The lymphatic system is made up of organs, tissues, ducts and veins that help in the production and
transport of lymph. The capillary filtration removes plasma while leaving blood cells in the human
circulatory system, and the average amount of blood processed each day is 20 litres. The filtered
plasma is reabsorbed directly into the blood vessel in around 17 litres, while the remaining three
litres remain in the interstitial fluid (tissue fluid). One of the lymph system's important functions is to
offer an additional return path for excess three litres to the blood vessel. Therefore, the human body
has roughly 600 lymph nodes which help to sustain fluid level in the body but infection such as
bacteria and viruses causes the lymph to grow and expand due to buildup of lymph fluid. As a result
the lymphatic system is a group of vessels and nodes that
help to remove waste and pathogens which is mostly located
around the heart and lungs or even close to the skin.
The primary lymphoid organs include the bone marrow and
the thymus. They create and produce special immune cells
called lymphocytes. However, the secondary lymphoid organs
include the lymph nodes, spleen, tonsils, and specialised
tissue throughout the body. These organs are where the
immune system’s cells fight and engulf the germs and
pathogens.The lymphatic system has three main function
which includes:
- Removed excess water or fluid from body tissue
- Defence and immunity against pathogen
- Absorb and transport fat
As a result, the lymphatic system is a network of small vessels that helps to transport excess fluid to
the bloodstream and filters infections from the blood. Moreover, the immune system is composed of
cells and organs that work together to fight disease-causing germs. Therefore, the lymphatic system’s
primary role is to remove bodily fluids and restore them to the bloodstream. This happens because
the blood pressure causes fluid leakage in the capillaries, which the fluid goes into the interstitial
space (tissue fluid).
Arterial and venous end capillary
The blood vessels help to carry blood
throughout the body such as arteries carry
blood away from the heart and veins carry
blood into the heart. The capillaries that
surround and carry oxygen, nutrients, and
other substances to body cells and tissue. The
capillaries also connect the arteries' branches
, to the veins' branches. The tunica externa, tunica medium, and tunica intima are the three primary
layers of the blood vessel walls, each of which has a hollow interior through which blood flows.
Capillaries are blood arteries that extend out from arterioles to build networks that enclose and
protect body cells, allowing oxygen to be absorbed from breathed air and CO2 to be released.
Furthermore, blood pressure is applied on the walls of blood arteries as it travels through the
circulatory system. This pressure is called hydrostatic pressure which forces lymph fluid out the
blood vessel into the tissue fluid.
Maintenance of hydrostatic pressure
The circulatory system's primary function is to provide oxygen and nutrients to body tissues while
also removing wastes such as CO2. The capillary walls are made up of a single layer of endothelial
cells, so the substance moves between the blood and surrounding tissue in several ways such as
diffusion through the plasma membranes of the endothelial cells.The oxygen moves down its
concentration gradient from the blood to the surrounding tissue, while carbon dioxide diffuses in the
reverse direction. At the arterial end of the capillary bed, blood plasma carries nutrients which travel
out into the tissue fluid. while tissue fluid containing waste reabsorbs back in at the venous end. This
helps in the maintenance of fluid equilibrium and it removes extra fluid and nutrients from tissues
fluid which is also known as interstitial space. Therefore, there are two pressure that aids to keep
balance of the fluid in the lymph is:
- Hydrostatic pressure
- Osmotic pressure
The hydrostatic pressure is defined as the pressure of the fluid in an interstitial space, which the
hydrostatic pressure form inside capillaries is higher than outside. This is because the blood has a
much higher protein content due to albumin
and this draws water into the blood
vessel.Furthermore, because the arterial end of
the capillary is closer to the heart, the
hydrostatic pressure at the arterial end is higher
than at the venous end.
Therefore, the hydrostatic pressure is higher in
arterial end capillary which causes the nutrient
and other substance in the blood to leak out
into the interstitial space (tissue fluid). In fact,
about 15% of the fluid is left in the tissue after
capillary exchange and only 85% is reabsorbed
back in the venous end capillary. The fluid is
picked up by the lymphatic system and returned
to the circulatory system. Therefore, the
lymphatic system helps to return excess fluid
and other substances back to the blood vessel.
Defence against pathogen and germs
Lymphatic system also helps to defend against pathogens and disease, this is because the lymphatic
system begins as an lymphatic capillary which is made up of overlapping endothelial cells. The