HomeostasisEdexcel GCSE Biology: Flashcards

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What is homeostasis?

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What is homeostasis?: Maintenance of a constant internal environment.
Why keep body temperature constant?: So enzymes work at optimum rate.
Why keep blood water content constant?: Prevents cells bursting/shrinking by osmosis.
Role of hypothalamus?: Monitors blood temperature and coordinates responses.
Effect of vasodilation/vasoconstriction?: Vasodilation widens vessels (heat loss); vasoconstriction narrows them (reduces heat loss).
How does shivering generate heat?: Muscle contraction increases respiration, releasing heat.
How does insulin control glucose?: Causes cells to take up glucose, converting it to glycogen.
How does glucagon control glucose?: Causes liver to break down glycogen into glucose.
Type 1 diabetes cause/treatment?: Little/no insulin produced; treated with insulin injections.
Type 2 diabetes cause/treatment?: Cells resist insulin; treated with diet, exercise, medication.
BMI equation?: BMI=mass(kg)÷height(m)².
What happens at filtration in the nephron?: Blood filtered at high pressure at the glomerulus into Bowman's capsule.
What is selectively reabsorbed?: All glucose and a variable amount of water.
Effect of ADH on the collecting duct?: Increases permeability, increasing water reabsorption, concentrated urine.
Two kidney failure treatments?: Dialysis and organ transplant.