F211 - Exchange Surfaces And Breathing

Question 0

Describe and explain the different adaptions for gas exchange in the lungs.

Answer 0

• Many alveoli which provides a large surface area for diffusion of gases to occur across.
• The alveolar epithelium and the capillary endothelium are one cell thick so there’s a short diffusion distance.
• All alveoli have a good blood supply by the capillaries and so the transfer of oxygen and carbon dioxide can happen much quicker and a diffusion gradient is maintained.
• Smooth muscle restricts the diameter of the airway.

Question 1

Describe the function and features of goblet cells.

Answer 1

• Goblet cells secrete mucus which traps microorganisms and dust from the air that’s been breathed in. This stops them reaching the alveoli.

Question 2

Describe the functions and features of Cillia.

Answer 2

• Cillia are hair like structures on the surface of epithelial cells. They move the mucus that’s secreted by the goblet cells upwards (away from the alveoli) towards the throat where it’s swallowed. This helps prevent lung infections.

Question 3

Describe the functions and features of Elastic fibres.

Answer 3

• Elastic fibres help the process of breathing outwards by recoiling to help push air out when exhaling.

Question 4

Describe the functions and features of smooth muscle.

Answer 4

Smooth muscle restricts the diameter of the airways.

During exercise, the smooth muscle relaxes, making the tubes wider so there’s less resistance to air flow.

Question 5

Describe the functions and features of Cartilage.

Answer 5

Cartilage is in the trachea and bronchi walls and supports them.

Question 6

What’s vital capacity?

Answer 6

The maximum volume of air that can be breathed in or out.

Question 7

What’s tidal volume?

Answer 7

The volume of air in each breath.

You can find this by measuring at least three waves and calculating the mean.

Question 8

How do you work out oxygen uptake in a graph?

Answer 8

It will be the total amount of gas lost in the chamber - so the difference between the gas at the start and the gas at the end.

Question 9

What’s breathing rate?

Answer 9

The number of breaths in a minute. (Known as the peaks in a spirometer reading).

Question 10

Why does the volume of air in the spirometer gradually decrease?

Answer 10

There’s a limited supply of oxygen in the chamber and it’s being converted into carbon dioxide as it’s breathed in.

Question 11

Why does a large, multicellular animal need a transport system?

Answer 11

A mammal has a small surface area to volume ratio and so diffusion is too slow. A transport system prevents the build up of waste and carbon dioxide. A constant supply of oxygen needs to be given to cells.

Question 12

How is a spirometer used?

Answer 12

• Person breathes into tube and wears nose clip. The air breathed out is sent towards soda lime through a valve. The soda lime absorbs carbon dioxide.
• The spirometer has a moveable lid on the oxygen filled chamber which is attached to a pen that records air that’s breathed in and out.

Question 13

What does ECG stand for?

Answer 13

Electrocardiogram.

Question 14

Why is it essential for there to be a delay between the excitation of the atria and the ventricles (contraction)?

Answer 14

This delay is due to the atrioventricular node waiting for the atria to contract and for all the blood to go into the ventricles. This is to prevent contraction of both the atria and the ventricles at the same time.

Question 15

Explain why the excitation wave is carried to the apex.

Answer 15

So the ventricular contraction starts at the apex and blood is pushed upwards into the pulmonary artery and aorta. It enables complete emptying of the ventricles.