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Learning Objectives• (a) identify on diagrams and name the larynx, trachea,
bronchi, bronchioles, alveoli and associated capillaries • (b) state the characteristics of, and describe the role of,
the exchange surface of the alveoli in gaseous exchange
• (c) describe the removal of carbon dioxide from the lungs, including the role of the carbonic anhydrase enzyme
• (d) describe the role of cilia, diaphragm, ribs and intercostal muscles in breathing
• (e) describe the effect of tobacco smoke and its major toxic components - nicotine, tar and carbon monoxide, on health
• (f) define and state the equation, in words and symbols, for aerobic respiration in human
• (g) define and state the equation, in words only, for anaerobic respiration in human
Why do living organisms respire?
• Need energy to move, excrete, grow, reproduce and maintain themselves.
• Food contains chemical energy.• Respiration is the release of this
energy when food (glucose) is broken down in living cells.
Aerobic Respiration
• Breakdown of glucose in the presence of oxygen with the release of relatively large amount of energy.
• Carbon dioxide and water are released as waste products.
• Enzymes catalysed the reactions in the mitochondria.
+ 2898 kJ
What is the energy used for?
1. Cell division and growth2. Synthesis of proteins, fats and vitamins3. Transmission of nerve impulses4. Maintenance of a constant body
temperature5. Active transport in the absorpton of
food substances by the small intestine6. Muscular contractions e.g. heartbeat &
respiratory movements.
Anaerobic Respiration• Breakdown of glucose in the
absence of oxygen to release energy.
• Can take place in yeast as well as the muscles.
Yeast• Respires anaerobically when oxygen is
absent.• Little energy is released.• Yeast cannot be very active under
such situations.• Alcoholic fermentation
+ 210 kJ
Anaerobic Respiration (Muscles)
• Muscle cells normally respire aerobically.
• Carry out anaerobic respiration when there is a shortage of oxygen.
Differences Aerobic
Respiration• Uses oxygen• No alcohol or
lactic acid made• Large amount of
energy released
• CO2 always released
Anaerobic Respiration
• Do not use oxygen• Alcohol or lactic
acid made• Small amount of
energy released
• CO2 sometimes released
What happens during exercise?
• Vigorous muscular contraction --> muscles first use oxygen to respire. (aerobic)
• Panting --> to remove carbon dioxide and take in more oxygen.
• Heart beats faster so that more oxygen can be brought to the muscles.
• LIMIT to the rate of breathing and heartbeat. They CANNOT keep on increasing.
• To continue vigorous exercise, more energy needs to be released.
• Muscle cells carry out ANAEROBIC respiration.
• Lactic acid is produced.GLUCOSE ------> Lactic acid
+small amount of energyC6H12O6 ---- 2CH3CH(OH)COOH + 150 kJ
• Lactic acid slowly builds up in the muscles.
• Muscle has an “OXYGEN DEBT”.• Lactic acid cause fatigue• Body needs to rest & recover• Muscular pain is due to the lactic
acid.
What happens during RESTING?
• Lactic acid is removed from the muscles and transported to the liver.
• Some of the lactic acid is oxidized to energy.• Converts remaining lactic acid into glucose
Lactic acid ---------------------> Energy(muscles) remaining ------------------->
glucose lactic acid
muscle
Oxidized
How do we know organisms respire?
1. To find out whether carbon dioxide is given off during respiration
2. To find out if carbon dioxide is given off during fermentation
3. To find out if heat is released during respiration
Gaseous exchange• Process of the
transfer of oxygen from the air to the cells and the transfer of carbon dioxide and water from the cells back to the surroundings.
Tissue Respiration• Oxidation of food with the release
of energy.• Occurs within the cell or tissues
(internal respiration)
The Structure of the Respiratory System
• The organs involved are:2 lungs in the thorax;The air passages leading to them.
• Each lung is filled with many tiny air sacs called alveoli, where oxygen diffuses into the blood.
The Air Passage Way
• Consist of:the nasal passages/cavity, pharynx, larynx, trachea, bronchi & bronchioles.
• Air enters by 2 external nostrils --- 2 nasal passages --- 2 internal nostrils --- pharynx --- larynx --- trachea (via glottis) --- bronchi --- bronchioles --- alveoli.
atmosphere
external nostril
nasal passages
pharynx
larynx
external nostril
larynx
pharynxnasal passages
atmosphere
external nostril
nasal passages
pharynx
larynx
trachea
external nostril
trachealarynx
pharynxnasal passages
atmosphere
external nostril
nasal passages
pharynx
larynx
trachea
bronchi
external nostril
trachealarynx
pharynx
bronchi
nasal passages
atmosphere
external nostril
nasal passages
pharynx
larynx
trachea
bronchi
bronchioles
external nostril
trachealarynx
pharynx
bronchi
bronchioles
nasal passages
atmosphere
external nostril
nasal passages
pharynx
larynx
trachea
bronchi
bronchioles
alveoli
external nostril
trachealarynx
pharynx
bronchi
bronchioles
cluster of alveoli (air sacs)
nasal passages
The Nose
• Air enters through two external nostrils (nares)
• Nasal passages lined with hairs and moist mucous membrane
• Trap dust & foreign particles, including bacteria.
• Air is warmed and moistened;• Detect harmful chemicals (by
sensory cells).
The Trachea• lies in front of esophagus• supported by C-shaped rings of
cartilage (which ensure it is always kept opened)
• Epithelium has gland cells to secrete mucus which traps dust particles
• bears cilia to sweep dust particles upwards into pharynx
The Lungs• Each lung lies in the pleural cavity.• The pleural cavity is lined by 2
transparent pleural membranes • Inner pleuron covers the lungs• Outer pleuron in contact with
thoracic wall and diaphragm• The pleural fluid helps to reduce
friction on the lungs when they rub against the rib cage during inspiration.
• The lower end of the trachea divides into 2 bronchi (singular: bronchus), one to each lung.
• Within the lungs, the bronchial tubes divide into smaller tubes – the bronchioles (*NO cartilage).
• Each bronchiole ends with many air sacs called alveoli.
• Alveoli provide a large surface area (100 m2)
• The wall of alveolus is very thin. Only one cell thick. Allows easy diffusion of O2 & CO2
Adaptations of lungs for efficient gaseous
exchange
• A thin film of moisture covers the surface of the alveolus. O2 dissolves in this liquid before diffusing across the wall of the alveolus.
• The walls of the alveoli are richly supplied with blood capillaries. The flow of blood maintains the concentration gradient of gases.
The Chest cavity• Chest wall is supported by ribs• Two sets of intercostal muscles
(internal and external) control the movement of the ribs
• The diaphragm separates the thorax from the abdomen
• The intercostal muscles and the diaphragm contract and relax, causing the volume of thoracic cavity to change
rib
sternum
vertebral column
Front view Side view
When you breathe in or inspire, the following events take place:
Movement of rib cage during inspiration
rib cage
rib
sternum
vertebral column
Front view Side view
• Your diaphragm contracts and flattens.
Movement of rib cage during inspiration
diaphragm contracts and flattens
rib cage
rib
sternum
vertebral column
Front view Side view
• Your external intercostal muscles contract while your internal intercostal muscles relax.
Movement of rib cage during inspiration
rib cage
diaphragm contracts and flattens
ribs and sternum raised
rib
sternum
vertebral column
Front view Side view
Ribs swing up
• Your ribs move upwards and outwards. Your sternum also moves up and forward.
Movement of rib cage during inspiration
rib cage
diaphragm contracts and flattens
ribs and sternum raised
ribs and sternum raised
rib
sternum
vertebral column
Front view Side view
Ribs swing up and increase volume of thorax
• The volume of your thoracic cavity increases.
Movement of rib cage during inspiration
rib cage
diaphragm contracts and flattens
ribs and sternum raised
volume of thorax increases
ribs and sternum raised
rib
sternum
vertebral column
Front view
Ribs swing up and increase volume of thorax
• Air pressure in your lungs causes them to expand to fill up the enlarged space in your thorax.
Movement of rib cage during inspirationSide view
rib cage
diaphragm contracts and flattens
ribs and sternum raised
volume of thorax increases and lungs expand
ribs and sternum raised
rib
sternum
vertebral column
Front view Side view
Ribs swing up and increase volume of thorax
• Expansion of your lungs causes the air pressure inside them to decrease.
Movement of rib cage during inspirationSide view
rib cage
diaphragm contracts and flattens
ribs and sternum raised
lungs expand, causing air pressure inside lungs to decrease
ribs and sternum raised
rib
sternum
vertebral column
Front view
Ribs swing up and increase volume of thorax
• Atmospheric pressure is now higher than the pressure within your lungs. This causes air to rush into your lungs.
Movement of rib cage during inspiration
rib cage
diaphragm contracts and flattens
ribs and sternum raised
lungs expand, causing air pressure inside lungs to decrease
air enters lungs
Side viewSide view
When you breathe out or expire, the following events take place:
rib
sternum
vertebral column
Side viewFront viewMovement of rib cage during expiration
rib cage
• Your diaphragm relaxes and arches upwards.
rib
sternum
vertebral column
Side viewFront viewMovement of rib cage during expiration
rib cage diaphragm relaxes and arches upwards
• Your internal intercostal muscles contract while your external intercostal muscles relax.
rib
sternum
vertebral column
Side viewFront viewMovement of rib cage during expiration
rib cage diaphragm relaxes and arches upwards
ribs and sternum raised
rib
sternum
vertebral column
Ribs swing down
• Your ribs move downwards and inwards. Your sternum also moves down to its original position.
Front viewMovement of rib cage during expiration
Side view
rib cage diaphragm relaxes and arches upwards
ribs and sternum returned to original position
ribs and sternum raised
rib
sternum
vertebral column
Ribs swing down and decrease volume of thorax
• The volume of your thoracic cavity decreases.
volume of thorax decreases
Front viewMovement of rib cage during expiration
Side view
rib cage diaphragm relaxes and arches upwards
ribs and sternum returned to original position
ribs and sternum raised
rib
sternum
vertebral column
Ribs swing down and decrease volume of thorax
• Your lungs are compressed and air pressure inside them increases as the volume decreases.
Front viewMovement of rib cage during expiration
lungs are compressed, causing air pressure inside lungs to increase
Side view
rib cage diaphragm relaxes and arches upwards
ribs and sternum returned to original position
ribs and sternum raised
rib
sternum
vertebral column
Front view
Ribs swing down and decrease volume of thorax
Movement of rib cage during expiration
• Air pressure within the lungs is now higher than atmospheric pressure. The air is forced out of your lungs to the exterior.
lungs are compressed, causing air pressure inside lungs to increase
Side view
rib cage diaphragm relaxes and arches upwards
air expelled from lungs
When you inhale, you…
Relax your Internal intercostal muscles and Contract your External intercostal muscles
R
IC
E
Inhalation
E
R
I
C
Exhalation
When you exhale, your…
External intercostal muscles Relax and your Internal intercostal muscles Contract
Oxygen• Alveolar air contains higher
concentration of oxygen than the blood.• Oxygen dissolves in the moisture lining
and diffuses into the blood capillaries.• Oxygen combines with haemoglobin to
form oxyhaemoglobin.
Carbon dioxide• Tissue cells produce carbon dioxide during
aerobic respiration.• Carbon dioxide diffuses into the blood and
enters red blood cells.• Carbon dioxide reacts with water to form
carbonic acid catalysed by carbonic anhydrase.
• Carbonic acid converted into hydrogencarbonate ions which diffuse out of the red blood cells into the plasma.
In the lungs• Hydrogencarbonate ions diffuse
back into the red blood cells• Converted into carbonic acid and
then into water and carbon dioxide• Carbon dioxide diffuses out of
blood capillaries into the alveoli and out of the lungs
How diffusion gradient is maintained?
• Continuous supply of blood through the capillary networks
• Continuous breathing of air in and out of the alveoli
Differences between inspired air and expired air
Component Inspired air Expired air
Oxygen 21% 16.4%
Carbon dioxide
0.03% 4.0%
Nitrogen 78% 78%
Water vapour Variable Saturated
Temperature Variable 370C
Dust particles Variable but usually presnet
little
Lung CapacityResidual air (1500 cm3)• Air that is left behindTidal air (500cm3)• Air that enters and leaves the lungs in each
breathing cycleComplemental air (1500cm3)• Additional air that can be taken inSupplemental air (1500cm3)• Additional air that can be forced outVital capacity (3500-4000cm3)=tidal air + complemental air + supplemental air
Stimulus for breathing• High concentration of carbon
dioxide in the blood or alveolar air
• Hyperventilation or overbreahting can cause death as no breathing occurs when there is no carbon dioxide in the lungs
Effects of Tobacco smoke on human
healthBronchitis• Redness and swelling of the lining of
air passages• Destruction of the cilia• Dust and harmful chemicals are able to
move past the bronchi and invade the alveoli
• Air passages become irritated and clogged with mucus and dust
• Lots of phlegm and coughing
Asthma
• Irritants cause allergic reactions in the respiratory tract
• Constriction of the respiratory tract
• Suffocation and death
Emphysema• Violent coughing breaks partition
walls between air sacs• Alveolar sacs may become less
elastic• Decrease surface area for gaseous
exchange• Lungs become inflated with air• Difficulty in breathing, wheezing
Lung cancer• Carcinogenic compound,
benzopyrene causes cancer cells to be produced
• Tar and resin promote proliferation of these cancer cells
• Shortness of breath • Coughing up of mucus and blodd
Tar• Contains cancer-causing
(carcinogenic) chemicals which induce uncontrolled cell division of the epithelium
• Paralyses cilia lining the air passages
Heart disease• Nicotine stimulates release of
adrenaline• Increases blood pressure and
heart rate• Increases chance of blood clot and
plaque deposit on the walls of coronary arteries
• Heart attacks and death
Smoking during Pregnancy
• Restricts blood vessels reducing amount of nutrients and oxygen to baby
• Low birth weight of baby• Prone to illness• Increase potential for birth defects and
abnormalities• Increased chances of a miscarriage• Increased chances of a premature birth• Has a greater risk of baby being born
dead
RESPIRATION
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 84
Aerobic Respiration
RESPIRATION
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 85
Aerobic RespirationAnaerobic
Respiration
RESPIRATION
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 86
Aerobic RespirationAnaerobic
Respiration
RESPIRATION
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 87
Aerobic RespirationAnaerobic
Respiration
RESPIRATION
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 88
Aerobic RespirationAnaerobic
Respiration
RESPIRATION
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 89
Aerobic RespirationAnaerobic
Respiration
RESPIRATION
Breathing mechanism
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 90
Aerobic RespirationAnaerobic
Respiration
How the body takes in oxygen and removes carbon dioxide
RESPIRATION
Breathing mechanism
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 91
Aerobic RespirationAnaerobic
Respiration
How the body takes in oxygen and removes carbon dioxide
RESPIRATION
Breathing mechanism
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 92
Aerobic RespirationAnaerobic
Respiration
How the body takes in oxygen and removes carbon dioxide
RESPIRATION
Breathing mechanism
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 93
Inspiration• External intercostal muscles contract, internal intercostal muscles relax.
• Ribs move upwards and outwards.
• Diaphragm contracts and flattens.
• Volume of thorax increases.
• Air pressure in thorax decreases.
• Air flows into the lungs.
Aerobic RespirationAnaerobic
Respiration
How the body takes in oxygen and removes carbon dioxide
RESPIRATION
Breathing mechanism
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 94
Inspiration• External intercostal muscles contract, internal intercostal muscles relax.
• Ribs move upwards and outwards.
• Diaphragm contracts and flattens.
• Volume of thorax increases.
• Air pressure in thorax decreases.
• Air flows into the lungs.
Expiration• External intercostal muscles relax, internal intercostal muscles contract.
• Ribs move downwards and inwards.
• Diaphragm relaxes and arches upwards.
• Volume of thorax decreases.
• Air pressure in thorax increases.
• Air flows out of the lungs.
Aerobic RespirationAnaerobic
Respiration
How the body takes in oxygen and removes carbon dioxide
RESPIRATION
Breathing mechanism
• Oxygen is required.
• Large amount of energy is released.
• Carbon dioxide and water are produced.
• Oxygen is not required.
• Small amount of energy is released.
• Lactic acid is produced in mammals. Ethanol and carbon dioxide are produced in yeast.
Differences
• Occurs in living cells.
• Enzymes are involved.• Oxidation of food substances with the release of energy.
April 20, 2023Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 95
Inspiration• External intercostal muscles contract, internal intercostal muscles relax.
• Ribs move upwards and outwards.
• Diaphragm contracts and flattens.
• Volume of thorax increases.
• Air pressure in thorax decreases.
• Air flows into the lungs.
Expiration• External intercostal muscles relax, internal intercostal muscles contract.
• Ribs move downwards and inwards.
• Diaphragm relaxes and arches upwards.
• Volume of thorax decreases.
• Air pressure in thorax increases.
• Air flows out of the lungs.
Gaseous exchange• Oxygen dissolves in film of moisture covering alveolar wall.
• Dissolve oxygen diffuses into blood capillaries.
• Carbon dioxide diffuses from blood into alveolar cavity.