Hormonal responses

• Homeostasis


  The regulation of the internal conditions of a cell or organism
• Components of a control system

  • Receptor
  • Coordination centre
  • Effector
• Control system


  1. Stimulus

  2. Response
• Endocrine glands


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

  
• The pancreas and pituitary gland secrete hormones involved in the reproductive system
• The adrenal gland secretes the hormone adrenaline
• The pituitary gland secretes growth hormones
• The thyroid gland secretes the hormone thyroxine
• Hormones secreted by the pancreas


  • Insulin
  • Glucagon
• Nervous control


  Neurones transport electrical signals to the effector
• Hormonal control


  Blood stream transports chemical signals to the target cells
• Nervous control


  • Localised response
  • Rapid response but short lasting
• Hormonal control


  • Widespread response
  • Slow but long lasting response
• The endocrine system has longer lasting effects than the nervous system
• The nervous system uses electrical signals
• The endocrine system uses the bloodstream to transport chemical signals
• Endocrine system organs


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

  
• Nervous control system


  Quickly, as an electrical signal
• Hormones


  • Insulin
  • Oestrogen
  • Thyroxine
  • Adrenaline
• Role of insulin


  Maintaining glucose levels in the blood
• When we eat a meal

  Blood glucose levels increase
• When we exercise or several hours after eating a meal

  Blood glucose levels decrease
• Glucose is a reactant in respiration
• Increasing blood sugar


  1. Glucose receptors in blood vessels detect increase

  2. Pancreas releases insulin

  3. Liver cells convert glucose into glycogen

  4. Blood glucose returns to normal
• Decreasing blood sugar


  1. Glucose receptors in blood vessels detect decrease

  2. Pancreas releases glucagon

  3. Liver cells convert glycogen into glucose

  4. Blood glucose returns to normal
• Eating a meal causes blood glucose levels to increase
• Exercising causes blood glucose levels to decrease
• Respiration uses glucose as a reactant
• Negative feedback controls blood glucose levels
• Hormones secreted by the pancreas

  • Insulin
  • Glucagon
• Type 1 Diabetes


  • Autoimmune condition, genetic
  • Usually diagnosed during childhood
  • Treated with insulin injections
• Type 1 Diabetes


  1. Blood glucose levels increase

  2. Measured using device

  3. Insulin injected, stimulates liver to convert glucose to glycogen

  4. Blood glucose returns to normal
• Type 2 Diabetes


  • Caused by obesity
  • Usually found in older adults
  • Treated with controlled diet and exercise