Gas Exchange

Question 1

Breathing out (humans)

Answer 1

Contraction of internal intercostal muscles
Relaxation of external intercostal muscles
Ribs to move down and in
Relaxation of diaphragm muscles
Diaphragm to become domed
Decrease in volume of thorax Increase in pressure in thorax
Air forced out of lungs

Question 2

Breathing in

Answer 2

Relaxation of internal intercostal muscles
Contraction of external intercostal muscles
Ribs to move out and up
Contraction of diaphragm muscles
Diaphragm to become flat
Increase in volume of thorax
Decrease in pressure in thorax
Air forced into lungs

Question 3

Gas exchange adaptions Human

Answer 3

Many alveoli and alveoli walls folded provide a large surface area
Many capillaries provide a large surface area
Alveoli or capillary walls are one cell thick so short distance between alveoli and blood
Squamous epithelium so short diffusion pathway
Ventilation and circulation maintains concentration gradient

Question 4

Fish gas exchange

Answer 4

Large number of filaments or lamella so large surface area
Walls of lamellae and capillary one cell thick so short diffusion distance
Large number of capillaries to maintain a concentration gradient and a large surface area
Counter current flow so diffusion gradient maintained cross whole lamellae.