This document discusses the process of respiration and gas exchange in the human body. It describes how oxygen passes from the lungs into the bloodstream in the alveoli, and carbon dioxide passes out of the bloodstream and into the lungs to be exhaled. It defines external respiration as the exchange of gases between the lungs and environment, and internal respiration as the transport of oxygen to cells and removal of carbon dioxide. Key lung volumes and capacities such as tidal volume, vital capacity, and total lung capacity are also outlined.

1. PRESENTED BY
AISHWARYA

2. CIRCULATION AND EXCHANGE
OF RESPIRATORY GASES

3. EXCHANGE OF GASES
 Inhaled oxygen enters the lungs and reaches the alveoli.
 Oxygen passes quickly through air-blood barrier into the blood in
the capillaries.
 Similarly, carbon dioxide passes from blood into the alveoli and
is then exhaled.

7. RESPIRATION
 The term respiration means the exchange of gases between body
cells and the environment.
 Breathing or pulmonary ventilation.
 This is movement of air into and out of the lungs.

8. TYPES:
• External respiration : Exchanging
air between the body and the
outside environment.
• Internal respiration : Bringing
oxygen to the cells and removing
carbon dioxide from them.

9. EXTERNAL RESPIRATION
 The air inhaled through the nostrils makes it way through the pharynx, larynx,
and trachea to the bronchioles.
 From the bronchioles, it finally reaches the lungs.
 In the lungs, air-filled sacs called alveoli have a highly vascular wall.
 The exchange of gases takes place between these vascular walls of the alveoli
and the bloodstream.
 Oxygen is taken up by the alveoli while carbon dioxide is released through
their walls.
 The air that is exhaled contains a higher concentration of carbon dioxide.
 This gaseous exchange between the alveolar walls and the bloodstream is
called external respiration.

10. INTERNAL RESPIRATION
 Internal respiration is the process by which oxygen breaks down
food into carbon dioxide and water in order to liberate energy in
the form of ATP.
 Internal respiration is also known as cellular respiration as it
occurs inside the living cells.
 The exchange of carbon dioxide and oxygen gases during cellular
respiration occurs between the blood and other cells of the body.

11. LUNG VOLUME
 Lung volumes are also known as respiratory volumes. It refers to the
volume of gas in the lungs at a given time during the respiratory
cycle.(measured by spirometer)
 Tidal volume(TV) : This is the amount of air passing in & out of lungs
during each cycle of breathing(15 cycles/min)
 Inspiratory reserve volume(IRV) : This is the extra volume of air
inhaled into lungs during maximal inspiration. i.e. above normal TV
 Expiratory reserve volume(ERV) : This is the extra volume of air
expelled from the lungs during maximal expiration.
 Residual volume(RV) : It is the volume of air remaining in the lungs
after expiration.

12. LUNG CAPACITY
 Lung capacity or total lung capacity (TLC) is the volume of air in the
lungs upon the maximum effort of inspiration. Among healthy adults,
the average lung capacity is about 6 liters.
 Inspirational capacity(IC) = Tidal volume + Inspiratory reserve volume
 Functional residual capacity(FRC) = Residual volume + Expiratory
reserve volume
 Vital capacity(VC) – This is the maximum volume of air which can be
moved in & out of the lungs.
VC = Tidal volume + IRV + ERV
 Total lung capacity(TLC) – It is the sum of all volume.
=TV + IRV + ERV + RV

14. ARTIFICIAL RESPIRATION
 Artificial ventilation (also called artificial respiration) is
a means of breathing induced by some manipulative
technique when natural respiration has ceased or is
faltering. Such techniques, if applied quickly and
properly, can prevent deaths.