Chapter 22 Lymphatic System
Hodgkin's lymphoma
A malignancy of lymphoid tissue: symptoms include swollen, nonpainful lymph nodes, fatigue, and often intermittent fever and night sweats. Characterized by presence of giant malignantly transformed B cells called Reed-Sternberg cells. Infection with Epstein-Barr virus (see mononucleosis) and genetic susceptibility appear to be predisposing factors. Treated with chemotherapy and radiation, high cure rate.
Which of the following best describes the arrangement of lymphatic vessels?
A one-way system of vessels beginning with blind-ended lymphatic capillaries (The lymphatic vessels form a one-way system in which lymph flows only toward the heart. It begins as blind-ended capillaries.)
Mononucleosis
A viral disease common in adolescents and young adults; symptoms include fatigue, fever, sore throat, and swollen lymph nodes. Caused by the Epstein-Barr virus which is transmitted in saliva ("kissing disease") and specifically attacks B lymphocytes. This attack leads to a massive activation of T lymphocytes, which in turn attack the virus-infected B cells. Large numbers of oversized T lymphocytes circulate in the blood stream. (these lymphocytes were originally misidentified as monocytes) Usually lasts four to six weeks.
Discuss the function of anchoring filaments that surround lymphatic capillaries.
Open the space between lymphatic capillary cells so leaked tissue fluid can enter.
Aggregates of lymphoid nodules located in the wall of the ileum are
Peyer's patches - These prevent bacteria from migrating through the wall of the intestine.
Which area does NOT contain a large collection of lymph nodes?
The brachial area - The extremities do NOT possess large collections of lymph nodes.
immunology
The branch of science that deals with the responses of the body when challenged by antigens
What lymphatic structure forms from the merging of the intestinal and lumbar trunks?
cisterna chyli - This structure is an enlarged collecting sac.
The pressure exerted by lymph after it enters the lymphatic capillary forces the endothelial cells of these vessel to _____
close
Trabeculae:
fibrous partitions made of collagen fibers that extend from capsule into interior of lymph node
What are the two major functions of the lymph nodes?
filtering and protection
What are the two categories of Phagocytes?
granulocytes (microphages - neturophils and eosinophils) and macrophages (fixed and wandering)
Note three areas where lymph nodes are densely clustered:
inguinal, axillary, and cervical regions of the body.
Thoracic duct
is the main collecting duct of the lymphatic system and receives lymph from the left side of the head, neck and chest, the left upper extremity, and the entire body below the ribs. (largest duct)
bone marrow
is the site of lymphocyte production
The inflammatory responses serves a protective and defensive role by eliminating
microbes, toxins, or foreign material from the site of injury, preventing their spread to other organs, and preparing the site for tissue repair. It is an attempt to restore tissue homeostasis.
What lymphatic structures trap bacteria in the posterior oral mucosa?
palatine tonsils - These tonsils are most often infected.
How do lymphatic capillaries differ from blood capillaries?
1). Blood capillaries carry blood from small arterioles to small venules. 2). Lymphatic capillaries carry lymphatic fluid from tissue to lymphatic venules. 3). In structure, lymph capillaries are slightly bigger in diameter but have thinner walls than blood capillaries
Thymus Gland
An endocrine gland located in the upper mediastinum that assists the body with the immune function and the development of antibodies. As part of the immune response it secretes a hormone, thymosin, that changes lymphocytes to T cells.
Lymphadenopathy
Any disease of the lymph nodes
Lymphoma
Any neoplasm (tumor) of the lymphoid tissue, whether benign or malignant.
Tonsils
Are multiple aggregations of large lymphatic nodules embedded in a mucous membrane at the junction of an oral cavity and the pharynx.
What is the function of B cells in the immune response?
B cells differentiate into plasma cells that secrete antibodies. Antibodies are proteins that bind to specific antigens and mark them for destruction. They provide humoral immunity.
Explain why the lymphatic system is a one-way system, whereas the blood vascular system is a two-way system.
Blood vessels form a complete circuit from and to the heart. The lymphatic system lacks arteries and begins with blind-ended lymph capillaries. it is a "return" system only.
Which sequence best describes the flow of lymph through the lymphatic system?
Capillaries - vessels - trunks - ducts ------- (Capillaries pick up lymph and ducts return it to the cardiovascular system).
Anchoring filaments
Collagen fiber which attach the endothelial cells of lymph capillaries to the surrounding tissue structures so that any increase in interstitial fluid volume opens the minivalves (loose connections between endothelial cells), rather than causing the lymph capillaries to collapse.
The organ Bone Marrow that compose the lymphatic system give it's general functions performed by this system.
Control Disease
Lymphangiography
Diagnostic procedure in which the lymphatic vessels are injected with radiopaque dye and then visualized with X rays.
What is cisterna chyli?
Enlarged terminus of the thoracic duct that receives lymph from the digestive viscera.
splenomegaly
Enlargement of the spleen due to accumulation of infectious microorganisms, typically caused by septicemia, mononucleosis, malaria, or leukemia.
Which of the following are NOT found in a lymph node?
Eosinophils are a type of leukocyte found in the blood.
Non-Hodgkin's lymphoma
Includes all cancers of lymphoid tissues except Hodgkin's lymphoma. Involves uncontrolled multiplication and metastasis of undifferentiated lymphocytes, with swelling of the lymph nodes, spleen, and Peyer's patches; other organs may eventually become involved. The seventh most common cancer. A rapid progressing type, which primarily affects young people, grows quickly but responds to chemotherapy' up to a 75% remission rate. A slowly progressing type, which affects the elderly, resists chemotherapy and so is often fatal.
Tonsillitis
Inflammation of the tonsils, typically due to bacterial infection. Tonsils become red, swollen, and sore.
Which statement is true of the thoracic duct?
It drains the lymph from the entire left side of the body and the right abdomen and leg.(The thoracic duct drains its lymph at the junction of the left internal jugular and subclavian veins.)
Which statement describes the lymphatic system''s role in relation to the cardiovascular system?
It maintains blood volume and hence, pressure. (As much as 3 liters of lymph must be returned to the blood volume each day.)
What lymphatic structure absorbs lipids in the intestine?
Lacteals are located in the intestinal villi.
Which of the following statements is true when comparing large lymphatic vessels to larger veins of the circulatory system?
Large lymphatic vessels have the same three layers, but are thinner and have more valves. (The larger lymphatic collecting vessels have the same three tunics as veins, but the collecting vessels are thinner-walled, and have more internal valves.)
Lacteals
Lmpyhatic capillaries located within the gastrointestinal (GI) tract, they allow for the absorption of lipid-soluble substnces from the GI tract. Specific lymphatic capillaries in the small intestine.
What is lymph?
Lymph is a clear to yellowish watery fluid which is found throughout the body. It circulates through body tissues picking up fats, bacteria, and other unwanted materials, filtering these substances out through the lymphatic system; a thin coagulable fluid (similar to plasma but) containing white blood cells (lymphocytes) and chyle
There are no lymphatic arteries. Why isn't this a problem?
Lymph is generated in the body tissues and only flows back toward the heart, so there is no need for arteries to carry lymph away from the heart.
Which of the following make up the principle lymphoid organs in the body?
Lymph nodes (The principle lymphoid organs in the body are the lymph nodes, which cluster along the lymphatic vessels of the body.)
What is the function of the lymphatic vessels?
Lymphatic vessels carry lymph from peripheral tissues to the venous system. The lymphatic system transports lymphocytes, is involved in the removal of foreign matter & cell debris by phagocytes & is part of the body's immune system. It also transports fats from the small intestine to the blood.
Which of the following is located in the spleen''s white pulp regions?
Lymphocytes
Which of the following is found lining the lymphatic sinuses of the lymph nodes?
Macrophages (Macrophages line the sinuses, they process foreign material passing through the sinuses).
Which of the following is NOT a lymphatic organ?
Macrophages are cells, not organs.
Abscess
Pus must drain out of the body or it accumulates in a confined space, causing this.
People suffering from a throat infection often complain of ""swollen glands."" What is the actual problem?
Some of the lymph nodes in the throat are full of bacteria. These swollen lymph nodes are called buboes.
immunity
Specific resistance to disease involves the production of a specific lymphocyte or antibody (Ab) against a specific antigen (Ag)
Name the vein that each of the two collecting ducts deposit their lymph.
Subclavian vein
Chyle
The lymph from the GI tract has a milky color due to the lipid, and for this reason the GI tract lymph is also called
How do lymphatic vessels resemble veins?
The lymphatic collecting vessels have three tunics and are equipped with valves.
The radical mastectomy is an operation in which a cancerous breast, surrounding tissues, and the underlying muscles of the anterior thoracic wall, plus the axillary lymph nodes, are removed. After such an operation, the arm usually swells, or becomes edematous, and is very uncomfortable -- sometimes for months. Why?
The lymphatic fluid is not being drained from the area due to a disruption of lymphatic vessels and nodes.
What factors are involved in the flow of lymphatic fluid?
The milking action of the skeletal muscles and on pressure changes within the thorax that occur during breathing.
In addition to lymphoid function, this organ holds a reservoir of platelets.
The spleen holds a reservoir of platelets; it also removes old and damaged red blood cells.
Collections of lymphoid tissue (MALT) that guard mucosal surfaces include
The thymus is the site of T cell maturation.
Enlarged terminus of the thoracic duct that receives lymph from the digestive viscera.
They are the same except that the lymph in the cisterna chyli is very fat-rich
How does the composition of lymph in the cisterna chyli differ from that in the general lymphatic stream?
They are the same except that the lymph in the cisterna chyli is very fat-rich
Explain how lymphatic vessels are similar to veins.
They carry low pressure fluid against gravity. They are equipped with valves.
Which statement is true regarding lymph nodes?
They have fewer efferent than afferent (incoming) vessels.(This slows the flow of the lymph through the node.)
Which of the following is the major lymphoid organ that ""trains"" T-lymphocytes to become immunocompetent?
Thymus ( T cells develop in the thymus).
The lymphoid organs, located in the throat, that defend against invading bacteria coming in through the mouth and nose are
Tonsils (The tonsils form a ring of lymphatic tissue around the entrance to the pharynx.)
The organ Thymus that compose the lymphatic system give it's general functions performed by this system.
Transport dietary fat
The organ Lymph nodes that compose the lymphatic system give it's general functions performed by this system.
Transport excess tissue fluid back to blood stream
Elephantiasis
Typically a tropical disease in which the lymphatics (particularly those of the lower limbs and scrotum) become clogged with parasitic roundworms, an infectious condition called filariasis. Swelling (due to edema) reaches enormous proportions.
When does inflammation occur?
When cells are damaged by microbes, physical agents, or chemical agents. The injury may be viewed as a form of stress.
The lymphatic capillaries are typically larger in diameter than blood capillaries, lack a basement membrane, and have overlapping endothelial cells. What do theses overlapping endothelial cells do?
act as one-way flaps to allow fluid to enter the lymphatic capillary, but prevent its loss.
This structure attached to the cecum is in an ideal place to destroy bacteria before it migrates into the large intestine.
appendix This structure extends from the cecum.
What lymphatic structure absorbs excess tissue fluid?
capillary - These vessels have pressure sensitive valves.
Lymphatic vessels
develop from lymph sacs, which develop from veins. Thus, they are derived from mesoderm.
What is the role of T cells?
directly attack virus-infected tissue cells, some help activate the B cells and cytotoxic T cells, and others can inhibit the immune response. They provide cellular immunity.
Right lymphatic duct
drains lymph from the upper right side of the body
The lymphedema condition, caused by tropical parasitic worms, is
elephantiasis. These worms particularly infect the lymphatics of the male''s lower limbs and scrotum.
To assist with lymph return,
lymph vessels possess valves, like veins, to prevent backflow. Lymphatics actually have more valves than veins.
Antibodies are
proteins that bind to specific antigens and mark them for destruction.
Inflammation is usually characterized by these four symptoms.
redness, pain, heat and swelling. Loss of function my be a fifth symptom, depending on the site and extent of the injury.
The structural framework of lymphoid tissue is offered by
reticular connective tissue. This tissue dominates in all lymphoid organs EXCEPT the thymus.
A major function of the lymphatic system is
return of tissue fluid to the cardiovascular system. (About 3 L of fluid are picked up each day.)
Which portion of the body is drained by the right lymphatic duct?
right upper extremity, head and thorax
lymphatic tissue
specialized reticular tissue containing large numbers f lymphocytes
sentinel node
the first node that receives lymph drainage from a body area suspected of being cancerous. When examined for presense of cancer cells, this node given the best indication of whether metastasis through the lymphatic vessels has occurred.
The spleen is
the largest mass of lymphatic tissue in the body and is found in the left hypochondriac region between the fundus of the stomach and the diaphragm. It is a site of B cell proliferation into plasma cells, phagocytosis of bacteria and worn out or damaged red blood cells and platelets, and storage of blood.
What name is given to the terminal duct draining most of the body?
thoracic duct