Linda Blackburn
Vocabulary SC 1332 – A&P II
1. Lymphatic System – is a vast collection of cells and biochemicals that travel in lymphatic vessels, and the organs and glands that produce them. Lymphatic vessels transport excess fluid away from the interstitial spaces in most tissues and return it to the bloodstream.
2. Pathogen – a disease causing agent, especially a living microorganism such as bacteria, viruses or fungi.
3. Lymphatic Pathways – contain the lymphatic capillaries, nodes and vessels that eventually connect with the veins in the thorax.
4. Lymphatic Capillaries – are microscopic, closed-ended tubes that extend into the interstitial spaces. They form complex networks which parallel the networks of the blood capillaries. Their thin walls make it possible for the tissue fluid from the interstitial space to enter.
5. Lymph – is a thin fluid containing white blood cells that moves throughout the lymphatic capillaries.
6. Lymphatic Vessels – are responsible for the transportation of lymph throughout the body. Their walls are made up of three layers: the endothelial lining, a middle layer of smooth muscle and elastic fibers and the outer layer of connective tissue. The vessels also contain semilunar valves – these prevent the backflow of lymph through the vessels.
7. Lymph Nodes – is composed of connective tissue. They are larger lymphatic vessels located throughout the body and which function to filter lymph of harmful bacteria and other microorganisms; they also produce and store lymphocytes. They also play a role in removing wastes from the tissues and are an integral part of the immune system.
8. Lymphatic Trunks – function to drain lymph from the lymphatic vessels. They are six lymphatic trunks and they are named for the region which they serve. These include the lumbar, the intestinal, the intercostals and bronchomediastinal, the subclavian and the jugular trunks.
9. Collecting Ducts – There are two collecting ducts in the body; the thoracic and the right lymphatic duct. These ducts provide the place for the lymphatic trunks to join and “dump” their lymph.
10. Thoracic Duct – is the larger and longer of the two ducts. This duct drains lymph from the intestinal, lumbar and intercostals trunks, as well as from the left subclavian, left jugular and the left bronchmediastinal trunks. It empties into the left subclavian vein near the junction of the left jugular vein.
11. Right Lymphatic Duct – originates in the right thorax at the union of the right jugular, right subclavian, and right bronchomediastinal trunks. It empties into the right subclavian vein near the junction of the right jugular vein.
12. Hilum – is an indented region of the lymph node where blood vessels and nerves join with the node.
13. Lymph Nodules – are small compartments within the lymph node that are divided by connective tissue. These nodules function to produce lymphocytes and macrophages. They may occur singly or in groups throughout the body.
14. Lymph Sinus – spaces within the lymph node provide a complex network of chambers and channels through which lymph circulates. Lymph enters the node, passes through the afferent lymphatic vessels, moves through the lymph sinuses and exits through the efferent lymphatic vessels.
Lymph nodes are found generally in groups or chains along the paths of larger lymphatic vessels; however, they are absent in the central nervous system. There are seven major locations of the lymph nodes and they are:
15. Cervical Region – these nodes follow the lower border of the mandible, anterior and posterior to the ears and deep within the neck along the paths of larger blood vessels. These nodes drain the skin of the scalp and face as well as the nasal cavity tissues and pharynx.
16. Axillary Region – are nodes in the underarm and they receive lymph from vessels that drain the upper limbs, thorax wall, mammary glands and the upper wall of the abdomen.
17. Supratrochlear Region – these nodes are located superficially on the medial side of the elbow. They may often enlarge in children in response to infections acquired through cuts and scrapes.
18. Inguinal Region – nodes in this region receive lymph from the lower limbs, external genitalia and the lower abdominal wall.
19. Pelvic Cavity – within the pelvic cavity, the nodes primarily follow the iliac blood vessels. They receive lymph from the lymphatic vessels of the pelvic viscera.
20. Abdominal Cavity – nodes within this cavity form chains along the main branches of the mesenteric arteries and the abdominal aorta. They receive lymph from the abdominal viscera.
21. Thoracic Cavity – these nodes are present within the mediastinum and along the trachea and the bronchi. They receive lymph from the thoracic viscera and the internal wall of the thorax.
22. Thymus – is a soft, bilobed structure enclosed in a connective tissue capsule. It is located within the mediastinum and extends from the root of the neck to the pericardium. The thymus is larger in youth and shrinks with age, eventually adipose and connective tissues replace the normal lymphatic tissue. It is ductless gland which produces lymphocytes and aids in producing immunity. The cells within the thymus secrete protein hormones, thymosins, which stimulate the maturation of T-lymphocytes after they leave the thymus and migrate to other tissues.
23. T-lymphocytes or T-cells – are small white blood cell developed in the thymus gland. They orchestrate the immune system’s response to infected or malignant cells. There are several different sub-categories of T-lymphocytes and each has a specialized function.
24. Spleen – is the largest lymphatic organ and is located in the upper left abdominal quadrant. It is enclosed in connective tissue and this tissue extends inward dividing the organ into chambers or lobules. The organ also has a hilum through which blood vessels and nerves may enter. The sinuses within these chambers of the spleen contain blood instead of lymph. The spleen functions to maintain a blood reservoir that houses macrophages which remove foreign particles, damaged red blood cells and other cellular debris and produces lymphocytes which are involved in immune responses.
25. Innate or Nonspecific Defense – a mechanism which protects against many pathogens and provides a general immune defense.
26. Adaptive or Specific Defense – a mechanism which provides a more directed response to specific pathogens. These responses are carried out by specialized lymphocytes that can recognize foreign molecules in the body and act against them.
27. Species Resistance – refers to the fact that a given kind of organism or species develops diseases that are unique to it. For example a species may be resistant to diseases that will affect other species because those species tissues fail to provide the temperature or chemical environment that a particular pathogen requires.
28. Mechanical Barriers – innate defense – consists of the skin and mucous membranes lining the passageways of the respiratory, digestive, urinary and reproductive systems. These barriers prevent some infectious organisms from entering the body and as long as these barriers are intact, many pathogens are unable to penetrate. Mechanical barriers are considered to provide the first line of defense.
29. Chemical Barriers – innate defense – these are enzymes in body fluids which provide another line of defense against pathogens. An example of a chemical barrier would be the lysozymes, present in the tears, which against certain bacteria on the eyes or the accumulation of salt from perspiration also will kill certain bacteria on the skin. These are considered to be the second line of defense. This is considered to be an innate or nonspecific defense. There are four types of chemical barriers and they are:
30. Interferons – hormonelike peptides that lymphocytes and fibroblasts produce in response to the presence of pathogens such as viruses or tumor cells. They will also stimulate phagocytosis and enhance the activity of natural killer cells which help to resist infections and the growth of tumors.
31. Defensins – are peptides produced by the neutrophils and almost all epithelial cells especially those in the intestinal epithelium, urogenital tract, kidneys and the skin. Defensins act by making holes in bacterial cell walls and membranes, thereby, crippling the microbes and assist in killing phagocytized bacteria.
32. Collectins – are proteins that provide a broad spectrum of protection against bacteria, yeasts, and some viruses. Collectins detect sugar molecules and the arrangement of those molecules that protrude from the pathogens, they “grab” onto these sugar clusters and cling to them, making the pathogen more easily phagocytized.
33. Complement – is a group of proteins in plasma and other body fluids that interact in a series of reactions or cascade. Complement stimulates inflammation, attracts phagocytes, and enhances phagocytosis.
34. Natural Killer Cells (NK) – innate defense - lymphocytes, which develop in the bone marrow, that defends the body against various viruses and cancer cells by secreting cytolytic substances called perforins. NK cells also secrete chemicals that enhance inflammation.
35. Perforins – a protein in natural killer cells that causes lysis (cutting) of the cells that it is targeting on contact and destroys it.
36. Inflammation – innate defense- it is a response of the body tissues to injury, physical (heat, ultraviolet light) or chemical factors (acids, bases) by producing redness, swelling, heat and/or pain.
37. Phagocytosis – innate defense- it is the act of removing foreign particles (solids) from the lymph as it moves from the interstitial spaces to the bloodstream by phagocytes. Neutrophils and monocytes are the most active phagocytic cells of the blood; neutrophils engulf and digest the smaller particles and monocytes phagocytize the larger ones. This provides an important defense against infection.
38. Mononuclear Phagocytic System – is a network of monocytes, macrophages and neutrophils which function to engulf and destroy foreign particles. This system is also known as the reticuloendothelial system.
39. Fever – innate defense – is a rise in the body temperature, technically above 98.6F degrees, usually in response to an infection. However, in practice, a person is usually not considered to have a significant fever until the temperature is above 100.4F degrees. A fever will inhibit microbial growth and increase phagocytic activity.
40. Immunity – is the resistance to certain pathogens or to their toxins or metabolic by-products. An immune response is the ability of the body to distinguish molecules that are a part of the body or “self” from those that are not part of the body or “nonself”.
41. Antigen – adaptive defense – it is any substance, usually a foreign substance, that generates an immune response in the body, especially one that elicits the production of antibodies. Antigens that are most effective in stimulating an immune response are large and complex and will be a protein, polysaccharides, glycoproteins or glycolipids.
42. Hapten – any small molecule that can generate an immune response but only when it is attached to a larger carrier such as a protein.
43. B-lymphocytes or B-cells – adaptive defense – are lymphocytes which play a major role in the humoral immune response. They are produced and eventually differentiate entirely within the red bone marrow into plasma cells that produce antibodies or into memory B cells.
44. Memory B-cell – a B-cell which is produced in a primary immune response and develops an affinity for a specific antigen. These cells can be rapidly activated again if and when the same antigen is encountered in the future.
45. Cellular Immune Response or Cell Mediated Immunity - is a response that does not involve the production of antibodies or complement. It is an immune response, by the T-lymphocytes that involves the activation of macrophages, natural killer cells and cytokines in response to an antigen.
46. Cytokines – are a small protein that is released by T-cells and some macrophages that has a specific effect which enhances certain cellular responses to antigens. The cytokines include interleukins (control lymphocyte differentiation and growth), colony-stimulating factors (stimulate bone marrow to produce lymphocytes), interferons (block viral replication, stimulate macrophages, stimulate B-cells to produce antibodies) and tumor necrosis factor (stops tumor growth, causes fever, stimulates lymphocyte differentiation).
47. Immunoglobulins (Ig) – protein produced by plasma cells and lymphocytes which plays an essential role in the body’s immune system. They attach to foreign substances and assist in destroying them. There are five classes of immunoglobulins and they are:
48. IgG – found in plasma and tissue fluid – defends against bacterial cells, viruses, and toxins; activates complement
49. IgA – is an exocrine gland secretion – defends against bacterial cells and viruses
50. IgM – is found in plasma – reacts with antigens occurring naturally on some RBC membranes following certain blood transfusions; activates complement
51. IgE – is found as an exocrine gland secretion – promotes inflammation and allergic reactions.
52. Plasma Cells – a result of B-cell proliferation which produces and secretes antibodies.
53. Humoral Immune Response – an antibody-mediated immune response. It involves the transformation of B-cells into plasma cells that will produce and secrete antibodies to a specific antigen.
54. Clone – genetically identical cells originating from division of a single cell. For example, your body has millions of T and B cells and because the members of each variety originate from a single early cell, they are all alike, thus, they form a clone.
55. Antigen-Presenting Cell – can sometimes be called an accessory cell. It is a cell which displays an antigen on its surface to other cells of the immune system allowing them to defend the body against that particular antigen. The result is a specific immune response that may consist of either a cellular response and/or an antibody response.
56. Major Histocompatibility Complex (MHC) or Human Leukocyte Antigens (HLA) - are a cluster of genes that code for cell surface proteins and help T-cells recognize that an antigen is foreign, not self. They generally help the immune system to distinguish between harmful and safe foreign substances in the body.
57. Helper T Cell – a specialized type of T cell with a CD4 receptor which becomes activated when it recognizes antigens on the surface of an virus infected cell and secretes lymphokines which stimulates B cells. Their destruction is nearly fatal to the immune system – an example of this would be the AIDS virus, where helper T-cells are infected and killed by the virus.
58. Cytotoxic T Cell – recognizes nonself antigens that cancerous cells or virally infected cells display on their surfaces near certain MHC proteins. It will bind to the infected cell and kill it.
59. Memory T Cell – are able to recognize foreign invaders such as viruses or bacteria that were encountered during a previous infection or vaccination. Therefore, when they encounter the invader for a second time, memory cells are able to produce a faster and stronger immune response than they were able to produce the first time they responded to the invader. They are able to do this through the immediate differentiation into cytotoxic T-cells.
60. Polyclonal Response – is the reaction by multiple clones of the B-cell. It ensures that a single antigen is recognized and attacked by an immune response by manufacturing several types of antibodies against a single microbe or virus.
Antibody molecules each begin with four chains of amino acids that are linked by pairs of sulfur atoms that attract by disulfide bonds. The four chains form a Y-shaped structure and are consist of a light chain (L-chain) and a heavy chain (H-chain).
61. Light Chain – is the smaller of the two types of amino acid chains in immunoglobulin.
62. Heavy Chain – is the larger of the two types of amino acid chains in immunoglobulin.
One end of each chain has a variable region which is specialized to fit the shape of a specific antigen molecule. The remaining portions of the chains are termed constant regions because their amino acid sequences are similar from molecule to molecule.
63. Antigen-Binding Sites – are specialized ends of the antibody molecule to which an antigen may bind.
64. Idiotypes – are the particular parts that actually bind the antigen.
65. Primary Immune Response – is the response of the immune system, by the B or T cells, the first time that an antigen is encountered that they are specialized to react with. Production and release of these antibodies may continue for several weeks. During this response, plasma cells release IgM followed by IgG into the lymph, the antibodies are transported to the blood and ultimately throughout the body, where they function to help destroy the antigen-bearing agents.
66. Secondary Immune Response – is the response of the memory B and T cells when they encounter the identical antigen in the future. The clones of these memory cells enlarge and they respond rapidly with IgG to the antigen to which they were previously sensitized.
67. Vaccine – is a preparation that includes an antigen that can stimulate a primary immune response against a particular pathogen but does not produce the severe symptoms of that disease. A vaccine results in the person developing artificially acquired active immunity.
68. Allergen – are antigens that trigger allergic responses.
69. Immediate-reaction (type I or anaphylactic) Allergy - occurs within minutes of contact of an allergen. Examples of this type of reaction are hives, eczema, hay fever, gastric disturbances or anaphylactic shock.
70. Antibody-Dependent Cytotoxic Reactions (type II) – is where an antigen binds to a specific cell, stimulating phagocytosis and complement-mediated lysis of the antigen. It may take 1-3 hours to develop and a transfusion reaction would be an example of this type of reaction.
71. Immune Complex Reaction (type III) – in this reaction phagocytosis and lysis cannot clear widespread antigen-antibody complexes from the circulation. This results in tissue damage due to the complexes blocking small vessels.
72. Autoimmunity – is the loss of the ability to tolerate self-antigens. It is an immune response against a person’s own tissues, where the immune system mistakenly attacks and destroys healthy tissues. An example of an autoimmune disorder would be lupus or multiple sclerosis.
73. Tissue Rejection Reaction – is a reaction in which the recipient’s cells may recognize the donor’s tissues as foreign and attempt to destroy the transplanted tissue. This type of reaction resembles the cellular immune response against a foreign antigen. Matching the cell surface molecules of donor and recipient can minimize the rejection reaction. Immunosuppressive drugs are also used to reduce rejection of transplanted tissues.
There are four major types transplant tissues or grafts and these include:
74. Isograft – taken from a genetically identical twin.
75. Autograft – tissue is taken from elsewhere in a person’s body.
76. Allograft – the tissue comes from an individual who is not genetically identical to the recipient but is of the same species.
77. Xenograft – the transplant tissue comes from a different species such as a pig or a baboon.
78. Autoantibodies – are produced when the immune system fails to distinguish self from nonself. These will attack and damage the body’s tissues and organs along with cytotoxic T-cells.
