Question

Name the structures which are present in veins and lymph ducts and absent in arteries.

Answer 1

Hint: Blood vessels are of two types-arteries and veins based on oxygen content. Lymph ducts collect tissue fluid. The structures which are present in veins and lymph ducts and absent in arteries keep in check the forward flow of its contents.

Complete answer:
Veins are thin- walled blood vessels. They carry deoxygenated blood away from various body parts to the heart and are superficial in position. The blood flows at a slow speed with low pressure. The lymph duct carries lymph and empties into the circulatory system. All the smaller lymphatic vessels drain lymph into two lymph ducts i.e the right lymphatic duct and thoracic duct. Arteries are thick-walled blood vessels that carry the blood away from the heart to various body parts. They are deep-seated, without any valves present in them. This is in contrast to veins and lymph vessels which do possess these valves. These structures prevent any backflow of blood or lymph. Valves keep the continuous forward motion of the fluid and prevent any backward intermixing of its contents.

Additional Information:
- Blood is the most common body fluid providing all the living cells with nutrients, oxygen, essential substances, and harmful substances also. The latter are continuously being removed for the healthy functioning of fluids.
- Blood is a special connective tissue containing a fluid matrix called plasma and formed elements.
- The fluid collected between the spaces of cells in a tissue is called lymph or interstitial fluid or tissue fluid. It is a colorless fluid due to the absence of RBCs. It acts as a middle man between the tissues and the blood system. All the metabolic wastes from tissues are collected in the lymph.

Note:
- Plasma in the blood is a cloured, viscous fluid that contains fibrinogens, globulins, a small number of minerals like ${ Na }^{ + }$, ${ Mg }^{ 2+ }$, ${ Cl }^{ - }$, glucose and amino acids, etc.
- The lymph contains lesser proteins than the blood and generally, only smaller proteins like albumin can be found in the lymph.
- Lymph contains more water than the plasma of the blood.