Gas Exchange

Question 1

Breathing out mechanisms

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 mechanisms

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

Gas exchange adaptation Fish

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.