Disturbances of Circulation

• Circulation is the mechanism of distribution and return of blood to and from tissues in a manner of circular movement. The most important disturbances in this mechanism generally are

Hyperemia

• Active engorgement of vascular beds due to increased arteriolar inflow . • Affected tissue is red (oxygenated blood) and warm, as arterioles and capillaries are filled with blood.

Types of Hyperemia

• Physiologic Hyperemia • High blood flow to the stomach and intestines

during digestion• High blood flow in the muscles during exercise• High blood flow in skin to dissipate heat• High neurovascular hyperemia (blushing)

Types of Hyperemia

• Pathologic Hyperemia• result of an underlying pathologic process

(usually inflammation).• arteriolar dilation is a response to

inflammatory stimuli / mediators.• red coloration is a cardinal sign of

inflammation = "Hyperemia of Inflammation"

• Gross appearance: The arteries are distended with blood and prominent - The affected part is swollen, enlarged and haevier than normal - If the organ is incised, blood flows freely from the cut surface.

• Microscopical appearance: The capillaries are dilated and filled with blood - The capillaries also appear to be more numerous than before because in normal state some capillaries are empty and collapsed much of the time.

Effect of active hyperaemia

• 1- It brings additional oxygen and nutrients to the affected part.

• 2- It helps in removal of waste materials and dilution of harmful chemical substances by bringing more fluid.

• 3- It brings an additional amount of antibodies and leucocytes to the area.

Passive hyperemia/Congestion

• Passive engorgement of a vascular bed generally caused by a decreased outflow of blood

Acute General Passive Hyperaemia

• Gross appearaOrgans throughout the body are cyanotic (have a bluish-red colour) due to large amount of non-oxygenated blood which they contain - The veins, particularly the large ones, are distended with blood - In case of "congestive heart failure" on necropsy, the vena cava and large veins of the abdominal and thoracic cavities are large, dark and filled with blood which has clotted -.

• The veins of mesentry and intestinal wall are prominent and dark - The liver contains much blood, as do also the lung.

• Microscopical appearance: The capillaries and veins are dilated and full of blood - In the liver, the sinsusoids and in the spleen the blood spaces are filled with blood.

• Effect: When the cardiac and pulmonary changes are severe and can not be corrected, the lack of oxygen and nutrients and the accumulation of waste materials result in death of the cells.

Chronic General Passive Hyperaemia

• Gross appearance: The veins throughout the body are engorged with blood - Oedema of the tissue - A transudate is found in the body cavities- When the condition persists for a long time there will be atrophy of the parenchymatous organs, and hyperplasia of connective tissue and fibrosis.

• Microscopical appearance: The venous capillaries appear dilated and engorged with blood Oedema first appears perivascular - Degenerative changes in parenchymatous organs - Other chnages are:

• Lung (brown induration of the lung) : There is, moreover, the picture of excessive destruction of erythrocytes, and haemosidrin precipitates - Presence of many macrophages engulfing golden-brown haemosidrin pigment and then called "heart failure cells" - Fibrosis of the interalveolar septa.

• Induration,brown colour,thickened alveolar septa,small hemorrhages,heart failure cells

• Liver (nut meg liver): Dilatation and engorgement of the central veins of the hepatic lobules with blood and they appear dark - Proliferation of connective tissue around the central veins – Pericentral(peripheral) degenerative changes including fatty change.

• Degenerative and necrosis due to hypoxia• In section the central vein conspicuously dilated but

empty because RBCs washed out during slide preparation

• Spleen (congestive spleenomegaly): The organ is enlarged and swollen due to congestion, oedema and fibrosis

Acute Local Passive Hyperaemia

• Gross appearance: The affected tissue or organ is swollen and increased in weight - When the organ is incised, blood oozes from the cut surface - The veins in the area are distended, and the affecetd tissue is bluish in colour - The lumen of the organ contains blood when haemorrhage occurs. Microscopical appearance: Veins and capillaries are distended with blood - There is oedema of the interstitial connective tissue - Disturbances of cell metabolism or necrosis are present when nutritional requirements of the tissue cannot be met

Chronic Local Passive Hyperaemia• Gross appearance: Oedema of the organ or tissue due to

increased permeability of the capillaries as a result of hypoxia - Multiple haemorrhages are present which are related to injury of the wall of the blood vessels - Increased connective tissue formation and shrinkage of the organ - In chronic local passive hyperaemia, due to gradual

• onset of obstruction, collateral circulation has had time to develop, and its veins are frequently enlarged leading to the formation of "varicose veins".

• Microscopical appearance: Dilatation of the obstructed veins is still prominent - New collateral branches are seen - Degeneration and necrosis of the cells of the organ - Increased fibrous connective tissue.

EDEMA

• Edema = the abnormal (excess) accumulation of fluid in interstitial tissue spaces or in body cavities.

• Edema fluid is outside both the vascular fluid and cellular fluid compartments (ie. within interstitium).

EDEMA

• Gross appearance; Pale watery appearance,subcut tissue jelly like,fluid oozes from cut surfaces,pits on pressure

• Microscopic appearance; Enlarged intracellular spaces,faint pink staining fluid,