Question

What are veins? Define and explain.

Answer 1

Vessels that transport blood from organs and tissues to the heart. Veins of the systemic circulation collect blood saturated with carbon dioxide, metabolites, hormones produced by the endocrine glands, and other substances from organs and parts of the body and transport it to the right atrium. Veins of the pulmonary circulation return oxygen-enriched blood from the lungs to the left atrium. Food absorbed in the gastrointestinal tract is transferred to the general bloodstream through the portal vein system. The veins originate in the capillary network where venules are formed, and on coalescing the venules form veins. The venous wall is much thinner and more plastic than the arterial wall, and its musculature is relatively weakly developed. Blood pressure is very low in the veins and below atmospheric pressure in the large ones. The flow of blood in the veins is greatly affected by the respiratory movements of the chest (suction) and movements of the diaphragm, while the deep veins of the extremities are affected by muscular contractions. The venous valves along the bloodstream allow blood to flow only to the heart. The numerous nerve endings in the walls of certain large veins (superior and inferior vena cava, portal vein, and others) take part in regulating blood circulation

Answer 2

✔BLOOD VESSELS:−

➡The vessels which carry blood to different parts of the body.

✔There are of three type:-

❇ Arteries :- The vessels which oxygenated blood from heart to different parts of our body. It has thick walls. It has narrow lumen. In Arteries blood flow under high pressure. In Arteries Internal walls are absent.

❇Veins:- The vessels which carry carbon dioxide rich blood from different parts of the body to the heart. It has thin wall. It has wide lumen. In Veins blood flow under low pressure. In veins internal walls are present.

❇ Capillaries:- These are present around the organs and are very thin which recieves the blood from arteries and supplied the blood to Veins after exchange of material with the cells of oragan.

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