Topic 11

Question 1

How does gas exchange work

Answer 1

Diaphragm
To intercostal muscles
Larynx
Trachea
Two bronchi
Small bronchioles
Alveoli

Question 2

How much oxygen is in inspired and expired air

Answer 2

21 - inspired
16 - expired

Question 3

How much carbon dioxide is in inspired and expired air

Answer 3

0.04 - inspired
4 - expired

Question 4

How much nitrogen is in inspired and expired air

Answer 4

78 - inspired
78 - expired

Question 5

How much water is in inspired and expired air

Answer 5

Inspired - variable
Saturated - expired

Question 6

Adaptations of humans and fish for oxygen and carbon dioxide

Answer 6

A very large surface area for diffusion of gases
Moist surfaces so that gases can dissolve before diffusion
A thin surface
A good blood supply so that lots of oxygen is removed quickly and lots of carbon dioxide is supplied quicklyn

Question 7

How does inspiration work

Answer 7

• external intercostal muscles contract and internal intercostals muscles relax, raising the ribs upwards and outwards
• the diaphragm contracts and flattens
• increase the volume inside the thorax causing the pressure inside to decrease
• since atmp is greater the air moves into the lungs and they inflate

Question 8

Expiration breathing out

Answer 8

• Intercostal muscles contract and the external intercostal muscles relax
• this lowers the ribs downwards and inwards
• the muscle in the diaphragm relaxes and bulges up due to pressure from the organs for example liver and stomach
• both actions decrease the volume inside the thorax causing the pressure inside the thorax to increase
• elastic recoil of the alveoli helps to force air out of the lungs