There are different types of blood vessels in our body each carrying out specialized functions.
Types of Blood Vessels
Three types of blood vessels are:
- Arteries
- Veins
- Capillaries
Arteries
Arteries are strong tubes and muscular in nature. These blood vessels carry oxygen-rich blood from the heart to all the tissues of the body. Aorta is one of the main arteries that arise from the heart and branches further.
Veins
Veins are elastic blood vessels which carry deoxygenated blood from all parts of the body to the heart. An exception is the umbilical and pulmonary veins. The Pulmonary vein carries oxygenated blood to the heart from the lungs and the umbilical vein carries oxygenated blood from the placenta to the foetus.
Capillaries
On reaching tissues, arteries branch further into extremely thin tubes called capillaries. Capillaries bring about the exchange of substances between blood and tissues.
Sinusoids
Sinusoids are a special type of wider capillaries present in bone marrow, liver, lymph nodes, spleen and some endocrine glands. They may be continuous, discontinuous or fenestrated.
Layers of Blood Vessels
Both arteries and veins consist of three layers.
- Tunica Intima: It is one of the innermost and thinnest layers of arteries and veins. It comprises endothelial cells. They are in direct contact with the flow of blood.
- Tunica Media: It is the middle layer of an artery or vein. Tunica media is made up of smooth muscle cells.
- Tunica Externa: It surrounds tunica media. It is made up of collagen and is also supported by the elastic lamina in arteries.
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