homeostasis and response

• oestrogen 


  a hormone secreted by the ovaries that inhibits the production of FSH and triggers the production of LH

  main female sex hormones
• progesterone

  a hormone that repairs the lining of the uterus after menstruation and prevents it breaking down
• ovulation

  the release of an egg (ovum) from the ovary into the fallopian tube
• testosterone

  a hormonal produced by the testes that controls the male sexual characteristics
• menstrual cycle

  the monthly cycle of an egg being released in females; controlled by hormones
• FSH ( follicle stimulating hormone)


  a hormone released by the pituitary gland that causes an egg to develop in the ovaries
• LH (luteinising hormone)


  a hormone that stimulates the release of an egg in the menstrual cycle
• contraception

  mechanisms that are used to prevent pregnancy occuring as a result of sexual intercourse
• endocrine system

  a system of glands that release hormones directly into the bloodstream
• hormone

  a chemical messenger produced by a gland that travels in the blood to its target organ
• pituitary gland

  a small gland at the base of the brain that produces hormones known as the 'master gland'
• type 1 diabetes 


  a condition where not enough insulin is produced by the pancreas
• type 2 diabetes 


  a condition where insulin is produced but the cells of the body do not respond to it
• homeostasis

  the process of keeping the internal conditions of the body constant
• receptors

  cells found in sense organs

  eg

  eyes, ears , nose
• effectors

  part of the body ( a muscle or a gland ) that produces a response or stimuli
• central nervous system (CNS)

  the part of the central nervous system made up of the brain and spinal cord
• synapse

  the gap between two neurons
• hormones play many roles in controlling human reproduction.
• hormones play many roles in controlling human reproduction.

  during puberty, the sex hormone causes secondary sexual characteristics to develop.
• after puberty, men produce sperm continuously but women have a monthly cycle of events called the menstrual cycle
• if the blood glucose concentration is too high:

  • the pancreas releases more of the hormone insulin.
  • insulin causes glucose to move from the blood into the cells.
  • in liver and muscle cells, excess glucose is converted to glycogen for storage.
• type 1 diabetes

  • is caused by the pancreas failing to produce sufficient insulin.
  • results in uncontrolled high blood glucose.
  • is usually treated with insulin injections.
• type 2 diabetes

  • is caused by the body cells no longer responding to insulin.
  • is treated with a carbohydrate-controlled diet and regular exercise.
• responding to a stimulus 


  reflex actions are automatic and rapid so they can protect the body. They do not involve the conscious part of the brain:

  1. the pain stimulus is detected by receptors.
  2. impulses from the receptor pass along a sensory neurone to the central nervous system.
  3. an impulse then passes through a relay neurone.
  4. a motor neurone carries an impulse to the effector.
  5. the effector (usually a muscle) responds eg to withdraw a limb away from the sauce of pain.
• hot plate (stimulus)

  finger tip ( receptor)

  sensory neurone

  relay neurone

  motor neurone

  effector cells (muscle)