Causes of Disease Flashcards
What is aetiology? What does idiopathic refer to?
Aetiology refers to the causes of disease which can have a single cause or be a product of multiple factors
Conditions with no known cause are called idiopathic
What does it mean when we refer to intrinsic causes of disease? Give some examples
= Changes in an individual’s genome
- Nuclear or mitochondrial
- Inherited mutations and other genetic variations
- de novo mutations
- Epigenetic modifications
Typically alter the function of a gene (or group of genes)
E.g. more/less protein or same amount but more/less activity
What are the different levels effects of genetic variations can manifest at?
Cell autonomously:
- Cell X no longer expresses structural protein Y, so cell X is the wrong shape
Cell non-autonomously
- Cell X no longer secretes protein hormone Y, so cell Z no longer functions
What are the extrinsic causes of disease?
Numerous!
- Injury - Infection - Nutrition and diet - Lifestyle, e.g. smoking, exposure to workplace toxins - Chemical poisoning (acute and chronic) - Exposure to radiation
What are the grey areas of the extrinsic and intrinsic classification system?
The terms intrinsic or extrinsic can be ambiguous
Causes of disease are often a chain of events
- Are allergies caused by a sensitive immune system (intrinsic) or the preceding allergen (extrinsic)?
Intrinsic or extrinsic depends on viewpoint,
i.e. extrinsic to what: cell, tissue, organ, body?
- Pay attention to the context!
Which category of extrinsic/intrinsic does age fit into?
Age really just means ‘time’, in the context of causes that accumulate
Age can be an intrinsic cause when it describes the biological process of ageing
For example:
Many diseases associated with chronic inflammation also have a biological ageing as a cause
Apply the intrinsic/extrinsic classification to Down’s syndrome and Covid-19
Cause of Down Syndrome Trisomy of chromosome 21, inherited at conception Intrinsic Cause of COVID-19 Infection with SARS-CoV-2 Extrinsic