Principles of Human Disease
Introduction to BB2712 module
Medical terminology
Disease - malfunctioning of body or mind
● Etiology – What is the cause?
● Pathology: structural and functional abnormalities that are expressed as diseases of organs or systems
● Pathogenesis: how the etiologic agents cause a disease, i.e. morphological and functional changes in the body
● Lesion: unit of abnormality, usually anatomical
● Symptoms: what a patient complains: e.g. pain, anxiety, restlessness
● Signs: what a doctor detects on examination: e.g. lump, irregular heart beat
● Inflammation: redness, swelling, heat, pain, loss of function
● Clinical management – Diagnosis and treatment?
● Prognosis – The prospect of recovery or survival from a disease
● Epidemiology – study of causes, distribution and control of a disease in a population
Examples of ‘symptoms’ in the slide include: headache, difficulty in breathing, chest pain and constipation
Examples of ‘signs’ in the slide include: white patches on tongue, skin tumour, skin rashes and consolidation of lung.
WHO definition for Health & Disease
- “Complete physical, mental and social wellbeing not merely absence of disease”…Health
- “Expression of discomfort due to “structural or functional abnormality”…Disease
What is normal?
- “ The most frequent state in a population as defined by age distribution, gender, etc”
“Reference Range”: e.g.
White Blood Cells (WBC): 4000 - 10000 (mm3 of blood)
Blood glucose (fasting): 3.6 to 6.0 mmol/liter (Diabetic:7.0 mmol/l and above)
Social wellbeing is the extent to which one feel a sense of belonging and social inclusion
Disease
A disorder of a structure or function, that affects part
or whole organism.
● Well defined abnormality e.g. tumour
● Poorly defined abnormality e.g. depression
● A failure of homeostasis or adaptation e.g. mountain sickness
Each disease is characterised by a set of features (causes, signs and symptoms, morphological and functional
changes, etc)
, Principles of Human Disease
Altitude sickness (mountain sickness):
1,500 metres (5,000 feet): At this height mild symptoms can occur such as breathlessness, but most people can
ascend up to 2400 meter (8000 feet) without difficulty.
3,000m (9,842 feet): Most people develop symptoms such as nausea and vomiting, dizziness, tiredness, loss
of appetite, shortness of breath. The best way to prevent altitude sickness is to travel to altitudes above
3,000m slowly. It usually takes a few days for the body to get used to a change in altitude.
At higher altitudes the 21% oxygen remains the same; however, the number of oxygen molecules per breath
is reduced and therefore less oxygenation of haemoglobin.
Syndrome
- A disease characterised by multiple abnormalities,
-e.g. Down’s syndrome (mental and heart defects)
Lesion
- the structural abnormality responsible/ results due to ill health
- Rash, growth on skin, patch of dead heart muscle in case of myocardial infarction
Classification of Diseases
• Causative agent e.g. infectious (Bacterial, fungal, viral and parasitic), Genetic, nutritional (kwashiorkor)
• Inflammatory / Degenerative/ Neoplastic etc.
• Acute (days to weeks) / Chronic (months to years)
• System involved e.g. cardiovascular, respiratory, nervous , endocrine immune system
• Primary and Secondary causes:
- Primary: cause unknown or unclear
- Secondary: cause known
• Congenital (abnormality is present at birth ) / Acquired:
Mild / Moderate / Sever
Benign /Malignant: e.g. tumour
Characteristics of Disease
• Etiology (cause)
• Pathogenesis (mechanism)
• Manifestations (morphological, functional and clinical changes (sign and symptoms)
• Complications (secondary effects)
• Prognosis (outcome)