Hormonal Coordination in humans

• The endocrine system is the body's coordination system that includes hormones
• A hormone is a chemical messenger secreted by a gland. It travels in the blood to a target organ, where it causes a response
• Glands secrete hormones
• The pituitary gland controls many other glands in the body
• The pituitary gland secretes a wide range of hormones, some of which may stimulate other endocrine glands
• Role of Pituitary gland:

  • Secretes human growth hormone
  • Stimulates the thyroid gland
  • Stimulates ovulation and the production of oestrogen in the ovaries
  • Stimulates the production of sperm and testosterone in the testes
• The thyroid gland secretes the hormone thyroxine - controls metabolism, heart rate and body temperature
• The pancreas secretes the hormone insulin - controls blood glucose levels
• The adrenal gland secretes adrenaline which controls the bodys fight or flight response
• The ovaries secrete oestrogen, which coordinates the menstrual cycle and the development of female secondary characteristics
• The testes secrete testosterone, which coordinates production of the sperm and the development of male secondary sexual characteristics
• The pancreas monitors and controls blood glucose concentration
• When blood glucose levels are too high the pancreas secretes insulin. Insulin binds to receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored
• When blood glucose levels are too low, the pancreas secretes the hormone glucagon. Glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood