Running Head: THE LYMPHATIC SYSTEM
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The Lymphatic System
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THE LYMPHATIC SYSTEM
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1. In our immune systems, the lymphatic system plays a very significant role and is made up
of:
The lymphatic organs e.g. thymus, bone marrow, lymph nodes and spleen
Lymphatic vessels-transport the lymph
Lymphatic fluid/lymph
The following diagram shows the anatomical positions of the lymphatic organs in the system.
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2. Physiological functions and histology of the lymphatic organ system:
Thymus-a primary epithelial organ in the lymphatic system where the maturation of T
cells occurs. The major lymphocytes in our adaptive immune system are T
lymphocytes/cells. Smaller quantities of other cells like plasma cells and B cells can also
be found here. A lack or loss of the thymus organ would lead to an increased
susceptibility to infections and in turn immunodeficiency. The septum which is made up
of epithelial cells divides the lobules in the thymus while the isthmus divides the two
identical lobes. These lobes can each be subdivided into a peripheral cortex and a central
medulla, which play a role in T cells development. Earlier thymocytes developments like
positive selection and gene rearrangement occur in the cortex while the later stages like
extensive negative selection occur in the medulla. Cells found in the thymus are the
hematopoietic cells (ones whose genesis is the bone marrow thymocytes i.e. developing T
cells) and stromal cells like the epithelial cells in the medulla and cortex. Stromal cells
are critical in acquisition of T cell tolerance.
Spleen-synthesis of blood cells and antibodies (to fight antigens), the recycling of old red
blood cells as well the filtering of the blood(by removing blood cells and bacteria that
have been coated by antibodies) occurs here. The spleen also acts as storage for platelets,
lymphocytes and other blood cells that can be needed in case of emergency situations.
For the first five months of prenatal development, the spleen also aids in the creation of
red blood cells. Found between the diaphragm and the stomach, the spleen is split into the
red pulp and the white pulp. The white pulp has macrophages and both B and T cells
around it in aggregations while the vascular red pulp has sinusoids (a leaky capillary) and
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parenchyma. Thanks to the slit epithelial cells lining the spleen, blood is filtered when
passing through allowing old or damaged blood vessels to undergo phagocytosis in the
red pulp. Trabeculae act as the connective tissues in the spleen and support it, together
with a dense capsule, as well as take blood vessels (Saladin, 1998).
Lymph nodes-These are stopover stations for the lymph that are distributed across the
body. The lymph passes through lymph nodes before going into the blood circulation. A
node filters debris and foreign particles from the lymph to aid in defense against
infections and microorganisms. They are bean/kidney like in shape, covered by dense
connective tissue that form a fibrous capsule and are connected through lymphatic
vessels. These capsules have extensions known as trabeculae that support the blood
vessel supply to the node. Each node also has a medulla (inner) and cortex (outer). The
medulla has blood vessels, medullary cords (containing macrophages, B cells and plasma
cells) and sinuses that secrete plasma cells activated by antigens. Afferent lymphatic
vessels allow lymph into the node. Elastin and reticular fibers that are thin form a
reticular network that will allow adherence by macrophages, lymphocytes and dendritic
cells to the surface and provide structural support for the node. The venules around this
area are endothelial and therefore allow exchange of blood. From the sub-capsular
sinuses through to the sinuses in the trabeculae and cortex, filtered lymph is drained so
that it can exit the node and get back into blood circulation through medullary sinuses.
Vessels in the nodes are small and do not allow macrophages to pass through hence
trapping them to function within the node. The outer cortex has follicles that contain B
cells and can become germinal centers in presence of antigen while the paracortex has
accessory cells and most T cells (Rouvière & Tobias, 1938).
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Lymphatic vessels-these are structures that have valves and thin walls and allow the
transport of the lymph. Afferent lymph vessels carry lymph to the node while those that
carry lymph from the node are known as efferent lymph vessels. They contain smooth
muscles, adventitia (attach vessels with surrounding tissue) and endothelial cells.
Lymphatic capillaries are much smaller and lack the adventitia as well as the smooth
muscle layer. Smaller or initial lymphatics collect lymph into the nodes while larger
lymphatics help in propelling the lymph through peristalsis (with the relaxation and
contraction of the smooth muscles), skeletal muscle contraction, arterial pulsation and the
valve system. This makes it a closed system without a centralized pumping organ like in
the cardiovascular system. Lymph is drained through lymph ducts into subclavian veins
so as to return into the general circulation (Swartz, 2001).
Lymph-this is the fluid circulating in the lymphatic system. Lymph capillaries collect
interstitial fluid, vessels transport it into the lymph nodes and after filtration it rejoins the
blood circulation through subclavian veins. Lymph has components like that of blood
plasma but it also has white blood cells. The fluid can transport bacteria to the nodes,
excess interstitial fluid and proteins back into blood circulation, metastatic cancer cells
and fats (originating from the digestive system in form of chyle).
3. Diseases associated with the lymphatic system
Lymphadenopathy-occurs due to enlargement of lymph nodes.
Castleman disease-inflammatory disorders that may cause node enlargement.
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Lymphoma-cancer affecting the lymph nodes and can be Hodgkin or Non
Hodgkin.
Lymphedema-when lymph node blockage causes swelling.
Fun facts about the lymphatic system:
It is believed that massage can help improve the flow of the lymph through manual
lymph drainage e.g. when there is a broken bones that has caused swelling.
Our bodies collect up to 2.5 liters of lymph every day.
Lymph flows upwards towards the neck and not in a loop like the cardiovascular system.
Your heartbeat and muscle movement aids in the smooth flow of the lymph.
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References
Rouvière, H., & Tobias, M. J. (1938). Anatomy of the human lymphatic system. Edwards
Brothers, Incorporated.
Saladin, K. S. (1998). Anatomy & physiology. WCB/McGraw-Hill.
Swartz, M. A. (2001). The physiology of the lymphatic system. Advanced drug delivery
reviews, 50(1), 3-20.
Running head: ORGAN SYSTEM INTERRELATIONSHIP
Organ System Interrelationship
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ORGAN SYSTEM INTERRELATIONSHIP
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Lymphatic System and Endocrine System
The Lymphatic system and Endocrine system do not have a particular body cavity place;
they are situated throughout the human’s body.
The lymphatic system supports the immune system in destroying and taking out waste,
toxins, pathogens, debris, and cancer cells. At the same time, the endocrine system is
involved in regulating mood, tissue function, metabolism, as well as growth and
development.
The lymphatic system absorbs fats including fat soluble vitamins from the system of
digestion and transports these nutrients to body cells, where they are utilized by the cells.
Moreover, hormones that are released by the endocrine system influences nearly each
particular cell, organ and body functioning.
In addition, the lymphatic system also eliminates the excess body fluids and waste
materials from the interstitial spaces in between the body cells and it transports tissue
fluid all through the body. The Endocrine system also uses blood streams in the
transportation of hormones all through the body.
The lymphatic system is also correlated to the cardiovascular system since lymphs
(organs of the lymphatic system) pull interstitial fluid and put it back into the blood.
On the other hand, the endocrine system is also correlated to the nervous system since the
release of certain hormones is stimulated by the nervous system.
Homeostatic interrelationship refers to the adjustment of physiological systems inside the
body. In terms of this, the lymphatic system usually has a homeostatic relationship with
the endocrine system which is very crucial and critical in any body of an individual as it
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supports major functions and protection of one’s internal organs such as getting rid of the
unwanted materials and toxin.
The lymphatic system is usually affected by a disease which is known as
lymphadenopathy. This disease causes the enlargement of lymph nodes and swelling due
to blockages of the lymph nodes. After a bacterium is recognized in the lymph fluid,
more infection is made by the lymph nodes in the fight of white blood cells hence causing
the swelling.
On both the lymphatic and endocrine system, there are exocrine glands that secrete
hormones externally on their surfaces. Moreover, the lymphatic system offers transport
means for the glucocorticoids hormones which are from the endocrine system and they
depress the immune inflammation and response in which lymphocytes seed the nodes of
the lymph.
Cancer of the lymphoma is disease of the lymphatic system and has great implication to
an individual and the society at large. It happens when the lymphocytes develop and
multiply hysterically. It largely affects the women who have had an operation aimed at
removing a breast cancer. It is very expensive to treat and can lead to death hence
affecting the society at large since most people loss their loved ones through it.
ORGAN SYSTEM INTERRELATIONSHIP
References
Carruthers, M. N., Stone, J. H., & Khosroshahi, A. (2012). The latest on IgG4-RD: a rapidly
emerging disease. Current opinion in rheumatology, 24(1), 60-69.
Deshpande, V., Zen, Y., Chan, J. K., Eunhee, E. Y., Sato, Y., Yoshino, T., ... & Aalberse, R. C.
(2012). Consensus statement on the pathology of IgG4-related disease. Modern
Pathology, 25(9), 1181-1192.
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