The Lymphatic System

By V F Murphy
Diagram of the Lymphatic System

Structure, distribution, and function of the lymphatic system

The lymphatic system forms a one-way flow system toward the heart. Through this system flows lymph, which starts from blind-ended capillaries. The capillaries are very permeable and feature a loose overlap feature, where with the aid of small anchoring filaments the vessel can take large particles and stay open where the external pressure is greater. This causes problems, however, as the vessel also carries large particles, such as viruses, pathogens, and cell debris hence can carry infection through the body.

Mechanism of transport

The capillaries soon acquire small one-way valves, which ensure flow is only in one direction. The fluid is further moved through the system by means of compression caused by general skeletal muscle movements, including pulmonary inspiration.
Composition of lymphoid tissue
Lymphoid tissue is whiteish tissue containing antibodies and immune cells.

Plastic surgeons should take note that the liposuction procedure can damage the lymphatic system. The result of this is the build-up of lymphatic fluids without adequate drainage.
The National Library of Medicine discusses this here:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880231/

The lymphatic system is important for the body's recovery process and it can get damaged during surgical procedures such as cosmetic surgery and cancer ...
It has been established that the lymphatic system can be affected by cosmetic surgery such as at www.paulwilsonaesthetics.co.uk and cancer treatments.

Major lymphoid organs:

Lymphatic capillaries are 10-50 micrometers in diameter and are referred to as the initial (or terminal) lymphatics. They start from a blind sac, or from anastomosing vessels. The endothelium is a single layer, with an incomplete basement membrane. There is a gap junction of 14nm, which makes it highly permeable to plasma proteins and carbon particles. The cell junctions are oblique, forming the flap valves noted above.

The vessel also carries large particles, such as viruses, pathogens, and cell debris hence can carry infection through the body
V F MurphyAnchoring filaments have been observed which keep the capillaries open at reverse pressure gradients from the surrounding interstitium. The capillaries then lead into collecting vessels, which flow into the afferent lymph trunks. Semi-lunar valves in these larger vessels direct flow centrally, and the vessel gains a Smooth Muscle Cell layer and connective tissue.
Function
There are a number of other lymphatic organs that form semi-independent parts in relation to the main system, but the lymphatic circulation itself leads from a microcapillary filtrate from interstitium throughout the body, back into the blood at the L and R subclavian veins. Without this recirculation, the cardiovascular system would stop in time, and massive swelling (edema) would take place.

Resources and references on Medical Engineering

Wikipedia article and background

Articles from Imeche,org