of O2 to the tissues under normalphysiological conditions.(1) A (2) B (3) C (4) D
7. Assertion :-A chemosensitive area is situated
adjacent to the rhythm centre which is highly
sensitive to CO2 and hydrogen ions.
Reason :- The role of oxygen in the regulation of
respiratory rhythm is quite insignificant.
(1) A (2) B (3) C (4) D
8. Assertion :- Pneumotaxic centre can moderate
the functions of the respiratory rhythm centre.
Reason :- Neural signal from pneumotoxic centre
can reduce the duration of inspiration and thereby
the alter the respiratory rate.
(1) A (2) B (3) C (4) D
9. Assertion :- Strong pneumotoxic signal results
complete filling of lungs.
Reason :- Strong pneumotaxic signal increases the
duration of inspiration as well as expiration.
(1) A (2) B (3) C (4) D
10. Assertion :-While ascending up a mountain, one
gets less oxygen resulting in hypoxia.
Reason :- Percentage of oxygen decreases in the
air at high altitudes.
(1) A (2) B (3) C (4) D
11. Assertion :- Major part of CO2 is transported in
the form of sodium bicarbonate.
Reason :- 0.3ml of CO2 is transported per 100ml
of blood in dissolved state in plasma of blood.
(1) A (2) B (3) C (4) D
12. Assertion :- Emphysema is a chronic disorder in
which alveolar walls are damaged due to which
respiratory surface decreases.
Reason :- One of the major cause of emphysema
is due to inflammation of bronchi and bronchioles.
(1) A (2) B (3) C (4) D
EXERCISE-IV (Assertion & Reason) Target AIIMS
These questions consist of two statements each, printed as Assertion and Reason. While answering these Questions you are required to choose any one of the following four responses.
(A) If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
(B) If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
(C) If Assertion is True but the Reason is False.
(D) If both Assertion & Reason are false.
Directions for Assertion & Reason questions
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Pre-Medical : BiologyALLEN13. Assertion :- In the alveoli, dissociation of CO2 from
carbamino-haemoglobin takes place.
Reason :- In the alveoli 2COP is low and
2OP is
high.
(1) A (2) B (3) C (4) D
14. Assertion :- Haemoglobin can not get saturatedwith oxygen more than 97%.Reason :- With a rise in PO2, the affinity betweenO2 & haemoglobin also increases.(1) A (2) B (3) C (4) D
15. Assertion :- The blood transports carbondioxidecomparatively easily.Reason :- During CO2 transport chloride ionsdiffuse from plasma into the erythrocytes to maintainthe ionic balance.(1) A (2) B (3) C (4) D
16. Assertion : Bohr effect occur at the level of alveoli
of lungs.
Reason : High concentration of CO2 allow
dissociation of oxyhaemoglobin.
(1) A (2) B (3) C (4) D
17. Assertion : Low concentration of oxygen allow
dissociation of oxyhaemoglobin.
Reason : CO has more affinity with Haemoglobin
as compares to oxygen.
(1) A (2) B (3) C (4) D
18. Assertion :- Mammals can breathe and eat at the
same time.
Reason :- Mammals have negative pressure
breathing.
(1) A (2) B (3) C (4) D
19. Assertion :- Carbonic acid is more formed inside
the RBC's than the plasma.
Reason :- An enzyme carbonic anhydrase is
present inside the RBC's.
(1) A (2) B (3) C (4) D
20. Assertion :- Smoking makes oxygen less available
to the body.
Reason :- In presence of CO, O2 binds less with
haemoglobin.
(1) A (2) B (3) C (4) D
21. Assertion :- The diffusion of CO2 is generally from
tissue to alveoli but not in reverse direction.
Reason :- Solubility of CO2 is 10 times more than
O2.
(1) A (2) B (3) C (4) D
22. Assertion :- Oxygen is easily diffused from alveoli
to tissue and CO2 from tissue to alveoli.
Reason :- Squamous epithelium of alveoli is two
cell th ick and blood capillaries have thin
endothelium.
(1) A (2) B (3) C (4) D
EXERCISE-IV (Assertion & Reason) ANSWER KEYQue. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ans. 2 1 3 2 1 4 2 1 4 3 2 3 1 2 2Que. 16 17 18 19 20 21 22
Ans. 4 2 1 1 1 3 3
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IMPORTANT NOTES
