Blood Capillaries vs Lymph Capillaries
Blood capillaries mainly help to feed the tissues. Lymph capillaries help absorb the excess fluid from the tissue.
Capillary tube means the tube with small internal diameter. The blood vessels also have capillaries. The Artery which is the tube that carries the blood from the heart divides into branches (small artery, arterioles). When it divides in to very tiny tubes it forms capillary network. Then from the capillaries, the small veins arise. These small veins join and form the large veins. The vein is the tube which carries blood towards the heart.
Capillaries are very small in internal diameter and have very thin tube wall also. So the exchange of the substance will be easy at capillary level. That means the oxygen and glucose carried by the blood from the artery are delivered to the tissues by capillaries and at the same time they receive the waste products from the tissue. Usually tissue wastes are carbon di-oxide and the products from the cells.
Blood capillaries may leak fluid from the capillary bed. However small amount will be re absorbed in to the capillaries or venules (small veins)
Lymph capillaries, as the name indicates are filled with lymph, a fluid containing white cells, chiefly lymphocytes. The lymph capillaries diameter is larger than the blood capillaries. And lymph capillaries will absorb the fluid which leak from the blood capillaries in to the tissue space. Unlike the blood capillaries, lymph capillaries do not leak the fluid from it.
Obstruction to the lymphatic will results in oedema (swelling). Decrease in protein levels in the blood, or kidney failure or heart failure results in more fluid leaking in to the tissue. This will be observed in the legs (ankle oedema) and around the eye (peri orbital oedema)
In summary capillaries are small tubes; small in diameter. Blood capillaries mainly help to feed the tissues. Lymph capillaries help absorb the excess fluid from the tissue.