What Are Blood Vessels?
Blood vessels are intricate networks of hollow tubes that transport blood throughout the entire body.
The process of transportation of digested food and oxygenated blood is taken up by diverse system in the human body and is called as circulatory system. The functional units of circulatory systems are referred as blood vessels and play huge role in collection of pure and impure blood.
Types of Blood Vessels
There are 4 types of blood vessels.
- ·Arteries
Arteries are elastic vessels that transport blood away from the heart.
Arteries are red blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries.The circulatory system is extremely important for sustaining life. Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products, maintenance of optimum pH,and the mobility of the elements, proteins and cells of the immune system. In developed countries, the two leading causes of death,myocardial infarction and stroke each may directly result from an arterial system that has been slowly and progressively compromised by years of deterioration.
- Veins
Veins are elastic vessels that transport blood to the heart. The capillaries formed by the arterioles continue as carriers of deoxygenated blood as they carry the waste products that have diffused in from the cells. These capillaries join together to form venules. The venules join together and form bigger vessels called the veins. The veins and venules are also lined by smooth muscles. However, the walls of the veins are not as thick as those of arteries. All the veins of the upper body except the pulmonary vein join together to form the superior vena cava and the veins of the lower body join together to form the inferior vena cava. These two veins pour their blood into the right auricle through separate openings. The pulmonary vein brings the blood from the lungs to the heart. Thus, the blood vessels that bring the blood to the heart are called the veins. The veins carry deoxygenated blood except for the pulmonary vein that carries oxygenated blood from the lungs. The blood drawn from the veins is dark red in colour.
A capillary is an extremely small blood vessel located within the tissues of the body, that transports blood from arteries to veins. Capillaries are most abundant in tissues and organs that are metabolically active. For example, muscle tissues and the kidneys have a greater amount of capillary networks than do connective tissues- Sinusoids
The liver, spleen and bone marrow contain vessel structures called sinusoids instead of capillaries. Similar to capillaries sinusoids are composed of endothelium. The individual endothelial cells however do not overlap as in capillaries and are spread out. Oxygen, carbon dioxide, nutrients, proteins and wastes are exchanged through the thin walls of the sinusoids. Circulation
Blood vessels carry blood from the heart to all areas of the body. The blood travels from the heart via arteries to smaller arterioles, then to capillaries or sinusoids, to venules, to veins and back to the heart.
Micro circulation deals with the flow of blood from arterioles to capillaries or sinusoids to venules. As the blood moves through the capillaries, substances such as oxygen, carbon dioxide, nutrients and wastes are exchanged between the blood and the fluid that surrounds cells.
