B12

• Human body temp nees to be kept at about 37 degrees so enzymes will work efficiently
• Core body temp deep inside body must be kept stable
• Body temp is monitored and controlled by thermoregulatory centre in brain
• Thermoregulatory centre has receptors that detect temp of blood flowing thru brain
• A healthy kidney produces urine by first filtering blood, reabsorbing glucose then dissolved mineral ions then as much water as body needs then releases urea, excess mineral ions and water in urine
• Urine is temporarily stored in bladder before being removed from body
• CO2 produced by respiration is removed via lungs when you breathe out
• Urea produced in liver from breakdown of excess amino acids is excreted by kidney in urine
• Process of deamination is amino group is removed from amino acids. This forms ammonia which is converted to urea which passes in blood to kidneys to be excrete
• If water contenct of blood is too low, pituitary gland releases ADH hormone into blood. This causes kidneys to reabsrob more water from urine into blood.
• ADH works by changing permeability of kidney tubules so they absorb more water from urine into blood.
• If water content of blood is too high, less ADH is released into blood so less water is reabsorbed in kidney resulting in more dilute urine
• A dialysis machine works as blood flows between partially permeable membranes surrounded by dialysis fluid.
• Dialysis fluid contains same concentration of useful substances like glucose and mineral ions as patient's blood.
• Urea diffuses out of blood into dialysis fluid
• Dialysis restores concentration of substances in blood back to normal but needs to be carried out at regular intervals
• In kidney transplants, there are proteins on surface of cells called antigens. The recipient's antibodes may attack antigens on donor organs because they're recognised as foreign so they must take immunosupressant drugs