Revision:OCR AS Biology - Human Health and Disease
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Human Health and Disease
Introduction to Health and Disease
Define Health and disease: Health is physical, mental and social well being. It is more than just being free from disease.
Disease is a malfunction of the mind or body leading to a condition of poor health.
Health is more than just simply the absence of disease, some may not suffering from the symptoms of a disease may have low physical fitness and may be developing a serious condition such as heart disease or lung cancer.
Categories of disease and illness
- Social - Living conditions and behavior are factors in development of disease
- Smoking related disease, TB
- Physical - Permanent or temporary damage to the body
- Changes to the mind, with or without known physical cause
- Non infectious - Any disease not caused by a pathogen
- Lung cancer, night blindness
- Infectious - Organisms (pathogen) invade the body
- Deficiency - Caused by poor diet
- Degenerative - Gradual decline in a function or functions of the body
- Inherited - An inherited genetic fault
- Self conflicted - Damage to the body
- Attempted suicide, drug abuse and lung cancer.
Reasons for collecting health statistics
- Make comparisons between populations at the same time
- Make comparisons between populations at different times
- Find out which diseases are important
- Find new, emerging diseases, such as SARS
- Inform policy-making about providing resources in the health service
- Find out how well government health policies are working
- Investigate the spread of disease and investigate the likely causes.
Difference between standards of Health in MEDC and LEDC
LEDC
- Poor sanitation leading to the spread of water-borne diseases like cholera, diarrhoea, dysentery and typhoid
- Unsafe water that often contains the pathogen of many diseases
- Densely populated cities and over crowded accommodation increasing the likelihood of air-borne diseases, such as TB and influenza being transmitted from person to person.
- Widespread poverty leading to poor diet and a lack of doctors and health facilities to treat disease. *Malnourished individuals are less able to fight infections.
- Many developing countries situated in warmer areas of the world where pathogens and the insects can spread and reproduce rapidly and build up large populations.
- More death at birth or in the early year of life.
MEDC
- Both the incidence of infectious disease and the mortality associated with disease have been reduced.
- Living conditions are substantially better than in developing countries, which improved hygiene, sanitation and nutrition.
- Successful vaccination programmes, and antibodies are readily available to cure bacterial infections.
- The relative affluence of developed countries brings an increase in deaths from cardiovascular diseases, cancer and road accidents, albeit that cardiovascular disease is more prevalent amongst the poorer sections of developed countries.
- Degenerative disease associated with old age are often seen.
Explain the terms
- Pandemic – an outbreak of disease that occurs across the world or across continents.
- Epidemic – an outbreak of disease in a population.
- Endemic – this describes diseases that are always in a population.
Advantages for health of the Human Genome Project are
- Genetic tests have been developed for inherited disease such as cystic fibrosis, more of these will be developed as now the sequences of the genes are known.
- Tests have also been developed to find out whether people have inherited alleles of genes that increase the likelihood that they will develop diseases such as breast cancer and Alzheimer's.
- Doctors will be able to diagnose diseases more accurately and choose more appropriate treatments, avoiding drugs likely to have side effects.
- Gene therapy may be carried out to insert properly functioning alleles. This has already happened to treat a rare immunodeficiency disease.
- Pharmaceutical companies may be able to develop drugs better able to target specific problems.
- Medical researchers will have more data when looking for causes of disease and finding cure.
Diet
Components of a balanced diet
- Sufficient energy for our needs provided by the macronutrients (carbohydrates, proteins and fat)
- Essential amino acids (essential means can't be made by the body, must be in the diet
- Essential fatty acids (linolenic acid and linoleic acid)
- Micronutrients – vitamins and minerals
- Water for replacing the water lost in urine, sweat, breath and faeces
- Fibre for preventing constipation
Energy and nutrient requirements of people
- Gender
- Males require more protein because their growth is greater than females during adolescence, and after that stage they have a greater mass of tissue to repair and replace.
- Males requires more of the vitamin B complexes that are needed for respiration and metabolism.
- Males require more calcium and phosphorus in adolescence because they develop larger bones than females during this stage of growth.
- Age
- Energy requirements increase with age, up to and including adolescence, as growth is rapid during these years and physical activity is generally at high level. These energy requirements remain almost constant up to the age of 60 years, after which they decrease as physical activity diminishes and body mass often decreases.
- Protein requirements increase with age, especially around puberty. This is because additional protein is needed for the rapid growth around adolescence and thereafter, to repair and replace cells.
- Calcium and phosphorus requirements are greater in the first year of life as they are laid down in the bones of infants. The rate again increases in adolescence when the second growth spurt involves relatively rapid elongation of the bones. After adolescence, the requirements remain constant.
- Requirements for other minerals and vitamins increases up to the age 20 years, but thereafter remains relatively constant.
- Activity
- The more physically active a person is, the greater their energy requirement. It follows that, compared to an office worker, a manual labourer requires a greater energy intake, especially of carbohydrate food.
- Pregnancy
- Energy during the last three months of pregnancy, when fetal growth is at its greatest and the mother has this additional mass to carry around.
- Protein needed to supply the growth needs of the rapidly dividing cells of the fetus.
- Vitamin A, C and D, although too much vitamin A can be harmful to the fetus in the early stages of pregnancy. For this reason pregnant women are recommended to avoid liver, which is very rich in vitamin A.
- Lactation
- More calcium, phosphorus and magnesium, as these are needed by the newly born to develop their bones.
- More zinc because it is present in a number of enzymes, including those involved in growth and metabolism.
Dietary reference value
- This is sets of figures relating to the requirements for energy and nutrient intake of all healthy individuals in the UK, this is sat by the department of Health in 1991.
- The three DRV are:
- Estimated Average Requirement – this is the population average
- Reference Nutrient Intake – this is at the top end of the range and is enough for about 97% of the population
- Lower Reference Nutrient Intake – this is at the bottom of the range and is enough for only about 2% of the population.
Use of Dietary Reference value:
- Chefs and caterers to design appropriate menus for groups of people living in communities such as schools, old people's home and prisons.
- Managers to plan food supplies for large groups of people.
- Dieticians and others to assess the dietary needs of individuals, e.g. The elderly and pregnant women.
- Individuals to calculate their own dietary requirements and to maintain or improve health.
- Food manufacturers to provide appropriate nutritional information on food labels.
Describe the functions of...
- Essential amino acids - Used to synthesis protein for growth and repair of cells
- Essential fatty acids - Used to make phospholipids and fats
- Vitamin A - Used to make rhodopsin for functioning of rod cells in the eye. Used to make retinoic acid, which aids cell development and growth, especially in epithelia.
- Vitamin D - A steroid hormone that controls absorption of calcium from the gut and its deposition in bones.
Consequences of malnutrition
- Energy
- Stunting results from chronic protein-energy malnutrition, occurs in children from 2-5 years of age.
- Wasting results from acute protein-energy malnutrition, occurs in individuals over 5 years of age. This is characterized by rapid weight loss in those who had near normal weight.
- Kwashiorkor
- Bloated appearance
- Moon face
- Apathetic
- marasmus
- Very think with wrinkled skin
- Old man's face
- Mentally alert
Anorexia nervosa
- Muscles waste (including heart muscles)
- Periods stop
- Blood pressure falls
- Hair becomes thin and sparse
- Hands and feet are cold
- There is increased susceptibility to infection
- There are personality changes.
Vitamin A
- Night blindness – rod cells do not make enough rhodopsin so people can not see in dim light
- xerophthalmia – the surface of cornea is scarred which leads to blindness
- Poor defence against disease such as measles.
- Dry, rough skin, as vitamin A is needed to make retinoic acid, which is needed to maintain epithelial tissues like the skin.
Vitamin D
- Rickets – occur in Children the bone become soft and grow irregularly, the joints become swollen and limbs and the chest may be distorted. Typically the legs are bow-shaped.
- Osteomalacia – occur in adults – this causes a softening of the bones, making them tender and painful, fracture of bone occur more easily. Muscle weakness as well as loss of appetite and weight.
Obesity
- Coronary heart disease – caused by increased blood pressure and blood cholesterol.
- Type II diabetes
- Cancer
- Osteoarthritis
- Rheumatoid arthritis
- Hypertension
Diet and coronary heart disease
- High level of salt – increases hypertension.
- High Blood cholesterol – contribute to the formation of plaques in the coronary arteries
- High fatty acid intake – saturated fatty acid increases the risk of CHD
- Eating dietary fibre – protect against obesity and reduce insulin levels in the blood, so reducing CHD.
- Moderate consumption of alcohol – shown by some studies to reduce the risk of CHD.
- Eating oily fish – such as mackerel and herring
- Formation of heart attack. Those who are over-weight are twice as likely to suffer from CHD than those with acceptable BMI.
- It is a Degenerative condition which involves the build-up of fatty tissue in the walls of arteries that supply heart muscles.
- If these arteries become narrowed as a result, the flow of blood decreases and the supply of nutrients and oxygen to heart muscle decreases.
- The muscle doesn't release enough energy, the heart becomes weak.
- There may be a blood clot in the coronary artery, so cutting off the supply of blood to that area completely and leading to a heart attack.
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