Anatomy_Key Terms_Ch21 Flashcards
lymphatic system
main function is to return excess tissue fluid back to the blood vascular system
immune system
protects our bodies from foreign organisms by fighting infections and conferring immunity to disease
lymphatic vessels
function to collect excess tissue fluid from the loose connective tissue around blood capilaries and return it to the bloodstream
lymph
(lympha=clear water), fluid once inside the lymphatic vessels
lymphatic capillaries
highly permeable vessels that collect the excess tissue fluid, located near blood capillaries in the loose areolar connective tissue
collecting lymphatic vessels
from lymphatic capillaries, lymph enters _ which accompany blood vessels: in general, the superficial _ in the skin travel with superficial veins, whereas the deep _ of the trunk and digestive viscera travel with the deep arteries
lymphangiography
”"”lymph vessel picturing””, radiographic procedure in which X-ray films are taken after lymphatic vessels are injected with radiopaque dye”
lymph nodes
cleanse the lymph of pathogens, bean-shaped organs situated along collecting lymphatic vessels
capsule
fibrous _ of dense connective tissue surrounds a lymph node
trabeculae (lymph)
fibrous strands extend inward from the capsule to divide the node into compartments
afferent lymphatic vessels
lymph enters the convex aspect of the node through several _
hilum (liver)
indented region on the other side of a lymph node from the convex aspect
efferent lymphatic vessels
lymph exits from the hilum through _
lymph sinuses
within the node, between the afferent and efferent vessels, lymph percolates through _ (subcapsular, cortical, and medullary)
lymph trunks
drain large areas of the body, largest collecting lymphatic vessels converge to form _
lumbar trunks
these paired trunks, which lie along the sides of the aorta in the inferior abdomen, receive all lymph draining from the lower limbs, the pelvic organs, and from some of the anterior abdominal wall
intestinal trunk
this unpaired trunk, which lies near the posterior abdominal wall in the midline, receives fatty lymph (chyle) from the stomach, intestines, and other digestive organs
brochomediastinal trunks
ascending near the sides of the trachea, these paired trunks collect lymph from the thoracic viscera and thoracic wall
subclavian trunks
located near the base of the neck, these paired trunks receive lymph from the upper limbs; they also drain the inferior neck and the superior thoracic wall
jugular trunks
located at the base of each internal jugular vein, these paired trunks drain lymph from the brain, head, and neck
lymph ducts
lymph trunks drain into the largest lymphatic vessels (some people have one, thoracic duct, some have two, thoracic and right lymphatic duct)
thoracic duct
present in all individuals, often joined by the left jugular, subclavian, and/or bronchomediastinal trunks just before it joins with the venous circulation
cisterna chyli
”"”sac of chyle””, most inferior part of the thoracic duct, located at the union of the lumbar and intestinal trunks, lies on the bodies of vertebrae L1 and L2”
venous angle
left _ is at the junction of the left internal jugular and left subclavian veins, where the thoracic duct empties into the venous circulation
right lymphatic duct
present in 20% of people, empties into the neck veins at or near the junction of the right internal jugular and subclavian veins, the right venous angle
cytotoxic, killer, or CD8+ T lymphocyte
a major type of T cell attacks foreign cells directly
natural killer cells (NK cells)
“third class of lymphocytes, do not recognize specific antigens, but instead act when they detect a lack of ““self”” cell surface molecules or the presence of certain sugars on a target cell”
dendritic cell
”"”professional”” antigen gatherer that patrols the body seeking antigens”
effector lymphocytes
short-lived lymphocytes that respond to the pathogen immediately and then die
cytotoxic (CD8+) T cells
travel to the infect region via the bloodstream and directly lyse the pathogenic cell
helper (CD4+) T cells
enter the circulation and stimulate the cells of the immune system by secreting chemicals called cytokines, cytokines styimulate the proliferation of activated B cells, cytotoxic T cells, and macrophages and amplify and fine-tune the immune response
memory lymphocytes/memory cells
wait within the lymphoid tissues until the body encounters the specific antigen again, maybe decades later; when it finally encounters its atigen, its proliferative response and its attack are most vigorous and rapid
lymphoid tissue
specialized type of connective tissue in which wast quantities of lymphocytes gather to fight invading microorganisms; has two general locations: the frequently infected mucous membranes of the digestive, respiratory, urinary, and reproductive tracts (MALT), and in all lymphoid organs except the thymus
mucosa associated lymphoid tissue
MALT, frequently infected mucous membranes of the digestive, respiratory, urinary, and reproductive tracts
lymphoid follicles or nodules
scattered, spherical clusters of densely packed lymphocytes evident within lymphoid tissue
germinal centers
lymphoid follicles often exhibit lighter-staining centers, _, of dividing lymphocytes
primary lymphoid organs
bone marrow and the thymus. they produce B and T lymphocyes, respectively
secondary lymphoid organs
lymph nodes, spleen, MALT that form the tonsils, aggregated lymphoid nodules in teh intestine, and the appendix. these organs store immunocompetent lymphocytes and memory lymphocytes, and they gather and destroy infectious microorganisms within their lymphoid tissue
lobules
contains an outer cortex and an inner medulla, numerous _ in the thymus
cortex (thymus)
of the lobule stains dark because it is packed with rapidly dividing T lymphocytes gaining immunocompetence
medulla (thymus)
contains fewer lymphocytes and stains lighter than the cortex
thymic corpuscles
in the medulla, which are composed of clusters of epithelial cells, function in the development of regulatory T cells (prevent autoimmune responses)
spleen
largest lymphoid organ, lies in the left superior quadrant of the abdominal cavity just posterior to the stomach
white pulp
thick sleeves of lymphoid tissue that collectively constitue the _
red pulp
surrounds the white pulp, has two parts (splenic sinusoids and splenic cords)
splenic sinusoids
blood sinusouds that arise from the distal branches of the central arteries outside of the white pulp
splenic cords
consist of a reticular connective tissue that is exceptionally rich in macrophages
tonsils
mere swellings of the mucosa lining the pharynx
