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What are the differences in blood, interstitial fluid, and lymph? Similarities?

Hi, this lecture attempts to describe the differences, hope it works. :-:)

The main function of blood is to deliver oxygen and nutrients to tissues throughout the body, and carry away carbon dioxide and cellular waste (mostly lactic acid and calcium salts). Blood handles the day-to-day transport of living body materials.

The lymphatic system, however, is meant to handle dangerous toxins and pathogens; a separate and parallel system to the circulatory system to transport materials too hazardous to be carried around in the bloodstream.

1. Unlike blood capillaries, lymphatic capillaries have a valve that prevents the lymph from going back to the extracellular fluid. Flow of blood into the blood capillaries is regulated by smooth muscles in the arterial wall supplying a particular capillary bed.
2. Unlike blood capillaries, lymphatic capillaries are NOT present in the central nervous system.
3. They are larger then blood capillaries
4. Endothelial cells of a lymphatic capillary overlap. When pressure is greater in the interstitial fluid, the cells are pushed apart, like the opening of a one-way swinging door, and
interstitial fluid enters the lymphatic capillary. When pressure is greater inside the lymphatic capillary, the cells are pushed together closely, and lymph cannot escape back into the interstitial fluid.
5. Unlike blood capillaries, lymphatic capillaries being blindly in the substance of the tissue
6. Flow in the capillaries is a continuous laminar process, in lymphatics however, flow is not continuous and increases and decreases in velocity depending on changes in the pressure of the interstitial fluid.
7. Larger lymphatic vessels contain flaps of smooth muscle, called "Angions" these are basically analogous to the valves in the veins, providing a unidirectional flow of lymph.
8. Here is one similarity between lymphatics, arteries and veins: As in all vessels, lymphatic vessels merge and become progressively larger terminating into the Right Lymphatic duct and the Thoracic duct on the right and left sides of the chest respectively.

Thanks for the info, guys! You guys are awsome (((((hugs)))))

At the capillaries there is an movement of fluid and molecules out of the blood into the interstitial space (space outside of the blood vessels around the cells in the body). This fluid must go somewhere once it leaves the capillary or it would build up (look up elephantiasis). This fluid this passes into the lymphatic system where it will eventually be returned to the bloodstream.

jleyendo gave a good explanation on yahoo answers

You're welcome :)