Endocrine System

• Homeostasis


  The maintenance of a constant internal environment
• Co-ordinated response


  Requires a stimulus, a receptor and an effector
• Nervous system


  • Consists of the brain and spinal cord, linked to sense organs by nerves
• Receptor


  Stimulation sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses
• Neurotransmitters


  Role at synapses
• Reflex arc


  Withdrawal of a finger from a hot object
• Eye


  • Structure and function as a receptor, focusing on near and distant objects, responding to changes in light intensity
• Skin


  • Role in temperature regulation, with reference to sweating, vasoconstriction and vasodilation
• Hormones


  • Adrenaline
  • Insulin
  • Testosterone
  • Progesterone
  • Oestrogen
  • ADH
  • FSH
  • LH
• Adrenaline


  Source: Adrenal Glands, Role: 'Fight or flight', Effects: Increase heart rate, increase blood sugar levels, increase breathing rate, increase blood flow to muscles
• Insulin


  Source: Pancreas, Role: Controls blood sugar level, Effects: Stimulates glucose to be stored as glycogen in the liver
• Testosterone


  Source: Testes, Role: Male sex hormone, Effects: Promotes male secondary sexual characteristics
• Progesterone


  Source: Ovaries, Role: Supports pregnancy, Effects: Maintains the uterus lining
• Oestrogen


  Source: Ovaries, Role: Female sex hormone, Effects: Promotes female secondary sexual characteristics, major role in menstrual cycle
• ADH


  Source: Pituitary gland, Role: Osmoregulation, Effects: Increases permeability of the collecting duct to water so more is re-absorbed into blood
• FSH


  Source: Pituitary gland, Role: Female sex hormone, Effects: Causes an egg to mature and the ovaries to produce oestrogen
• LH


  Source: Pituitary gland, Role: Female sex hormone, Effects: Ovulation
• A change in the environment is a receptor
• Vasoconstriction is when your blood vessels get narrower
• The sclera contains light sensitive cells
• Your circular muscles contract for the lens to get thicker
• A nerve impulse is faster than a hormone traveling in the blood
• Insulin controls blood glucose levels
• Progesterone builds up the uterus lining
• A sensory neurone takes messages to the central nervous system
• A synapse is a gap between two neurones
• The central nervous system includes the brain and the spinal cord
• X


  Sensory neurone
• Z


  Motor neurone
• Reflex arc


  Type of pathway
• The actual time taken was 0.0089s, slower due to synapses