additional muscles needed.thoracic cavity volume increases to increase air intake and lung depth
alveoli characteristics
one cell thick - speeds up rate of diffusion, large surface area - greater CO2 absorption, extensive capillary network - excellent blood supply
gaseous exchange at alveoli during exercise
high partial pressure of oxygen in the alveoli, create a larger diffusion gradient, diffuse into blood faster than at rest (opposite for carbon dioxide)
gaseous exchange at muscles during exercise
oxygen - high partial pressure in blood, low partial pressure in muscle, oxygen goes from blood to muscle via diffusion
