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All 9 Flashcards — Homeostasis & negative feedback
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Question
Define homeostasis.
Answer
Keeping the body's **internal environment** near a constant **set point**, despite changes outside.
Question
What is a 'set point'?
Answer
The **normal value** a regulated variable is held close to (e.g. ~37 °C core temperature, ~pH 7.4 blood).
Question
Name four blood/body variables kept constant by homeostasis.
Answer
**Blood glucose**, **temperature**, **blood pH**, and **water/solute balance**.
Question
Define negative feedback.
Answer
A control loop where the **response opposes the change**, returning the variable toward its set point.
Question
List the stages of a homeostatic control loop, in order.
Answer
**Stimulus → receptor → control centre → effector → response** (the response opposes the change).
Question
Why is it called NEGATIVE feedback?
Answer
Because the response acts in the **opposite direction** to the change — a rise triggers a fall, a fall triggers a rise.
Question
How does positive feedback differ from negative feedback?
Answer
Positive feedback **amplifies** the change (drives it further from normal); it is **not** homeostatic.
Question
Give one example of positive feedback in the body.
Answer
The **LH surge** before ovulation (or **oxytocin** in childbirth) — the change is amplified to drive a process to completion.
Question
Which brain structure is the control centre for several homeostatic loops?
Answer
The **hypothalamus** — it compares the variable with the set point and signals the effectors.
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Full study notes for Homeostasis & negative feedback
Topic 4.9 hub
Homeostasis
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