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Quiz yourself on Homeostasis IntroGet your flashcardsBuild my revision planTrack my progress⚙️ Why Stable Conditions Matter: The Enzyme Connection
Homeostasis is not just about comfort. It is a survival requirement, and the reason comes down to enzymes.
Every chemical reaction that keeps you alive — breaking down glucose in respiration, building proteins, digesting food, contracting muscles — is catalysed by an enzyme. Enzymes are proteins, and proteins are extremely sensitive to their environment. They only work properly within a narrow temperature range and pH range. These are their optimum conditions.
If temperature rises too far above 37°C, the enzyme's active site changes shape — it denatures. Substrate molecules can no longer fit, the enzyme stops working, and the reaction it was catalysing stops. If this happens to enough enzymes, cells die. If temperature falls too far below 37°C, enzyme-substrate collisions become too infrequent, reactions slow dangerously, and cells cannot generate enough energy to survive.
The same logic applies to pH: blood that becomes too acidic or too alkaline changes the charge distribution on enzyme molecules, altering their shape and destroying their function.
Homeostasis exists primarily to keep enzymes working. Everything else — sweat glands, the hypothalamus, insulin, the kidneys — ultimately serves this one purpose.
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