3.1.2- Mammalian Gaseous Exchange Systems

Question 1

Define what the bronchi and the bronchioles are.

Answer 1

Smaller airways that lead into the lungs.

Question 2

What is the diaphragm?

Answer 2

A layer of muscle that lies beneath the lungs that an contract and relax to control expiration and inhalation of air into the lungs.

Question 3

What are the intercostal muscles?

Answer 3

Muscles between the ribs. External intercostal muscles can raise the ribcage.

Question 4

Explain what the trachea is.

Answer 4

It is the main airway that leads from the back of the mouth into the lungs.

Question 5

Explain what ventilation is.

Answer 5

The refreshing of air into lungs so that there is a higher concentration gradient than in the blog and a lower concentration of carbon dioxide.

Question 6

Explain what the gaseous exchange system in mammals consists of.

Answer 6

The lungs and associated airways.

Question 7

Explain how air can pass into the lungs.

Answer 7

By going through the nose, along the trachea to the bronchi and bronchioles and then to the alveolar finally.

Question 8

Where does the exchange of gases in the mammalian gaseous exchange system take place?

Answer 8

At the surface of the alveoli.

Question 9

The lungs are protected by the ________.

Answer 9

Ribcage.

Question 10

The Lungs are protected by the ribcage- what is the ribcage held together by?

Answer 10

Intercostal muscles.

Question 11

The action of what two things helps to produce breathing movements?

Answer 11

Diaphragm and intercostal muscles.

Question 12

Gases pass by _______ through the alveoli’s thin cell wall.

Answer 12

Diffusion.

Question 13

Explain what gases pass where to where in the gaseous exchange system.

Answer 13

O2 passed from air in alveoli to the blood in capillaries. CO2 passes from blood in capillaries In the air in the lungs.

Question 14

How does the lungs help to ensure the hey diffusion through it can continue?

Answer 14

It maintains a steep concentration gradient of O2 and CO2 either side of the diffusion surface.

Question 15

How large is the total estimated surface area for the exchange surfaces in humans?

Answer 15

About 70m^2

Question 16

Explain why the lungs can provide such a large surface area for exchange of gases.

Answer 16

Despite the alveoli only being about 100-300 micrometers, there are so much that it provides a huge surface area.

Question 17

Explain how the capillaries and the ovaries are adapted so that there is a short diffusion path for the gases. (Five reasons).

Answer 17

• They are both only one cell thick, creating a short diffusion path of about one micrometer thick
• Both consist of squamous cells- flattened, v thin
• Capillaries are close in contact with alveoli
• Capillaries are v narrow, making the RBC’s squeezed against the wall, making them closer to the air in the alveoli and reducing flow rate.

Question 18

What is a surfactant?

Answer 18

A substance that reduces the surface tension of a liquid in cm which its dissolved.

Question 19

Explain why the alveoli must produce a surfactant.

Answer 19

It reduces the cohesive forces between water molecules as these can lead to the break down of alveoli.

Question 20

Explain why a good blood supple is essential for the mammalian gaseous exchange system to work.

Answer 20

It helps to maintain a steep concentration gradient in order that the gases can continue diffusion. Blood transports co2 from tissues to lungs- ensures high conc of co2 in blood compared to air in alveoli so it continues to diffuse from blood to lungs. Opposite way round for O2.

Question 21

Explain why ventilation is essential for the enabling f gaseous exchange in the mammalian has exchange system.

Answer 21

It replaces the used air with fresh air and brings more O2 and removes Co2. It keeps the conc of co2 in lungs lower than in blood and the conc of O2 in lungs higher than in the blood, so that fussy shin can continue as the conc gradient is maintained.

Question 22

What is inspiration.

Answer 22

The breathing in of air into the lungs.

Question 23

Explain what expiration is.

Answer 23

The removal of air from the lungs.

Question 24

Explain the five things that Happen during inspiration.

Answer 24

• diaphragm contracts and moves down and flattens
• external ic muscles contract to raise the ribcage
• internal ic muscles contract
• pressure in chest cavity drops below pressure in the atmosphere
• air rushes into lungs as it is a lower pressure

Question 25

Explain the five things that happen during expiration.

Answer 25

Diaphragm relaxes and pushed up. External IC muscles relax. Internal IC muscles contract to help push air out more forcefully. Lung pressure increases above atmospheric pressure. Air forced out of lungs due to this pressure difference.

Question 26

Define what the alveoli is.

Answer 26

Tiny folds in the lung epithelium that increase its surface area.