8.2.1 Causes and Effects of Non-Infectious Disease Flashcards
(16 cards)
Non-Infectious Disease
Non-infectious (or non-communicable) diseases are not caused by a pathogen and are not contagious.
- Influenced by factors such as age, gender, economic and social conditions, race, lifestyle, environment, genetics and nutrition
- Account for nearly two-thirds of deaths worldwide, stemming from a range of risk factors such as poor diet, tobacco use, alcohol consumption, lack of physical activity, poor hygiene and limited access to clean water
Genetic Diseases
Genetic diseases are caused by mutations of the genes or chromosomes of an individual, which naturally code for specific proteins. This means that if the gene is abnormal, it may lead to the incorrect production of a protein and therefore a genetic disease. They can also occur when cell division occurs abnormally, and an incorrect number of chromosomes are produced.
Single Gene Abnormalities
Genetic Diseases
Caused when the person inherits mutated genes from their parents and can be dominant or recessive in nature.
- If the abnormal gene occurs on a sex chromosome, the disease is sex linked.
Chromosomal Abnormalities
Genetic Diseases
Caused by mutations to the chromosomes that carry genes and can be structural or numeral (aneuploidy).
This may be due to non-disjunction, trisomy or monosomy, causing a syndrome is the embryo is carried to term.
Syndromes
Genetic Diseases - Chromosomal Abnormalities
Turner Syndrome is the only full monosomy syndrome that can be seen in humans and is non-fatal.
Down Syndrome (trisomy 21) is the most common trisomy syndrome, causing a number of physical and intellectual symptoms.
- Prevention is only possible through genetic counselling of couple at risk, one such factor being older couples as eggs and sperm have a higher chance of being defective as the individual ages.
- Management depends on the severity, but additional supportive educational programs assist in the daily life of Down sufferers.
Klinefelter Syndrome is caused by an additional sex chromosome (XXY), causing hormonal and physical symptoms.
Cri du chat Syndrome is a rare disease caused by a deletion in chromosome 5, causing intellectual and physical symptoms.
Cystic Fibrosis (CF)
Genetic Diseases
Cystic fibrosis is an inherited disease caused by the mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene on chromosome 7, which alters the protein that would typically regulate the movement of sodium chloride (NaCl) in and out of the cells. This results in the symptom of mucus-secreting organs secreting very thick mucus, which impact and damage the lungs and digestive system.
- The CFTR gene is recessive gene, meaning both parents must have the gene to develop it.
- Life Expectancy: 30-40 years
The condition is managed through physiotherapy to redirect mucus, inhalers, enzyme pills, vitamins and antibiotics to loosen mucus and routinely support the symptoms.
Diseases Caused by Environmental Exposure
Humans are constantly interacting with their environment throughout their lives and there are many factors that can cause disease. Environmental diseases can be divided into:
- Lifestyle diseases
- Physical diseases
- Chemical diseases
Lifestyle Diseases
Diseases Caused by Environmental Exposure
Caused by a lifestyle choice, such as substance abuse, drinking and smoking (e.g. cardiovascular disease, diabetes, cancers, chronic lung disease)
- A more specific example of cardiovascular disease is atherosclerosis, which is commonly known as ‘hardening of the arteries’, and can be caused by insufficient physical activity, drinking alcohol excessively, being exposed to high levels of stress, smoking and having an unbalanced diet that is too high in calories.
Physical Diseases
Diseases Caused by Environmental Exposure
Caused by excessive exposure to factors in the environment (e.g. skin cancer from UV)
- These factors often affect the health of the individual by altering their genetic material in some way, causing problems in bodily functioning.
- Skin cancer is a result of UV light changing the DNA of skin cells, causing continued abnormal cell division and the development of carcinomas or melanomas.
Chemical Diseases
Diseases Caused by Environmental Exposure
Caused by exposure to chemicals in the environment (e.g. lead poisoning, asbestos)
- Factors in the environment that can cause this are the pollution of the land, chemicals in waterways and pollution in the air/waterways
Nutritional Diseases
Diseases caused by a diet lacking balance or the correct amounts of nutrients, leading to malnutrition. The two types are:
Undernutrition - insufficient intake of correct type and/or quantity of food
- Kwashiorkor - lack of protein
- Marasmus - lack of energy and protein (caloric deficiency)
- Anorexia, Bulimia - eating disorders
- Vitamin Deficiencies - blindness/dry skin (Vitamin A), scurvy (Vitamin C)
- Mineral Deficiencies - anaemia (iron), goitre (iodine)
Overnutrition - consuming more kilojoules of energy than those expended
- Obesity - overweight, leading to several health problems (e.g. high blood pressure, diabetes, cancer, reduced life expectancy
Cancer
Cancer is caused when abnormal cells divide in an uncontrolled way as a result of exposure to one or more risk factors.
Normal cell growth and mitosis is disrupted by mutations to:
- DNA Repair Genes - genes that stop the cell cycle and repair incorrect/damaged sections of DNA
- Proto-oncogenes - genes that code for proteins that stimulate cell growth and mitosis, a mutation resulting in the expression of oncogenes that would otherwise be silent, resulting in uncontrolled cell production
- Tumour Suppressor Gene - genes that code for proteins that slow down/stop cell growth and mitosis, as well as inducing cell death if cell count becomes too high
Tumours
Cancer
Abnormal growths of tissue, often forming a solid mass somewhere on the body.
Benign Tumours - These are not classed as tumours as they do not spread to other tissues, though they may still be precancerous.
- Squamous Cell Carcinoma - a type of skin cancer that begins as a lesion but will spread if not treated
Malignant Tumours - Abnormal cancerous cells that are not confined by the boundaries of the initial tumour, continuing the replicate quickly in a disorganised manner. This causes them to redirect nutrients away from themselves and adjacent tissue.
- Metastasis - abnormal cells from the primary tumour breaking away from the initial tumour to travel through the bloodstream or lymphatic system to form a secondary tumour elsewhere.
Types of Cancer
Cancer
The type of cancer is usually named after the organ or tissue that the primary tumour forms in, but they can be classified into several broad groups:
- Sarcoma - forms in muscle or other connective tissues like in bone or blood vessels
- Carcinoma - forms in epithelial tissue, such as skin or tissue that lines or covers the internal organs
- Lymphoma/Myeloma - forms in the lymphatic system and plasma cells of the immune system
- Leukemia - forms in the bone marrow and other blood-forming tissues
- CNS Cancer - begins in the brain or spinal cord
Causes of Cancer
There are many causes of cancer, but we do know that there are several chemical, physical, and biological agents, known as carcinogens, that could cause mutations to genes that control cell division.
These include:
- Tobacco
- UV radiation
- Asbestos
- Smoking
- Excessive alcohol consumption
- Inherited mutated genes
- Viruses
Melanoma
Cancer
A disease in which cells in the skin divide uncontrollably due to changes in the DNA of the genes that control cell division. These cells are called melanocytes, which contain the pigment melanin (gives the skin colour).
The exact cause is unknown, but the risk factor is increased by:
- UV radiation
- Fair complexions
- Severe sunburn
- History of skin cancer
- Moles
- Family history
- Compromised immune system
- Old age
- Males
