Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Histology Exam 3 > Lymphoid > Flashcards

Lymphoid Flashcards

0
Q

What makes up the encapsulated lymph organs?

A

Lymph nodes, thymus, spleen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Functions of the lymphatic system

A

Defence/immune response
Maintenance of body fluids
Extramedullary hematopoiesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the diffuse lymphoid system?

A

Not encapsulated parts of the lymphoid system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The lymphoid system does what?

A

Protects the body against foreign macromolecules, virus, bacteria, and other invasive micro-organisms, also kill virally transformed cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Three types of body defence

A

Epithelial barriers
Innate immune system - macrophages, neutrophils, NK cells, complement
Adaptive immune system - T and B lymphocytes, antigen presenting cells (APC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Function of lymphatic vessels

A

Collect excess interstitial fluid from cells/tissues and returns it to the cardiovascular system/general circulation
Moves lymph through lymph nodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the flow in lymphatic vessels

A

Passive fluid flow, no pressure

Valves to control back flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Tissue deposits lymph into….

A

Lymphatic capillaries to the lymphatic vessels to the lymphatic ducts and then into the great veins of the neck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The smaller of the lymph ducts does?

A

Collects lymph from the upper right quadrant of the body and dumps into the right lymphatic duct and into the subclavian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The larger of the lymphatic ducts does?

A

Begins in the abdomen and ascends through the thorax/neck collects lymph from the remainder of the body then to the thoracic duct and then to the subclavian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe lymphatic vessels (compare to blood vessels)

A

Thinner walls, single layer of attenuated endothelial cells with an incomplete basal lamina, more valves, contains lymph, unfenestrated
Blood vessels are thicker walls with three tunicas, contains blood, fenestrated/unfenestrated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is lymphedema (elephantitis)?

A

Blockage of lymph flow resulting in a build up of lymph fluid. Either inherited (primary) or caused by injury/disease of lymph vessels (secondary)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is filariasis?

A

Tropical parasite infection that is common cause of secondary lymphedema when nematodes colonize the lymphatic system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is cellulitis?

A

Inflammation/infection of the lymphatic system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

T or F: Lymphedema can develop months-years post therapy in cancer patients

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the treatment of lymphadema?

A

Varies on severity and degree of fibrosis includes compression and gradient pumps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is lymphangitis?

A

Lymph vessel inflammation commonly seen with strep infection. Bacteria enter through ann injury and enter lymphatic system and multiply rapidly and spread. The infected vessels become inflamed causing red streaks below the skin surface. Growth is so rapid that immune system doesn’t respond fast enough.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Complications of lymphangitis

A

Abscess formation, cellulitis (generalized infection of the lower skin layers) or septicemia (blood poisoning). Can be secondary to malignancy like breast, lung, stomach, pancreas, and prostate cancers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Who is most at risk for developing lymphangitis?

A

Radical mastectomy, leg vein removal for coronary bypass, recurrent lymphangitis caused by tinea pedis (fungal foot infection)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

T or F: Lymphatic vessels are commonly used for cancer metastasis

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What composes the innate immune system?

A

NK cells, neutrophils
Macrophages - differentiate in connective tissues like the histiocytes, macrophages kupffer cells, langerhans cells, or microglia
Mediate phagocytosis and present the antigen to lymhocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What composes the adaptive immune system

A

B cells - generated and differentiate in the bone marrow bursa,, produce antibody and participate in humoral immune response, plasma cells and memory B cells
T cells - generated in the bone marrow, differentiate in the thymus. Participate in cell-mediated immune response, cytotoxic, helper, suppressor, and memory T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

List the nonspecific contributors to the innate immune system

A

Complement - a system of blood-borne macromolecules known as:
Macrophages and neutrophils - phagocytose invaders
Natural killer cells - kill tumor cells, virally infected cells, bacteria, and parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the basic functions of the adaptive immune system

A

Reacts to a SPECIFIC antigentic component of the pathogen

Ability to react against that component improves with each subsequent confrontation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the four distinctive adaptive immune response properties?

A

Specificity
Diversity
Memory
Self/Non self recognition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What cells contribute to the adaptive immune system response?

A

T lymphocytes
B lymphocytes
Antigen presenting cells (APC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How do adaptive immune response cells communicate?

A

Signaling molecules known as cytokines which are released in response to encounters with foreign antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Humoral immunity is mediated by?

A

Antibodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is Ig-A?

A

Secretory antibody in tears, saliva, gut, nasal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Structure of antibody?

A

Two heavy chains connected with disulfide bonds, two light chains attached to heavy chain by disulfide bonds. Variable regions on both chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is Ig-D?

A

Activates B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is Ig-E?

A

Degranulates mast cells and basophils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is Ig-G?

A

Opsonin, NK cytotoxicity (most common)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is Ig-M?

A

1st isotype formed in the primary response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Lymphoid immune cells participate in:

A

Eliminating non-self organisms, eliminating cancerous cells (surveillance theory), rejection of implants/transplants, autoimmune diseases, lymphoma (cancer of lymphoid tissue)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What factors weaken the immune response mediated by lymphoid immune cells?

A

Cancer treatment, AIDS, stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Function of the primary lymphoid organs?

A

Responsible for the development and maturation of lymphocytes into mature immunocompetent cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Examples of primary lymphoid organs? Function?

A

Thymus - T cells mature here
Pre/postnatal bone marrow - B cells mature here in the bursa
Fetal liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are secondary lymphoid organs?

A

Mature distribution of lymphoid cells. Responsible for the appropriate environment for immunocompetent cells to interact with each other, antigens, and with other cells to mount an immune response to invading pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Examples of secondary lymphoid organs

A

Lymph nodes, spleen, mucosal associated lymphoid tissues (MALT) postnatal bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Two categories of lymphatic organs (structural). Examples?

A

Encapsulated (dense) - bound by connective tissue capsules like the thymus, spleen, lymph nodes
Unecapsulated (diffuse) - MALT, BALT, GALT, tonsils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the thymus?

A

Primary lymphoid organ
Site of T cell maturation
Located in the superior mediastinum and extending over the vessels of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Functions of the thymus?

A

Responsible for immunological competence of T cells

Elimination of self-reactive T cells (establishing and maintaing self-tolerance)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Structure of the thymus

A

Lobes and lobules
2 lobes that arise separately during embryonic development
lobules are formed by incomplete divisions of lobes and formed by septa (trabeculae) extending into the lobes from the dense collagenous connective tissue of the thymus capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are thymocytes?

A

Immature immuno-incompetent T cells that migrate from the bone marrow.
Leave the vasculature at the corticomedullary junction and migrate to the periphery of the cortex - moving deeper with maturation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Thymocytes migrate into the…

A

Cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What does the thymus cortex contain?

A

macrophages, APCs, and epithelial reticular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What happens to the thymocytes once in the cortex of the thymus?

A 
They proliferate (cortex stains DARK, lots of thymocytes)
They mature and are instructed.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What color does the cortex stain?

A

Dark due to lots of thymocytes present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the blood thymus barrier?

A

Present ONLY in the cortex and is essential for the thymocyte instruction (o interaction with the blood)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

After maturation and instruction of thymocyte in the cortex, what happens?

A

IF recognition of MHC I/II by CD4/CD8 molecules present by the APC it is positively selected and sent to the medulla as a immuno-competent naive T cell
IF not, then pruning by anergy or apoptosis
IF recognition of self antigens presented by APC undergoes negative election and is pruned. IF not, then migrates to medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Describe positive selection in the thymus cortex

A

Recognition of SELF-MHC I/II by CD4/CD8 molecules presented by APC results in positive selection and sent to medulla
IF fails it is pruned

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Describe negative selection in the thymus cortex

A

IF recognition of self-antigens presented by APC then the thymocyte is pruned
IF not, sent to the medulla as immuno-competent naive T cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What percent of thymocytes survive to be immunocompetent naive T-cells?

A

2 %

This is why the medulla of the thymus stains light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What color does the medulla stain in the thymus?

A

Light due to few thymocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

After making it to the medulla, what happens to the immunocompetent naive T cells?

A

Exit the medulla via venules and efferent lymphatic vessels to migrate to secondary lymphatic organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is anergy?

A

Failure to separate, no clonal expansion

57
Q

What are Hassall’s corpuscles?

A

Type VI reticular cells in whirl-shape that are located in the medulla of the thymus

58
Q

What is the function of MHC?

A

Regions on the cell that contains antigen presenting proteins on the cell surface
May be referred to as HLA (human leukocyte antigen)
For us HLA=MHC

59
Q

What stimulate thymic matruration of T-cells?

A

hormones produced by epithelial reticular cells

60
Q

Describe thymic testing

A

Test ability of nascent T cells to recognize HLA I/II molecules and self-epitopes which is mediated by Type II/III epithelial reticular cells and bone marrow dendritic APCs

61
Q

The T cell receptor complex (TCR) is composted of what?

A

CD3 and wither CD4 or CD8

62
Q

Helper T cells have what MHC? Cytotoxic T cells?

A

Helper - CD4

Cytotoxic - CD8

63
Q

The TCR can recognize an epitope antigen if it is?

A

Bound to an MHC molecule - MHC restricted

Role of APC!

64
Q

What is unique about APC?

A

Can express both HLA I and II

Most nucleated cells express just HLA I

65
Q

What is the function of the blood thymus barrier?

A

Isolates thymocytes from exposure to foreign antigens / blood-borne macromolecules therefore T cells exit the medulla as naive immunocompetent mature lymphocytes.
Exclusively located in the thymus cortex

66
Q

Describe the vasculature in the thymus

A

Vessels do not gain access to the cortex directly but do so from the trabeculae and enter the corticomedullary junction where thy form capillary beds that penetrate the cortex
Self-macromolecules are allowed to cross in order to participate in T-cell education and development of self-tolerance

67
Q

The capillary layers in the thymus are composed of…?

A

Continuous endothelium
Perivascular connective tissue and basement membrane
Epithelial reticular sheath

68
Q

T or F: Encountering self HLA in the thymus is critical for T cell education and required for the rescue from anergy/apoptosis

A

T, if too affined toward the self antigens they are pruned

69
Q

What is thymic involution?

A

As age, the thymus parenchyma is replaced by adipocytes

70
Q

Life of WBC neutophils

A

Circulate freely in the blood stream, often first responders, contribute to inflammation, last 6 hrs to 2 days (thought to prevent virus use to reproduce via infection)

71
Q

Life of eosinophil

A

Allergic response, help to identify foreign substances or trigger asthma related symptoms, circulate 8-12 hours before settling in tissue where they live for 8-12 days

72
Q

Life of basophils

A

Play big role in inflammatory response, especially for allergies because they contain histamine (inc blood flow) and heparin (prevent blood clotting) Last for 4 hrs to 5 days.

73
Q

Life of lymphocytes

A

Large (NK cells), Small (Helper and cytotoxic T cells, B cells)
NK cells destroy both tumors and infected cells and live up to 2 weeks
Helper T cells record information of newly-encountered antigens and release cytokines to attract cytotoxic T cells when antigen reappears. Lasts only about 26 weeks! Although memory is preserved through division.
Cytotoxic T cells last anywhere from 1 year to live.
B cells secrete antibodies that stick to antigens in effect marking them for killer cells to destroy. Vary widely in life span from 10 days to 15 months

74
Q

Life of monocytes

A

Precursor cells for macrophages and dendritic cells

Stored in spleen,monocytes enter blood upon infection and differentiate at the site of infection. Lasts several months

75
Q

Life of platelets

A

Small cells that form blood clots and seal broken blood vessels.
average life is between 9-12 days.

76
Q

Which cells undergo V(D)J recombination?

A

T and B cells to make variety (in thymus and bone marrow respectively)
Natural killer cells do not

77
Q

What lymphatic organs are encapsulated?

A

Thymus, lymph nodes, spleen

78
Q

Describe lymph nodes

A

Secondary (peripheral) lymphoid organs
Small (<3 cm in diameter)
Encapsulated with fibrous CT in oval shaped structures interposed in the path of lymph vessels
Parenchyma is composed of T and B cells, APCs, and macrophages
FUNCTIONs to distribute mature lymphoid cells.

79
Q

Lymph nodes are responsible for providing an environment to?

A

Allow immunocompetent cells to interact with each other, antigens, and with other cells to mount an immune response against pathogens

80
Q

2 functions of lymph nodes

A

1) lymph filtration to remove bacteria and foreign substances from the lymph via resident macrophages in the sinuses
2) Antigen presentation and recognition
APCs that contact antigens migrate to the nearest lymph node and present their epitope-MHC complex to the lymphocytes
If an antigen is recognized and a B cell becomes activated, that B cell migrates to a primary lymphoid nodule and proliferates forming a germinal center and a secondary lymphoid nodule

81
Q

Describe the capsule of a lymph node

A

Dense connective collageous tissue surrounding the node
Contributes to the 3D structure of the node cortex via trabeculae
Subdivides the outer region of the cortex into incomplete compartments

82
Q

The capsule and trabeculae combine to make?

A

The reticular CT that forms the architectural framework of the node

83
Q

Describe the path of lymph upon entering a lymph node

A

Enters via an afferent lymphatic vessel (located on the convex side of the node and has valves to prevent back blow)
Then to subcapsular sinus
Then to cortical sinus (also called trabecular or paratrabecular sinus)
Then to medullary sinus
Then to efferent lymphatic vessel (exit on the hillum, valves also present)

84
Q

Describe lymph circulation

A

Not closed, no central pump.
Occurs with low pressure mainly on the movement of skeletal muscle to squeeze fluid. Lymph flows only one way via valves (semilunar)

85
Q

How do T and B lymphocytes enter the lymph node

A

Enter via the paracortex from vasculature via endothelial venules

86
Q

After entering the paracortex in lymph nodes, what happens to B cells?

A

Migrate to the cortex in primary lymphoid nodules

87
Q

What happens to T cells upon entering the paracortex of the lymph node?

A

Stay in paracortex

88
Q

Cells are activate via MHC-epitope presentation in the lymph node, what happens?

A

Proliferate and form secondary lymphoid nodules. New memory and plasma B cells exit the secondary lymphoid nodules

89
Q

Upon leaving the secondary lymphoid nodules, what happens to B cells?

A

Majority migrate to the medulla and form medullary cords. Then migrate to the medullary sinuses and exit via efferent lymphatic vessels

90
Q

What happens to B cells that leave the efferent lymphatic vessels?

A

Majority of plasma B cells migrate to the bone marrow and produce antibodies
Majority of memory B cells take up residence in other secondary lymphatic organs

91
Q

10% of new plasma B cells do what?

A

Stay in the medulla and release antibodies into the medullary sinus (instead of exiting)

92
Q

What is the thymus dependent region of the lymph node?

A

Paracortex

93
Q

DCs and APCs migrate to the paracortex and present antigen to T cells via MHC epitope complexes and…

A

If T cells are activated they profilerate and expand the paracortex depth (swollen lymph nodes as in infection
The new T cells exit the paracortex and migrate to the medullary sinuses and exit via the efferent lymphatic vessels

94
Q

High endothelial venules are the point of entry for B and T cells in the lymph node and are located in the?

A

Paracortex

95
Q

Lymphoid nodules in lymph node are aggregates of B cells located in?

A

The cortex

96
Q

What is the mantle zone (corona)?

A

Peripheral to a germinal center, dense accumulation of B lymphocytes migrating out from the germinal center

97
Q

What is a germinal center?

A 
Where B cells (centroblasts) proliferate, migrate, express slgs, switch immunoglobin class, and are exposed to antigen bearing follicular dendritic cells
B cells (centrocytes) that do not synthesize proper slgs undergo apoptosis and are eaten by macrophages
Surviving cells exit the secondary nodule as memory B cells or plasma cells and migrate to the medullary sinus
98
Q

Function of the dark zone of the geminal center of the secondary lymphoid nodule

A

Naive B cell entry, clonal expansion, and somatic hypermutation

99
Q

Function of light zone in the geminal center of a secondary lymphoid nodule

A 
Apoptotic B cell due to disadventageous mutation
Improved affinity of cells are selected by DCs and differentiaton and class switching to plasma or memory B cells occurs here
100
Q

A secondary lymphoid nodule is composed of?

A

Geminal center and mantle zone

101
Q

Medullary sinuses are point of exit for B and T cells located in the?

A

Medulla

102
Q

What is the spleen?

A

Secondary lymphoid organ
Largest encapsulated lymphoid organ in the body
Located in the upper left quadrant of the abdominal cavity

103
Q

Functions of the spleen?

A

Filters blood
Forms lymphoid cells (T and B cell profileration)
Eliminates or inactivates blood-borne antigens
Destroys aged platelets and erythrocytes
Participates in fetal hematopoiesis
Can resume hematopoietic function in the adult

104
Q

Describe spleen structure

A

Capsule of collagenous connective tissue
Trabeculae that arise from the capsule and guide blood vessels
Hilum (concave surface) as in lymph nodes which is the entry point of arteries and accompanying nerve fibers
The capsule and trabeculae suspend the reticular connective tissue that forms the architectural framework of the organ

105
Q

Describe the path of blood into the spleen for filtration

A

Splenic artery enters at the hilum
Then to trabecular artery
Then to central arteries (above and including makes up the white pulp)
Then into the pencillar arteries in the red pulp

106
Q

What vasculature is present in the white pulp of the spleen?

A

Splenic artery, trabecular artery, and central arteries

107
Q

From the pencillar artery, where does blood go?

A

To the pulp arterioles, terminal arterial capillaries, and macrphage sheathed arterioles

108
Q

Where is the central artery in the spleen?

A

In the center of the periarterial lymphatic sheath (PALS), it branches but maintains the PALS until it leaves the white pulp to form the pencillar arteries

109
Q

The terminal arterial capillaries split to?

A

Open circulation in the open ended vessels in the splenic cords of bilroth
Closed circulation to the splenic sinuses then to pulp veins then to trabecular veins then to splenic vein and exits at the hilum

110
Q

What is the red pulp? What is function?

A

Appears as red areas surrounding greyish areas (white pulp) in FRESH cut spleen secitions.
In combination with the marginal zone / marginal sinuses, macrophages and phagocytes in the red pulp filter the blood removing microorganisms and aged RBC and platelets

111
Q

What composes the red pulp?

A

Splenic sinuses and splenic cords of bilroth

112
Q

What are splenic sinuses?

A

Located in red pulp and are spaces with discontinuous basal lamina

113
Q

What are the splenic cords of bilroth?

A

Sponge material in the red pulp of spleen composed of a loose network of reticular fibers

114
Q

Where do T and B lymphocytes enter the spleen?

A

At the marginal zone, where the marginal sinuses contain cells/antigens from the blood, first contact of APCs, B cells, T cells

115
Q

After entering the marginal zone, where do T and B cells go?

A

To the white pulp (contains all the spleen’s lymphoid cells/tissue)

116
Q

From the white pulp, where do T and B lymphocytes go in the spleen?

A

To the PALS (periarterial lymphatic sheath)

117
Q

Once in the PALS, what happens to the B and T cells?

A

B cells migrate to the lymphoid nodules within the PALS

T cells stay in the PALS

118
Q

Once in the lymphoid nodule, what do B cells do?

A

The lymphoid nodule displaces the central arterole to a peripheral position
If B cells are activated via MHC-epitope, they proliferate ad form secondary lymphoid nodules and new memory and plasma B cells exit the secondary lymphoid nodules

119
Q

Once in PALS, what do T cells do?

A

If activated via MHC-epitope presentation they proliferate and exit the spleen via the marginal sinuses located in the marginal zone and migrate to the site of antigen challenge or just join the circulating lymphocyte pool

120
Q

T and B cells exit the spleen via??

A

The marginal sinuses located in the marginal zone

121
Q

What is the white pulp?

A

Appears greyish in fresh cut spleen sections
Part of the infection fighting immune system
Produces lymphocytes (B and T cells) and antibodies

122
Q

What composes the white pulp?

A

Lymphoid nodules and PALS

123
Q

What is the marginal zone?

A

Surrounds white pulp and separates it from the red pulp

124
Q

What does the marginal zone of spleen contain?

A

Marginal sinuses, capillary loops at which blood-borne cells, antigens, and particulates first contact the splenic parenchyma
Contains plasma cells, T cells, B cells, macrophages, and dendritic APCs

125
Q

What happens in the marginal zone?

A

Macrophage phagocytosis of antigens, bacteria, foreign particles, and old RBC/platelets
APCs sample the blood for antigens and macrophages attack pathogens
Circulating T and B cells entering the blood and migrating to the white pulp can contact APCs for epitope-MHC complex presentation and activation

126
Q

What is MALT??

A

Mucosal-associated lymphoid tissue
Non-encapsulated localized lymphocyte infiltration and lymphoid nodules in the mucosa of the GI, respiratory, and urinary tracts

127
Q

What is the function of MALT?

A

Response to airborne/ingested antigens

128
Q

Three principal examples of MALT

A

GALT - gut-associated lymphoid tissue
BALT - bronchus-associated lymphoid tissue
Tonsils

129
Q

GALT is primarily composed of?

A

Lymphoid follicles along the length of the GI tract, generally isolated from one another

130
Q

What are Peyer’s patches?

A

Prominent accumulation of GALT in the ileum where GALT forms aggregates composed of B cells surrounded by a looser region of T cells and APC

131
Q

T or F: Afferent lymph vessels are absent in GALT

A

T, but there is efferent lymph drainage

132
Q

What are M cells (microfold cells)?

A

Located in the epithelial lining adjacent to the lymphoid follicles in the ileum and thought to capture antigens and transfer them to macrophages located in Peyer’s patches

133
Q

What is BALT?

A

Similar to Peyer’s patches, but located int he walls of bronchi

134
Q

T or F: There are no afferent lymph vessels in BALT

A

T, just efferent lymph drainage

135
Q

What makes up BALT?

A

B cells are majority, but also APCs and T cells

M cells are also present in epithelium of bronchi and are thought to transfer antigens to macrophages within the BALT

136
Q

What is the tonsil?

A

Incompletely encapsulated aggregates of lymphoid nodules that guard the entrance of the oral pharynx to be interposed in the path of airborne and ingested antigens

137
Q

How do tonsils react to pathogens?

A

Lymphocyte proliferation mounting an immune response

138
Q

What are the three types of tonsil?

A

Palatine, pharyngeal, and lingual

139
Q

Where is the palatine tonsil found?

A

The boundary of the oral cavity and oral pharynx (aka at the back of throat)

140
Q

Describe the structure of the palatine tonsil

A

A dense fibrous capsule separates the deep aspect of the tonsil from the surrounding connective tissue (incompletely encapsulated)
Superficial aspect is covered by an epithelial layer that dips into 10-12 crypts which invaginate the tonsilar parenchyma

141
Q

What composes the parenchyma of the palatine tonsil?

A

Composed f lymphoid nodules many of which display germinal centers (indicative of B cell activation by antigen and subsequent proliferation)

Histology Exam 3 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions