Lymphoid Tissue Part 2 Flashcards by sophie rosen

largest lymphoid organ in the body

spleen

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immune functions of the spleen (4)

• b-& t-cell replication, manufacture of Ab, Ag removal
• Removes particulate matter & aged or defective rbc’s
from circulation via phagocytosis
• Recycles Fe from Hb
• Hemopoiesis in fetus

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removal of spleen

splenectomy

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if the spleen is removed, function is taken over by (2)

liver and bone marrow

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Dense, fibro-elastic outer capsule contains

smooth Mm cells

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mooth Mm cells are important in

splenic contraction in some species

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smooth Mm cells act as a reservoir for

rbc’s

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Characteristic large, thick bands of dense connective tissue — extend into body of spleen

trabeculae

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Characteristic large, thick bands of dense connective tissue — extend into body of spleen

trabeculae

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Characteristic large, thick bands of dense connective tissue — extend into body of spleen

trabeculae

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Characteristic large, thick bands of dense connective tissue — extend into body of spleen

trabeculae

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trabecular contain trabecular (2)

Aa & Vv

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Unlike lnn, spleen lacks (2)

cortex & medulla

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Bulk of spleen composed of spongy matrix of

red pulp

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Within red pulp are (2)

pulp cords & sinusoids

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cords of Bilroth

pulp cords

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Sinusoids contain mostly

blood

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Pulp cords are more —, contain large #’s of (2)

cellular

macrophage and lymphocytes

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Pulp cords supported by connective tissue skeleton of (2)

reticular cells & reticular fibers

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scattered throughout red pulp are discreet nodules of

white pulp

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white pulp contains large #’s of

wbc’s

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Areas of white pulp =

follicular areas+/-germinal 
centers (contain 1’ b-cells), 
with central A in middle and 
surrounded by thin, 
basophilic mantle zone
surrounded by paler 
marginal zone

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white pulp functions as a site of (2)

Ag presentation, phagocytosis

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white pulp contains large numbers of (3)

macrophages
plasma cells
t helper cells

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Splenic nodules

enlarged germinal centers visible to naked | eye

Central Aa surrounded by --- rather than b-cells form

t-cells | periarteriolar lymphatic sheaths (PALS)

periarteriolar lymphatic sheaths (PALS) lack --- --- because

germinal centers, because minimal t-cell proliferation

periarteriolar lymphatic sheaths (PALS) are less --- --- in humans than other species & require --- --- to make positive ID

well developed | immunohistochemical staining

PALS is often used interchangeably with

1' follicles in white pulp

Branches of splenic A enter white pulp within trabeculae via

trabecular Aa

Branches of splenic A enter white pulp within trabeculae via trabecular Aa, branch & form

central Aa to white pulp

Central Aa continue into red pulp, branch into

perpendicular penicillar Aa

perpendicular penicillar Aa branch into

arterioles

arterioles terminate in

2-3 sheathed capillaries

sheathed capillaries

blind ending capillaries, lack endothelial lining

sheathed capillaries are surrounded by

macrophages

Forms a non-continuous

perivascular sheath, or cuff

perivascular sheath, or cuff acts as part of filtering mechanism, active in

phagocytosis

Blood cells leave sheathed capillaries via ---, enter sinuses in --- ---

diapedesis | red pulp

Sinusoids lined by endothelial cells called

stave cells

Endothelial slits between stave cells allow

free passage of blood cells

Blood drains out of spleen via ---, empties into ---

trabecular Vv | splenic V

--- --- model of spleen

Open circulation

palatine tonsil

``` Paired structures located at junction of oral & pharyngeal cavities, within tonsillar crypts, between anterior& posterior tonsilar pillars(= palatoglossal& palatopharyngeal arches) ```

Lingual tonsils

present at base of tongue & pharyngeal tonsils (=adenoids) in nasopharynx, associated with Eustacian tubes

Palatal, lingual, & pharyngeal | tonsils collectively referred to as

Waldeyer’s ring

Waldeyer’s ring forms a ring of

immunologic protection ~ GI & respiratory tracts

Palatal & pharyngeal tonsils | collectively referred to as

NALT | nasal associated lymphoid tissue

palatine tonsil is similar to lnn, but

unencapsulated

Base of tonsil supported by cup-shaped, collagenous ---

hemicapsule

palatine tonsil cortex and medulla

none

--- --- scattered throughout parenchyma

Lymphoid follicles

lymphoid follicles may include

germinal centers

Luminal surface of palatine & lingual tonsils covered by characteristic

stratified squamous nonkeratinized epithelium

Luminal surface of palatine & lingual tonsils covered by characteristic stratified squamous nonkeratinized epithelium—invades tonsil, forming

blind-ended tonsilar crypts

Lymph node

cortex with 1’ & 2’ follicles & medulla | with medulary cords & sinusoids

Thymus

mostly t-cells, not b-cells; Hassal’s | corpuscles; cortex & medulla present

Spleen

robust capsule & trabeculae; nocortex & | medulla, red & white pulp instead

Palatine tonsil

hemicapsule & skin-like epithelium | with crypts; nocortex & medulla

appendix

Blind-ended sac, vestigial | cecum

Atrophies in adults; contains | mostly

b-cells

Important digestive organ in | ---; used for --- ---

herbivores bacterial fermentation

inflammation of appendix

appendicitis

surgical removal of appendix

appendectomy

MALT in gut

GALT

MALT in respiratory tract

BALT

T in pharynx

NALT

Diffuse, unencapsulated lymphoid aggregates associated with --- ---

mucosal surfaces

Located in subepithelial connective | tissue of

lamina propria

MALT contains mainly

B cells

MALT produces

1' IgA

IgA

secretory IgA

MALT may contain

germinal centers, similar to lnn

Samples --- material, produces ---, secretes --

antigenic lymphoblasts Ab

MALT in gut contains specialized M-cells called

squamoid | enterocytes

squamoid | enterocytes are located in

``` surface epithelium with microfolds on surface (notmicrovilli) ```

MALT is responsible for (2)

Ag sampling & transfer from gut lumen into | lymphoid follicles

MALT formed during

fetal development

MALT distribution (age wise)

maximum in childhood, progressively | atrophies with age

Peyers patches

Special type of MALT scattered throughout small intestine

where are peyers patches most common and least common?

most common in ileum, least common in duodenum

Peyes patches project into lumen of gut in dome areas with

cuboidal mucosa

peyers patches also contain

also contain M-cells

Peyers patches are histologically similar to

MALT

Lymphoid aggregates contain large #’s of both

b-& t-cells

peyer’s patches do not produce appreciable quantities of

IgA

--- --- are frequent in Peyers patches

Germinal centers

Peyers patches are associated with

foci of b-cells

Lymphoid Tissue Part 2 Flashcards

(88 cards)