PATHOLOGY

Detailed explanation-1: -A venule is a very small vein in the microcirculation that allows blood to return from the capillary beds to drain into the venous system via increasingly larger veins. Post-capillary venules are the smallest of the veins with a diameter of between 10 and 30 micrometres (m).

Detailed explanation-2: -There are two types of venules: small and large. The small venules have an endothelial lining on a basement membrane and the larger venules have, in addition to the endothelial wall, a muscular wall. Fluid and macromolecular exchange take place mostly at the beginning of the venules.

Detailed explanation-3: -The small cardiac vein runs in the coronary sulcus between the right atrium and right ventricle, and opens into the right extremity of the coronary sinus.

Detailed explanation-4: -Superficial veins include the very small spider veins of between 0.5 and 1 mm diameter, and reticular or feeder veins.