Animal Circulation
Which animals have a 2-chambered heart?
Fish
During which phase does the heart relax and fill with blood?
Diastole
Which blood vessels carry blood away from the heart?
Arteries
“Gases diffuse from high to low ___.”
Partial pressure
How many oxygen molecules can one hemoglobin bind?
4
Which animals have a 3-chambered heart and partially mix oxygenated and deoxygenated blood?
Amphibians (and most reptiles)
What closes at the start of ventricular systole?
AV valves
“CO = ___ × ___”
HR × SV
Why is countercurrent exchange more efficient in fish gills?
Maintains diffusion gradient along entire gill
Most carbon dioxide is transported in blood as what?
Bicarbonate
Why is a 4-chambered heart more efficient than a 3-chambered heart?
It completely separates oxygenated and deoxygenated blood.
What happens to ventricular filling if there is no AV node delay?
Filling decreases.
Which type of blood vessel has the greatest total cross-sectional area?
Capillaries
Why is countercurrent exchange more effective than tidal flow for oxygen uptake?
It maintains a diffusion gradient along the entire surface.
What effect does high CO₂ have on hemoglobin’s oxygen binding?
It decreases oxygen binding (more O₂ released).