Endocrine System

• Endocrine gland


  A gland that produces hormones

  
• Hormones


  Signaling molecules that enable systems of the body to communicate with each other
• Hormones


  • Travel through the bloodstream and affect a tissue somewhere else in the body
  • Secreted directly into the bloodstream by endocrine glands
• Exocrine glands


  Produce enzymes, sweat and tears
• Nervous impulses


  Very fast and very specific in terms of what tissues they stimulate, with short-lived effects
• Hormones from the endocrine system

  Chemical, travel slower, longer lasting and less specific
• Hormones go to every cell though not all cells respond to them
• Fight or flight


  An example of a nervous impulse
• Hypothalamus


  • Releases antidiuretic hormone which regulates the reabsorption of water in the collecting duct (nephron)
  • Tells the cell of the collecting duct to make more aquaporins

  
• Pituitary gland


  • Releases many hormones that may help with growth, adrenalin, sex and more

  
• Thyroid gland

  • Thyroxine regulates/increases the metabolism in your body
  • Calcitonin reduces blood calcium levels
  • Parathyroid hormone increases blood calcium levels
• Thymus gland

  • Thymosin stimulates the production of T lymphocytes
• Adrenal glands


  • Adrenaline promotes 'flight or fight' response
  • Cortisol is released in response to stress to increase blood sugar levels
• Pancreas


  • Insulin stimulates the liver, skeletal muscles and most body cells to take glucose from the blood and store it as glycogen
  • Glucagon stimulates the liver and skeletal muscles to convert glycogen to glucose and release it into the blood
• Lipid hormones/steroids

  Hydrophobic but lipid soluble, can easily diffuse across the phospholipid bilayer
• Lipid hormones


  • Testosterone
  • Progesterone
  • Cortisol
• Amino-acid based hormones


  Polar molecules (hydrophilic), cannot travel through the plasma membrane and will most likely need to attach to a receptor
• Cells

  • Must communicate to perform many synchronous functions in the body
  • Send and receive special chemicals called signalling molecules
  • Hormones are one of the most important signalling molecules
• Hormone molecules

  Function by binding to specific receptors on target cells that are complimentary to the hormone