Question

1) How do nutrients move from the blood in your capillaries to the cells of your tissues? Where does the interstitial space come into this picture?

2) What is lymph, and where does it come from? What are lymphatic capillaries, lymphatic ducts, and lymph nodules and nodes?

Answer 1

1. Nutrients are absorbed in to the plasma of the blood and are carried in that form to different parts of the body. Arteries rich in nutrients reach all tissues of the body. From the arteries, arterioles and from there nutrients enter in to capillaries. Capillaries are very fine and narrow. Because of that pressure in the capillaries is very high. Due to that, lot of plasma of the blood comes out and occupies the gaps present between the cells. These gaps are called interstitial space or intercellular spaces. When the plasma is coming out of the capillaries, all nutrients are also coming out along with the plasma. The plasma that is getting collected in the intercellular spaces is called as the interstitial fluid. From the interstitial fluid, cells absorb different nutrients by simple diffusion, facilitated diffusion or by active transport.

2. When blood plasma comes out of capillaries, and occupies intercellular spaces, it forms tissue fluid. Lymph is nothing but the tissue fluid that is getting drained from the tissue through another set of capillaries called lymph capillaries. These capillaries are slightly different from the blood capillaries because they start like blind tubes, they are wider and have more porous.

Lymph is colorless fluid, same in composition as the blood plasma. But lymph coming out from different tissues varies slightly in composition.

Lymphatic capillaries start in every tissue to drain the tissue fluid. Otherwise the tissue will accumulate the fluid and swell. fine tubes, which are wider than the blood capillaries, more porous start in every tissue as blind tubes. These tubes that are draining the tissue fluid are called lymph capillaries.

Lymph capillaries unite to form lymphatic vessels. Lymph nodes are small bean shaped structures present along the length of the lymphatic vessels.

There are 2 important lymph ducts formed by the fusion of many lymphatic vessels coming out from the tissues.

1. Thoracic duct which is formed by the fusion of many lymphatic vessels on the left side of the body. This duct starts at Cisterna of chili which is a sac like dilation near first and second lumbar vertebra. the contents of the thoracic duct are poured in left subclavian vein.

Lymphoid nodules are collection of lymphoid tissue, usually located in the loose connective tissue, beneath the epithelium. Payer's patches in the intestine are such lymphatic nodules.

Lymph nodes are bean shaped nodes located along the length of the lymph vessels. These nodes are very important in defence of the body.

2. Right lympahtic duct formed by lymphatic vessels on the right side of thorax head and neck. It discharges its contents in to right subclavian. It is a very short duct.