Structure and function of the human respiratory system. Gas exchange in the alveoli. Transport of oxygen and carbon dioxide in the blood.

Question 1

Explain the essential features of the alveolar epithelium that make it
adapted as a surface for gas exchange

Answer 1

flattened cells - one cell thick shirt diffusion distance
folded for a large surface area
permeable allows diffsion of o2 and co2
moist gases can dissolve for diffusion
good blood supply from large network of cappilaries to maintain a conc gradient

Question 2

Describe how gas exchange occurs in the lungs

Answer 2

Oxygen diffuses from alveolar air space into blood down its concentration gradient
across alveolar epithelium then capillary endothelium

Question 3

ventillation importance

Answer 3

Brings in air containing higher conc. of oxygen & removes air with lower conc. of oxygen
Maintaining concentration gradients

Question 4

inspiration

Answer 4

breathing in
Diaphragm muscles contract
flattens
External intercostal muscles contract, internal
intercostal muscles relax
ribcage pulled up / out
Increasing volume and decreasing pressure in thoracic cavity
Air moves into lungs down pressure gradient

Question 5

Expiration

Answer 5

.Diaphragm relaxes → moves upwards
2. External intercostal muscles relax, internal
intercostal muscles may contract → ribcage
moves down / in
3. Decreasing volume and increasing pressure
(above atmospheric) in thoracic cavity
4. Air moves out of lungs down pressure gradient

Question 6

Transport of oxygen and carbon dioxide in the blood.

Answer 6

oxygen moves from the lungs to the bloodstream
At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network capillaries, which are located in the walls of the alveoli.

Question 7

Describe the gross structure of the human gas exchange system

Answer 7

trachea
bronchi
bronchioles
lungs
capillary network surrounding alveoli