What is osmoregulation?
Reveal answer
Control of the water content of the blood.
Key words: water
3(i) EXCRETION · RECALL
3.22B Excretion and osmoregulation by the kidney
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What happens after drinking a lot of water?
Reveal answer
Blood dilute → less water reabsorbed → large volume of dilute urine.
Key words: dilute
What happens when dehydrated?
Reveal answer
Blood concentrated → more water reabsorbed → small volume of concentrated urine.
Key words: concentrated
Why must water content be controlled?
Reveal answer
Too dilute → cells swell/burst; too concentrated → cells shrink (osmosis).
Key words: osmosis
What is meant by the term osmoregulation?
Reveal answer
Control of water and solute balance in body fluids.
Key words: osmoregulation
What is meant by the term filtrate?
Reveal answer
Fluid filtered from blood into a nephron.
Key words: filtrate
What is meant by the term selective reabsorption?
Reveal answer
Controlled return of useful substances from filtrate to blood.
Key words: selective reabsorption
What is meant by the term negative feedback?
Reveal answer
Response that reverses a deviation from a set condition.
Key words: negative feedback
Two kidney roles, Excretion. What is regulated/removed? Kidney contribution?
Reveal answer
What is regulated/removed: Urea and other metabolic wastes. Kidney contribution: Filtration with incomplete reabsorption into urine.
Key words: Excretion
Two kidney roles, Water balance. What is regulated/removed? Kidney contribution?
Reveal answer
What is regulated/removed: Blood water content. Kidney contribution: Variable collecting-duct water reabsorption.
Key words: Water balance
Two kidney roles, Ion balance. What is regulated/removed? Kidney contribution?
Reveal answer
What is regulated/removed: Excess mineral ions. Kidney contribution: Selective reabsorption and urinary loss.
Key words: Ion balance
Two kidney roles, Useful solute conservation. What is regulated/removed? Kidney contribution?
Reveal answer
What is regulated/removed: Glucose and required ions. Kidney contribution: Selective reabsorption to blood.
Key words: Useful solute conservation
True or false, and why? “Kidneys only remove urea.”
Reveal answer
False. They also regulate water and ions and retain useful substances.
True or false, and why? “Everything in plasma becomes urine.”
Reveal answer
False. Cells/proteins remain in blood and most useful small solutes are reabsorbed.
True or false, and why? “Kidneys add water to the body.”
Reveal answer
False. They conserve or excrete water already present.