MEDICAL PHYSIOLOGY

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: -Vein is a larger blood vessel that carries blood towards the heart. Venule is a smaller minute blood vessel that drains blood from capillaries to the larger veins. Vein is larger in size and the diameter is measured by millimeters. Venule is very smaller in size and the diameter is measured by micrometers.

Detailed explanation-3: -Venules. Venules in the upper and mid dermis usually run in a horizontal orientation. The diameter of the postcapillary venule ranges from 12 mm to 35 mm. Collecting venules range from 40 mm to 60 mm in the upper and mid dermis and enlarge to become 100 to 400 mm in diameter in the deeper tissues.

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