Circulatory Disturbances. HYPERAEMIA AND CONGESTION. Increased volume of blood in a particular tissue 1- Hyperaemia : Active process Local increase of blood to an organ due to active dilatation of arterioles and capillaries. Tissue is redder due to increase of oxygenated blood
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1- LOCAL VENOUS CONGESTION
Sudden occlusion of a vein by thrombus, ligature or strangulation.
- Effects: oedema and haemorrhage
2- chronic venous congestion:
Gradual and incomplete venous obstruction resulting from :Pressure by tumor , enlarged lymph node, pregnant uterus or Liver cirrhosis
- Oedema (since capillary bed congestion leads to increase fluid transudation).
- Haemorrhage due to capillary rupture; breakdown and phagocytosis of the red cell.
- Stasis predisposes to thrombosis and causes hypoxia, which can result in parenchymal cell degeneration or death.
- Gradual opening of collaterals
- Development of varicose (thickening, dilatation, elongation and tortuosity of the chronically congested veins or vein collaterals).
b- General venous congestion
1. Acute general venous congestion:
Causes: Acute heart failure
Effects: Rapid generalized congestion of organs & generalized oedema.
2. Chronic general venous congestion:
Gradual venous congestion affecting the whole venous system
Causes: It is caused by right ventricular heart failure due to chronic obstructive lesions affecting the heart, the pulmonary vessels and the lung
- Sites: Oedema appears first around the ankles (gravity effect) then gradually become generalized and may involve the peritoneum (ascites), pleura and pericardium.
Congestion of the lung
Over filling of
the neck vein
supply to tissue
Inferior vena cava
right or let sided
distension of leg veins
1) Increased hydrostatic capillary blood pressure and so the fluids tend to move outside the vascular system.
2) Decreased osmotic pressure of the blood: due to hypoproteinemia
3) excess retained sodium ion and water → Increased osmotic pressure of the interstitial fluids.
4) Decreased power of lymphatics to drain excess fluids as in lymphatic obstruction.
5) Increased capillary permeability as in inflammation and hypersensitivity leads to escape of proteins in the oedema fluid. This will lower the plasma osmotic pressure.
1- Localized oedema
-a-Venous obstruction: e.g.
-Ankle oedema due to the pressure caused by enlarged uterus on the iliac vein.
-Liver cirrhosis and bilharzial hepatic fibrosis cause intestinal oedema and ascitis.
-b-Lymphatic obstruction: causes lymphatic oedema. It is caused by tumour or disease as elephantiasis.