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Chapter 16
Lymphatic System
| Term | Definition |
|---|---|
| what are the 3 important functions of the lymphatic system | return of interstitial fluid to the bloodstream, lipid absorption, and defense against disease. |
| auto | self |
| -gen | become, be produced |
| humor- | moisture, fluid |
| immun- | free, exempt |
| inflamm- | on fire |
| nod- | knot |
| patho- | disease, sickness |
| lymphatic capillaries | microscopic, closed-ended tubes |
| The walls of lymphatic capillaries are formed from | a single layer of squamous epithelial cells called endothelium |
| lymph | fluid inside lymphatic capillaries |
| The size of the lymphatic pathway small to large | capillary, afferent vessel, nodes, efferent vessel, trunk, collecting duct, subclavian vein |
| 3 parts of lymphatic vessel wall | an endothelial lining, a middle layer of smooth muscle and elastic fibers, and an outer layer of connective tissue |
| semilunar valves | which help prevent backflow of lymph |
| lymph nodes | specialized organs |
| lymphatic trunks | drain lymph from the lymphatic vessels |
| lumbar trunk | drains lymph from the lower limbs, lower abdominal wall, and pelvic organs |
| intestinal trunk | drains the abdominal viscera |
| intercostal and bronchomediastinal trunks | drain lymph from portions of the thorax |
| subclavian trunk | drains upper limbs |
| jugular trunk | portions of the neck and head |
| collecting ducts | thoracic and right lymphatic duct |
| thoracic duct features and origination | wider and longer of the two collecting ducts. It originates as an enlarged sac, the cisterna chyli |
| thoracic duct drains lymph from | intestinal, lumbar, and intercostal trunks, as well as from the left subclavian, left jugular, and left bronchomediastinal trunks. |
| thoracic duct empties into | the left subclavian vein near its junction with the left jugular vein. |
| right lymphatic duct originates in the | right thorax at the union of the right jugular, right subclavian, and right bronchomediastinal trunks. |
| right lymphatic duct empties into the | right subclavian vein near its junction with the right jugular vein. |
| right lymphatic drains lymph from | the right side of the head and neck, the right upper limb, and the right thorax |
| what happens after lymph leaves the two collecting ducts | it enters the venous system and becomes part of the plasma just before blood returns to the right atrium. |
| Capillary blood pressure | filters water and small molecules from the plasma |
| plasma colloid osmotic pressure | The osmotic effect of these plasma proteins which helps to draw fluid back into the blood capillaries by osmosis. |
| lymph formation prevents the accumulation of excess tissue fluid, or edema by | The accumulation of tissue fluid increasing the tissue fluid hydrostatic pressure, the force which moves tissue fluid into lymphatic capillaries, forming lymph |
| lymph flow is aided by | contracting skeletal muscles in the limbs, contraction of smooth muscle in the walls of the larger lymphatic trunks, and pressure changes from the action of skeletal muscles used in breathing. |
| lymph flow peaks | during exercise, due to the actions of skeletal muscles and pressure changes associated with breathing. |
| as lymph is returned to the blood it enters the ____ circulation | venous |
| mucosa-associated lymphoid tissue (MALT). | The unencapsulated diffuse lymphatic tissue associated with the digestive, respiratory, urinary, and reproductive tracts |
| lymphatic nodules | are compact masses of lymphatic tissue included in the MALT |
| lymphatic nodules comprise | the tonsils and appendix |
| What are the lymphatic organs, including the lymph nodes, thymus, and spleen made of? | encapsulated lymphatic tissue :a capsule of connective tissue with many fibers encloses each organ. |
| hilum | indented region of the lymph node where blood vessels and nerves join a lymph node |
| where do afferent vessels enter a lymph node | enter separately at various points on its convex surface |
| where do efferent vessels exit a lymph node | hilum |
| lymphatic nodules/lymphatic follicles | compartments, functional units of the lymph node |
| what are contained within lymphatic nodules | Masses of B lymphocytes (B cells) and macrophages in the cortex |
| where do B lymphocytes proliferate? | germinal centers within lymphatic nodules |
| the medulla contains mostly what kind of cells? | T cells (T lymphocyte) |
| lymphatic sinuses | Spaces in a lymph node that provide a complex network of chambers and channels through which lymph circulates |
| The lymph nodes in the cervical region | drain the skin of the scalp and face, as well as the tissues of the nasal cavity and pharynx. |
| lymph nodes of the axillary region | drain the upper limbs, the wall of the thorax, the mammary glands (breasts), and the upper wall of the abdomen. |
| The lymph nodes in the supratrochlear region | located superficially on the medial side of the elbow, enlarge in children in response to infections acquired through cuts and scrapes on the hands. |
| Lymph node of inguinal region | lymph from the lower limbs, the external genitalia, and the lower abdominal wall. |
| pelvic cavity lymph nodes | receive lymph from the lymphatic vessels of the pelvic viscera, follow the iliac blood vessels. |
| The lymph nodes in the abdominal cavity | form chains along the main branches of the mesenteric arteries and the abdominal aorta and receive lymph from the abdominal viscera. |
| The lymph nodes in the thoracic cavity | in the mediastinum and along the trachea and bronchi. They receive lymph from the thoracic viscera and from the internal wall of the thorax. |
| Thymus | is a soft, bilobed gland enclosed in a connective tissue capsule |
| where is the thymus? | in the mediastinum, anterior to the aortic arch and posterior to the upper part of the body of the sternum, and extends from the root of the neck to the pericardium |
| largest lymphatic organ | spleen |
| where is spleen located | It is in the upper left portion of the abdominal cavity, just inferior to the diaphragm, posterior and lateral to the stomach |
| the venous sinuses in the spleen are filled with ___ instead of lymph? | blood |
| White pulp of spleen | distributed throughout the spleen in tiny islands, is composed of splenic nodules, which are similar to the lymphatic nodules in lymph nodes and are packed with lymphocytes. |
| Red pulp of spleen | fills the remaining spaces of the lobules, includes the venous sinuses and the space around the venous sinuses, contains abundant red blood cells, which impart its color, plus many lymphocytes and macrophages. |
| the spleen filters___ much as the lymph nodes filter___ | Blood/lymph |
| what are the 3 cell types within lymphatic tissue | macrophages, B cells, Tcells |
| where are lymph nodes generally located | along larger lymphatic vessels |
| what structures lack lymph nodes? | central nervous system |
| pathogens | disease causing agents |
| Pathogens include: | simple microorganisms such as bacteria, complex microorganisms such as protozoa, and spores of multicellular organisms such as fungi. |
| Viruses are pathogens, but they are not considered organisms, because | their structure is much simpler than that of a living cell and they must infect a living cell to reproduce. |
| innate defense | immune mechanisms are general in that they protect against many types of pathogens, responses function the same way regardless of the type of pathogen or the number of exposures. |
| innate mechanisms include | species resistance, mechanical barriers, inflammation, chemical barriers (enzyme action, interferon, and complement), natural killer cells, phagocytosis, and fever. |
| adaptive defense | these protective mechanisms are very precise, targeting specific pathogens |
| adaptive defense mechanisms include | more directed responses are carried out by specialized lymphocytes that recognize foreign molecules (nonself antigens) in the body and act against them. |
| innate defense responds | quickly |
| adaptive defense responds | slowly |
| species resistance | species may be resistant to diseases that affect other species. |
| mechanical barriers | The skin and mucous membranes lining the passageways of the respiratory, digestive, urinary, and reproductive systems that prevent the entrance of some infectious agents and provide a first line of defense |
| pus | white blood cells, bacterial cells, and damaged tissue |
| exudates | These fluids contain fibrinogen and other clotting factors that may stimulate formation of a network of fibrin threads in the affected region |
| chemical barriers | enzymes that kill pathogens and protect the body |
| Interferons | are proteins that lymphocytes and fibroblasts produce in response to viruses or tumor cells, stimulate phagocytosis and enhance the activity of other cells that help to resist infections and the growth of tumors. |
| Defensins | peptides produced by neutrophils and other types of granular white blood cells in the intestinal epithelium, the urogenital tract, the kidneys, and the skin, make holes in bacterial cell walls and membranes, crippling the microbes. |
| collectins | proteins that provide broad protection against bacteria, yeasts, some viruses,detect the sugar molecules or pattern in which they are clustered, binding much like velcro clings to fabric, thus making the pathogen more easily phagocytized. |
| complement | proteins (complement system), in plasma and other body fluids, that interact in an expanding series of reactions or cascade. |
| classical pathway | rapid complement activation when a complement protein binds to an antibody attached to its specific antigen |
| alternative pathway | slower complement activation triggered by exposure to foreign antigens, in the absence of antibodies. |
| natural killer cells (NK) | small population of lymphocytes that are distinctly different from the lymphocytes that provide adaptive defense mechanisms, secrete perforins. |
| perforins | secretions from NK cells, cytolytic (“cell-cutting”) substances that lyse the cell membrane, destroying the infected cell . |
| the most active phagocytic cells of the blood are | neutrophils and monocytes |
| Neutrophils engulf and digest | smaller particles |
| monocytes phagocytize | larger particles |
| interleukin-1 (IL-1) | IL-1 raises the thermoregulatory set point in the brain’s hypothalamus to maintain a higher body temperature. AKA endogenous pyrogen (“fire maker from within”) |
| antigens may be | proteins, polysaccharides, glycoproteins, or glycolipids. |
| The antigens most effective in eliciting an immune response are | large and complex, with few repeating parts. |
| hapten | small molecule that combines with a larger molecule to become an antigen |
| T cells make up ___ of circulating lymphocytes while B cells make up ___ | 70/80 vs 20/30 |
| T cell activation requires that | processed fragments of the antigen be attached to the surface of another type of cell, called an antigen-presenting cell |
| cellular immune response | when Activated T cells interact directly with the antigen-presenting cell. |
| cytokines | polypeptides synthesized and secreted by T cells and some macrophages that enhance certain cellular responses to antigens |
| what other substances do T cells secrete? | toxins that kill their antigen-bearing target cells, growth-inhibiting factors that prevent target cell growth, and interferons that inhibit the proliferation of viruses and tumor cells. |
| helper T cell | activated when its antigen receptor combines with a displayed foreign antigen. Once activated, the helper T cell proliferates and resulting cells stimulate a type of B cell (plasma cell) to produce antibodies that are specific for the displayed antigen. |
| CD4 helper T cells | the type that HIV targets, is responsible for stimulating Bcells to aid immunity |
| cytotoxic T cell | bind to the surfaces of antigen-bearing cells, where they release perforin protein that cuts porelike openings, destroying these cells, ontinually monitor the body’s cells, recognizing and eliminating tumor cells and cells infected with viruses. |
| CD8/memory T cells | Cd8 cells produce memory T cells after contact with the antigen studded portion of a cell. This memory T cell than reacts to that pathogen in the future, destroying before the body starts to display symptoms (think antibodies) |
| antibody titer | number of circulating antibodies in the bloodstream. |
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