Animal coordination, control & 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 that secretes hormones affecting other glands.
  • Pancreas: Secretes insulin to control blood glucose levels.
  • Thyroid: Secretes thyroxine to control metabolic rate, heart rate, and temperature.
  • Adrenal gland: Secretes adrenaline for the 'fight or flight' response.
  • Ovary: Secretes oestrogen for the menstrual cycle and female characteristics.
  • Testes: Secretes testosterone for sperm production and male characteristics.
• How does the blood transport hormones in the body?

  It carries hormones to target organs or tissues where they exert their effects
• How does the speed and duration of hormonal responses compare to the nervous system?

  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 reaction to a dangerous situation, preparing for either confrontation or escape
• What are the aspects of the fight-or-flight response?

  • Increased heart rate for faster oxygen delivery to muscles
  • Increased blood pressure
  • Increased blood flow to muscles through dilation of blood vessels
  • Increased blood sugar levels from glycogen breakdown in the liver
• 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
• What is the role of TSH in the production of thyroxine?

  TSH acts on the thyroid to stimulate the production of thyroxine
• How is the level of thyroxine controlled in the body?

  Through negative feedback mechanisms
• What are the key events in the menstrual cycle?

  1. Breakdown of the uterine lining (menstruation)

  2. Building up of the uterine lining

  3. Ovulation (release of an egg on day 14)

  4. If no fertilization, the cycle repeats after 28 days

  
• What hormones control the menstrual cycle?

  1. Follicle stimulating hormone (FSH): Maturation of eggs and stimulates oestrogen production.

  2. Oestrogen: Causes uterine lining growth and regulates FSH and LH.

  3. Luteinising hormone (LH): Triggers ovulation.

  4. Progesterone: Maintains uterine lining and inhibits FSH and LH.

  
• What is the function of the contraceptive pill?

  To prevent egg maturation by maintaining high levels of oestrogen
• What are the side effects of the mixed contraceptive pill?

  Changes in mood, mood swings, depression, breast pain, and increased blood pressure
• What are the different hormonal contraception methods?

  • Contraceptive pill: Mixed and progesterone-only options.
  • Contraceptive patch: Contains oestrogen and progesterone, lasts for 1 week.
  • Contraceptive implant: Releases progesterone, lasts for 3 years.
  • Contraceptive injection: Contains progesterone, lasts for 2-3 months.
  • Plastic intrauterine device (IUD): Releases progesterone, lasts for 5-10 years.
• What are non-hormonal methods of contraception?

  • Chemical methods: Spermicides that 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 (cutting and tying tubes).
  • Abstaining from intercourse.
• What is the purpose of fertility drugs in assisted reproductive therapy?

  To increase the chance of pregnancy
• What hormones are primarily used in fertility drugs?

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

  1. Mother is given FSH and LH to stimulate egg maturation.

  2. Eggs are extracted and fertilized in the lab.

  3. Fertilized eggs develop into embryos.

  4. One or two embryos are inserted into the uterus.
• What are the benefits and cons of IVF?

  Benefits:

  • Provides a way for infertile couples to have children.

  Cons:

  • Physically and emotionally stressful.
  • Low success rate (26%).
  • Risk of multiple births.
  • Can be expensive if repeated.
• What is homeostasis?


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

  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 automatic control systems in homeostasis?

  • Receptors: Detect stimuli (changes).
  • Coordination centres: Process information (e.g., brain, pancreas).
  • Effectors: Bring about responses to restore optimum conditions.
• What is thermoregulation?


  The act of keeping internal body temperature constant
• What happens if body temperature exceeds 37 degrees Celsius?

  Enzymes become less effective and may denature
• Where is the thermoregulatory centre located in the human body?

  In the hypothalamus of the brain
• What mechanisms are involved in regulating body temperature when it is too high?

  • Sweating: Evaporation cools the body.
  • Vasodilation: Increased blood flow to the skin surface.
• What mechanisms are involved in regulating body temperature when it is too low?

  • Sweating stops.
  • Shivering: Rapid muscle contractions generate heat.
  • Hairs stand on end: Insulating layer traps warm air.
  • Vasoconstriction: Reduced blood flow to the skin surface.
• What is the role of insulin in the body?

  To regulate blood glucose levels
• What happens when carbohydrates are consumed?

  They are broken down into glucose, affecting 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, evaporating from the skin surface.
  • Vasodilation occurs, increasing blood flow to the skin surface.
• What happens when human body temperature decreases too much?

  • Sweating stops.
  • Skeletal muscles contract rapidly (shivering) to generate heat.
  • Hairs stand on end to trap warm air.
  • Vasoconstriction occurs, reducing blood flow to the skin surface.
• What is the role of insulin in blood glucose regulation?

  Insulin helps glucose move from the blood into muscle cells and converts excess glucose into glycogen for storage.
• What triggers the pancreas to produce insulin?

  High glucose levels in the blood
• What is glucagon's role in blood glucose regulation?

  Glucagon stimulates the liver to break down glycogen into glucose when blood glucose levels are low.