Lymph Drainage - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 176

Chapter 4
Lymph Drainage

The circulatory system has a specialized compartment that transports the lymph , 1
Lymph originates from the interstitial fluid that enters the lumen in lymphatic
vessels , or lymph vessels (capillary filtration). Interstitial fluid is the part of plasma
leaking into tissues through thin walls of blood capillaries. Plasma escaping blood
capillaries contains oxygen, glucose, amino acids, and other nutrients.
Lymph is convected unidirectionally from tiny lymphatic capillaries that infuse
almost every body's tissue toward large thoracic veins close to the heart, i.e.,
subclavian veins on left and right sides of the neck base via left and right thoracic
ducts (length 38-45 cm; caliber 5mm) of the lymphatic system. Lymph return a

fraction of carried particulate matter to the blood stream. Therefore, lymph enables
to recycle plasma.
The lymph is carried along the lymph vascular network by intrinsic contractions
of mural cells of mid-size and large lymphatic vessels and by extrinsic compression
of lymphatic vessels by skeletal muscle activity, among other sources of increase in
external pressure such as breathing. Valves prevent lymph from flowing backward.
Lymph flow can cease during long periods of complete physical inactivity.
Lymphatic vessels convey lymph from nearly all the body's tissue, except
the central nervous system, tiny vessel walls, and avascular tissues, such as the
transparent structures of the eye (central cornea, lens, vitreous humor) 2 and articular
cartilage, 3 in addition to epithelia and endothelia. Lymphatic vessels are not detected
in cortical bone, but in connective tissue overlying the periosteum [ 318 ]. On the

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1 Latin lympha: eau.
2 The cornea has some peripheral blood vessels. The lens remains avascular even after injury.
Ocular cells involved in avascular repair synthesize thrombospondin-1, a regulator of early wound
repair. The cornea is innervated, but not the lens.
3 Cartilage is classified in 3 types — elastic, hyaline, and fibrocartilage, according to the relative
amounts of constituents (chondroblasts and chondrocytes on the one hand and collagen-1 and -2,
elastin fibers, and proteoglycans on the other.