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B12: Homeostasis in Action - Coggle Diagram
B12: Homeostasis in Action
12.1 Controlling body temperature
Monitored & controlled by the thermoregulatory centre in the hypothalamus, contains receptors sensitive to the temperature of the blood
Skin contains temperature receptors and sends nerve impulses to thermoregulatory centre
If body temperature is too high, blood vessels supplying the skin capillaries blood dilate (vasodilation), sweat is produced to transfer thermal energy from the skin to the environment
If body temperature is too low, blood vessels vasoconstrict, piloerection, and sweating stops to minimise thermal energy loss
Skeletal muscles contract and exothermic reactions of respiration needed for muscle contraction raise the temperature
12.2 Removing waste products
Water leaves the body via the lungs when exhaling (no control)
Water, mineral ions, and urea are lost through sweat (no control)
Urea, excess water, and mineral ions are removed by the kidney as urine (carefully balanced)
If body cells gain or lose too much water by osmosis they don't function properly
12.3 The human kidney
Urine produced by filtering blood (in nephron)
Reabsorbs all glucose, plus any mineral ions and water needed by the body (selective reabsorption)
Excess mineral ions and water, and urea are removed and excreted as urine
Water balance in the blood is maintained by ADH (made in pituitary gland), changes how much water is reabsorbed by the tubules
12.5 Kidney transplants
Healthy kideny from a donor replaces the function of the diseased or damaged kidney
To prevent rejection of tissue types, donors are matched as closely as possible and use immunosuppressant drugs
12.4 Dialysis - an artificial kidney
Those with kidney failure are treated with dialysis or with a transplant
Concentration of dialysis fluid - equal amounts of glucose & mineral ions as blood to prevent all of them being drawn out the blood by diffusion, no urea so it's drawn out of the blood