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HDM Midterm > Lecture 4: Lymphoid Tissue > Flashcards

Lecture 4: Lymphoid Tissue Flashcards

1
Q

What are the primary lymphoid organs and what is their function?

A

Thymus
Red bone marrow

Produce lymphocytes needed to recognize antigens

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2
Q

_________ lymphoid organs consist of diffuse lymphoid tissue where lymphocytes are activated in response to Ags

A

Secondary

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3
Q

Lymphoid tissue can be classified functionally as primary vs. secondary. It can also be classified as _____________ vs. ____________

A

Non-encapsulated

Capsulated

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4
Q

Non-encapsulated lymphoid tissue is diffuse and nodular. It can exist as single entities or aggregates. What are some examples?

A

Single: primary nodules and secondary nodules

Aggregate: tonsils, Peyer’s patches, Vermiform appendix

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5
Q

Diffuse lymphoid tissue consists of __________ CT housing lymphocytes deep to epithelium

It is located in what 3 locations?

A

Reticular

GI tract, GU tract, respiratory passages

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6
Q

Nodular lymphoid tissue consists only of _______ lymphocytes that are inactive or naive. The cells are _________ distributed and lack a _______ _________

A

Small; uniformly; germinal center

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7
Q

What happens when a primary follicle is exposed to Ag?

A

Becomes a secondary follicle which will differ in appearance

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8
Q

What type of epithelium is displayed by primary nodules?

A

Nonkeratinized stratified squamous

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9
Q

Where are primary nodules/follicles found?

A

Esophagus
Oral cavity
Anus
Vagina

[areas exposed to outside environment]

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10
Q

Visually, how would you see a difference between primary and secondary follicles?

A

Secondary will have a germinal center, while primary do NOT

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11
Q

Secondary follicles have a germinal center which stains _______ than the outer portion. It posseses an outer ring called a _______, which contains smaller lymphocytes.

Memory cells will collect in the _________

A

Lighter; mantle

Mantle

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12
Q

T and B lymphocytes have a distinct distribution regarding the secondary follicle/nodule. Where would you find each type of cell?

A

B cells localize to the follicle, in the germinal center and the mantle

T cells localize to the tissue surrounding the follicle

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13
Q

Tonsils are large, irregular masses of lymphoid tissue that help protect against inhaled or ingested substances. They can be partially encapsulated.

What are the 3 tonsils?

A

Pharyngeal
Palatine
Lingual

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14
Q

The palatine tonsil is characterized by ___________ ___________ epithelium and possesses 10-20 deep invaginations called ________ _________.

The epithelial lining is densely populated with __________. Dense CT acts as partial __________.

A

Stratified squamous; tonsillar crypts

Lymphocytes; capsule

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15
Q

Do palatine tonsils contain germinal centers?

A

Yes

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16
Q

Which tonsil exists as a single structure?

A

Pharyngeal tonsil

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17
Q

The pharyngeal tonsil is located at the posterior wall of the _____________. It is covered with ___________ _________ ciliated epithelium.

It has a thin, underlying __________.

A

Nasopharynx; pseudostratified columnar

Capsule [still categorized as non-encapsulated]

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18
Q

Does the pharyngeal tonsil have crypts or germinal centers?

A

No crypts, just invaginated mucosa with shallow infoldings

Only has GC’s after responding to an Ag

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19
Q

The lingual tonsil is positioned along the base of the tongue and is covered with _______ _______ epithelium.

A

Stratified squamous

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20
Q

Does the lingual tonsil have germinal centers, crypts, or a capsule?

A

Germinal centers = yes

Varying number of crypts

Lacks a capsule

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21
Q

What type of non-encapsulated lymphoid tissue is MALT, and where is it found?

A

Aggregate nodular

Typically found in GI tract (GALT), respiratory airways (BALT), and urinary tract

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22
Q

GALT is aggregate nodular tissue that is prominent in small intestines, especially the ________.

_________ ________ are large collections of lymphatic nodules.

It is characterized by an abundance of ______, and is covered by __________ ________ epithelium with ________ cells

A

Ileum

Peyer patches

Villi; simple columnar; goblet

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23
Q

What type of non-encapsulated lymphoid tissue is the vermiform appendix?

A

Aggregate nodular

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24
Q

The vermiform appendix is a short, small-diameter projection off the ______ that is almost completely filled with lymphoid tissue.

It is covered in ______ ______epithelium with _______ cells.

It is characterized by _____, but lacks _____ or a _______

A

Cecum

Simple columnar; goblet

Crypts; villi; capsule

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25
Q

Capsulated lymphoid tissue includes what 2 subcategories of lymphoid tissue?

A

Lobules

Lacking lobules

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26
Q

What is the primary example of lobulated capsulated lymphoid tissue?

A

Thymus

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27
Q

What are the 2 examples of capsulated lymphoid tissue lacking lobules?

A

Spleen

Lymph nodes

28
Q

The thymus is a _________ structure located in the ________.

___________ invade this tissue and proliferate. Lymphocytes then mature into ____ cells.

It is functional at birth and remains active in T-cell production until puberty, followed by a period of _____________ (decreased activity of the thymus and it is replaced by _______ tissue)

A

Bilobed; mediastinum

Lymphoblasts; T

Involution; adipose

29
Q

The thymus is surrounded by a _______ ______ capsule.

Septa extend from capsule to penetrate the parenchyma, forming _______.

The lobules posses a darker staining __________ and a lighter staining ________.

A

Connective tissue

Lobules

Cortex; medulla

30
Q

Does the thymus contain lymphoid nodules or germinal centers?

A

No

31
Q

What is the specific site of T lymphocyte maturation in the thymus, and what all is contained there?

A

Thymic cortex

Contains T-lymphoblasts (thymocytes), macrophages, Thymic Epithelial cells (TECs)

32
Q

What are the 2 types of cortical thymic epithelial cells?

A

Subcapsular (squamous)

Cortical (stellate)

33
Q

Which subtype of cortical TECs forms the cortical compartment? A subset will form a sheet like structure separating the cortex/medulla.

A

Subcapsular (squamous)

34
Q

The cortical (stellate) cortical TECs produce the ____________ (keratin and desmosomes), as well as secretes _________ for T cell development

A

Cytoreticulum

Cytokines

35
Q

Where is the functional blood-thymus barrier?

A

In the cortex only

36
Q

What forms the blood-thymus barrier?

A

TECs, basal lamina, and endothelial cells

Macrophages prevent circulating antigens from reacting with developing T cells

37
Q

The blood-thymus barrier consists of thymic cortical epithelial cells joined by _______, dual basal laminae produced by TECs and endothelial cells, and capullary endothelial cells linked by _________ ________

A

Desmosomes

Tight junctions

38
Q

What part of the thymus houses mature T cells migrating from the cortex?

A

The thymic medulla

39
Q

T cells in the thymic medulla enter ____________ _________ to exit the thymus

A

Postcapillary venules

40
Q

What are the 4 major components in the thymic medulla?

A

TECs (medullary epithelial cells)

Macrophages

Dendritic cells

Hassal’s corpuscles

41
Q

What are Hassal’s corpuscles?

A

Closely packed whorls of keratinized TECs in the thymic medulla

Secretes cytokines that aid in maturation of T cells

42
Q

Which part of the thymus would you find the following?

Immature/maturing T cells, subcapsular TECs, cortical TECs, and macrophages

A

Cortex

43
Q

Which part of the thymus would you find the following?

Mature T cells, medullary TECs, Hassall’s corpuscle, dendritic cells, macrophages

A

Medulla

44
Q

Where would you find the spleen and what does it do?

A

Found in left upper quadrant

Initiates immune response to blood antigens

Reservoir for platelets

Recycling of erythrocytes

Hematopoiesis

45
Q

The spleen is surrounded by a CT capsule. ________ separates it into incomplete compartments.

The parynchema contains _______ fibers. The _______ pulp is rich in lymphoid tissue. The ______ pulp is rich in RBCs.

It is served by a single splenic artery and vein.

A

Trabeculae

Reticular; white; red

46
Q

Which pulp of the spleen is associated with the venous supply and contains platelets, erythrocytes, macrophages, and plasma cells?

A

Red pulp

47
Q

Which pulp of the spleen consists of T and B cells?

A

White

48
Q

The white pulp of the spleen is characterized by lymphoid nodules and _________ arteriole.

__________ _______ ________ are T cells surrounding the arteriole.

__________ zone consists of small lymphocytes surrounding the GC.

_________ zone consists of a blend of lymphocytes that span from white to red pulp.

A

Central

Periarteriolar lymphoid sheaths (PALS)

Corona/mantle (MnZ)

Marginal zone (MgZ)

49
Q

The red pulp is involved in blood filtration and erythrocyte turnover. It is composed of splenic _______ and _______.

The ______ are reticular tissue rich in macrophages and lymphocytes.

The red pulp contains __________ arteries and _________-sheathed capillaries

A

Sinusoids; cords

Cords

Penicillar; macrophage

50
Q

The splenic sinusoids of the red pulp are lined with _______ cells, which are specialized endothelial cells that separate healthy vs. unhealthy RBCs

A

Stave (“barrel” cells)

51
Q

The splenic artery branches from the _______ ______, and divides into _________ arteries that enter into the parynchema.

A

Celiac trunk; trabecular

52
Q

Trace splenic blood flow from the splenic artery to the splenic cords

A 
Splenic artery
Trabecular arteries
Central arteriole (PALS)
White pulp
Penicillar arteries
Splenic sinuses
Splenic cords
53
Q

Throughout splenic blood flow, ___________ remove old/dead erythrocytes from circulation, while viable erythrocytes re-enter circulation through the _________

A

Macrophages; sinuses

54
Q

_________ is the clear, yellowish fluid comprised of interstitial fluid, solutes, and foreign materials

A

Lymph

55
Q

Lymphatic ___________ are closed-ended tubules that are found among capillary beds

A

Capillaries

56
Q

The human body has 400-450 _______ _____, which are small encapsulated structures positioned along lymphatic vessels

A

Lymph nodes

57
Q

Where are the highest concentrations of lymph nodes?

A

Axilla
Thorax
Inguinal
Around neck vasculature

58
Q

What are the functions of the LNs?

A

Filter lymph
Remove debris
Facilitate Ab production
Produce lymphocytes

59
Q

The outer cortex of the lymph node receives lymph from _________ lymphatic vessels

Sinuses converge at the __________ lymphatic vessel (singular) in the central medulla.

The ___________ is the region between the cortex and medulla.

The _______ refers to the exit for efferent lymphatics and entry for neurovasculature

A

Afferent
Efferent
Paracortex
Hilum

60
Q

Trace lymph flow through the LN from afferent to efferent

A 
Afferent
Cortex
Paracortex
Medulla
Efferent
61
Q

The ___________ __________ of the LN includes the major spces for lymph flow.

Lymphatic follicles and germinal centers are restricted to the ______ of the LN.

Immune cells are suspended on _________ fibers

A

Subcapsular sinus

Cortex

Reticular

62
Q

Germinal centers of LNs contain activated follicles that have been presented with an antigen. Active B cells are contained in the _______ zone.

A

Mantle

63
Q

Describe the cortical distribution of T and B cells in the LN

A

B cells localized to lymphatic follicle

T cells localized to paracortex

64
Q

_________ _________ _________ refer to the cuboidal lining of endothelial cells that facilitates movement of lymphocytes into lymphoid tissue

A

High endothelial venules

65
Q

Where are high endothelial venules (HEVs) located?

A

Paracortex

66
Q

Lymphocytes move from the blood into the LNs via HEVs through a process called ___________, which is promoted by integrins and glycoproteins

A

Diapedesis

67
Q

The medulla of the LN is _______ staining than the cortex due to lower population of lymphocytes.

It is characterized by medullary _______, which are masses of lymphoid tissue extending from the paracortex, as well as T cells, B cells, and plasma cells.

It also contains medullary _______, which are dilated spaces that separate the medullary cords, as well as clusters of macrophages and neutrophils

A

Lighter

Cords

Sinuses

HDM Midterm (10 decks)

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