What are veins and venules?
A venule is a very small blood vessel in the microcirculation that allows blood to return from the capillary beds to drain into the larger blood vessels, the veins. Venules range from 7μm to 1mm in diameter. Veins contain approximately 70% of total blood volume, 25% of which is contained in the venules.
What are arterioles?
Arterioles are considered as the primary resistance vessels as they distribute blood flow into capillary beds. Arterioles provide approximately 80% of the total resistance to blood flow through the body.
What are the 4 main veins?
Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins.
- Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.
- Systemic veins return oxygen-depleted blood from the rest of the body to the right atrium of the heart.
What are the characteristics of veins and venules?
Veins and venules have much thinner, less muscular walls than arteries and arterioles, largely because the pressure in veins and venules is much lower. Veins may dilate to accommodate increased blood volume.
What do venules look like?
Venule walls have three layers: an inner endothelium composed of squamous endothelial cells that act as a membrane, a middle layer of muscle and elastic tissue, and an outer layer of fibrous connective tissue. The middle layer is poorly developed so that venules have thinner walls than arterioles.
What is tunica intima?
The innermost layer of the vein is the tunica intima. This layer consists of flat epithelial cells. These cells allow fluid to flow smoothly and are interspersed with valves that ensure the flow continues in one direction. This continuous layer of epithelial cells holds cells and fluid within the vessel lumen.
Are venules a blood vessel?
blood vessel Very small branches that collect the blood from the various organs and parts are called venules, and they unite to form veins, which return the blood to the heart.
Do venules connect to veins?
Venules are small blood vessels in the microcirculation that connect capillary beds to veins.