Topic 7: Animal Coordination & Homeostasis

• What are the two communication systems in the human body?

  The nervous system and the endocrine system
• What is the role of hormones in the endocrine system?

  They act as chemical messengers that produce responses in target tissues
• What is the function of glands in the endocrine system?

  They secrete hormones directly into the bloodstream
• What are the main glands of the endocrine system and their functions?

  • Pituitary gland: The master gland; secretes hormones affecting other glands.
  • Pancreas: Secretes insulin; controls blood glucose levels.
  • Thyroid: Secretes thyroxine; controls metabolic rate, heart rate, and temperature.
  • Adrenal gland: Secretes adrenaline; involved in the 'fight or flight' response.
  • Ovary: Secretes oestrogen; involved in the menstrual cycle and female characteristics.
  • Testes: Secretes testosterone; involved in sperm production and male characteristics.
• How does the hormonal system compare to the nervous system in terms of speed and duration of action?

  The hormonal system is slower but acts for a longer duration
• What hormone is produced by the adrenal glands for the fight-or-flight response?

  Adrenaline
• What is the fight-or-flight response?

  It is the body's response to a dangerous situation
• What are the aspects of the fight-or-flight response?

  • Increased heart rate: Allows oxygen to reach muscles quickly.
  • Increased blood pressure: Supports increased heart rate.
  • Increased blood flow to muscles: Blood vessels dilate for better contraction.
  • Increased blood sugar levels: Liver breaks down glycogen into glucose for muscle use.
• What does thyroxine regulate in the body?

  Metabolic rate
• What happens when thyroxine levels are low?

  It stimulates the production of TRH in the hypothalamus
• How does negative feedback control thyroxine levels?

  High thyroxine levels inhibit TRH release, stopping TSH production
• What are the main hormones involved in the menstrual cycle and their functions?

  1. FSH: Matures an egg in the ovary; stimulates oestrogen production.
  2. Oestrogen: Grows the uterine lining; stimulates LH production; inhibits FSH.
  3. LH: Triggers ovulation; produced in response to oestrogen.
  4. Progesterone: Maintains uterine lining; supports pregnancy; inhibits FSH and LH.
• What is the contraceptive pill composed of?

  Oestrogen and progesterone
• What is the effect of the mixed contraceptive pill on FSH?

  It inhibits FSH so no eggs mature
• What is the purpose of the contraceptive patch?

  It releases oestrogen and progesterone to prevent ovulation
• How long does the contraceptive implant last?

  3 years
• What is the role of the copper intrauterine device (IUD)?

  It kills sperm and prevents fertilized embryos from implanting
• What are the non-hormonal methods of contraception?

  • Chemical methods: Spermicides kill or disable sperm (70-80% effective).
  • Barrier methods: Condoms (prevent STDs) and diaphragms (used with spermicide).
  • Copper IUD: Kills sperm and prevents embryo implantation.
  • Surgical methods: Male and female sterilization (permanent but reversible).
  • Abstaining: Prevents fertilization by avoiding intercourse.
• What hormones are used in fertility drugs to increase the chance of pregnancy?

  FSH and LH
• What is In Vitro Fertilisation (IVF)?

  It involves fertilizing eggs in a lab and inserting embryos into the uterus
• What are the benefits and cons of IVF?

  Benefits:

  • Provides a way for infertile couples to have a child.

  Cons:

  • Physically stressful with potential hormonal reactions.
  • Emotionally stressful with a low success rate (26%).
  • Can lead to multiple births, posing risks.
  • Expensive if repeated.
• What is homeostasis?

  The maintenance of a constant internal environment
• Why is homeostasis important?

  It maintains enzyme action and all cell functions
• What does homeostasis control in the human body?

  • Blood glucose concentration
  • Body temperature
  • Water levels
• What are the components of control systems in homeostasis?

  Receptors, coordination centres, and effectors
• Where is the thermoregulatory centre located?

  In the hypothalamus of the brain
• What happens when body temperature exceeds 37 degrees Celsius?

  Sweat is produced and vasodilation occurs
• What mechanisms occur when body temperature decreases too much?

  Sweating stops, shivering occurs, and vasoconstriction happens
• What is the normal human body temperature?

  37.5 degrees Celsius
• What is thermoregulation?

  The act of keeping internal body temperature constant
• What is osmoregulation?

  The act of keeping the concentration of the blood at a constant level
• What happens if blood becomes too dilute?

  Water moves into cells, causing them to swell and potentially burst
• What happens if blood becomes too concentrated?

  Water moves out of cells, causing them to shrink
• What is the role of insulin in the body?

  It regulates blood glucose levels
• What is glucagon's role in the body?

  It raises blood glucose levels
• What is the normal human body temperature in degrees Celsius?

  37.5 degrees Celsius
• What happens when human body temperature becomes too high?

  • Sweat is produced from sweat glands.
  • Vasodilation occurs, increasing blood flow to the skin surface.
• Where are sweat glands located in the skin?

  In the dermis layer of the skin
• What is the process of vasodilation?

  It means more blood flows closer to the surface of the skin.
• What mechanisms occur when body temperature decreases too much?

  • Sweating stops.
  • Skeletal muscles contract rapidly (shivering).
  • Hairs stand on end to trap warm air.
  • Vasoconstriction occurs to reduce heat loss.