Endocrine system

• Endocrine vs Nervous system:

  • uses hormones
  • slower
  • Travels in blood
  • Entire body
• Glands -> secrete hormones -> blood -> cell changes
• Pituitary gland - releases hormones that control other glands
• Thyroid gland - produces thyroxine, regulates metabolism
• Adrenal gland - produces adrenaline and cortisol, which increase heart rate
• Pancreas - produces insulin that regulates blood glucose levels
• Ovaries - produce oestrogen and progesterone, which control the menstrual cycle
• Testes - produce sperm and testosterone
• What does adrenaline do?

  1. Increases heart rate
  2. Increases blood pressure
  3. Increases blood flow to muscles
  4. Increases blood sugar (glucose) levels by stimulating the liver to break glycogen down into glucose
• How is the production of thyroxine regulated?

  1. The pituitary gland produces Thyroid Stimulating Hormone (TSH), which stimulates the thyroid gland to produce thyroxine.
  2. Thyroxine then inhibits the production of TSH from the pituitary gland.
• 1. If thyroxine levels are too low - the pituitary gland will release TSH. This then stimulates the thyroid gland to release more thyroxine. So thyroxine levels in the blood increase back up to normal.
  2. If thyroxine levels are too high - the thyroxine will inhibit the pituitary gland from producing TSH. Less TSH means that the thyroid gland won't release as much thyroxine. So thyroxine levels in the blood fall back to normal.