Synapses, Reflexes and Hormones

• What is a synapse?

  The connection between two neurones
• How is a nerve signal transferred across a synapse?

  By the diffusion of chemicals
• What are reflexes?

  Rapid, automatic responses to stimuli
• Why are reflexes important?

  They reduce the chance of injury
• What are the five steps in a reflex arc?

  1. Stimulation of pain receptor
  2. Impulses travel along sensory neurone
  3. Impulses passed along relay neurone
  4. Impulses travel along motor neurone
  5. Muscle contracts and arm moves
• What is the endocrine system?

  A system made of glands secreting hormones
• How do hormones travel in the endocrine system?

  Through the bloodstream to target organs
• What hormone do testes produce?

  Testosterone
• How do the effects of hormones compare to nerves?

  Hormones are slower but last longer
• What is the pituitary gland known as?

  The master gland
• What does the pituitary gland do?

  Stimulates other glands
• What hormone does the thyroid produce?

  Thyroxine
• What hormone does the adrenal gland produce?

  Adrenaline
• What hormone does the pancreas produce?

  Insulin
• What hormone do ovaries produce?

  Oestrogen
• What are the main hormones produced by the endocrine glands mentioned?

  • Testes: Testosterone
  • Pituitary gland: Stimulates other glands
  • Thyroid: Thyroxine
  • Adrenal gland: Adrenaline
  • Pancreas: Insulin
  • Ovaries: Oestrogen