Homeostasis & Response

• What is homeostasis?

  Regulation of internal conditions
• What may the control system involve?

  Nerves and hormones for responses
• What are the components of all control systems?

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

  Detect stimuli
• What do coordination centres do?

  Receive and process information
• What is the function of effectors?

  Bring about responses to restore levels
• What is the negative feedback control mechanism?

  • Receptor detects change
  • Coordination centre compares to set point
  • Effector produces response to correct difference
• How does the nervous system help humans?

  Enables reaction to surroundings and coordination
• What does the CNS do?

  Coordinates the response of effectors
• What are reflex actions?

  Automatic and rapid responses to stimuli
• What are the steps of a reflex action?

  1. Pain stimulus detected by receptors
  2. Impulses travel along sensory neurone to CNS
  3. Impulse passes through relay neurone
  4. Motor neurone carries impulse to effector
  5. Receptor responds
• How do neurones communicate?

  Via synapses between neurones
• What happens at a synapse?

  A chemical is released to generate an impulse
• What is the independent variable in the caffeine reaction time experiment?

  • Whether the subject has had caffeine or not
• What is the dependent variable in the caffeine reaction time experiment?

  • Distance the ruler travels
• What are the control variables in the caffeine experiment?

  • Age
  • Mass
  • Sex
• What is the endocrine system?

  Glands that secrete hormones into blood
• What are hormones?

  Chemical messengers in the blood
• How do hormones act compared to nervous impulses?

  Slower and act for longer
• What does the pituitary gland control?

  Growth and development in young animals
• How is blood glucose controlled?

  • Monitored by the pancreas
  • If too high, insulin is released
  • If too low, glucagon is released
• What happens when blood glucose is too high?

  Pancreas releases more insulin
• What does insulin do?

  Causes glucose to move into cells
• What happens when blood glucose is too low?

  Pancreas releases glucagon
• What does glucagon do?

  Stimulates glycogen to glucose conversion
• What causes Type 1 diabetes?

  Pancreas fails to produce insulin
• How is Type 1 diabetes treated?

  With insulin injections
• What is a risk factor for Type 2 diabetes?

  Obesity
• How is Type 2 diabetes treated?

  With exercise and a controlled diet
• What distinguishes Type 2 diabetes from Type 1?

  Type 2 cannot be treated with insulin
• What are endocrine glands sometimes called?

  Ductless glands
• How do enzymes from glands like salivary glands function?

  They pass into tubes called ducts
• What is the difference between endocrine and exocrine glands?

  Endocrine glands secrete hormones into blood
• the pill - oral contraception which contains hormones which prevent the body from forming the hormone FSH. (FSH causes the eggs to mature)
• The advantage of the pill is that it is highly effective if taken correctly.
• A disadvantage of the pill is that it must be taken everyday and if a woman forgets to take it there is a risk of pregnancy.
• Side effects Of the pill:

  • increased risk of breast cancer and blood clots
• Implant, injection, skin patch - these contain progesterone which stops eggs from maturing or being released.
• Advantage of the implant, injection and skin-patch:

  • more convenient to take
  • has more of an effect as the duration of these contraception is longer
  • implant lasts 3 years
  • injection lasts 13 weeks
  • patch lasts a week
• Implant, injection and skin patch is a hormonal form of contraception, they have side effects.