Topic 5 – Health, Disease and the Development of Medicines

• Maintaining a constant internal environment

  • Water
  • Glucose
  • Temperature
  • Ions
• Temperature


  Enzymes functioning normally
• Negative feedback


  A mechanism that counteracts a change in the body
• Negative feedback mechanism


  1. Stimulus

  2. Receptor

  3. Sensory

  4. CNS

  5. Motor

  6. Effector

  7. Response
• Relay neurone connects Sensory to Motor (within the CNS)
• Sense organs


  • Eye
  • Mouth
  • Tongue
  • Ear
  • Nose
  • Skin
• Reflex


  Automatic, goes to spinal cord (faster), protection
• Voluntary response


  Goes to brain (slower), requires thinking
• Synapse


  1. Impulse arrives to end of neurone

  2. Neurotransmitters released

  3. Diffuse across and bind to receptors

  4. New Impulse generated on next neurone
• Drugs affect synapses
• Fair test, keep these SAME: Hand, Height, Position and Person dropping it
• Parts of the brain

  • Cerebral Cortex
  • Medulla
  • Spinal Cord
  • Cerebellum
• Medulla


  Unconscious activity, Heartbeat/breathing
• Spinal Cord


  Connects brain to neurones
• Cerebellum


  Muscle control (Sitting up)
• Studying the brain


  1. Studying patients with brain damage and which part of body is affected

  2. Electrodes in brain – to see which part gets stimulated and moves

  3. MRI scans – detailed picture showing which part of brain are active
• Parts of the eye

  • SCLERA
  • CORNEA
  • LENS
  • CILIARY MUSCLES and SUSPENSORY LIGAMENTS
  • OPTIC NERVE
  • IRIS
• Focusing on nearby objects

  1. C.M CONTRACT

  2. S.L SLACKEN

  3. Lens ^Rounded = ^Refraction
• Focusing on far objects

  1. C.M RELAX

  2. S.L TIGHTEN

  3. Lens ^Flattened = ^Refraction
• Accommodation


  Changing shape of lens to focus light onto the retina
• Long-sighted (hyperopia)


  Lens too weak, eyeball too short
• Short-sighted (myopia)


  Lens too strong, eyeball too long
• Treatments for vision defects


  • Contact lenses
  • Laser
  • Replacement lens surgery
• Thermoregulation


  1. Temperature receptor

  2. Thermoregulatory centre (Brain)

  3. Effector (sweat glands/muscles)
• Responses to hot and cold

  • Sweat
  • Vasodilation
  • Erectors relax
  • No sweat
  • Vasoconstriction
  • Erector muscles contract
  • Shiver
• Endocrine glands


  • Pituitary
  • Thyroid
  • Ovaries
  • Adrenal
  • Testes
  • Pancreas
• Hormones


  Chemical messengers, released by endocrine glands, travel in the blood and bind to target cell
• Nerves


  Faster (impulses), short lasting effect, act in precise area
• Hormones


  Slower (speed of blood), long lasting effect, act in general way
• Controlling blood glucose


  1. Blood glucose high (ate a meal)

  2. Pancreas releases INSULIN

  3. Insulin travels to liver

  4. Liver: Glucose -> Glycogen

  5. Blood Glucose

  6. Blood glucose low (fasting or exercise)

  7. Pancreas releases GLUCAGON

  8. Glucagon travels to Liver

  9. Liver: Glycogen -> Glucose

  10. Blood glucose
• Glycogen


  Storage form of glucose, found in Liver and Skeletal muscle
• Type 1 diabetes


  Born with, pancreas does not produce insulin
• Type 2 diabetes


  Obesity, liver becomes resistant to insulin
• Kidneys filter the blood
• Substances filtered out in urine

  • Urea
  • Ions
  • Water
• Urea


  Body can't store excess amino acids, produced from deamination in the liver
• Ions


  Gained from food and drink, need to maintain balance, excess removed by sweat and urine
• Water


  Lost through breathing, sweat and urine, needs to be in balance
• Water controlled by ADH

  1. Too much water: Receptor in brain detects, co-ordination centre co-ordinates response, P.gland releases less ADH, more urine

  2. Too little water: Receptor in brain detects, co-ordination centre co-ordinates response, P.gland releases more ADH, less urine
• Level of ions and water won't be controlled, death!