Disturbances of Circulation - L3-5

Hyperaemiam

Congestion

Ishaemia Define: [blank_start]Inadequare blood supply of tissue[blank_end] [blank_start]relative to its needs[blank_end] Consequences: [blank_start]Hypoxia[blank_end], [blank_start]Malunutrition[blank_end], [blank_start]Build up of waste products[blank_end] Causes: [blank_start]Cardiac arrest[blank_end], [blank_start]Arterial obstruction[blank_end], [blank_start]Venous obstruction[blank_end], C[blank_start]apillary damage[blank_end], [blank_start]Shock[blank_end] E.g.: [blank_start]Heart attack[blank_end], [blank_start]Arteritis[blank_end], [blank_start]Bed sores[blank_end]

Effects of Congestion Gradual onset - [blank_start]collateral circulation can develop so[blank_end] [blank_start]effects are minimised[blank_end] Chronic congestion - [blank_start]continues for long time[blank_end] = [blank_start]serious effects[blank_end] e.g [blank_start]Odema[blank_end], [blank_start]Hypoxia[blank_end], [blank_start]Haemorrhage[blank_end]

Ischaemia - [blank_start]Inadequate blood supply of a tissue[blank_end] [blank_start]relative to its needs[blank_end] Infarction - [blank_start]Localised area of necrosis[blank_end] [blank_start]caused by ischemia[blank_end] Hypoxia - [blank_start]Deficiency in the amount of oxygen[blank_end] [blank_start]reaching the tissue[blank_end]

Acute infarct - [blank_start]Swelling of affected tissue[blank_end] Colour: [blank_start]Dark red[blank_end] Shape: [blank_start]Wedge[blank_end]

Sub-acute infarct - [blank_start]Degeneration and necrosis of ischaemia[blank_end] tissue What happens: [blank_start]Fluid forced[blank_end] out of area [blank_start]Swelling[blank_end] decreases Area becomes [blank_start]paler[blank_end] Line of [blank_start]hyperaemia[blank_end]

Chronic infarct - [blank_start]affected tissue is pale and shrunken due[blank_end] to fibrosis Fibrosis - [blank_start]Healing of the infarct[blank_end]

Thrombus - [blank_start]Blood clot/solid structure that forms[blank_end] within the [blank_start]flowing blood stream from the normal[blank_end] [blank_start]constituents of blood during life[blank_end] Thrombosis - [blank_start]Process by which a thrombus forms[blank_end] Embolus - [blank_start]Abnormal mass circulating in the blood[blank_end] stream Embolism - [blank_start]Arrest of a circulating mass within[blank_end] a vessel

Three Components of Virchow's Triad 1. [blank_start]Endothelial Injury[blank_end] 2. [blank_start]Abnormal Blood Flow[blank_end] 3. [blank_start]Hypercoagulability[blank_end]/[blank_start]Abnormal blood composition[blank_end]

Virchow's Triad

Different types of embolus 1. [blank_start]Thromboemboli[blank_end] 2. [blank_start]Gas[blank_end] 3. [blank_start]Fat[blank_end] 4. [blank_start]Neoplasms[blank_end] 5. [blank_start]Foreign bodies[blank_end] 6. [blank_start]Parasites[blank_end] 7. [blank_start]Clumps of bacteria[blank_end] 8. [blank_start]Pus[blank_end] 9. [blank_start]Injected material[blank_end]

Diapedesis - [blank_start]Small momentary spurting losses of blood[blank_end] [blank_start]occur between endothelial cell[blank_end] [blank_start]of otherwise normal capillaries[blank_end] Haematoma - [blank_start]Local accumulation of blood[blank_end], [blank_start]usually clotted[blank_end] Petechiae - [blank_start]Very small haemorrhagic spots[blank_end] Ecchymoses - [blank_start]Slightly larger foci of haemorrhage[blank_end] Bruising - [blank_start]Subcutaneous haemorrhage[blank_end]

Haemorrhage Compensatory Mechanisms 1. [blank_start]Blood redistribution[blank_end] 2. [blank_start]Restoration of blood volume[blank_end] 3. [blank_start]replacement of lost erythrocytes[blank_end]

Classifications of Shock 1. [blank_start]Hypovolaemic[blank_end] shock 2. [blank_start]Vasculogenic[blank_end] ([blank_start]septic[blank_end]) shock 3. [blank_start]Cardiogenic[blank_end] shock

Oedema - [blank_start]Excessive accumulation of tissue fluid[blank_end] Anasarca - [blank_start]Generalised subcutaneous oedema[blank_end] Ascites - [blank_start]Fluid in abdomen[blank_end] Hydropericardium - [blank_start]Fluid in pericardical sac[blank_end] Hydrothorax - [blank_start]Fluid in pleural cavity[blank_end]

Starling's Equilibrium Filtration Pressure = [blank_start]Hydrostatic pressure[blank_end] in plasma and tissues - [blank_start]Colloid osmotic pressure[blank_end] in plasma and tissues Movement of [blank_start]fluid[blank_end] between [blank_start]vascular[blank_end] and [blank_start]extravascular[blank_end] compartments depends on the balance between [blank_start]hydrostatic pressure[blank_end] and [blank_start]colloid osmotic pressure[blank_end]

Increased hydrostatic pressure Results from: [blank_start]Increased fluid pressure[blank_end] within vessels which overcomes the [blank_start]attractive osmotic force[blank_end] of [blank_start]circulating protein[blank_end] leading to a net increase in [blank_start]outflow of fluid[blank_end] that is not matched by [blank_start]reabsorption by venules[blank_end] or by [blank_start]increased removal by lymphatics[blank_end]

Decreased plasma oncotic (osmotic) pressure A reduction in [blank_start]circulating proteins[blank_end] [blank_start]Albumin[blank_end] is the most [blank_start]abundant[blank_end] protein and most [blank_start]effective osmotic force[blank_end] Hypoalbuminaemia = [blank_start]most important cause[blank_end] of decreased osmotic pressure

Lymphatic Blockage Seen if there is an [blank_start]extensive tumour invasion[blank_end] of a regional node OR if [blank_start]lymph nodes are surgically removed[blank_end]

Increased vascular permeability Most commonly results from [blank_start]inflammation[blank_end] Increase in vascular permeability by [blank_start]increasing the size of the gaps[blank_end] between [blank_start]endothelial cells[blank_end] Causes an increase in the loss of [blank_start]fluid[blank_end], [blank_start]proteins[blank_end] and [blank_start]inflammatory cells[blank_end]

Examples of Oedema Pulmonary oedema rise in [blank_start]pulmonary venous pressure[blank_end] causes [blank_start]leakage of fluid[blank_end] into the [blank_start]alveoli[blank_end] of the lung Cerebral oedema Oedema of the [blank_start]brain[blank_end]