Human health and physiology

5.1.1     Explain why digestion of large food molecules is essential (cross reference topic 2).

The need for increasing the rate of digestion is the important point.

5.1.3    State the source, products and optimum pH conditions for one amylase, one protease and one lipase.

Any human enzymes can be selected. Details of structure or mechanisms of action are not required.

5.1.4    Draw a diagram of the digestive system including mouth, oesophagus, stomach, small intestine, large intestine, anus, liver, pancreas, gall bladder.

The important points are the relative sizes, positions and order – not artistic accuracy.

Microscopic details of the structure of the intestinal wall are not required.

5.1.6     Define absorption.

Refer briefly to the differing needs of groups of individuals: such as young, old, sick, active, pregnant and lactating.

5.1.8    Explain the general importance of vitamins and minerals.

Lists of vitamins and minerals are not required, only an explanation of their general importance. The option on Diet and Human Nutrition deals with specifics.

An example could be chosen from anorexia, obesity, a specific deficiency disorder, etc., according to local conditions or needs. The specific problem could exemplify the main concepts in this sub-topic.

 

5.2.1     Describe the action of the heart in terms of collecting blood, pumping of blood and opening and closing valves.

5.2.1- A basic understanding limited to the collection of blood by the atria

5.2.2  which is then pumped out by the ventricles into the arteries. The direction of flow being controlled by atrio-ventricular and semilunar valves. All blood vessels connected directly to the heart including coronary vessels should be known. Care should be taken to show relative wall thickness of the four chambers. The histology of heart is not required.

Histology of heart muscle, names of nerves or transmitter substances is no required. The intention is that the students understand that the heart beats ‘of its own accord’ and is made to peed up or slow down, under involuntary control, by means of nerves and hormones.

5.2.4     Explain the relationship between the structure and function of arteries, capillaries and veins.

Detailed classification of leucocytes is not required.

5.2.6    State that the following are transported by the blood: heat, nutrients, oxygen, carbon dioxide, hormones, antibodies, waste products.

No chemical details are required.

An example could be chosen from coronary heart disease, heart pacemakers, haemophilia, etc., according to needs/wishes of teachers. The specific problem could exemplify the main concepts in this sub-topic.

 

5.3.1    State that disease can be caused by a variety of organisms.

Specific names of specific diseases are not expected, just the range of types of organisms. The point is the appreciation that many ‘types’ of organism cause disease.

 

5.3.2    Explain how skin and mucous membranes act as barriers against microbes.

A diagram of a section of a skin is not required.

 

5.3.3    Outline that phagocytic leucocytes ingest disease causing organisms in the blood and in body tissues.

Details of the sub-divisions and classifications of phagocytes is not required.

5.3.4     State the difference between antigen and antibody.

5.3.5     Explain antibody production.

B-lymphocytes in bone marrow produce, during development, clones of identical cells programmed to secrete a specific antibody when recognising one type of antigen (surface recognition sites, humoral immunity and memory cells may mentioned). Details of the structure of the antibody molecules is not required, beyond the ‘existence of an antigen binding site’.

AIDS, being a syndrome has very varied symptoms, being determined mostly by secondary infections, therefore knowledge of these is not required. An in-depth knowledge of the immune system and AIDS is required by AHL only. The effects of AIDS at SSC should be limited to a reduction in helper T-cells, which lowers the communication between cells of the immune system leading to infection by certain bacteria, fungi, protoctists and viruses.

Notes: The emphasis in on basic knowledge that can lead to a better understanding of gas exchange in relation to general health and fitness.

5.4.1     Describe four features of alveoli that allow them to carry out gas exchange efficiently.

5.4.2     Explain the necessity for a ventilation system.

The important points are the relative positions and relative sizes – not artistic accuracy.

5.4.4     State the difference between breathing and cell respiration.

Limited to increases in stoke volume of heart and increased tidal volume of lungs leading to a lowering of rate of both heart beat and ventilation rate.

5.4.6    Explain how and why breathing rate varies with exercise.

Limited to the effect of changes in carbon dioxide concentration leading to a lowering of blood pH, which is detected by chemosensors (in the aorta and carotid arteries) that send impulses to the breathing centre of the brain (in the brain stem). This then sends nerve impulses to the diaphragm and intercoastal muscles to increase the contraction/relaxation rates. Emphasis that this is under involuntary control, but can be controlled voluntarily to some extent. Mention of inspiratory and expiratory centres, partial pressure, carotid and aortic bodies, and a formula for pulmonary ventilation is not required.

5.4.7    Outline one health problem concerned with gas exchange.

An example could be chosen form smoking and cancer, tuberculosis, asthma, emphysema, etc.  The specific problem could exemplify the main concepts in this topic.

5.5        Homeostasis

5.5.1     Define homeostasis.

For thermoregulation refer to monitoring of both skin temperature (by thermoreceptors in the skin) and blood temperature (by thermoreceptors) in heat centres in the (hypothalamus) brain. Heat can be gained or lost by active mechanisms, most are under unconscious control although conscious behavioral mechanisms are important. Warming up mechanisms (vasoconstriction, increased cell metabolism, shivering), cooling down mechanisms (vasodilation, sweating – refer to 2.1.6, decreased metabolism). Conduction, convection and radiation, in outline only. Knowledge of brown fat or two heat centres in hypothalamus is not required.

For glucose regulation, refer to monitoring of glucose (by chemoreceptors) in the pancreas. Levels rise due to diet or release from live and muscles by demand and falls due to respiration or conversion to other metabolites or for storage (glycogen). If levels are low, the pancreas secretes glucagon which stimulates liver cells to convert (enzymically) glycogen directly to glucose and amino acids indirectly to glucose. If levels are high, other pancreas cells secrete insulin that stimulate cell respiration, increased absorption of glucose by muscle cells, increased conversion of glucose to fat (in adipose tissue) and to glycogen in liver and muscle cells. Reference to islets of Langerhans, a and b cells, specific enzymes, hypothalamus control or types of diabetes are not required.

5.5.3    Explain the concept of negative feedback (cross reference 5.6.4 and 5.6.9)

Its importance is illustrated by 5.5.2.

5.5.4    State that the nerve and the endocrine systems are involved in homeostasis.

Refer to thermoregulation (mainly nerves) and glucose regulation (mainly hormones).

No structural or functional division of the nervous system or details of impulse transmission or synapses are required.

5.5.6    State that the endocrine system consists of glands which release hormones that are transported in the blood.

The nature and action of hormones or direct comparisons between nerve and endocrine systems are not required.

5.5.7     Define excretion.

5.5.8     Define osmoregulation.

Details of structure or physiology are not required.

5.6        Reproduction

5.6.1     Explain that sexual reproduction promotes variation in a species (cross reference 3.3.3)

The important points are relative positions of the organs – not artistic accuracy. Do not include any histological details.

MALE URINOGENITAL SYSTEM

FEMALE URINOGENITAL SYSTEM

5.6.3    Explain the role of hormones in regulating the changes of puberty (testosterone, oestrogen) in boys and girls, and in the menstrual cycle (FSH, LH, oestrogen and progesterone).

Reference to the fact that in males LH is called ICSH and the involvement of the hypothalamus (releasing factors) in both sexes are not expected. Emphasise feedback control (cross reference 5.5). Menstrual cycle should include graphs showing relative changes of hormone levels and endometrium.

 



 

Histological changes in the ovary, testis and mammary glands are not required.

5.6.5    State the difference between copulation and fertilisation.

Acrosome reaction, meiotic details, etc., are required only for AHL (topic 11) not here.

5.6.6    Describe early embryo development up to the implantation of the blastocyst.

Limited to several mitotic cleavages to form a solid ball of cells (blastomers) are called a morula; further divisions to hollow blastocyst. Refer to time scale involved and absorption of nutrients by the blastocyst. Details of the implantation process and changes to the zona pellucida and corona radiata are not required.















 

5.6.7    State that the fetus is supported and protected by the amniotic fluid.

Embryonic details of fetus, structure of amniotic membranes or placenta are not expected.

 

5.6.8     State that materials are exchanged between the maternal and fetal blood in the placenta.

Refer to the three stages of birth (labour, delivery and afterbirth) and the interaction between nerves and hormones. Mention the unusual situation of positive feedback. Details of lactation, breast feeding and changes in fetal circulation are not required.

 

5.6.10    Describe four methods of family planning and contraception.

5.6.11    Discuss the ethical issues of family planning and contraception.

Amniocentesis involves withdrawing some amniotic fluid containing embryonic cells sing a syringe. It can be diagnose nearly 400 conditions from chromosomal abnormalities to biochemical disorders. CVS involves removing tissue, very early in the pregnancy, from the chorion, via the vagina. Mention possible risks from the procedures.

5.6.13    Outline the process of in vitro fertilisation (IVF).

5.6.15    Outline three developments from human embryo research including embryo storage and early detection of chromosome abnormalities.

A third example could be early diagnosis of biochemical or other abnormalities, production of contraceptive vaccines, use of nerve tissue to relieve Parkinson’s disease, etc. It cross references with 2.7.9. This area will undoubtedly develop during the life of the syllabus. This area is also clearly full of ethnical issues with different national legal situations, both of which will change. This situation means that discussion of ethnical issues will not be examined.