Lymphoid Organs Flashcards
Scattered throughout red pulp of spleen are discreet nodules of ______, which contain large #’s of wbc’s•
white pulp
Central Aa continue into red pulp, branch into perpendicular _______—branch into arterioles, terminate in 2-3 _______
penicillar Aa; sheathed capillaries
If spleen is removed (splenectomy), function taken over by ______ and _______
liver & bone marrow
Hemopoiesis in fetus is a function of
spleen
Sinusoids lined by endothelial cells called
stave cells
Lymphatic sinuses are filled with ______
reticular fibers & Mφ processes
As T cells mature they express what 3 things?
Ag specific t-cell receptors; CD (cluster of differentiation) surface markers; Class I & II HLA (human leukocyte Ag) surface markers
Secretion of hormones regulating t-cell development & maturation is a function of
Function of thymus
Characteristic large, thick bands of dense connective tissue ______ extend into body of spleen, contain trabecular Aa & Vv
trabeculae
Thymic blood vessels also surrounded by connective tissue sheath called _________—forms continuous antigenic barrier; isolates thymus from immune system
blood-thymus barrier
The outer fibrous capsule of lymph nodes are made of ______ tissue
dense, irregular CT
Recycles Fe from Hb is a function of
spleen
MALT produces ______
primary IgA (secretory IgA)
Thymus has a highly cellular ____ packed with lymphocytes, mostly t cells and macrophages
cortex
Aggregation & proliferation of t-cells & induction of cytotoxic immunity
Function of lymph node
epithelial cells within thymus, provide nurse function & structural support; Secrete various hormones (thymotaxin, thymosin, & thymopoietin)—attract, regulate & promote t-cell proliferation & differentiation into Tc, Ts & Th cells
Nurse cells
GALT is mucosa associated lymphoid tissue in
gut
fatty infiltration & lymphatic depletion that happens in the thymus
thymic involution
Highly vascular; largest lymphoid organ in body
spleen
Palatal & pharyngeal tonsils collectively referred to as
NALT(nasal associated lymphoid tissue)
post-capillary venules (= high endothelial venules) are lined by ________ endothelium
cuboidal to columnar endothelium
BALT is Mucosa associated lymphoid tissue in
respiratory tract
Central Aa surrounded by t-cells rather than b-cells form ___________ ; Lack germinal centers, because minimal t-cell proliferation•Less well developed in humans than other species & require immunohistochemical staining to make positive ID•Term often used interchangeably with 1’ follicles in white pulp
periarteriolar lymphatic sheaths (PALS)
Lymphoid organ characterized by hemicapsule & skin-like epithelium with crypts; no cortex & medulla
Palatine tonsil
Special type of MALT scattered throughout small intestine; most common in ileum, least common in duodenum•Project into lumen of gut in
Peyer’s patches
Interspersed throughout cortex & medulla of lymph node are very thin, collagenous _______
trabeculae
Within cortex or lymph nodes are densely packed, highly cellular
lymphoid follicles
outer cellular Layer of lymph node that contains b cells, t cells, and plasma cells
cortex
lack endothelial lining; surrounded by Mφ; Forms a non-continuous perivascular sheath, or cuff—Acts as part of filtering mechanism, active in phagocytosis
Blind ending capillaries
Network of blind-ended vessels in connective tissue; Provide a route which allows cells & large molecules in ECS to re-enter bloodstream; Assist circulation of lymphocytes, concentrate Ag for elimination within lymph nodes
Lymph vessels
If a follicle in the cortex contains a pale region called a germinal center, it is referred to as a _______; indicates the follicle is responding to an antigen
secondary follicle
lymphocytes of all types, derived from bone marrow; enter node via bloodstream
lymphoid cell
Endothelium of sinus is continuous on side adjacent to ________
capsule
Aggregation, activation, & proliferation of b-cells with subsequent Ab production
Function of lymph node
The thymus is embryologically derived from epithelial outgrowth of __________
3rd pharyngeal pouch
Luminal surface of palatine & lingual tonsils covered by characteristic ___________ epithelium —invades tonsil, forming blind-ended tonsilar crypts
stratified squamous nonkeratinized epithelium
•Clonal proliferation of Tc cells is a function of
Function of thymus
fibroblast-like cells with phagocytic capability
reticular cells
Clonal deletion of self-Ab’s is a function of______ ; Development of immunologic self-toleranceFailure of clonal deletion may => autoimmune diseases
Function of thymus
After leaving the lymph node through a single efferent vessel, lymph returns to bloodstream via ______ or ________
thoracic ductor R lymphatic duct
Blind-ended sac, vestigial cecum; Atrophies in adults; contains mostly b-cells; Important digestive organ in herbivores; used for bacterial fermentation
Appendix
T/F: Palatine tonsils have a distinct cortex and medulla
False; does not
Lymphoid organ characterized by mostly t-cells, not b-cells; Hassal’s corpuscles; cortex & medulla present
Thymus
What types of cells does the cortex of the thymus have?
lymphocytes, mostly t cells and macrophages
T/F: In white pulp of spleen, the follicular areas may or may not have germinal centers containing primary b cell
True
Both diffuse and dense lymphoid tissue contain large number of what type of cells?
Lymphocytes
If appendix is inflamed, it is called _______; treatment with _______
appendicitis; surgical removable
Peyer’s patches are most common in _____ and least common in ______
ileum; duodenum
________ divide thymus into lobules
Interlobular septa or trabeculae
Functions as site of Ag presentation, phagocytosis; contains large #’s of Mφ, plasma cells, & t-helper cells
White pulp of spleen
T/F: Endothelial slits between stave cells allow free passage of blood cells
True
MALT is located within subepithelial connective tissue of _______
lamina propria
Thymus looks similar to lymph nodes but lack what?
Lymphoid follicles, medullary cords and sinuses
in Medullary sinuses, Lymph drains from hilus of node via
single, efferent lymph vessel
Base of tonsil supported by cup-shaped, collagenous
hemicapsule
Within red pulp are what 2 things?
pulp cords and sinusoids
Non-specific filtering of particulate matter & microorganisms from lymph
Function of lymph node
Is spleen an open or closed circulation model?
Open
The thymus has a thin capsule made of ________ tissue
dense irregular CT
Is palatine tonsil encapsulated or unencapsulated?
Unencapsulated
Interaction of circulating lymphocytes with Ag in lymph
Function of lymph node
Palatal, lingual, & pharyngeal tonsils collectively referred to as _______—forms a ring of immunologic protection ~ GI & respiratory tracts
Waldeyer’s ring
Which type of lymphoid tissue is common in respiratory and digestive tracts as MALT?
Diffuse
NALT is Mucosa associated lymphoid tissue in
pharynx
________ tonsils (= adenoids) in nasopharynx, associated with Eustacian tubes
pharyngeal
(immune accessory cell) Mφ at periphery of germinal centers; Ag-presenting cells
follicular dendritic cells
Production of mature, immunocompetent Th & Tc cells is a function of
Function of thymus
b and t cells Migrate across walls of specialized _________ lined by cuboidal to columnar endothelium; located in deep, inner cortex of node at corticomedullary junction, or paracortical zone
post-capillary venules (= high endothelial venules)
Lymph vessels assist circulation of _______ and concentrate ______ for elimination within lymph nodes
Lymphocytes; antigens
What types of cells does the medulla of the thymus have?
mostly b-cells, plasma cells & Mφ
encapsulated aggregates of lymphocytes & lymphoid tissue, distributed throughout body; Arranged in chains or clusters along vessels of lymphatic origin
Lymph nodes
b- & t-cell replication, manufacture of Ab, Ag removal is a function of
spleen
Tissue trabeculae contain _______ and ______
trabecular Aa & Vv
endothelium & basement membrane of blood vessels;
blood-thymus barrier
(splenic circulation) Branches of splenic A enter white pulp within trabeculae via ______, branch & form ______ to white pulp
trabecular Aa; central Aa
Lymphoid aggregates contain large #’s of _______ and _____ cells
b and t
Proliferation of lymphocytes leads to what changes in lymph nodes?
swollen glands and lymph node enlargement
Component of red pulp of that contains mostly blood
Sinusoids
Lymphocytes respond to Ag by ↑ Ab production via _______
clonal expansion
T/F: Spleen lacks cortex and medulla
True
What sinuses are in the outer cortex of lymph node?
cortical, trabecular, and peritrabecular sinuses
diapedesis is facilitated by complementary ____ that are present on both endothelial cells & lymphocytes
adhesion molecules (= addressins)
Diffuse, unencapsulated lymphoid aggregates associated with mucosal surfaces; Located in subepithelial connective tissue of lamina propria•Contains mainly b-cells
MALT (Mucosa associated lymphoid tissue)
______ Responsible for Ag sampling & transfer from gut lumen into lymphoid follicles
M cells
Blood cells leave sheathed capillaries via _____, enter sinuses in __________ pulp
diapedesis; red pulp
______ lymphoid tissue is organized into discreet structures or organs
Dense
Degenerates at puberty, vestigial in adults; Undergoes fatty infiltration & lymphatic depletion
Thymus
Lymphoid follicles scattered throughout parenchyma—may include germinal centers in what lymphoid organ?
Palatine tonsils
T/F: Inner surface of capsule has continuous epithelium to isolate thymus
True
malignant tumors of immune system that involve blood
leukemia
Paired structures located at junction of oral & pharyngeal cavities, within tonsillar crypts, between anterior & posterior tonsilar pillars
Palatine tonsil
Sites of b-cell proliferation, (2’ hemopoiesis), contain what types of cells?
lymphoblasts, Mφ, & immature b- & t-cells
_______ tonsils present at base of tongue
Lingual
Blood thymus barrier consists of what cells and fibers
epithelioreticular cells, reticular fibers, fibroblasts, Mφ, plasma cells
are eosinophilic, lamellated structures within both medulla & cortex, represent degenerate reticular & epithelial nurse cells
Thymic or Hassal’s corpuscles
Blood drains out of spleen via ______ which empties into _______
trabecular Vv; splenic V
MALT in gut contains specialized ________ cells; squamoid enterocytes— located in surface epithelium with microfoldson surface (not microvilli)
M cells
Project into lumen of gut in dome areas with cuboidal mucosa; also contain M-cells; Histologically similar to MALT; Germinal centers frequent; associated with foci of b-cells
Peyer’s patches
less cellular inner layer of lymph node
medulla
T/F: Lymphatic drainage to regional lnn important in metastasis of tumor cells
True
Lymphoid organ characterized by cortex with 1’ & 2’ follicles & medulla with medullary cords & sinusoids
Lymph node
Bulk of spleen composed of spongy matrix of ______
red pulp
Lobular, lymphatic organ located in mediastinum; Embryologically derived from epithelial outgrowth of 3rd pharyngeal pouch; important hematopoietic organ during fetal development
Thymus
Blood vessels enter & leave lnn at _______
hilus
Appendix contains mostly _____ cells
B cells
Removes particulate matter & aged or defective rbc’s from circulation via phagocytosis is a function of
spleen
Cells of lymph nodes that are made of fibroblasts and reticular cells
stromal cells
MALT formed during ____________
fetal development
T/F: MALT may contain germinal centers similar to lymph. nodes
True
Areas of white pulp of spleen with central A in middle and surrounded by thin, basophilic mantle zone surrounded by paler marginal zone
follicular areas
MALT contains mostly _____ cells
B cells
Component of red pulp that are more cellular, contain large #’s of Mφ, lymphocytes
Pulp cords
Because t-cells not fully differentiated, no _____ lymph vessels to thymus, only _____, for lymph drainage
afferent; efferent
Post capillary venules are located in deep inner cortex of the lymph node at ___________
paracortical zone or corticomedullary junction
lymphoid tissue where b- & t-cells acquire surface receptors(bone marrow with b-cells & thymus with t-cells)
Primary lymphoid tissue
Darker staining rim surrounding germinal center called _______; it is the region of Ag presentation in a follicle
mantle zone
_______ cells and ______ and ______ fibers form connective tissue skeleton of lymph nodes
stromal cells; collagen and reticular fibers
What type of lymphoid tissue makes up lymph nodes, spleen, thymus, and tonsil?
Dense
The ____ of the spleen is important in splenic contraction in some species, acts as a reservoir for rbc’s
fibro-elastic outer capsule
Endothelium of sinus is discontinuous on side adjacent to _______
parenchyma
b- & t-cells leave bloodstream & enter node via
diapedesis
space beneath capsule where numerous afferent lymph vessels drain into
subcapsular sinus
Lymphoid organ characterized by robust capsule & trabeculae; no cortex & medulla, red & white pulp instead
Spleen
Extensions of cortical tissue that extend into medulla are called
medullary cords
Mature b- & t-cells migrate to all other lymphoid tissue, referred to as
Secondary lymphoid tissue
Medullary sinuses contain what cells?
lymphocytes, plasma cells, Mφ
immune accessory cell primarily found in germinal centers; possess numerous phagocytic vesicles that stain prominently
Tingible body Mφ
broad, lymphatic channels in inner, less cellular medulla; contain lymphocytes, plasma cells, Mφ; converge on hilus
Medullary sinuses
T/F: Peyer’s patches produce appreciable quantities of IgA
False: do not
Spleen contains a dense fibro-elastic outer capsule contains _____ cells
smooth muscle
enlarged germinal centers visible to naked eye
Splenic nodules
Medullary cords are separated by vorad lymphatic channels called
medullary sinuses
______ lymphoid tissue is located throughout body, associated with mucous membranes
Diffuse
______ distribution is at its maximum in childhood, progressively atrophies with age
MALT
In what lymphoid organ are secondary follicles absent; limited local clonal expansion of t-cells
Thymus
_______ Samples antigenic material, produces lymphoblasts, secretes Ab
MALT
malignant tumors of immune system that involve solid organs
lymphomas
Pulp cords of red pulp of spleen supported by connective tissue skeleton of what cells and fibers?
reticular cells & reticular fibers
Ag presenting cells including Mφ, b- & t-cells; originate in bone marrow
immune accessory cell
Component of red pulp of spleen supported by connective tissue skeleton of reticular cells & reticular fibers
Pulp cords
T/F: Lymphatic sinuses are open spaces like blood sinuses
False
What are the three hormones nurse cells secrete?
thymotaxin, thymosin, & thymopoietin
