homeostasis

• homeostasis is the process of maintaining a constant internal environment
• thermoreceptors in the SKIN detect surface/environment temperature
• thermoreceptors in the HYPOTHALAMUS detect core body temperature (the temp of the blood flowing through all the organs inside us)
• If too HOT:

  Muscles cause vasodilation; sweat glands secrete sweat
• If too COLD: Muscles cause vasoconstriction + shivering
• Heat loss increased to cool body:

  • More water evaporates
  • Vasodilation of arterioles in surface of skin therefore more heat loss by radiation
  • Less air trapped
  • Take off clothes
  • Hair erector muscles relax
  • Sweating increases
  • Hairs lie flat
• Heat loss reduced to conserve heat:

  • Shivering
  • Hairs are raised
  • Vasoconstriction of arterioles therefore less heat loss by radiation
  • Less water evaporates
  • Sweating decreases
  • Put on clothes
  • Pale skin
  • Hair erector muscles contract
  • More air trapped
• Shivering = rapid contraction of muscles - generates heat
• Hairs are raised - trap insulating layer - less heat loss
• Vasoconstriction of arterioles in surface of skin - blood diverted away from surface - less heat loss by radiation
• Sweating = use of thermal energy to evaporate water from the surface of the skin
• Hairs lie flat - no insulating layer
• Vasodilation of arterioles in surface of skin = blood diverted to surface - more heat loss by radiation
• The hypothalamus has thermoreceptors which detect our core body temperature by measuring the temperature of our blood
• Sweat glands secrete sweat which cools the body by evaporation
• Hormone = a chemical messenger thats released into the bloodstream
• effectors are muscles or glands
• ENDOCRINE glands secrete hormones into the blood
• EXOCRINE glands secrete chemicals out of the organ
• master gland = pituitary gland
• Nervous system (reflex)

  • very rapid
  • information travels along nerve cells
  • info travels as an electrical impulse
  • receptor cells are involved
  • received by effectors
  • short lived effect
• Endocrine system (hormonal)

  • relatively slow
  • info travels in the bloodstream
  • info travels as a chemical messanger
  • receptor cells involved
  • received by target organ
  • long lived effect
• glucaGON = the hormone
• glyCOgen = how we store glucose
• Glucose RISES

  • detected by cells in the pancreas
  • insulin produced by the cells in the pancreas causes glucose to move into cells
  • causes excess glucose to be converted to glycogen in liver and muscles cells
  • glucose is back at a normal level
• Glucose FALLS

  • detected by cells in the pancreas
  • glucagon produced by the cells in the pancreas causes the breakdown of glycogen
  • glucose is released back into the bloodstream
  • glucose is back at a normal level
• insulin and glucagon are released by the pancreas
• insulin is released when blood glucose concentration is too high
• glucagon is released when the blood glucose concentration is too low
• bgl might be high after eating
• bgl might be low after exercising
• when glucose RISES:

  • detected by cells in the pancreas
  • insulin produced by the cells in the pancreas causes glucose to move into cells
  • causes excess glucose to be converted to glycogen in liver and muscle cells
  • glucose levels drop
• when glucose DROPS:

  • detected by cells in the pancreas
  • glucagon produced by the cells in the pancreas causes the breakdown of glycogen
  • glucose is released back into the bloodstream
  • glucose levels increase
• glycogen is how our body stores glucose, it's a polymer
• main symptoms of diabetes:

  thirst, frequent urination, tiredness, weight loss and loss of muscle bulk
• insulin causes glucose to move out of the blood and into cells
• Type ONE diabetes is caused when the body's immune system attacks and destroys the cells that produce insulin
• Type ONE diabetes is treated with insulin injections and paying attention to your lifestyle
• Type TWO diabetes is caused when the body doesn't produce enough insulin or the body's cells don't respond to insulin
• Type TWO diabetes is treated by eating a healthy diet and monitoring blood glucose, medication may be needed at some point