Animal Coordination, control and homeostasis

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  • Section 7 - Animal coordination, control and homeostasis
    • Hormones
      • Hormones are chemical messengers sent in the blood
        • Produced in endocrine glands, making up endocrine system
          • Pituatary gland - produces many hormones that regulate body conditions
          • Thyroid gland - produces thyroxine, which regulates rate of metabolism, heart rate and temperature
          • Adrenal glands - Produce adrenaline for a "fight or flight" response
          • Ovaries - produce oestrogen involved in menstrual cycle
          • Testes - produces testosterone, which controls puberty and sperm production in males
          • The Pancreas - Produces insulin to regulate the blood glucose level
      • Neurones: VERY FAST action, SHORT TIME, PRECISE AREA
      • Hormones: SLOWER action, LONG TIME, GENERAL way
    • Adrenaline and Thyroxine
      • Adrenaline prepares you for "fight or flight"
        • When the brain detects a stressful situation, nervous impulses are sent to the adrenal glands, getting the body ready for action
        • Activates processes that increase the supply of oxygen and glucose to the cells
      • Thyroxine regulates metabolism
        • Negative feedback system
          • Body detects when the level of a system has gone above or below the normal level, it triggers a response to bring it back to normal again
          • Used to keep the amount of thyroxine in the blood at the right level
    • The Menstrual Cycle
      • Monthly sequence of events where the egg is released and uterus is prepared in case of fertilisation
      • Stage 1 - Day one, the lining of the uterus breaks down and is released
      • Stage 2 - From day 4-14, the lining is repaired until it becomes a spongy layer full of blood vessels for an egg to be implanted there
      • Stage 3 - Egg released at day 14
      • Stage 4 - Lining maintained until day 28 when the cycle repeats
      • Controlled by 4 hormones: FSH (follicile stimulating hormone), Oestrogen, LH (Luteinising hormone), Progesterone
    • Controlling Fertility
      • Hormones can be used to treat infertility
        • Clomifene therapy
          • Clomifene drug causes more FSH and LH to be released and women to ovulate more regularly, improving pregnancy chances if the couple have intercouse during this period
        • IVF
          • Eggs are collected from the woman's ovaries and fertilised in a lab using the man's sperm. They are grown into embryos, and once they are tiny balls of cells 1 or 2 are transferred to the woman's uterus to improve the chance of pregnancy
      • Contraceptives are used to prevent pregnancy
        • Oestrogen can be used to prevent the release of an egg
        • Progesterone can be used to reduce fertility by stimulating the production of thick cervical mucus, preventing the egg and sperm from meeting
        • Barrier methods such as condoms or diaphragms
      • Hormonal methods are more effective if used correctly, and couples don't have to worry about them before intercourse
      • Hormonal methods have unpleasant side effects and don't prevent STIs
    • Homeostasis - control of blood glucose
      • Maintaining a constant internal environment
        • Blood glucose regulation
          • the amount of glucose in your blood can't be too low or high
        • Thermoregulation
          • reducing and increasing body temperature based on warmth of environment
        • Negative feedback systems keep conditions in the body steady
        • Osmoregulation
          • Keeping a balance in the water gained and the water peed, sweated and breathed out
      • Insulin and Glucagon control blood glucose concentration
        • If blood glucose is too high, insulin is added
        • If blood glucose is too low, Glucagon is added
    • Diabetes
      • Type 1 diabetes is caused by lack of insulin
        • Pancreas produces little or no insulin
        • Type 1 Diabetic people are treated with insulin therapy
          • Insulin injected into subcutaneous tissue at mealtimes
        • Also need to think about limiting simple carbohydrates and taking regular excercise
      • Type 2 diabetes is caused by resistance to insulin
        • Correlation between type 2 diabetes and obesity. People are classified as obese if they have a BMI of over 30.
        • If waist-to-hip ratio is too big people are at higher risk due to increased fat around abdomen
        • Type 2 diabetes can be controlled by eating a healthy diet and regular excercise




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