Hormonal Coordination

• endocrine system


  • sends hormones around body
• hormone


  chemical messenger

  • acts on specific target organ
• how endocrine system works

  1. glands secrete hormones into bloodstream
  2. blood carries hormone to target organ
  3. response
• difference between nervous system and endocrine system

  • nervous - electrical impulses
  • endocrine - hormones
  • nervous - extremely fast signals
  • endocrine - slower, lost lasting effects
• endocrine glands


  • pituitary
  • thyroid
  • pancreas
  • adrenal
  • ovaries
  • testes
• pituitary (master) gland


  • secretes hormones into the blood
  • effect on the body or stimulate glands to produce hormones
• pancreas


  • secretes insulin
  • controls blood glucose levels
• thyroid gland


  • secretes thyroxine
  • controls metabolic rate located at base of neck
• adrenal gland


  • secretes adrenaline
  • controls body’s response to stressful situations located at top of kidneys
• ovary


  • secretes oestrogen
  • involved in menstrual cycle, development of female secondary sexual characteristics
• testes


  • secretes testosterone
  • involved in production of sperm, development of male secondary sexual characteristics
• why blood glucose concentration is controlled

  • glucose releases energy in respiration
  • important it is kept constant
• what monitors/controls blood glucose concentration?

  pancreas
• how blood glucose concentration is controlled

  • eating carbohydrates increase glucose levels in blood
  • pancreas produces insulin if glucose levels are too high
  • glucose moves from blood to muscle for respiration
  • excess glucose converted and stored as glycogen in liver
• types 1 diabetes


  • pancreas doesn’t produce enough insulin
  • blood glucose level gets very high
  • kidneys excrete glucose with urine
• treating type 1 diabetes

  • replacement insulin injections before meals, glucose taken into bloodstream
  • limit carbohydrate intake
• curing type 1 diabetes

  • pancreas/pancreatic cell transplant
  • difficult and risky
• type 2 diabetes


  • body stops responding to insulin
  • risk factor: obesity, lack of exercise, genetics
• treating type 2 diabetes

  • balanced diet
  • losing weight
  • regular exercise
  • drugs make insulin more effective, help pancreas make more insulin
• blood glucose concentration is too low

  • pancreas releases hormone glucagon
  • glucagon triggers liver to convert glycogen to glucose
• menstrual cycle


  • every 28 days, ovary releases an egg
  • uterus lining thickens
  • ovulation: egg -> uterus, fertilised if sperm present
  • menstruation/period - uterus lining breaks down
• Follicle Stimulating Hormone (FSH)


  • causes egg to mature in ovary
  • stimulates ovaries to produce oestrogen
• Luteinising Hormone (LH)


  • ovulation - mature egg is released
• oestrogen

  • causes uterus lining to grow again, stimulates production of LH, inhibits secretion of FSH
• progesterone


  • maintains lining of the uterus inhibits release of FSH and LH
• hormones in the menstrual cycle

  • FSH
  • LH
  • oestrogen
  • progesterone
• oral contraceptives e.g. pill

  • prevent body from producing FSH and egg maturing
• oral contraceptive advantages


  • highly effective
  • more regular + lighter periods
• oral contraceptive disadvantages


  • taken everyday
  • risk of pregnancy
  • risk of side effects e.g. blood pressure, breast cancer
• other hormonal methods:


  implant - last 3 years

  injection - last around 13 weeks

  patch - lasts 1 week

  • all have progesterone
• hormonal methods advantages


  • highly effective
  • convenient, less likely to fail
  • regular + lighter periods
• hormonal methods disadvantages


  • no protection against STIs
• barrier methods

  • prevent sperm reaching egg
  • condoms
  • diaphragm
• barrier methods advantages

  • no side effects
  • reduce risk of STIs
• barrier method disadvantages 


  • condom breaks/slips off
  • cap doesn’t protect against UTIs
• surgical methods

  • sterilisation stops egg reaching uterus or sperm leaving penis
  • vasectomy - block/seal oviducts or cut/seal off tubes carrying sperm
• surgical methods advantages


  • sterilisation is highly effective
  • no hormones involved
• surgical methods disadvantages


  • no protection against STIs
  • sterilisation is difficult to reverse
  • risk of infections
• natural form

  • abstaining from sexual intercourse after ovulating
• natural forms disadvantage


  • hard to tell when woman has ovulated
  • no protection against STIs