What is a disease?
-Any state in which the health of the organism is impaired -A consequence of a failure of homeostasis
What is homeostasis?
-“Steady State” -Maintaining an appropriate steady state of the internal environment despite changes in the external -Usually desirable -Allows constant function of cells, organelles, proteins
Pathogenesis
The pathological mechanism which results in clinically evident disease (eg interaction between Mycobacterium tubercuolsis and hosts response produce caseating lesion of TB)
Aetiology
-The cause of disease -eg Mycobacterium tuberculosis is the aetiological agent
Predisposition
-a susceptibility to disease which, given right circumstances, will manifest as clinically evident disease. -eg inherited mutation/ environmental factors (eg poor housing/ infection control)
Risk Factor
-A factor that is associated with an increased probability of developing a particular disease
Causes of disease
Extrinsic Factors
- Physical agents
- Trauma eg bone fracture
- Radiation eg Cancer
- Temp eg burns/frostbite
- Chemical agents
- Toxic substances eg Tobacco lung damge
- Inflammatory agents eg Asthma
- Biological agents
- Bacterial eg various infections
- Virus eg AIDs / Hepatitis
- Fungi and Parasites eg athlete’s foot
- Nutritional
- Various eg malnutrition
Causes of disease
Intrinsic Factors
- Genetic eg sickle-cell disease, CF
- Metabolic eg diabetes, gallstones
- Cellular
- Autoimmune eg rheumatoid arthritis
- Degenerative and Aging eg Alzheimer’s
- Structural
- Congenital eg spina bifida
- Aquired eg atheroma, osteoarthritis
