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89 Cards in this Set

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structures that produce the cell components of the immune system
primary lymphoid organs
examples of primary lymphoid organs
bone marrow and thymus
in these organs, lymphocytes differentiate from lymphoid stem cells, proliferate and mature into functional cells
primary lymphoid organs
structures that are the sites to trap antigen from defined tissues or vascular spaces where immune responses occur
secondary lymphoid organs
examples of secondary lymphoid organs
lymph node, spleen, tonsils and aggregates of lymphocytes and antigen-presenting cells in lung and mucosa of digestive track
major cells of the lymphatic system
lymphocytes and macrophages
cells found in peripheral blood, lymph nodes, spleen, thymus, tonsils, appendix, and scattered in many other tissues - have very little cytoplasm and round nucleus
lymphocytes
these cells originate in bone marrow, mature in fetal liver and bone marrow and migrate to secondary (peripheral) lymphoid organs
B cells
when B cells are activated, they differentiate into...
plasma cells
precursors of cells that produce immunoglobulins (antibodies)
B cells
these cells are located in CT and lymphoid tissues, but NOT found in circulation
plasma cells
these cells originate in bone marrow, mature in thymus, the migrate to secondary lymphoid organs like lymph nodes and spleen
T cells
macrophages are derived from
blood monocytes
macrophages in liver
Kupffer cell
macrophages in lung
alveolar macrophage
macrophages in brain
microglia
functions of macrophages
phagocytosis and antigen presentation
how are lymphatic capillary walls different from blood capillary walls?
more permeable
which organs lack lymphatics?
brain, spinal cord, internal ear, cartilage, bone and bone marrow
lymphatic vessels resemble veins with these exceptions:
thinner walls
contain more valves
lymph nodes at intervals along course
intima, media and adventitia are poorly demarcated
collecting vessels originate as microscopic blind-end vessels called
lymphatic capillaries
lymphatic valves originated by
local folding of the tunica intima
what are the two main lymphatic ducts?
thoracic duct and right lymphatic duct
structure that arises in the abdomen and travels up along vertebral column through the thorax and empties into superior vena cava
thoracic duct
structure that is short and carries drainage from the right upper portion of the body
right lymphatic duct
dense localized collections of lymphocytes arranged in rounded masses that are sharply defined but not encapsulated
lymphatic nodules
what type of lymph nodules do not have germinal centers
those that are in a state of rest
primitive reticular cells give rise to what?
medium sized lymphocytes in addition to macrophages
4 functions of lymphatic nodule
1. production of new lymphocytes
2. functional differentiation of B lymphocytes
3. phagocytic potential of free and fixed macrophages
4. activity against bacteria and foreign matter
aggregate nodules are a close grouping of lymph nodules that are present in lamina propria and are also called what?
peyer's patches
the top of the peyer's patch nodule facing the lumen is covered with what/
intestinal epithelium
aggregates of more or less encapsulated lymphatic tissue situated at the entrance of the oral and nasal pharynx
tonsils
structure located at the entrance to the throat
palatine tonsil
the palatine tonsil is composed of what types of tissue?
diffuse and nodular lymphoid tissue
what covers the free surface of the palatine tonsil?
non-keratinized stratified squamous epithelium
what lines the lingual tonsil?
non-keratinized stratified squamous epithelium
leukocyte infiltration is less in the lingual tonsil than in what?
palatine tonsil
clinical name for pharyngeal tonsils
adenoids
location of pharyngeal tonsils
median dorsal wall of the nasopharynx
epithelium of pharyngeal tonsils
pseudostratified with cilia and goblet cells
oval-shaped structures occurring in series along the lymphatic vessels
lymph nodes
what extends from the covering capsule of lymph nodes to the center of the node?
fibrous septa or trabeculae
trabeculae in lymph nodes separates what from each other?
cortical nodules
what lines both the cortical and medullary sinuses of lymph nodes?
reticular cells and macrophages capable of phagocytosis
cellular component/lymphoid tissue of lymph node
parenchyma
portion of cortical parenchyma that is adjacent to medulla and is free of nodules
deep cortex, paracortex, or thymus-dependent cortex
area of lymph node where lymphoid tissue is found in dense strands or cords
medullary parenchyma
medullary parenchyma is the chief site of what 3 structures?
B lymphocytes, macrophages and plasma cells
where are T lymphocytes most common in lymph node?
paracortex (deep cortex)
system of irregular channels lined with reticular cells
lymphatic sinuses
3 parts to the lymphatic sinus system
subscapular sinus
trabecular sinus
medullary sinus
the emigration of lymphocytes from the blood into the lymph nodes occurs only at these endothelial cells
high endothelial venules
largest of all lymphoid organs
spleen
2 types of parenchyma in spleen
white pulp and red pulp
channels that intervene between veins and arteries
splenic sinuses
surrounds and follows arteries, thickens into ovoid masses called splenic nodules
white pulp
what forms the periarterial lymphoid sheaths?
white pulp
PALS are mainly composed of what cells?
T lymphocytes
germinal centers are mainly composed of what cells?
B lymphocytes
transitional area bw white and red pulp that is looser in texture than white pulp
marginal zone
which area of the spleen receives the incoming arterial blood?
marginal zone
first site for blood borne cells and particulate matter with splenic parenchyma
marginal zone
this area of the splenic parenchyma consists of splenic sinuses separated by splenic cords
red pulp
density and firmness of red pulp depends on what?
amount of blood present
arterial blood flow into the spleen
splenic artery --> trabecular arteries --> central artery (supplies white pulp) --> penicillar arterioles --> arterial capillaries --> splenic cords --> splenic sinuses
splenic sinuses conduct blood to what structure?
pulp veins
splenic veins are lined with what?
conventional epithelium and continuous basal lamina
pulp veins converge to form what?
trabecular veins (then splenic vein)
7 major functions of spleen
1. form RBCs during fetal life
2. Remove and destroy damaged RBCs
3. Retrieve iron from red cell hemoglobin
4. generate lymphocytes and monocytes
5. filter blood
6. actively phagocytize bacteria
7. produce antibodies
broad, flat bilobed mass of lymphoid tissue enclosed by a connective tissue capsule
thymus
first organ to become lymphoid during embryonic life
thymus
cortex parenchyma of the thumus consists of what cells?
lymphocytes, reticular cells and macrophages
this area of the thymus consists of a concentric mass of epithelioreticular cells joined together by many desmosomes
medulla
distinguishing feature of the thymus
hassall's corpuscles
isolated mass of closely packed, concentrically arranged type VI epithelioreticular cells
hassall's corpuscles
hassall's corpuscles produce ______ that function in differentiation and maturation of T lymphocytes
interleukins
what protects developing T lymphocytes from exposure to antigens?
blood-thymus barrier
components of blood-thymus barrier
1. endothelium and its basal lamina
2. macrophages in perivascular tissue
3. type I epithelioreticular cells with their basal lamina
major function of the thymus
differentiation and proliferation of t-lymphocytes
thymus is eventually replaced by what?
adipose tissue
produce antibodies in response to cell-free and cell-bound antigens
B lymphocytes
20-30% of circulating lymphocytes
B lymphocytes
60-80% of circulating lymphocytes
T lymphocytes
respond to cell-bound antigens (viral, fungal infected, and tumors)
T lymphocytes
5-10% of circulating lymphocytes
NK (natural killer) cells
stroma
reticular fibers and cells
diffuse lymphatic tissue is mainly found where?
GI tract and respiratory tract
sites of B lymphocyte proliferation
germinal centers
aggregated lymphatic nodules in ileum
peyer's patches