homeostasis

• Adrenaline


  Produced by adrenal gland to prepare the body for fight or flight response
• Effects of adrenaline


  • Increased heart rate (oxygen reaches muscles faster)
  • Increased blood pressure
  • Increased blood flow to muscles
  • Increased blood sugar
• Thyroxine


  Regulates metabolic rate and important in growth and development
• Thyroxine regulation


  1. Low levels of thyroxine stimulate production of TSH in the hypothalamus

  2. TSH is released from pituitary gland

  3. TSH acts on thyroid to produce thyroxine

  4. When levels return to normal, thyroxine inhibits release of TSH to stop thyroxine production
• Contraceptive injection


  Has a similar effect as contraceptive implant, lasts 2-3 months
• Menstrual cycle


  1. FSH causes maturation of egg in ovary

  2. Oestrogen is produced

  3. Oestrogen stimulates LH and inhibits FSH

  4. Ovulation occurs

  5. Progesterone maintains uterus lining
• Hormonal contraception


  • Mixed pill contains oestrogen and progesterone
  • Progesterone-only pill has less side effects
  • Contraceptive patch contains oestrogen and progesterone
  • Contraceptive implant and IUD contain progesterone and prevent ovulation
• Insulin and glucagon regulate blood glucose levels
• Insulin regulation


  1. If glucose too high, pancreas produces insulin

  2. Insulin binds to cells causing glucose to move from blood into muscles for respiration

  3. Excess glucose converted to glycogen and stored in liver
• Glucagon regulation


  1. If glucose levels decrease, pancreas produces glucagon

  2. Glucagon binds to liver cells causing breakdown of glycogen into glucose
• Homeostasis


  Maintenance of a constant internal environment, including thermoregulation
• Thermoregulation


  1. Sweat produced in sweat glands evaporates off skin, increasing energy transfer away from body

  2. Blood vessels constrict/dilate to reduce/increase heat loss
• Diabetes


  • Type 1: Pancreas doesn't produce enough insulin
  • Type 2: Cells no longer respond to insulin, often due to obesity
• Urinary system


  1. Blood containing impurities travels in renal artery to kidneys

  2. Kidneys regulate salts, ions and urea in blood, excess sent to ureter for excretion and bladder
• Nephron structure and function

  • Ultrafiltration occurs in glomerulus, small substances pass into Bowman's capsule
  • Selective reabsorption of water, ions and glucose occurs in convoluted tubule and loop of Henle
  • ADH regulates water reabsorption in collecting duct
• Dialysis involves blood being taken from the arm, mixed with anticoagulant, and passed through a machine with a partially permeable membrane separating it from dialysis fluid
• Transplantation has a risk of bodily rejection, which is suppressed using immunosuppressive drugs