Human endocrine system

• The endocrine system is composed of glands which secrete chemicals called hormones directly to the bloodstream
• The blood carries the hormone to a target organ where it produces an effect compared to the nervous system, the effects of the endocrine system are slower but act for longer
• Pituitary gland:

  • A small gland located at the base of the brain.
  • It is often called the 'master gland'
  • It produces and secrets many hormones into the blood
  • The hormones are released in response to changes in body conditions
  • These hormones released act on other glands to stimulate other hormones to be released
• Hormones released by the pituitary gland

  • Anti diuretic hormone [ADH]
  • Thyroid stimulating hormone [TSH]
  • Luteinising hormone [LH]
  • Follicle stimulating hormone [FSH]
  • Prolactin [PRL]
  • Growth hormone [GH]
• Anti-diuretic hormone [ADH]


  • Target: Kidney
  • Effect: Controls water levels in the blood
• Thyroid-stimulating hormone [TSH]


  • Target: Thyroid
  • Effect: Stimulate the thyroid gland to release thyroxine
• Luteinising hormone [LH]


  • Target: Ovaries
  • Effect: Stimulates egg release and progesterone production
• Follicle-stimulating hormone [FSH]


  • Target: Ovaries
  • Effect: Stimulates egg ripening and oestrogen production
• Prolactin [PRL]


  • Target: Breasts
  • Effect: Stimulates the breasts to produce milk
• Growth hormone [GH]


  • Target: All cells in the body
  • Effect: Stimulates growth and repair
• Pancreas

  • produces and secretes insulin [decreases blood glcuose concentration] and glucagon [increases blood glucose concentration]
  • blood glucose concentration is monitored and regulated by the pancreas which is an example of negative feedback
• 1. Blood glucose concentration is too high
  2. Pancreas releases insulin
  3. Liver and muscle cells convert excess glucose into glycogen
• 1. Blood glucose concentration is too low
  2. Pancreas releases glucagon
  3. liver and muscle cells convert glycogen into glucose
• Diabetes

  A condition that causes a person's blood level to become too high
• Type one diabetes

  • pancreas fails to produce enough insulin
  • uncontrolled high glucose levels
  • treated with insulin injections
• Type two diabetes

  • body cells no longer respond to the insulin produced by the pancreas
  • obesity is a risk factor
  • treated by controlling carbs in the diet and exercise
• The adrenal glands produce and secrete the hormone adrenalin.

  Adrenalin prepares the body for rapid activity by increasing the heart rate and blood glucose.

  It diverts blood flow to the muscles and lungs.

  It is often cause the 'fight or flight' hormone.
• The thyroid produces and secretes the hormone thyroxine.

  Thyroxine regulates the metabolic rate, this is the rate at which energy is released in the body.

  Thyroxine also regulates breathing, heart rate, and body temperature.