Paper 2

• What is the main focus of homeostasis?

  Regulation of internal conditions
• Why do cells require a constant temperature and pH?

  To maintain optimum conditions for function
• What are the components of control systems in the body?

  Receptors, coordination centres, effectors
• What is the role of receptors in control systems?

  • Detect stimuli (changes in the environment)
  • Send information to coordination centres
• What does the nervous system enable humans to do?

  React to surroundings and coordinate behaviour
• How does information from receptors travel to the CNS?

  As electrical impulses along neurones
• What are the main components of a reflex arc?

  Sensory neurone, synapse, relay neurone, motor neurone
• Why are reflex actions important?

  They are automatic and rapid responses
• What does the brain control?

  Complex behaviour
• What is the role of the cerebral cortex?

  Controls higher brain functions
• What is the function of the cerebellum?

  Coordinates voluntary movements
• What does the medulla control?

  Involuntary actions like breathing
• How do neuroscientists study brain function?

  By studying patients and using imaging techniques
• What makes investigating brain disorders difficult?

  The complexity and delicacy of the brain
• What is the function of the eye?

  To detect light and enable vision
• What are the main structures of the eye and their functions?

  • Retina: detects light
  • Optic nerve: transmits visual information
  • Sclera: protects the eye
  • Cornea: refracts light
  • Iris: controls light entry
  • Ciliary muscles: adjust lens shape
  • Suspensory ligaments: hold lens in place
• What is accommodation in the eye?

  Changing lens shape to focus
• How does the eye focus on a near object?

  Ciliary muscles contract, lens thickens
• How does the eye focus on a distant object?

  Ciliary muscles relax, lens thins
• What are two common eye defects?

  Myopia and hyperopia
• How are myopia and hyperopia treated?

  With spectacle lenses or surgery
• What is the role of the thermoregulatory centre?

  Monitors and controls body temperature
• What happens if body temperature is too high?

  Blood vessels dilate and sweating occurs
• What happens if body temperature is too low?

  Blood vessels constrict and shivering occurs
• What is the endocrine system composed of?

  Glands that secrete hormones
• How do hormones affect target organs?

  They produce specific effects in the organs
• What is the role of the pituitary gland?

  Secretes hormones in response to conditions
• How does the pancreas control blood glucose levels?

  By producing insulin and glucagon
• What happens when blood glucose is too high?

  Insulin moves glucose into cells
• What is Type 1 diabetes?

  Insufficient insulin production by pancreas
• How is Type 1 diabetes treated?

  With insulin injections
• What is Type 2 diabetes?

  Body cells no longer respond to insulin
• What is the effect of osmotic changes on cells?

  Cells do not function efficiently
• How is Type 2 diabetes commonly treated?

  With diet and exercise regime
• How is excess water, ions, and urea removed from the body?

  Via the kidneys in urine
• What happens when blood is too concentrated?

  ADH is released to reabsorb water
• What is the role of ADH in the body?

  Controls water reabsorption in kidneys
• What are the treatments for kidney failure?

  Organ transplant or kidney dialysis
• What hormones are involved in the menstrual cycle?

  FSH, LH, oestrogen, progesterone
• What does oestrogen do during puberty?

  Causes maturation of eggs in ovaries