Can the Lymphatic Flow of the Leg Be Disrupted if Lymph Glands Are Removed in the Right Abdomen

Learning Objectives

By the end of this department, you lot volition be able to:

• Describe the construction and part of the lymphatic tissue (lymph fluid, vessels, ducts, and organs)
• Describe the structure and role of the primary and secondary lymphatic organs
• Discuss the cells of the immune system, how they function, and their relationship with the lymphatic system

The allowed organisation is the circuitous drove of cells and organs that destroys or neutralizes pathogens that would otherwise cause disease or death. The lymphatic system, for well-nigh people, is associated with the immune organization to such a degree that the two systems are virtually duplicate. The lymphatic organization is the organisation of vessels, cells, and organs that carries excess fluids to the bloodstream and filters pathogens from the claret. The swelling of lymph nodes during an infection and the transport of lymphocytes via the lymphatic vessels are but ii examples of the many connections betwixt these critical organ systems.

Functions of the Lymphatic Organisation

A major function of the lymphatic organization is to drain body fluids and return them to the bloodstream. Blood pressure causes leakage of fluid from the capillaries, resulting in the accumulation of fluid in the interstitial infinite—that is, spaces between individual cells in the tissues. In humans, xx liters of plasma is released into the interstitial space of the tissues each day due to capillary filtration. Once this filtrate is out of the bloodstream and in the tissue spaces, it is referred to every bit interstitial fluid. Of this, 17 liters is reabsorbed direct past the blood vessels. Only what happens to the remaining three liters? This is where the lymphatic system comes into play. It drains the excess fluid and empties it back into the bloodstream via a serial of vessels, trunks, and ducts. Lymph is the term used to depict interstitial fluid one time it has entered the lymphatic system. When the lymphatic system is damaged in some fashion, such as by beingness blocked by cancer cells or destroyed by injury, poly peptide-rich interstitial fluid accumulates (sometimes "backs up" from the lymph vessels) in the tissue spaces. This inappropriate aggregating of fluid referred to equally lymphedema may lead to serious medical consequences.

Every bit the vertebrate immune system evolved, the network of lymphatic vessels became convenient avenues for transporting the cells of the immune system. Additionally, the transport of dietary lipids and fat-soluble vitamins captivated in the gut uses this organisation.

Cells of the allowed organisation not merely use lymphatic vessels to make their way from interstitial spaces back into the circulation, just they also use lymph nodes as major staging areas for the development of critical immune responses. A lymph node is one of the small, bean-shaped organs located throughout the lymphatic organisation.

Exercise Questions

Visit this website for an overview of the lymphatic system. What are the three main components of the lymphatic system?

Prove Reply

The three main components are the lymph vessels, the lymph nodes, and the lymph.

Structure of the Lymphatic Organisation

The lymphatic vessels begin as open-ended capillaries, which feed into larger and larger lymphatic vessels, and eventually empty into the bloodstream by a serial of ducts. Along the fashion, the lymph travels through the lymph nodes, which are commonly found near the groin, armpits, neck, chest, and belly. Humans have about 500–600 lymph nodes throughout the body.

Effigy 1. Lymphatic vessels in the arms and legs convey lymph to the larger lymphatic vessels in the torso.

A major distinction betwixt the lymphatic and cardiovascular systems in humans is that lymph is not actively pumped past the heart, but is forced through the vessels past the movements of the torso, the contraction of skeletal muscles during body movements, and breathing. One-manner valves (semi-lunar valves) in lymphatic vessels continue the lymph moving toward the heart. Lymph flows from the lymphatic capillaries, through lymphatic vessels, and and so is dumped into the circulatory organisation via the lymphatic ducts located at the junction of the jugular and subclavian veins in the cervix.

Lymphatic Capillaries

Lymphatic capillaries, also chosen the last lymphatics, are vessels where interstitial fluid enters the lymphatic organisation to become lymph fluid. Located in almost every tissue in the body, these vessels are interlaced amidst the arterioles and venules of the circulatory system in the soft connective tissues of the body. Exceptions are the central nervous system, bone marrow, bones, teeth, and the cornea of the eye, which do not contain lymph vessels.

Figure 2. Lymphatic capillaries are interlaced with the arterioles and venules of the cardiovascular system. Collagen fibers anchor a lymphatic capillary in the tissue (inset). Interstitial fluid slips through spaces between the overlapping endothelial cells that compose the lymphatic capillary.

Lymphatic capillaries are formed by a one cell-thick layer of endothelial cells and stand for the open terminate of the system, allowing interstitial fluid to flow into them via overlapping cells. When interstitial pressure is low, the endothelial flaps shut to prevent "backflow." As interstitial pressure increases, the spaces between the cells open upward, allowing the fluid to enter. Entry of fluid into lymphatic capillaries is likewise enabled past the collagen filaments that ballast the capillaries to surrounding structures. Every bit interstitial pressure level increases, the filaments pull on the endothelial cell flaps, opening upwards them even further to let piece of cake entry of fluid.

In the small intestine, lymphatic capillaries called lacteals are critical for the send of dietary lipids and lipid-soluble vitamins to the bloodstream. In the small intestine, dietary triglycerides combine with other lipids and proteins, and enter the lacteals to course a milky fluid chosen chyle. The chyle then travels through the lymphatic organisation, eventually entering the liver and and so the bloodstream.

Larger Lymphatic Vessels, Trunks, and Ducts

The lymphatic capillaries empty into larger lymphatic vessels, which are similar to veins in terms of their iii-tunic construction and the presence of valves. These one-way valves are located fairly shut to ane some other, and each ane causes a bulge in the lymphatic vessel, giving the vessels a beaded appearance.

The superficial and deep lymphatics eventually merge to form larger lymphatic vessels known every bit lymphatic trunks. On the right side of the torso, the right sides of the head, thorax, and right upper limb drain lymph fluid into the correct subclavian vein via the right lymphatic duct. On the left side of the torso, the remaining portions of the body drain into the larger thoracic duct, which drains into the left subclavian vein. The thoracic duct itself begins only beneath the diaphragm in the cisterna chyli, a sac-similar chamber that receives lymph from the lower abdomen, pelvis, and lower limbs by way of the left and right lumbar trunks and the intestinal trunk.

Effigy 3. The thoracic duct drains a much larger portion of the body than does the right lymphatic duct.

The overall drainage system of the trunk is asymmetrical. The right lymphatic duct receives lymph from just the upper right side of the body. The lymph from the rest of the torso enters the bloodstream through the thoracic duct via all the remaining lymphatic trunks. In general, lymphatic vessels of the subcutaneous tissues of the skin, that is, the superficial lymphatics, follow the same routes every bit veins, whereas the deep lymphatic vessels of the viscera generally follow the paths of arteries.

The Organization of Allowed Part

The immune organisation is a collection of barriers, cells, and soluble proteins that interact and communicate with each other in extraordinarily complex ways. The modernistic model of allowed function is organized into three phases based on the timing of their effects. The three temporal phases consist of the following:

• Barrier defenses such as the peel and mucous membranes, which deed instantaneously to prevent pathogenic invasion into the body tissues
• The rapid but nonspecific innate immune response, which consists of a multifariousness of specialized cells and soluble factors
• The slower but more than specific and constructive adaptive allowed response, which involves many cell types and soluble factors, but is primarily controlled past white blood cells (leukocytes) known every bit lymphocytes, which assistance command immune responses

The cells of the blood, including all those involved in the allowed response, ascend in the bone marrow via various differentiation pathways from hematopoietic stalk cells. In contrast with embryonic stem cells, hematopoietic stem cells are present throughout adulthood and permit for the continuous differentiation of blood cells to replace those lost to historic period or function. These cells can be divided into three classes based on function:

• Phagocytic cells, which ingest pathogens to destroy them
• Lymphocytes, which specifically coordinate the activities of adaptive immunity
• Cells containing cytoplasmic granules, which assist mediate immune responses against parasites and intracellular pathogens such as viruses

Figure 4. All the cells of the immune response as well as of the blood arise by differentiation from hematopoietic stem cells. Platelets are cell fragments involved in the clotting of blood.

Lymphocytes

As stated above, lymphocytes are the main cells of adaptive immune responses (see Table ane for more details). The 2 basic types of lymphocytes, B cells and T cells, are identical morphologically with a large central nucleus surrounded by a thin layer of cytoplasm. They are distinguished from each other by their surface poly peptide markers also as past the molecules they secrete. While B cells mature in cherry os marrow and T cells mature in the thymus, they both initially develop from bone marrow. T cells migrate from bone marrow to the thymus gland where they further mature. B cells and T cells are found in many parts of the body, circulating in the bloodstream and lymph, and residing in secondary lymphoid organs, including the spleen and lymph nodes, which will be described later in this section. The human body contains approximately 10¹² lymphocytes.

B Cells

B cells are immune cells that role primarily by producing antibodies. An antibiotic is any of the group of proteins that binds specifically to pathogen-associated molecules known equally antigens. An antigen is a chemical structure on the surface of a pathogen that binds to T or B lymphocyte antigen receptors. In one case activated by binding to antigen, B cells differentiate into cells that secrete a soluble form of their surface antibodies. These activated B cells are known equally plasma cells.

T Cells

The T jail cell, on the other hand, does not secrete antibody but performs a diverseness of functions in the adaptive immune response. Different T jail cell types have the power to either secrete soluble factors that communicate with other cells of the adaptive immune response or destroy cells infected with intracellular pathogens. The roles of T and B lymphocytes in the adaptive allowed response will be discussed further in this chapter.

Plasma Cells

Some other type of lymphocyte of importance is the plasma cell. A plasma cell is a B cell that has differentiated in response to antigen binding, and has thereby gained the ability to secrete soluble antibodies. These cells differ in morphology from standard B and T cells in that they contain a big amount of cytoplasm packed with the poly peptide-synthesizing machinery known as rough endoplasmic reticulum.

Natural Killer Cells

A fourth of import lymphocyte is the natural killer cell, a participant in the innate immune response. A natural killer jail cell (NK) is a circulating claret cell that contains cytotoxic (prison cell-killing) granules in its extensive cytoplasm. Information technology shares this mechanism with the cytotoxic T cells of the adaptive immune response. NK cells are among the torso's first lines of defence against viruses and certain types of cancer.

Tabular array i. Lymphocytes
Blazon of lymphocyte	Main function
B lymphocyte	Generates diverse antibodies
T lymphocyte	Secretes chemical messengers
Plasma cell	Secretes antibodies
NK jail cell	Destroys virally infected cells

Exercise Question

Visit this website to larn about the many different cell types in the allowed system and their very specialized jobs. What is the role of the dendritic jail cell in an HIV infection?

Bear witness Reply

The dendritic cell transports the virus to a lymph node.

Primary Lymphoid Organs and Lymphocyte Development

Agreement the differentiation and development of B and T cells is critical to the agreement of the adaptive immune response. Information technology is through this process that the body (ideally) learns to destroy only pathogens and leaves the body'southward own cells relatively intact. The primary lymphoid organs are the bone marrow, spleen, and thymus gland. The lymphoid organs are where lymphocytes mature, proliferate, and are selected, which enables them to attack pathogens without harming the cells of the torso.

Bone Marrow

Effigy 5. Red os marrow fills the head of the femur, and a spot of xanthous bone marrow is visible in the heart. The white reference bar is ane cm.

In the embryo, claret cells are made in the yolk sac. As development proceeds, this function is taken over by the spleen, lymph nodes, and liver. Later, the bone marrow takes over nigh hematopoietic functions, although the concluding stages of the differentiation of some cells may have place in other organs. The cherry-red bone marrow is a loose collection of cells where hematopoiesis occurs, and the yellow os marrow is a site of energy storage, which consists largely of fat cells. The B cell undergoes nearly all of its development in the red bone marrow, whereas the immature T cell, called a thymocyte, leaves the bone marrow and matures largely in the thymus gland.

Thymus

The thymus gland is a bilobed organ plant in the space betwixt the sternum and the aorta of the heart. Connective tissue holds the lobes closely together but also separates them and forms a capsule.

Fiugre 6. The thymus lies above the heart. The trabeculae and lobules, including the darkly staining cortex and the lighter staining medulla of each lobule, are conspicuously visible in the light micrograph of the thymus of a newborn. LM × 100. (Micrograph provided by the Regents of the University of Michigan Medical School © 2012)

View the University of Michigan WebScope to explore the tissue sample in greater detail.

The connective tissue capsule farther divides the thymus into lobules via extensions called trabeculae. The outer region of the organ is known as the cortex and contains large numbers of thymocytes with some epithelial cells, macrophages, and dendritic cells (two types of phagocytic cells that are derived from monocytes). The cortex is densely packed and so it stains more than intensely than the remainder of the thymus. The medulla, where thymocytes migrate earlier leaving the thymus, contains a less dumbo collection of thymocytes, epithelial cells, and dendritic cells.

Aging and the Immune System

By the year 2050, 25 percentage of the population of the United states volition exist 60 years of age or older. The CDC estimates that eighty percent of those 60 years and older have i or more chronic disease associated with deficiencies of the immune systems. This loss of immune part with age is called immunosenescence. To treat this growing population, medical professionals must improve understand the crumbling process. One major crusade of age-related allowed deficiencies is thymic involution, the shrinking of the thymus gland that begins at birth, at a rate of nigh three percentage tissue loss per year, and continues until 35–45 years of historic period, when the rate declines to about i per centum loss per twelvemonth for the rest of ane'due south life. At that step, the total loss of thymic epithelial tissue and thymocytes would occur at nigh 120 years of historic period. Thus, this historic period is a theoretical limit to a healthy human being lifespan.

Thymic involution has been observed in all vertebrate species that take a thymus gland. Creature studies have shown that transplanted thymic grafts between inbred strains of mice involuted according to the age of the donor and not of the recipient, implying the process is genetically programmed. At that place is evidence that the thymic microenvironment, so vital to the development of naïve T cells, loses thymic epithelial cells co-ordinate to the decreasing expression of the FOXN1 cistron with age.

It is also known that thymic involution can be contradistinct by hormone levels. Sex hormones such as estrogen and testosterone enhance involution, and the hormonal changes in meaning women cause a temporary thymic involution that reverses itself, when the size of the thymus and its hormone levels render to normal, usually after lactation ceases. What does all this tell us? Can nosotros reverse immunosenescence, or at least slow it downwards? The potential is there for using thymic transplants from younger donors to proceed thymic output of naïve T cells loftier. Factor therapies that target gene expression are as well seen equally hereafter possibilities. The more we larn through immunosenescence research, the more opportunities in that location volition be to develop therapies, even though these therapies volition likely take decades to develop. The ultimate goal is for everyone to live and be salubrious longer, merely at that place may be limits to immortality imposed by our genes and hormones.

Secondary Lymphoid Organs and their Roles in Active Immune Responses

Lymphocytes develop and mature in the primary lymphoid organs, only they mountain allowed responses from the secondary lymphoid organs. A naïve lymphocyte is one that has left the master organ and entered a secondary lymphoid organ. Naïve lymphocytes are fully functional immunologically, simply have yet to encounter an antigen to answer to. In addition to circulating in the blood and lymph, lymphocytes concentrate in secondary lymphoid organs, which include the lymph nodes, spleen, and lymphoid nodules. All of these tissues have many features in mutual, including the following:

• The presence of lymphoid follicles, the sites of the formation of lymphocytes, with specific B cell-rich and T cell-rich areas
• An internal structure of reticular fibers with associated stock-still macrophages
• Germinal centers, which are the sites of rapidly dividing B lymphocytes and plasma cells, with the exception of the spleen
• Specialized post-capillary vessels known as high endothelial venules; the cells lining these venules are thicker and more columnar than normal endothelial cells, which permit cells from the blood to directly enter these tissues

Lymph Nodes

Lymph nodes function to remove droppings and pathogens from the lymph, and are thus sometimes referred to as the "filters of the lymph". Whatever bacteria that infect the interstitial fluid are taken upwardly by the lymphatic capillaries and transported to a regional lymph node. Dendritic cells and macrophages within this organ internalize and kill many of the pathogens that laissez passer through, thereby removing them from the torso. The lymph node is also the site of adaptive allowed responses mediated past T cells, B cells, and accessory cells of the adaptive immune organisation. Like the thymus, the bean-shaped lymph nodes are surrounded by a tough capsule of connective tissue and are separated into compartments by trabeculae, the extensions of the capsule. In add-on to the structure provided by the capsule and trabeculae, the structural support of the lymph node is provided by a series of reticular fibers laid down by fibroblasts.

Figure 7. Lymph nodes are masses of lymphatic tissue located forth the larger lymph vessels. The micrograph of the lymph nodes shows a germinal center, which consists of speedily dividing B cells surrounded by a layer of T cells and other accessory cells. LM × 128. (Micrograph provided by the Regents of the University of Michigan Medical School © 2012)

The major routes into the lymph node are via afferent lymphatic vessels. Cells and lymph fluid that leave the lymph node may do so by another set of vessels known as the efferent lymphatic vessels. Lymph enters the lymph node via the subcapsular sinus, which is occupied past dendritic cells, macrophages, and reticular fibers. Within the cortex of the lymph node are lymphoid follicles, which consist of germinal centers of rapidly dividing B cells surrounded by a layer of T cells and other accessory cells. As the lymph continues to flow through the node, it enters the medulla, which consists of medullary cords of B cells and plasma cells, and the medullary sinuses where the lymph collects before leaving the node via the efferent lymphatic vessels.

Spleen

In addition to the lymph nodes, the spleen is a major secondary lymphoid organ. It is virtually 12 cm (five in) long and is attached to the lateral border of the stomach via the gastrosplenic ligament. The spleen is a frail organ without a potent capsule, and is nighttime cherry-red due to its extensive vascularization. The spleen is sometimes called the "filter of the claret" because of its extensive vascularization and the presence of macrophages and dendritic cells that remove microbes and other materials from the blood, including dying carmine claret cells. The spleen too functions equally the location of immune responses to blood-borne pathogens.

Figure 8. (a) The spleen is attached to the stomach. (b) A micrograph of spleen tissue shows the germinal center. The marginal zone is the region between the ruby pulp and white pulp, which sequesters particulate antigens from the circulation and presents these antigens to lymphocytes in the white pulp. EM × 660. (Micrograph provided by the Regents of the University of Michigan Medical Schoolhouse © 2012)

The spleen is also divided by trabeculae of connective tissue, and inside each splenic nodule is an area of red pulp, consisting of mostly cerise blood cells, and white pulp, which resembles the lymphoid follicles of the lymph nodes. Upon inbound the spleen, the splenic artery splits into several arterioles (surrounded past white pulp) and somewhen into sinusoids. Claret from the capillaries afterwards collects in the venous sinuses and leaves via the splenic vein. The scarlet pulp consists of reticular fibers with fixed macrophages attached, free macrophages, and all of the other cells typical of the blood, including some lymphocytes. The white pulp surrounds a fundamental arteriole and consists of germinal centers of dividing B cells surrounded by T cells and accompaniment cells, including macrophages and dendritic cells. Thus, the scarlet pulp primarily functions as a filtration system of the blood, using cells of the relatively nonspecific immune response, and white pulp is where adaptive T and B cell responses are mounted.

Lymphoid Nodules

The other lymphoid tissues, the lymphoid nodules, have a simpler architecture than the spleen and lymph nodes in that they consist of a dense cluster of lymphocytes without a surrounding gristly capsule. These nodules are located in the respiratory and digestive tracts, areas routinely exposed to environmental pathogens.

Tonsils are lymphoid nodules located along the inner surface of the pharynx and are important in developing immunity to oral pathogens. The tonsil located at the dorsum of the throat, the pharyngeal tonsil, is sometimes referred to equally the adenoid when bloated. Such swelling is an indication of an active immune response to infection. Histologically, tonsils do not incorporate a complete sheathing, and the epithelial layer invaginates deeply into the interior of the tonsil to form tonsillar crypts. These structures, which accrue all sorts of materials taken into the body through eating and breathing, actually "encourage" pathogens to penetrate deep into the tonsillar tissues where they are acted upon by numerous lymphoid follicles and eliminated. This seems to be the major role of tonsils—to help children's bodies recognize, destroy, and develop amnesty to common environmental pathogens so that they will be protected in their later lives. Tonsils are often removed in those children who have recurring pharynx infections, especially those involving the palatine tonsils on either side of the pharynx, whose swelling may interfere with their animate and/or swallowing.

Effigy 9. (a) The pharyngeal tonsil is located on the roof of the posterior superior wall of the nasopharynx. The palatine tonsils lay on each side of the pharynx. (b) A micrograph shows the palatine tonsil tissue. LM × 40. (Micrograph provided by the Regents of the University of Michigan Medical School © 2012)

Mucosa-associated lymphoid tissue (MALT) consists of an aggregate of lymphoid follicles direct associated with the mucous membrane epithelia. MALT makes up dome-shaped structures plant underlying the mucosa of the alimentary canal, breast tissue, lungs, and optics. Peyer'southward patches, a type of MALT in the small intestine, are specially important for immune responses against ingested substances. Peyer's patches contain specialized endothelial cells called M (or microfold) cells that sample fabric from the abdominal lumen and ship information technology to nearby follicles so that adaptive allowed responses to potential pathogens can be mounted.

Effigy 10. LM × xl. (Micrograph provided by the Regents of the University of Michigan Medical School © 2012)

Bronchus-associated lymphoid tissue (BALT) consists of lymphoid follicular structures with an overlying epithelial layer found along the bifurcations of the bronchi, and between bronchi and arteries. They also have the typically less-organized structure of other lymphoid nodules. These tissues, in improver to the tonsils, are effective against inhaled pathogens.

Chapter Review

The lymphatic system is a series of vessels, ducts, and trunks that remove interstitial fluid from the tissues and return it the blood. The lymphatics are also used to ship dietary lipids and cells of the allowed organisation. Cells of the immune system all come from the hematopoietic system of the bone marrow. Chief lymphoid organs, the bone marrow and thymus gland, are the locations where lymphocytes of the adaptive immune system proliferate and mature. Secondary lymphoid organs are site in which mature lymphocytes congregate to mount allowed responses. Many immune system cells utilize the lymphatic and circulatory systems for transport throughout the body to search for and then protect against pathogens.

Cocky Check

Respond the question(s) beneath to meet how well you understand the topics covered in the previous section.

Critical Thinking Question

Depict the catamenia of lymph from its origins in interstitial fluid to its elimination into the venous bloodstream.

Show Answer

The lymph enters through lymphatic capillaries, and then into larger lymphatic vessels. The lymph tin simply go in one direction due to valves in the vessels. The larger lymphatics merge to course trunks that enter into the blood via lymphatic ducts.

Glossary

adaptive immune response:relatively slow but very specific and effective immune response controlled by lymphocytes

afferent lymphatic vessels:lead into a lymph node

antibody:antigen-specific protein secreted by plasma cells; immunoglobulin

antigen:molecule recognized past the receptors of B and T lymphocytes

barrier defenses:antipathogen defenses deriving from a barrier that physically prevents pathogens from inbound the body to establish an infection

B cells:lymphocytes that act by differentiating into an antibody-secreting plasma cell

bone marrow:tissue institute inside bones; the site of all blood jail cell differentiation and maturation of B lymphocytes

bronchus-associated lymphoid tissue (BALT):lymphoid nodule associated with the respiratory tract

chyle:lipid-rich lymph inside the lymphatic capillaries of the small intestine

cisterna chyli:bag-similar vessel that forms the outset of the thoracic duct

efferent lymphatic vessels:lead out of a lymph node

germinal centers:clusters of rapidly proliferating B cells found in secondary lymphoid tissues

high endothelial venules:vessels containing unique endothelial cells specialized to allow migration of lymphocytes from the blood to the lymph node

allowed system:series of barriers, cells, and soluble mediators that combine to response to infections of the body with pathogenic organisms

innate immune response:rapid but relatively nonspecific immune response

lymph:fluid contained within the lymphatic system

lymph node:ane of the bean-shaped organs found associated with the lymphatic vessels

lymphatic capillaries:smallest of the lymphatic vessels and the origin of lymph flow

lymphatic system:network of lymphatic vessels, lymph nodes, and ducts that carries lymph from the tissues and back to the bloodstream.

lymphatic trunks:big lymphatics that collect lymph from smaller lymphatic vessels and empties into the blood via lymphatic ducts

lymphocytes:white blood cells characterized past a large nucleus and small-scale rim of cytoplasm

lymphoid nodules:unencapsulated patches of lymphoid tissue found throughout the trunk

mucosa-associated lymphoid tissue (MALT):lymphoid nodule associated with the mucosa

naïve lymphocyte:mature B or T cell that has not nonetheless encountered antigen for the first fourth dimension

natural killer cell (NK):cytotoxic lymphocyte of innate immune response

plasma cell:differentiated B cell that is actively secreting antibody

principal lymphoid organ:site where lymphocytes mature and proliferate; scarlet bone marrow and thymus gland

correct lymphatic duct:drains lymph fluid from the upper right side of torso into the right subclavian vein

secondary lymphoid organs:sites where lymphocytes mount adaptive immune responses; examples include lymph nodes and spleen

spleen:secondary lymphoid organ that filters pathogens from the claret (white pulp) and removes degenerating or damaged blood cells (cerise pulp)

T jail cell:lymphocyte that acts by secreting molecules that regulate the immune organisation or by causing the destruction of foreign cells, viruses, and cancer cells

thoracic duct:large duct that drains lymph from the lower limbs, left thorax, left upper limb, and the left side of the head

thymocyte:immature T cell institute in the thymus

thymus:main lymphoid organ; where T lymphocytes proliferate and mature

tonsils:lymphoid nodules associated with the nasopharynx

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