B5 homeostasis and response

• Homeostasis is the maintenance of a constant internal environment and keeps your body functioning properly
• Homeostasis


  • Needs to control blood glucose levels
  • Needs to control water levels
  • Needs to control temperature
• Brain


  The control center that sends signals to various parts of the body
• Pancreas


  • Responsible for producing insulin
• Effector muscles


  • Do things like moving, for example shivering
• Glands


  • Responsible for the production of other hormones
• Nervous system


  Consists of the brain, spinal cord, neurons, receptors and effectors
• Reflex


  1. Stimulus picked up

  2. Signal travels to spinal cord

  3. Response sent back
• Nerve cells


  Have a long cell body to send fast electrical signals
• Synapse


  Where signal transfers from one nerve cell to another, a slower chemical signal
• Brain


  • Has the cerebral cortex, cerebellum and medulla
• Doctors can map the brain using MRI and CT scans and giving stimuli
• Short-sightedness

  Image focuses before the retina
• Long-sightedness


  Image focuses behind the retina
• Correcting short-sightedness


  Needs a diverging lens
• Correcting long-sightedness


  Needs a converging lens
• Temperature regulation


  1. Hairs stand up to trap air when cold

  2. Sweating and vasodilation when hot

  3. Shivering to produce heat when cold
• Endocrine system


  • Pituitary gland
  • Thyroid
  • Adrenal glands
  • Pancreas
  • Ovaries
  • Testes
• Testosterone


  Produced by testes, has effects of growing muscles, making voice and penis grow, increasing hair growth
• Oestrogen


  Produced by ovaries, responsible for maturation of eggs and menstrual cycle
• Insulin


  Produced by pancreas, important for regulating blood glucose levels
• Adrenaline


  Produced by adrenal glands, important for fight-or-flight response
• Thyroxine


  Produced by thyroid, important for regulating metabolism
• FSH and LH


  Produced by pituitary gland, control reproductive functions
• Blood glucose regulation


  1. Glucose levels rise after a meal

  2. Pancreas produces insulin

  3. Insulin causes cells to remove glucose from blood

  4. Glucose levels fall

  5. If too low, pancreas produces glucagon

  6. Glucagon converts stored glycogen to glucose

  7. Glucose levels rise again
• Type 1 diabetes


  Pancreas doesn't produce enough insulin
• Type 2 diabetes


  Cells become resistant to insulin
• Symptoms of both types of diabetes include loss of weight, increased urination, thirst, blurred vision, fatigue, hunger
• Treatment for type 1 diabetes

  Insulin injections
• Treatment for type 2 diabetes

  Controlling diet and exercise
• Kidneys


  • Remove urea, control ion content, control water content of blood
• How kidneys function

  1. Ultrafiltration

  2. Reabsorption

  3. Release
• ADH


  Antidiuretic hormone that controls water reabsorption
• Kidney dialysis


  Machine that takes over kidney function, time consuming and impacts life
• Kidney transplant


  Alternative to dialysis, but long waiting lists and risk of rejection
• Follicle stimulating hormone (FSH)


  Rises to make egg grow
• Luteinizing hormone (LH)


  Short-acting, triggers egg release
• Oestrogen


  Builds up uterine lining
• Progesterone


  Builds up uterine lining, decreases if no implantation
• Contraception methods


  • Condoms (barrier)
  • Pill (hormonal)
  • Coil/IUD (hormonal)
  • Diaphragm (barrier)