6.4 Gas Exchange Flashcards Preview

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Flashcards in 6.4 Gas Exchange Deck (11):
1

Define ventilation

The movement of air to and from a gas exchange surface (alveoli).

2

Define gas exchange

The diffusion of respiratory gasses across a gas-exchange surface.

3

Define cell respiration

Reaction within cells which uses oxygen and produces carbon dioxide. Released energy is captured within ATP molecules for use within the cell.

4

Explain the need for a ventilation system

The body needs oxygen to make ATP via cell respiration. The body needs to get rid of carbon dioxide which is a product of cell respiration. The ventilation system passes oxygen over the alveoli, so it can diffuse into the blood stream, and exhales carbon dioxide.

5

Outline the features of alveoli that adapt them to gas exchange

Thin wall
Rich capillary network
High SA:V ratio
Moist

6

Explain how the thins walls of alveoli adapt them to gas exchange

Made up of single layer of flattened cells and so are the walls of the capillaries so diffusion distance is small, allowing rapid gas exchange. 

7

Explain how the rich capillary network helps alveoli with gas exchange

Alveoli are covered by a dense network of capillaries that help to maintain a concentration gradient.

8

Explain how a high SA:V ratio helps alveoli with gas exchange

Great numbers of spherically-shaped alveoli optimise surface area for gas exchange.

9

Explain how the moistness of alveoli helps them with gas exchange

Some cells in the lining secrete fluid to allow gases to dissolve and to prevent alveoli from collapsing (through cohesion).

10

Describe what happens during inspiration

Diaphragm muscles contract and flatten downwards. External intercostal muscles contract, pulling ribs upwards and outwards
This increases the volume of the thoracic cavity (and therefore lung volume). The pressure of air in the lungs is decreased below atmospheric pressure. Air flows into the lungs to equalise the pressure.

11

Describe what happens during expiration

Diaphragm muscles relax and diaphragm curves upwards. Abdominal muscles contract, pushing diaphragm upwards. External intercostal muscles relax, allowing the ribs to fall. Internal intercostal muscles contract, pulling ribs downwards. This decreases the volume of the thoracic cavity (and therefore lung volume). The pressure of air in the lungs is increased above atmospheric pressure. Air flows out of the lungs to equalise the pressure.