B11 Hormonal Coordination

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  • Created by: Lucy Hart
  • Created on: 29-02-20 19:40
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  • B11 Hormonal Coordination
    • B11.1 Principles of Hormonal Control
      • endocrine system is composed of glands that secrete chemicals (hormones) directly into bloodstream
        • pituitary - master gland, secretes variety of hormones into blood in response to changes in body conditions
        • thyroid - controls metabolic rate
        • pancreas - controls glucose in blood (insulin)
        • adrenal - fight or flight (adrenaline)
        • ovaries + testes - secondary sexual characteristics
      • effects are slower + long lasting compared to nervous system
    • B11.4 Role of Negative Feedback
      • maintain a steady state so response causes the opposite
      • thyroxine
        • thryoxine in blood falls, detected by sensors, TSH increases stimulating production of TSH
        • controlled by negative feedback whereas adrenaline isn't
    • B11.6 Hormones + Mentrual Cycle
      • lasts 28 days, day 14 ovulation, 14 days after lining shed
      • 1. FSH (pitutiary) causes eggs to mature + stimulates oestrogen
        • 2. oestrogen (ovaries) causes the lining of the uterus to develop, inhibits FSH + stimulates LH
          • 3. LH (pituitary) - stimulates ovulation
            • 4. progesterone - maintains the lining of the uterus, inhibiting FSH + LH
    • B11.7 Contraception
      • hormone based
        • patch, injections, implant
        • mixed pill
          • progesterone + oestrogen
          • inhibit production of FSH so no eggs mature + stop lining developing
        • single pill
          • progesterone
          • less side effects
      • chemical
        • spermicides
      • barrier
        • condom
        • diaphragm
      • intrauterine devices
        • small structures inserted in uterus
      • surgical methods
        • vasectomy - sperm ducts cut + tied
    • B11.8 Infertility Treatments
      • don't produce enough FSH
      • IVF
        • 1. mother given FSH to stimulate eggs followed by LH to bring eggs to ovulation
          • 2. collect eggs + fertilise with sperm in lab
            • 3. warm in environment for embryos to develop
              • 4. inserted back into uterus
      • DisAds - expensive, not always successful, health risks, multiple pregnancy
    • B11.9 Plant Hormones + Responses
      • responses of plants - tropisms
        • phototropism - response to light
          • auxin moves to dark side causing uneven growth resulting in shoot leaning towards light
        • gravitropism - response to gravity
          • shoots grow on side with most auxin making it bend + grow away from gravity
          • roots grow more on the side with least auxin making it bend + grow down towards the force of gravity
    • B11.10 Using Plant Hormones
      • gibberellins - speeding up germination
      • ethene - speeding up ripening
      • auxin - weed killers
    • 11.6 Human Reproduction
      • female hormone
        • oestrogen - rising levels at puberty (8-14) trigger development of secondary characteristic
      • testosterone
        • testes - trigger secondary charateristic (9-15)
    • B11.2 Control of Blood Glucose Levels
      • pancreas monitors + controls blood glucose concentration
      • 1. blood glucose rises after meal
        • 2. pancreas releases insulin which moves glucose to cells
          • 3. glucose converted into insoluble carbohydrate + stored in liver (glycogen)
            • 4. blood glucose falls
              • 5. glucagon makes liver break down glycogen releasing into blood
    • B11.3 Treating Diabetes
      • type 1
        • pancreas doesn't secrete enough insulin
          • treatment - need replacement insulin (injections) before meals
          • cures - transplant (not enough donors), transplanting pancreatic cells (limited success)
      • type 2
        • stop body responding to own insulin
        • linked to obesity, lack of exercise
          • treatment - exercise, balanced diet

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