homeostasis and response

• what is homeostasis?


  the process of keeping the internal conditions of the body constant
• what are receptors?


  cells found in the sense organs (eyes, ears, nose)
• what are effectors?


  part of the body (muscle or gland) that produces a response to a stimuli
• reflex actions are automatic and rapid so they can protect the body; they do not involve the conscious part of the brain
• how does the body respond to a stimulus?

  steps:

  1. the pain stimulus is detected by receptors
  2. impulses from the receptor pass along the 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
• what is the central nervous system?


  the part of the nervous system made up of the brain and the spinal cord
• what is negative feedback?


  a set of events that detects a variable and then corrects any change in the variable away from a set value
• what is a synapse?

  the gap between two neurones (nerve cells) where electrical and chemical signals are transmitted
• investigating reaction time: RP

  investigating the effect of a factor on human reaction time
• method for investigating reaction time RP

  method:

  1. experimenter holdings a metre ruler from the end
  2. the subject has their finger and thumb a small distance apart, either side of the ruler, on the 0cm line
  3. the experimenter lets go of the ruler and subject has to trap it
  4. the distance the ruler travels from the 0cm line is noted
  5. repeat experiment on subjects that have drunk caffeine and subjects that have not
• what is the independent variable of investigating reaction time?


  whether the subject has taken caffeine or not
• what is the dependent variable of investigating reaction time RP?

  the distance the ruler travels
• what is the control variable of reaction time RP?

  the age, sex and mass of subjects
• what is the endocrine system?

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

  a chemical messenger produced by a gland that travels in the blood to its target organ
• what does the body do if glucose concentration is too high?

  it:

  • 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
• what does the body do if blood glucose concentration is too low?

  the pancreas releases glucagon and glucagon stimulates glycogen to be converted into glucose and released
• what is type 1 diabetes?

  a condition where not enough insulin is produced by the pancreas
• what causes type 1 diabetes?

  the pancreas failing to produces sufficient insulin
• what does type 1 diabetes result in?

  uncontrolled high blood glucose
• how is type 1 diabetes treated?

  insulin injections
• what is type 2 diabetes?

  a condition where insulin is produced but the cells of the body do no respond to it
• what is type 2 diabetes caused by?


  body no longer responding to insulin
• how is type 2 diabetes treated?

  carbohydrate-controlled diet and regular excercise
• what is adrenaline?


  hormone released from the adrenal gland, which prepares the body for 'fight or flight'
• what is thyroxine?


  a hormone released by the thyroid gland that controls the metabolic rate of the body
• what causes secondary sexual characteristics to develop?

  the sex hormones during puberty
• what is oestrogen?


  a hormone secreted by the ovaries that inhibits the production of FSH and triggers the production of LH
• what is ovulation?


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


  a hormone produced by the testes that controls the male sexual characteristics
• what is the menstrual cycle?

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


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


  a hormone that stimulates the release of an egg in the menstrual cycle
• what is progesterone?


  a hormone that repairs the lining of the uterus after menstuation and prevents it breaking down
• why might doctors give women FSH and LH in a fertility drug?

  if her own level of FSH is too low too stimulate eggs to mature
• what is contraception?


  mechanisms that are used to prevent pregnancy ocurring as a result of sex
• what is a fertility drug?

  a drug that makes it more likely for sex to result in pregnancy
• what is in vitro fertilisation (IVF)?

  a process in which an egg is fertilised by sperm outside of the body
• what are the steps of IVF?

  steps:

  • giving a woman FSH and LH to stimulate the growth of many eggs
  • collecting eggs from the woman
  • fertilising the eggs with sperm from the father in a laboratory
  • inserting one or two embryos into the womans uterus
• what are some disadvantages of IVF?

  :

  • expensive
  • emotionally and physically stressful
  • success rates are not high
  • can lead to multiple births which are a risk to both the babies and the mother