Lymph - Anatomy & Physiology
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Introduction
Lymph, a fluid, is formed from interstitial fluid that is filtered into the lymph vessels. Lymph is transported through lymphatic vessels before eventually reentering the blood stream. Lymph transports lymphocytes and triacylglcerides.
Formation
Lymph is formed by the filtration of interstitial (tissue) fluid into lymphatic capillaries. As fluid enters the tissue space from the blood stream pressure builds up in this space and as this hydrostatic pressure increases it causes the interstitial fluid to diffuse into the lymphatic capillaries once the interstitial fluid has entered the lymphatic capillaries it is called lymph.
Composition
Lymph has a similar composition to blood plasma however lymphatic capillaries are more permeable than blood capillaries to proteins and this means that lymph has a higher concentration of proteins.
Circulation
Lymph travels unidirectionally from tissue into the blood stream via lymphatic capillaries which join to form vessels and these then join to form ducts. As there is no central pump lymph is moved through the vessels via compression the the vessels by skeletal muscle contraction. All lymph passes through lymph nodes before it reenters the blood stream. Further details of the lymphatic vessels can be found here.