Effect on the host

1. Derangement of functions

2. Derangement of structures

• Arbitrary divisions: <50 yrs = young; > 50 yrs = old
• Old: increased chance of

1. Degenerative disease: most common, esp. of vascular system -> stroke, haemorrhage, coronary heart disease
2. Malignancy: eg. Lung, breast, kidney

• Process of exclusion/inclusion

• Certain diseases affect males or females
• Eg. SLE very common in women of child-bearing age

• Major symptoms resulting in seeking medical advice
• What are symptoms? Clinical manifestation of disturbances of normal physiological function of the body

• A natural Hx of disease process which may be modified by intervention
• Past health
• Personal Hx
• Fam Hx: eg. DM, polycystic disease of kidney, hereditary nephritis, thalassaemia
• Obstetric Hx (female)

• Look at Pt - therefore, perform clinical general physical examination while taking Hx
• Eg. Jaundice and distended abdomen -> chronic liver disease
• Eg. Cafe au lait -> renal failure (anaemia superimposed on increased pigmentation of skin - uraemia)
• Also caused by subacute bacterial endocarditis

• CVS, RS, Abdominal, CNS, MSS, Urinalysis

1. Reduced intake - dietary malnutrition/ addict/ old age
2. Massive proteinuria - nephrotic syndrome (+/- hyperlipidaemia)
3. Impaired production (chronic) - liver disease
4. Excessive loss - protein losing enteropathy
5. Impaired absorption - malabsorption syndrome, IBD

Results in

1. Reduction in hydrostatic pressure in capillaries
2. Oedema

Starling's Law: Increased pressure at venous end of capillary bed leads to fluid moving from capillary to interstitial fluid, resulting in oedema

1. CHF, constrictive pericarditis, pericardial effusion
2. Increased intrathoracic pressure, chronic lung disease, COAD, fibrosing alveolitis (lung parenchyma)

1. Decreased oxygen tension - high altitude
2. Aw obstruction: reversible (asthma), irreversible (CB)
3. V/Q disturbances - COAD - emphysema
4. Defect in oxygen transfer (between alveoli and capillary bed) - alveolitis, CHF

Leads to hypoxia

1. Stimulate respiratory centre
2. Increase resp rate and effort
3. Dyspnoea