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Respiration

∙ Why do all living beings need energy?1

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∙ From where does this energy comes?

∙ What is respiration?

Definition of Respiration

A biochemical process by which Organic Compounds

(foods) are oxidized to liberate chemical energy.

∙ It is a stepwise process leading to the formation

of ATP

∙ What is ATP?

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Overall process of respiration

C6H12O6 + 6 O2 →6 CO2 + 6 H2O + 38 ATP.

Respiration in Animals

Animals show various methods of respiration.

Organism Organs / Method of

respiration

1. Single celled organisms

2. Sponges and Jellyfish

3. Annelids

4. Fish / arthropods

5. Terrestrial vertebrates

6. Eel / Frogs

Cell membrane

Through water

Outer body surfaces Gills

Internal lungs

Skin

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∙ Respiratory surfaces are covered with thin, moist

epithelial cells that allow Oxygen and

Carbondioxide.

Human Respiratory System

∙ It consists of

→ Nostrils – Exterior openings

→ Nasal Chambers –-Seperated into right & left halves called "nasal

septum"

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-Septum is made of bone & cartilage 

-Air enters nasal cavities through two openings called "nostrils"

-Nasal hairs in nostrils filter large particles of dust 

-Contains receptor cells for the sense of smell

→ Pharynx –-Located behind the oral cavity & between the nasal cavities & the larynx -Includes 3 parts:1) Nasopharynx- upper section2) Oropharynx- middle section 3) Laryngopharynx- lower section -Pharynx conducts food toward esophagus & air to the larynx as it moves toward the lungs -Contains 2 other structures: 1. the openings from Eustachian tubes (auditory tubes); connects the nasopharynx w/middle ear 2. tonsils

→ Larynx – -Located between pharynx & trachea -Functions:1. Passageway for air during breathing 2. Produces sound (your voice); voicebox3. Prevents food & other foreign objects from entering the breathing structures (trachea)

→ Trachea – the tube connecting the throat to the bronchi.

→ Bronchi and Bronchioles – the trachea divides into two bronchi (tubes). One

leads to the left lung, the other to the right lung. Inside the lungs each of the bronchi divides into smaller bronchi. the bronchi branches

off into smaller tubes called broncheoli which end in the pulmonary alveolus.

→ Lungs – a pair of organs found in all vertebrates.

The structure of the lungs includes the bronchial tree – air tubes branching off from the bronchi into smaller and smaller air tubes, each one ending in a pulmonary alveolus. Pulmonary alveoli – tiny sacs (air sacs) delineated by a single-layer membrane with blood capillaries at the other end.

The exchange of gases takes place through the membrane of the pulmonary alveolus, which always contains air: oxygen (O2) is absorbed from the air into the blood capillaries and the action of the heart circulates it through all the tissues in the body. At the same time, carbon dioxide (CO2) is transmitted from the blood capillaries into the alveoli and then expelled through the bronchi and the upper respiratory tract.

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The inner surface of the lungs where the exchange of gases takes place is very large, due to the structure of the air sacs of the alveoli.

→ Diaphragm –  a sheet of internal skeletal muscle that extends across the bottom of

the rib cage. The diaphragm separates the thoracic cavity (heart, lungs & ribs) from the abdominal cavity and performs

an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases and air is

drawn into the lungs.

→ Inter costal muscles – Intercostal muscles are groups of muscles

found in the chest area. Intercostal muscles run along the ribs and are responsible for

movement of the chest and breathing. When a person breathes, intercostal muscles help the

chest cavity expand and shrink.

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Mechanism of Respiration

It comprises of following steps:-

1. Breathing –

It is a process by which air rich in Oxygen is taken

in by the lungs (Inspiration) and air containing

more CO2 and water vapour is forced out of the

lungs ( Expiration).

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∙ Alternate Inspiration and Expiration together form

the respiratory cycle. It occurs 16-20 times per

minute in man.

∙ It is controlled by medulla oblongata.

2. Transport of gases

It takes place in 3 steps

a. External respiration :

∙ Exchange of CO2 and O2 takes place through lungs

depending upon internal and external

concentrations of these gases.

∙ Haemoglobin combines with O2 to form instable

Oxy-haemoglobin.

∙ CO2 is brought from the tissues in the form of

Sodium and potassium bicarbonates and also

Carbomino - haemoglobin.

∙ These forms are then broken down to release CO2.

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H2CO3 →H2O + CO2↑

b. Internal respiration :

∙ It is the transfer of CO2 and O2 between tissue cells

of the lungs and blood.

c. Cellular Respiration :

∙ It is the formation of ATP molecules by Oxidation

of food in the mitochondria

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H3 2 3

Pot.bicarbonate Carbonic acid

KHCO K H CO

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∙ Energy is released when ATP molecules are

broken down.

How does medulla Oblongata regulates the

process of respiration?

Respiratory Volumes

∙ Tidal Volume (TV) –

It is the volume of air breathed in and out during

effortless breathing. In an adult it is about 500 ml.

∙ Inspiratory Reserve Volume (IRV) –

Volume of air during forced inspiration is called

inspiratory reserve volume. It is about 2500 ml to

3000 ml.

∙ Expiratory Reserve Volume (ERV) –

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Volume of air during forced expiration is called

expiratory reserve volume. It is about 1000 ml.

∙ Residual Volume (RV) –

The volume of air left behind in the lungs and

respiratory passage after forced expiration is called

residual volume. It is about 1000 ml.

∙ Vital Capacity (VC) –

It is the total volume of air expired after a maximum

inspiration. This includes ERV, TV and IRV.

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