What is homeostasis?
Reveal answer
Maintaining a constant internal environment.
Key words: constant
3(j) CO-ORDINATION AND RESPONSE · RECALL
3.31 Homeostasis
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What is negative feedback?
Reveal answer
Change detected → response opposes change → return to normal.
Key words: opposes
Name three conditions kept constant in humans.
Reveal answer
Body temperature, blood glucose, water content.
Key words: temperature · glucose
What is meant by the term set range?
Reveal answer
Acceptable interval around which a regulated variable fluctuates.
Key words: set range
What is meant by the term coordination centre?
Reveal answer
Part of a control system that processes receptor information and directs effectors.
Key words: coordination centre
Two homeostatic variables, Blood water content (Too little water). Corrective response?
Reveal answer
More ADH and renal water reabsorption.
Key words: Blood water content
Two homeostatic variables, Blood water content (Too much water). Corrective response?
Reveal answer
Less ADH and more dilute urine.
Key words: Blood water content
Two homeostatic variables, Body temperature (Too high). Corrective response?
Reveal answer
Sweating and skin vasodilation.
Key words: Body temperature
Two homeostatic variables, Body temperature (Too low). Corrective response?
Reveal answer
Reduced skin blood flow and increased heat production.
Key words: Body temperature
True or false, and why? “Homeostasis keeps values exactly constant.”
Reveal answer
False. Variables fluctuate within regulated ranges.
True or false, and why? “Negative feedback means a harmful response.”
Reveal answer
False. “Negative” means it opposes the original change.
True or false, and why? “One organ controls homeostasis alone.”
Reveal answer
False. Receptors, coordination systems and effectors across organs cooperate.
Why must human body temperature be kept close to 37 °C?
Reveal answer
Enzymes work best at about this temperature.
Key words: enzymes
Why must the water content of the blood be kept constant?
Reveal answer
Stops too much water entering or leaving cells by osmosis → cells could burst or shrink.
Key words: osmosis
Which organs control the water content of the blood?
Reveal answer
The kidneys.
Key words: kidneys