B11: Hormonal coordination: humans

• Thyroid


  Located in the neck, produces thyroxine
• Pituitary gland


  Located in the brain, sends signals to other glands
• Pancreas


  Located above the stomach, produces insulin
• Adrenal glands


  Located above the kidneys, produces adrenaline
• Testes


  Produces sperm and testosterone
• Ovaries


  Releases eggs and oestrogen
• Thyroxine


  Controls growth and metabolism.
• Insulin


  Controls blood sugar levels
• Adrenaline


  Prepares the body for dangerous situations:

  -increases heart rate

  -pupils dilate

  -blood moves from the digestive system and to the muscles

  -mental awareness
• ADH


  Anti-diuretic hormone

  Secreted from the pituitary gland
• How does ADH control water reabsorbtion

  Secreted when blood is too concentrated, and travels to the kidneys where in increases the permeability of kidney tubules to water
• Kidney failure


  When the kidneys are unable to filter the blood, which leads to a build-up of toxic material and uncontrolled ion and water balance, causing cells to be damaged
• Kidney dialysis


  A specialist machine which carries out the function of the kidneys
• Dialysis fluid


  Contains the same concentration of glucose and ions as healthy blood, so the excess waste molecules are lost while the useful ones remain
• Four hormones involved in the menstrual cycle

  -Oestrogen

  -progesterone

  -FSH

  -LH
• FSH


  Secreted by the pituitary glands, and triggers the production of oestrogen in the ovaries
• Oestrogen


  Causes the uterus lining to regrow and triggers LH to produce, and restricts FSH from being released
• LH


  Triggers ovulation
• Progesterone


  Sustains the uterus lining
• Contraceptive pill


  Inhibits FSH so eggs don’t mature

  Prevents the uterus lining from developing

  Immobilises sperm
• IUS


  Intrauterine system

  -a small plastic device inserted in the uterus

  -it releases progesterone to thicken the cervical mucus and prevents the uterus lining from thickening
• IUD


  Intrauterine device

  -copper device inserted in the uterus, preventing an embryo from implanting
• Fertility drugs


  they contain FSH (which stimulates insulin production as well as eggs maturing in the ovary) and LH (which triggers ovulation)
• How are thyroxine levels maintained?


  When levels of thyroxine fall, the receptors in the brain detect it.

  Then, the pituitary gland releases more TSH

  This causes more thyroxine to be produced, and levels return to normal