Hormones and blood glucose, the eye, excretion and the kidney, plant responses, reproduction and DNA.
Hormones and homeostasis
Homeostasis keeps internal conditions steady. Hormones are chemical messengers made by glands, carried in the blood to target organs — slower but longer-lasting than nerves.
| Hormone | Gland | Effect |
|---|---|---|
| Insulin | pancreas | lowers blood glucose (→ glycogen) |
| Glucagon | pancreas | raises blood glucose |
| Adrenaline | adrenal | "fight or flight" |
| ADH | pituitary | more water reabsorbed by kidney |
Blood glucose control: high glucose → insulin → cells take up glucose / liver stores glycogen; low glucose → glucagon → glycogen → glucose. Type 1 diabetes = no insulin (treated by injection).
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