GCSE edexcel biology : topic 7

• what does BMI stand for?

  Body Mass Index
• when are people classed as obese?

  when they have a BMI over 30
• which type of diabetes correlates with obesity?

  type 2
• what is type 2 diabetes?

  a condition when the pancreas doesn't produce enough insulin or when a person becomes resistant to insulin (their body's cells don't respond properly to the hormone)
• what are the dangers of injecting too much insulin in insulin therapy?

  it could result in a dangerously low blood glucose level
• what do people with type 1 diabetes need to consider apart from insulin therapy?

  •limiting their intake of foods rich in simply carbohydrates (sugars) which cause the blood glucose level to rise rapidly. •taking regular exercise which helps to remove excess glucose from the blood
• what does the amount of insulin someone with type 1 diabetes needs to inject depend on?

  the person's diet and how active they are
• where is insulin normally injected in people with type 1 diabetes?

  in the subcutaneous tissue - the fatty tissue just underneath the skin
• how can a person with type 1 diabetes be treated?

  with insulin therapy: this usually involves injecting insulin into the blood and is often done at mealtimes so the glucose is removed from the blood quickly once the food has digested.
• what is type 1 diabetes?

  a condition when the pancreas produces little to no insulin
• which types of contraceptives are more effective when used correctly?

  hormonal contraceptives
• what is the cervix?

  the entrance to the uterus
• what is the entrance to the uterus also called?

  the cervix
• how can progesterone be used as a contraceptive?

  progesterone can be used to reduce fertility by stimulating the production of thick cervical mucus, preventing sperm from getting through the cervix and reaching an egg
• how can oestrogen be used as a contraceptive?

  oestrogen can be used to prevent the release of an egg. although oestrogen is naturally used to stimulate the release of eggs, if it is taken every day to maintain a high level of oestrogen then it inhibits the production of FSH and as a result egg development and egg production stop.
• how does IVF work?

  eggs are collected from the female's ovaries and they are fertilised in a lab using the male's sperm. before egg collection FSH and LH are given to stimulate egg production. when the embryos have developed into balls of cells on or two of them are implanted into the uterus to improve the chance of pregnancy.
• what are the main methods an infertile couple could resort to in order to become pregnant?

  clomifene therapy and IVF
• what happens if a fertilised egg implants in the uterus?


  the woman becomes pregnant and the level of progesterone will remain high to maintain the lining of the uterus during pregnancy
• what is the womb also known as?

  the uterus
• what is another name for the uterus?

  the womb
• what is the menstrual cycle?

  a monthly sequence of events in which the female body releases an egg and prepares the uterus in case the egg is fertilised.
• what can an underactive thyroid gland cause?

  weight gain because less thyroxine means that the metabolic rate decreases, this results in less of the glucose which is taken into the body being broken down in respiration and so more is stored as fat.
• what system controls the levels of hormones in the blood?

  the negative feedback system
• describe the process in which adrenalin prepares the body for a fight-or-flight response.

  •adrenalin binds to specific receptors in the heart which causes the heart muscle to contract more frequently and more forcefully so heart rate and blood pressure. •this increases blood flow to the muscles so the cells receive more oxygen and glucose for increased respiration •adrenalin binds to receptors in the liver to cause the liver to break down its glycogen stores to release glucose. •this increases blood glucose level so there's more glucose in the blood to be transported to cells. overall, heart rate increases, blood pressure increases, blood flow increases, blood glucose levels increases, and respiration increases in cells for more energy in the fight-or-flight response.
• what response does adrenalin prepare the body for?

  fight-or-flight response
• why are neurone responses quick? why can't hormones be used for these types of responses?


  the information needs to be passed to the effectors really quickly, for example, pain signals or warnings from your eyes, hormones can't be used for these types of responses because the hormones are too slow to carry the information quickly.
• what are the differences between neurones and hormones?

  neurones: fast action, act for a short amount of time, act in a precise area. hormones: slower action, act for a long amount of time, act in a more general way.
• what are the endocrine glands that you need to know?

  •the pituitary gland •the thyroid gland •the ovaries •the testes •the adrenal glands •the pancreas
• what are the target organs for the pituitary gland?

  the ovaries, the kidney
• what are endocrine glands?


  where hormones are produced
• what glands make up the endocrine system?

  endocrine glands
• what are hormones?

  hormones are chemicals released directly into the blood, which affect target cells. Hormones control 'things' in organs and cells that need constant regulation and adjustment.
• What is the cause of type 1 diabetes?

  the person's insulin-producing cells have been destroyed, so they do not release insulin.
• Why must blood glucose concentration be controlled?

  To maintain a constant internal environment for the body's enzymes to function correctly. Too little or too much glucose can damage organs, resulting in unconsciousness or death.
• When insulin is present which substance is formed from glucose in the target cells?

  glycogen
• What is the target organ for insulin?

  The liver or a muscle
• How does clomifene therapy work?

  •Clomifene is a drug which blocks the effect of oestrogen, this makes the body increase the amounts of the two hormones essential for ovulation: FSH and LH. •FSH causes the eggs to mature in the ovaries and LH triggers the release of one or more mature eggs from the ovaries (ovulation) •by knowing when the woman will be ovulating the couple can have intercourse during this time to increase the chance of becoming pregnant.
• What is clomifene therapy?

  Clomifene therapy is a drug treatment to stimulate ovulation.
• How are hormones used in IVF?

  FSH and LH are used to stimulate egg production so that more than one egg can be collected for IVF
• describe the process of IVF.

  •The woman's natural menstrual cycle is suppressed with medication •FSH and LH are used to stimulate the ovaries to produce more eggs than normal •the eggs are monitored and hormones are used to help them mature •the eggs are collected •the eggs are out in contact with the sperm and left for a few days to fertilise •one or two embryos are placed into the womb