GCSE Biology · Edexcel 1BI0 · Topic 7D
Thermoregulation and osmoregulation
Key points
- Homeostasis is keeping the internal environment constant so that enzymes and cells work properly.
- Thermoregulation (higher tier): the hypothalamus detects blood temperature. When too hot, sweating and vasodilation (more blood flow near the skin) release heat. When too cold, shivering and vasoconstriction keep heat in.
- Osmoregulation: the kidneys filter the blood, reabsorb useful substances such as glucose and some water, and remove urea and excess water as urine.
- A nephron has a glomerulus (filtration), a convoluted tubule (selective reabsorption) and a collecting duct.
- ADH from the pituitary makes the collecting duct more permeable to water when the body is short of water, so less, more concentrated urine is made.
- Kidney failure is treated by dialysis or a transplant.
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Homeostasis is keeping conditions inside the body steady despite changes outside. This sub-topic covers two examples: controlling body temperature (thermoregulation) and controlling water and urea levels (osmoregulation), which is the job…
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