specific topic review

• Endocrine system

  Allows different parts of our body to communicate with each other
• Endocrine system


  Similar job to nervous system, but with lots of differences
• Endocrine system


  • Consists of a series of glands found throughout the body
  • Glands secrete hormones, which are small chemical molecules passed into the blood and spread throughout the body
• Hormones


  Act as signals to trigger certain changes inside cells
• Pituitary gland


  • Produces multiple different hormones
  • Some hormones directly tell the body what to do
  • Some hormones tell other glands to release their own hormones
  • Not actually part of the brain, but attached to it
• Thyroid gland


  • Produces the hormone thyroxine
  • Relates to the rate of our metabolism
  • Plays an important role in growth and development
• Thyroid stimulating hormone (TSH)

  1. Pituitary gland detects low levels of thyroxine

  2. Pituitary gland releases TSH

  3. TSH stimulates the thyroid to produce more thyroxine

  4. Brings the level of thyroxine back up to normal
• Negative feedback


  If thyroxine levels are too low, they are stimulated to rise again, and if they went too high, they are brought back down
• Adrenal glands


  • Produce the hormone adrenaline
  • Normally released during the fight-or-flight response
  • Increases heart rate and gets blood pumping faster
• Pancreas


  • Produces the hormone insulin
  • Helps regulate blood glucose concentrations
• Testes


  • Produce the hormone testosterone
  • Control puberty
  • Produce male gametes (sperm) for reproduction
• Ovaries


  • Produce the hormone estrogen
  • Influence puberty and the menstrual cycle
  • Hold female gametes (egg cells)
• Endocrine system vs. Nervous system

  • Endocrine system uses hormones (small molecules secreted by glands and transported in the blood)
  • Nervous system uses electrical impulses transferred along nerve cells
  • Hormones spread more slowly and their effects last longer
  • Nerve impulses are sent very fast and the effects don't last long (often less than a second)
  • Hormones act more generally and interact with many different cells
  • Nerve impulses are sent to one specific area
• Human body

  A) pituitary gland

  B) adrenal gland

  C) pancreas

  D) testis

  E) ovary

  F) thyroid gland

  
• How the hormone ADH is used to control the water level in the blood

  1. Blood becomes too concentrated

  2. Pituitary gland releases ADH

  3. ADH causes kidneys to reabsorb more water

  4. Blood water level returns to normal

  5. Pituitary gland stops releasing ADH
• How the blood becomes too dilute

  1. Person drinks large amount of water

  2. Concentration of water in blood rises

  3. Pituitary gland stops releasing ADH

  4. Kidneys reabsorb less water

  5. Concentration of water in blood returns to normal
• Kidney dialysis


  Process to adjust levels of water, ions and urea when kidneys fail
• How kidney dialysis works

  1. Patient's blood passes over a semipermeable membrane

  2. Urea, ions and water pass through but not larger molecules

  3. Dialysis fluid contains normal concentrations of water and ions but no urea

  4. Urea diffuses from blood into dialysis fluid

  5. Water and ions diffuse from blood into dialysis fluid to return to normal concentrations
• Kidney dialysis


  • Patients have to visit hospital several times a week
  • Patients have to eat controlled diet
• Kidney transplant


  Diseased kidney replaced with healthy kidney from donor
• Donated kidney


  May be rejected by patient's immune system
• Advantages of kidney dialysis

  • No shortage of dialysis machines
• Disadvantages of kidney dialysis

  • Frequent treatments make it inconvenient
  • Patients require controlled diet
  • Expensive and requires long-term treatment
• Advantages of kidney transplant

  • Patients can lead normal life
• Disadvantages of kidney transplant

  • Shortage of donors
  • Patients have to take anti-rejection drugs for life
  • Expensive initially
• Hormones


  Chemicals released by glands into the bloodstream that trigger effects in specific target organs
• Endocrine system


  • The system that involves the release of hormones into the bloodstream
• Secondary sexual characteristics


  Physical features that develop during puberty and distinguish the two sexes, e.g. pubic hair in men
• Testosterone


  Hormone produced by the testes that stimulates the production of sperm
• oestrogen

  Hormone produced by the ovaries
• Ovulation


  The release of an egg from the ovary every 28 days
• Menstrual cycle


  The 28-day cycle involving the release of an egg and the preparation of the uterus lining
• Key hormones in the menstrual cycle

  • Follicle Stimulating Hormone (FSH)
  • Luteinizing Hormone (LH)
  • Estrogen
  • Progesterone
• Follicle Stimulating Hormone (FSH)


  Causes an egg to mature in the ovary
• Luteinizing Hormone (LH)


  Causes the mature egg to be released (ovulation)
• Estrogen


  Maintains the uterus lining
• Progesterone


  Maintains the uterus lining and prevents further egg maturation and release
• Menstrual cycle


  1. FSH released by pituitary gland

  2. FSH causes egg maturation and estrogen production in ovary

  3. Estrogen inhibits further FSH release

  4. LH released by pituitary gland

  5. LH triggers ovulation

  6. Ovary releases progesterone

  7. Progesterone maintains uterus lining

  8. If no fertilization, progesterone levels fall, uterus lining shed (period)
• Hormones


  Used to treat infertility
• IVF (In Vitro Fertilization)

  1. Mother treated with FSH and LH to cause several eggs to mature

  2. Eggs collected from mother

  3. Sperm from father used to fertilize eggs in laboratory

  4. Fertilized eggs develop into embryos

  5. Embryos inserted into mother's uterus