organisms exchange substances with their environment

Question 1

pulmonary ventilation rate definition

Answer 1

total volume of air going into (or out of) your lungs in one minute

Question 2

Pulmonary ventilation rate equation (dm^3/min)

Answer 2

tidal volume x breathing rate
tidal volume- volume of air normal taken in each breath
breathing rate- number of breaths taken in one minute

Question 3

how alveoli are adapted for gas exchange

Answer 3

• maximise surface area- forms sacs, large number of alveoli in lungs so large area for gaseous exchange to occur, folded and small, many small capillaries with high surface area
  * maintain high conc gradient- good blood supply of deoxygenated blood, alveoli well ventillated- breathing replaces deoxygenated air with oxygenated air, circulatory system replaces oxygenated blood with deoxygenated blood
• minimise diffusion distance thin cell walls, one cell thick. Made of epithelial tissue. Capillary walls also one cell thick and pushed up agains alveoli. Capillary has smaller diameter/same diameter of a red blood cell so red blood cells have to contort to move through, slowing their movement and allowing adequate time for complete loading of oxygen- this also increases surface area allowing more oxygen to diffuse through, also decreases diffusion distance as red blood cells are flattened against capillary walls