5 Countercurrent Mechanisms

Question 1

Thermoregulation on skin

Answer 1

vasomotor response to prevent heat loss

heat from arterial blood goes to venous blood

flow side by side

Question 2

Oxygen exchange (fish)

Answer 2

maximize O2 in blood

maximize time blood is exposed to water of high O2 concentration

blood and H20 flow across gills in opposite directions

Question 3

Maximize H20 reabsorption through kidneys

Answer 3

vasa recta preserves osmotic gradient while giving blood to renal medulla

decrease solute dissipation of osmotic gradient

descending limb: solute -> vessels, opposite for ascending limb

Question 4

Water conservation through salt regulation of sea birds

Answer 4

purpose: to keep high concentration of salt in gland’s blood to later remove

Question 5

Water conservation of desert rodents

Answer 5

purpose: decrease H2O loss during exhalation

cool air in, warm air out

temporal separation, not spatial