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KS4 Homeostasis In Humans
Learning Objectives

5.3.1 Human endocrine system

Students should:

• Know that the endocrine system is composed of glands which secrete hormones directly into the blood stream.
• Know that the blood carries the hormone to a target organ where it produces an effect.
• Know that compared to the nervous system the effects of the endocrine system are slower but act for longer.
• Know that the pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions and that these hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
• Be able to identify the position of the following on a diagram of the human body:
  pituitary gland, pancreas, thyroid, adrenal gland, ovary, testes.

​5.3.2 Control of blood glucose concentration

Students should:

• Know that blood glucose concentration is monitored and controlled by the pancreas.
• Know that if the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes glucose to move from the blood into the cells.
• Know that in the liver and muscle cells excess glucose is converted to glycogen for storage.
• Know that Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin.
• Know that Type 1 diabetes is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections.
• Know that in Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas.
• Know that a carbohydrate controlled diet and an exercise regime are common treatments for Type 2 diabetes.
• Know that obesity is a risk factor for Type 2 diabetes.
• Be able to compare Type 1 and Type 2 diabetes and explain how they can be treated.
• Evaluate information around the relationship between obesity and diabetes, and make recommendations taking into account social and ethical issues.
• Know that if the blood glucose concentration is too low, the pancreas produces glucagon that causes glycogen to be converted into glucose and released into the blood. (HT only)
• Be able to explain how glucagon interacts with insulin in a negative feedback cycle to control blood glucose levels in the body. (HT only)

5.3.3 Maintaining water and nitrogen balance in the body

Students should:

• Know that water leaves the body via the lungs during exhalation.
• Know that water, ions and urea are lost from the skin in sweat.
• Know that there is no control over water, ion or urea loss by the lungs or skin.
• Know that excess water, ions and urea are removed via the kidneys in the urine.
• Know that if body cells lose or gain too much water by osmosis they do not function efficiently.
• Know that the digestion of proteins from the diet results in excess amino acids which need to be excreted safely and that in the liver these amino acids are deaminated to form ammonia. (HT only)
• Know that ammonia is toxic and so it is immediately converted to urea for safe excretion. (HT only)
• Know that the kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water.
  (NB: Knowledge of other parts of the urinary system, the structure of the kidney and the structure of a nephron is not required.)
• Be able to translate tables and bar charts of glucose, ions and urea before and after filtration.
• Know that the water level in the body is controlled by the hormone ADH which acts on the permeability of the kidney tubules. (HT only)
• Know that ADH is released by the pituitary gland when the blood is too concentrated and it causes more water to be reabsorbed back into the blood from the kidney tubules and that this is controlled by negative feedback. (HT only)
• Know that people who suffer from kidney failure may be treated by organ transplant or by using kidney dialysis.
• Know the basic principles of the operation of a dialysis machine and describe how kidney dialysis works.
• Evaluate the advantages and disadvantages of treating organ failure by mechanical device or transplant.

5.3.4 Hormones in human reproduction

Students should:

• Be able to describe the roles of hormones in human reproduction, including the menstrual cycle.
• Know that during puberty reproductive hormones cause secondary sex characteristics to develop.
• Know that Oestrogen is the main female reproductive hormone produced in the ovary.
• Know that at puberty eggs begin to mature and one is released approximately every 28 days and that this is called ovulation.
• Know that testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production.
• Know that several hormones are involved in the menstrual cycle of a woman, including:
  - Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary.
  - Luteinising hormone (LH) stimulates the release of the egg.
  - Oestrogen and progesterone are involved in maintaining the uterus lining.
• Be able to explain the interactions of hormones in the control of the menstrual cycle and be able to extract and interpret data from graphs showing hormone levels during the menstrual cycle. (HT only)
• Know that the hormones involved in promoting the release of an egg are: (HT only)
  - follicle stimulating hormone (FSH): this is secreted by the pituitary gland and causes eggs to mature in the ovaries. It also stimulates the ovaries to produce hormones including oestrogen.
  - Oestrogen: this is secreted by the ovaries and inhibits the further production of FSH and stimulates the release of luteinising hormone(LH).  It makes the lining of the uterus grow again after menstruation
  - LH:  from the pituitary this stimulates the release of an egg from the ovary.
  - Progesterone: this is secreted by the empty follicle in the ovary after the egg is released. It inhibits both FSH and LH and maintains the lining of the uterus during the second half of the cycle.

5.3.5 Contraception

Students should:

• Be able to evaluate the different hormonal and non-hormonal methods of contraception.
• Know that fertility can be controlled by a variety of hormonal and non-hormonal methods of contraception, including:
  - oral contraceptives that contain hormones to inhibit FSH production so that no eggs mature.
  - injection, implant or skin patch of slow release progesterone to inhibit the maturation and release of eggs for a number of months or years
  - barrier methods such as condoms and diaphragms which prevent the sperm reaching an egg
  - intrauterine devices which prevent the implantation of an embryo or release a hormone
  - spermicidal agents which kill or disable sperm
  - abstaining from intercourse when an egg may be in the oviduct
  - surgical methods of male and female sterilisation.
• Show why issues around contraception cannot be answered by science alone.
• Be able to explain everyday and technological applications of science; evaluate associated personal, social, economic and environmental implications; and make decisions based on the evaluation of evidence and arguments.

5.3.6 The use of hormones to treat infertility

Students should:

• Be able to explain the use of hormones in modern reproductive technologies to treat infertility.
• Know that you can give FSH and LH in a 'fertility drug' to a woman whose own level of FSH is too low to stimulate eggs to mature, and she may then become pregnant in the normal way.
• Know the steps of In Vitro Fertilisation (IVF) treatment, including that:
  - IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
  - The eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
  - The fertilised eggs develop into embryos.
  - At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus (womb).
• Know that the developments of microscopy techniques have enabled IVF treatments to develop.
• Be able to identify social and ethical issues associated with IVF treatments.
• Know that although fertility treatment gives a woman the chance to have a baby of her own:
  - it is very emotionally and physically stressful
  - the success rates are not high
  - it can lead to multiple births which are a risk to both the babies and the mother.
• Be able to evaluate from the perspective of patients and doctors the methods of treating infertility.

5.3.7 Negative feedback

Students should:

• Be able to explain the roles of thyroxine and adrenaline in the body as negative feedback systems.
• Know that adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
• Know that thyroxine from the thyroid gland stimulates the basal metabolic rate playing an important role in growth and development.
• Know that both adrenaline and thyroxine are controlled by negative feedback.
• Be able to interpret and explain simple diagrams of negative feedback control.

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