University:
California State University, Northridge
Course:
BIOL 211 | Human Anatomy
Academic year:

2023
Views:

402

Pages:

3
Author:

Alexa Livingston

Ques 2 Explain about external respiration. Answer:External Respiration The processes of breathing or "respiration" are often described in two parts: External Respiration and Internal Respiration. This page is about external respiration, which is the processes by which external air is drawn into the body in order to supply the lungs with oxygen, and (used) air is expelled from the lungs in order to remove carbon dioxide from to body. Summary of Processes: Inspiration (= inhalation) Concentration of Gases Expiration (= exhalation) 1. Intercostal 1. Intercostal muscles muscles relax. contract. 2. Sternum moves 2. Sternum moves downwards and upwards and inwards. outwards. 3. Ribs move 3. Ribs move downwards and Inspiration Expiration upwards and inwards. Oxygen outwards. 4. Diaphragm Carbon 21% 17% 4. Diaphragm relaxes Dioxide flattens. 0.04% 4.04% forming a bellNitrogen _ shape. 78% 78% Inert 5. Increase in 5. Volume in 0.96% 0.96% Gases volume of thoracic cavity various various Water thoracic cavity. decreases. Vapour 6. Pressure in 6. Pressure in thoracic cavity thoracic cavity decreases. increases. 7. Air is drawn into 7. Air is expelled thoracic cavity. from thoracic cavity. Terminology: In order to describe how a person's respiratory system is (or could be) functioning some special terms are used to refer to the quantities of gas that pass in and out of the structures used for external respiration. Minute Volume is the amount of air drawn into the lungs during one minute while the person is at rest. (Typically due to around 12-16 breaths/minute, so approx. 6-8 litres/minute.) Residual Volume is the air that remains in the lungs after expiration. (Typically approx. 0.35 litres.) Tidal Volume is the amount of air taken into the lungs during one breath when the person is at reast. (Typically approx. 0.5 litres.) Vital Capacity is the maximum volume of inspired breath, following maximum expiration. (Typically approx. 3.5 - 4.5 litres.)