HISTO: Lymphatic System Flashcards Preview

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Flashcards in HISTO: Lymphatic System Deck (145)
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1
Q

Specific lymphoid organs

A

Thymus, spleen, lymph nodes

2
Q

MALT =

A

Mucosa-associated lymph tissue, in respiratory, reproductive and urinary system

3
Q

GALT =

A

Gut-associated lymphatic tissue, e.g. Tonsils, Peyer’s patches and appendix. Aggregates of lymphocytes. e.g. Lamina propria (plasma cells)

4
Q

All Lymphocytes originate in

A

Bone marrow

5
Q

T lymphocytes mature in the

A

Thymus

6
Q

Any substance that can induce a specific immune response is called an:

A

antigen

7
Q

Immune cells react to small molecular domains of the antigen called:

A

Epitopes

8
Q

An immune response is generated against a specific antigen, which can be:

A
  • soluble substance (e.g., a foreign protein, polysaccharide, or toxin)
  • an infectious organism, bacteria , protozoa, foreign tissue or transformed tissue
9
Q

First line of defense against microbial aggression is by:

A

Innate immunity (non-specific)

10
Q

The initial contact with antigen or foreign agent initiates a reactions that involve effector cells, and immunity conferred by “memory cells:

A

Adaptive immunity (specific)

11
Q

Various secreted substances that neutralize foreign cells:

A

thiocyanate in saliva
lysozyme
interferon
complement in serum

12
Q

Adaptive immunity induces _____ against antigens through somatic rearrangements of genes that encode immunoglobulins and specific receptors on T lymphocytes

A

acquired resistance

13
Q

Production of proteins called antibodies that mark invaders for destruction by other immune cells is which type of defense?

A

Humoral immune response

14
Q

Destruction of transformed and virus-infected cells, etc. by specific “killer” cells is which type of defense?

A

Cellular immune response

15
Q

Lymphocytes T (approximately 60- 80%) in blood or lymph represent a circulating pool of:

A

immunocompetent cells

16
Q

These cells exit the systemic circulation to enter the lymphatic tissue (surveillance).

A

T lymphocytes

17
Q

This population (approximately 30%) migrate directly to the tissues and lymphoid organs:

A

B lymphocytes

18
Q

Where a B lymphs found?

A

in the connective tissue that underlies the lining epithelium of the respiratory, gastrointestinal, and urogenital tracts

19
Q

Are part of nonspecific (innate) immunity, are named for their ability to kill certain types of target cells. They constitute about 5% to 10% of circulating lymphocytes

A

NK cells (natural killer)

20
Q

Participate as antigen presenting cells (APCs), that phagocytose and process antigens, attach them to MHC II and present them to T-cells

A

Supporting cells

21
Q

Examples of Supporting cells:

A

Reticular cells
dendritic cells
macrophages
Langerhans cells
epithelioreticular cells

22
Q

What are cluster of differentiation (CD) markers?

A

Membrane markers for cells in lymphatic tissue to identify

23
Q

B-lymphocytes markers:

A

CD9, CD19, CD20

24
Q

T-lymphocytes markers:

A

CD2, CD3, CD5, CD7, helper CD4+ and cytotoxic CD8+, CD40L

25
Q

NK cells markers:

A

CD16, CD56 and CD94

26
Q

products of a “supergene” located on chromosome 6 in humans

A

MHC I and MHC II
from major histocompatibility gene complex

27
Q

Where are MHC I expressed?

A

Is expressed on the surface of all nucleated cells and platelets

28
Q

Presents peptides fragments (8 to 10 amino acids in length) to cytotoxic CD8+ T lymphocytes.

A

MHC I

29
Q

Where are MHC II expressed?

A

on a restricted population of cells known as antigen-presenting cells (APCs)

30
Q

present exogenous (foreign) peptides (18 to 20 amino acids) to helper CD4+ T lymphocytes

A

MHC II

31
Q

These cells are further subdivided by their ability to secrete cytokines

A

Helper CD4+ T lymphocytes

32
Q

Which lymphocytes are MHC II restricted

A

CD4+ T

33
Q

T lymph important surface markers

A

CD4 and CD8

34
Q

synthesize interleukin 2 (IL-2), interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α)

A

Helper TH1 cells

35
Q

TH1 helper cells intercact with?

A

cytotoxic CD8+ T lymphocytes (CTLs), NK cells, and macrophages

36
Q

interact with B lymphocytes and are essential for initiating antibody-mediated immune responses that control extracellular pathogens

A

Helper TH2 cells

37
Q

What does TH2 synthesize?

A

IL-4, IL-5, IL-10, and IL-13

38
Q

Their principal function is to destroy extracellular bacteria and fungi by recruiting neutrophils to the site of inflammation

A

Helper TH17 cells synthesize IL-17 and IL-22

39
Q

What are defensins?

A

antimicrobial peptides

40
Q

Kill other target cells such as virus-infected cells, cancer-transformed cells, cells infected with parasites, and transplanted cells.

A

Cytotoxic CD8+ T lymphocytes (CTLs)

41
Q

Cytotoxic CD8+ T lymphocytes (CTLs) produce:

A

proteins called fragmentings and perforins that create holes in the cell membrane and induce apoptosis

42
Q

Which lymphocytes are MHC I restricted

A

Cytotoxic CD8+ T lymphocytes (CTLs)

43
Q

T lymphocytes that can functionally suppress an immune response to foreign and self- antigen by influencing the activity of other cells in the immune system

A

Regulatory (suppressor) T lymphocytes

44
Q

regulatory cells that can diminish the ability of T lymphocytes to initiate immune responses:

A

CD4+CD25+FOXP3

45
Q

Which gene can cause polyendocrinopathy, enteropathy, X- linked (IPEX) syndrome, recessive disorder characterized by dysfunction of the T regulatory (Treg)

A

Mutations of the FOXP3 gene

46
Q

Represent a small population of T cells (<5%) with a distinct T cell receptors (TCRs) on their surface made of one γ chain and one δ chain

A

Gamma/delta (γ/δ) T lymphocytes

47
Q

Where do Gamma/delta (γ/δ) T lymphocytes develop?

A

These cells develop in the thymus and migrate into various epithelial tissues (e.g., the skin, oral mucosa, intestines, and vagina).

48
Q

Which lymphs participate in humoral immunity?

A

B lymphs

49
Q

B cells express which molecules on the cell surface?

A

major histocompatibility complex II (MHC II)

50
Q

During differentiation, the BCR isotope switches from ___ to ___

A

immunoglobulin M (IgM) in immature B cells to a mixture of immunoglobulin D (IgD) and IgM in mature

51
Q

what are Immunoglobulins?

A

Antibodies that are circulating plasma glycoproteins that interact with specific antigen

52
Q

Late stage in differentiation of B-lymphocytes

A

plasma cells

53
Q

where are plasma effector cells found?

A

Abundant in medullary cords of lymph nodes, marginal zone and cords of spleen and connective tissue

54
Q

A few antigen-specific B lymphocytes remain in circulation as:

A

memory cells

55
Q

IgG function:75-80%

A

Longest half- life (23 days) of all five. Stimulates chemotaxis. Activates complement. Crosses the placenta

56
Q

IgM function:5-10%

A

Produced in initial immune response. Activates complement system and macrophages

57
Q

IgA function:10-15%

A

Glandular secretions: saliva, tears, milk, mucus. Aids in defense against microbes and foreign molecules penetrating body via cell linings of these cavities

58
Q

IgD function:

A

In the membrane of lymphocytes. Acts as an antigen receptor on surface of mature B lymphocytes

59
Q

IgE function:

A

Fc portion binds to mast cells and basophils. Responsible for anaphylactic and hypersensitive reactions. Increased levels in parasitic infections

60
Q

the initial response to an antigen

A

inflammation

61
Q

Degradation of antigens by macrophages may lead to

A

presentation of a portion of the antigen to immunocompetent cells.

62
Q

Primary immune response is:

A

characterized by a lag period of several days before antibodies (mostly IgM) or specific lymphocytes directed against the invading antigen can be detected in the blood1

63
Q

Secondary immune response is:

A

Usually more rapid and intense (characterized by higher levels of secreted antibodies, usually of the IgG class). The secondary response is the basis of most immunizations for common bacterial and viral diseases.

64
Q

Interactions between an antigen–MHC complex with its specific T-cell receptor (TCR) requires

A

costimulary signal from CD28 and B7

65
Q

in cell-mediated immune response, cytotoxic CD8+ T lymphocytes (CTLs) target destroy

A

virus infected cells

66
Q

these cells Participate in antibody-dependent cell-mediated cytotoxicity (ADCC)

A

Nk cells

67
Q

Cytokines are

A

soluble polypeptide substances, synthesized mainly by activated T lymphocytes

68
Q

Interleukins are synthesized mainly by

A

helper CD4+ T lymphocytes

69
Q

the first cytokine to be discovered and characterized

A

Interleukin 2 (IL-2) induces proliferation of T cells

70
Q

which kill HIV-infected helper CD4+ T cells

A

Cytotoxic CD8+ T cells

71
Q

play a critical role in the acute rejection of transplanted cells and organs

A

Cytotoxic T cells

72
Q

X-linked agammaglobulinemia causes:

A

B lymphocytes do no develop, resulting in scarcity of plasma cells and immunoglobulins

73
Q

mediated by IgE antibodies that are responsible for the antibody-induced discharge of mast cell or basophil granules

A

hypersensitivity reaction

74
Q

involved in the pathogenesis of many autoimmune and infectious diseases and also play an important role in the prevention of graft rejection

A

Regulatory (suppressor) T cells

75
Q

Blocking the B7-CD28 costimulatory signal can treat:

A

rheumatoid and juvenile idiopathic arthritis and is in clinical trials for prevention of transplant rejection

76
Q

What can guard the body against pathogenic substances and are the site of the initial immune response?

A

Diffuse lymphatic tissue and lymphatic nodules

77
Q

Primary nodule:

A
  • Rounded aggregation of closely packed small lymphocytes.
  • Mesh of follicular dendritic cells (stellate cells) as a framework
78
Q

Secondary nodule with germinal center:

A
  • A germinal center is located in the central region of the nodule and appears lightly stained in histologic sections. The germinal center develops when a B lymphocyte that has recognized an antigen undergoes extensive division and proliferation.
79
Q

lymphoblasts:

A

The lighter staining is attributable to presence of the large lymphocytes

80
Q

plasmablasts:

A

migratory B cells committed to secreting antibodies

81
Q

Solitary lymphoid nodule is:

A
  • Lamina propria of gut and respiratory tract
82
Q

What are Peyer’s patches?

A

Are located in the ileum (distal portion of the small intestine) and consist of numerous aggregations of lymphatic nodules containing T and B lymphocytes.

83
Q

an important component of the immune functions of small intestine:

A

IgA

84
Q

where does the Appendix arise from?

A

from the cecum (no villi). The lamina propria is heavily infiltrated with lymphocytes and contains numerous lymphatic nodules. Chronic inflammatory changes

85
Q

form a ring of lymphatic tissue at the entrance of the oropharynx:

A

tonsils

86
Q

palatine tonsils:

A

Stratified squamous epithelium non-keratinized. Many tonsillar
crypts. Incomplete fibrous capsule

87
Q

lingual tonsils:

A

Stratified squamous epithelium non-keratinized. 1 crypt.

88
Q

Pharyngeal tonsils:

A

Pseudostratified columnar epithelium, ciliated with goblet cells. Plicae (folds). Thin capsule.

89
Q

the principal molecule of mucosal immunity:

A

IgA

90
Q

filter lymph along the pathway of lymphatic vessels and initiate adaptive immune responses to antigens

A

lymph nodes

91
Q

They express surface molecules and produce substances (chemokines) that attract lymphocytes and dendritic cells.

A

reticular cells (type III collagen)

92
Q

are bone-marrow derived antigen presenting cells (APCs) Very efficient at antigen presentation. They express exceptionally high level of MHC II and costimulatory molecules necessary for activation of T cells

A

dendritic cells

93
Q

In the lymph node, DCs are usually localized in _____ rich areas

A

T lymphocyte–

94
Q

Usually found in germinal centers. They are NOT Antigen Presenting cells APCs. They lack MHC II molecules.

A

follicular DCs

95
Q

Phagocytic and APC, express MHCI, MHCII and costimulatory signals

A

macrophages

96
Q

Superficial (outer) cortex (SC) of lymph node has:

A

Lymphoid nodules, germinal centers (B-lymphocyte differentiation), diffuse lymphoid tissue

97
Q

Deep cortex (DC) (paracortex) of lymph node has:

A

Diffuse lymphoid tissue
Mainly T-lymphocytes.

98
Q

is the thymus dependent region of the lymph node

A

Deep cortex (DC) (paracortex)

99
Q

T cells are distributed within the ____ cortex

A

Deep cortex

100
Q

Location of B cells in lymph node

A

the accumulations of which are found within germinal centers (GC) of the superficial cortex (SC).

101
Q

Beneath the capsule of the lymph node is the

A

subcapsular sinus (afferent)

102
Q

Lymphatic sinuses are lined by

A

macrophage processes

103
Q

what are Medullary cords?

A

Aggregations of lymphoid tissue around lymph sinuses. Small lymphocytes.

104
Q

Both B and T cells leave the bloodstream through:

A

High endothelial venules (HEVs).

105
Q

HEV endothelium expresses:

A

water channels (aquaporin-1
[AQP1] molecules

106
Q

what is Lymphadenitis?

A

a reactive (inflammatory) lymph node enlargement, is a common complication of microbial infections. “swollen glands”

107
Q

which pathway regulated lymphocytes exit

A

S1P exit pathway

108
Q

DiGeorge Syndrome (DGS) is a

A

primary immunodeficiency, often characterized by cellular T-cell deficiency (lack of T lymphocytes in the paracortex of the lymph node)

109
Q

Sentinel lymph node is:

A

the first one downstream from the region of the tumor

110
Q

lymphadenopathy is:

A

The normal histological organization is lost; the node enlarges, becomes filled with lymphocytes

111
Q

Lymphoepithelial organ situated in the superior mediastinum anterior to the great vessels

A

thymus

112
Q

thymus develops from:

A

Common lymphoid progenitor (CLP) cells, from the bone marrow, to become immunocompetent T lymphocytes invade the region
—-bilaterally from the third and the fourth branchial (oropharyngeal) pouch

113
Q

thymus capsule is formed by:

A

dense irregular ct

114
Q

thymus cortex has:

A

Closely packed developing T lymphocytes with their intensely staining nuclei (also called thymocytes)

115
Q

thymus medulla has:

A

Loosely packed T lymphocytes and a large number of epithelioreticular cells. Contains mostly large lymphocytes.

116
Q

involution of thymus can be:

A

Age involution
Accidental involution due to stress, radiation, steroids that decrease T lymphocytes production.

117
Q

Type I epithelioreticular cells of thymus cortex

A

The occluding junctions between these cells reflect their function as a barrier that isolates developing T cells from the connective tissue of the organ

118
Q

Type II epithelioreticular cells: thymus CORTEX

A

Form maculae adherents (desmosomes) that join long cytoplasmic processes of adjacent cells, these cells are stellate shape. They have a large nucleus with abundant euchromatin.

119
Q

involved in thymic cell education in type II

A

MHC I and MHC II

120
Q

Type III epithelioreticular cells: thymus CORTEX

A

They form occluding junctions between cytoplasmic processes of adjacent cells.

121
Q

responsible for phagocytosis of T cells that do not fulfill thymic education requirements, these T cells die before leaving the cortex

A

macrophages

122
Q

Thymus-blood barrier three major elements:

A

1) Capillary endothelium with occluding junctions and its basal lamina
2) Perivascular connective tissue space occupied by macrophages
3) Type I epithelioreticular cells with occluding junctions and their basal lamina

123
Q

Type IV epithelioreticular cells thymus MEDULLA

A

ocated between the cortex and the medulla close to type III cells. They possess occluding junctions between adjacent cells and also type III cells. In cooperation with type III cells, they create the barrier at the corticomedullary junction.

124
Q

Type V epithelioreticular cells: thymus medulla

A

. Like the type II cells located in the cortex, are joined by desmosomes to provide the cellular framework of the medulla and to compartmentalize groups of lymphocytes.

125
Q

Type VI epithelioreticular cells form the thymic (Hassall) corpuscles:

A

Studies of these cells reveal keratohyalin granules, bundles of cytoplasmic intermediate filaments. Are joined by desmosomes. The center of a thymic corpuscle may display evidence of keratinization.

126
Q

in thymus: The immunocompetent T lymphocytes migrate to ___ in spleen

A

Periarterial lymphatic sheath (PALS)

127
Q

hormones that are necessary for the maturation of T cells in thymus:

A

Thymulin, Thymic humoral factor, Thymosin-I, Thymopoietin. Colony stimulating factors and Interferon γ.

128
Q

a phenomenon called cross-talk:

A

T cells control the microarchitecture of the thymic epithelioreticular cells

129
Q

Largest lymphoid organ, situated left upper quadrant of the abdominal cavity and has a rich blood supply.

A

spleen

130
Q

spleen function:

A

Filters blood to clear it of particulate matter and senescent
erythrocytes.

131
Q

spleen white pulp:

A

thick accumulation of lymphocytes surrounding an artery.

132
Q

spleen red pulp:

A

Irregularly shaped blood vessels, and large numbers of red blood cells that it filters and degrades.
* venous sinuses

133
Q

Macrophages and______, increase in number towards the periphery of the PALS and during immune-responses to blood-borne antigens.

A

specialized dendritic cells

134
Q

Periarterial lymphatic sheath (PALS) is:

A

Made up of T-lymphocytes of the recirculating pool in loose framework of reticular cells and fibers.

135
Q

Splenic cords (cords of Billroth) are:

A

meshwork of reticular cells and reticular fibers. Large numbers of erythrocytes, platelets, macrophages, monocytes, lymphocytes, dendritic cells, plasma cells, and granulocytes reside in splenic cords

136
Q

Splenic sinuses are

A

special sinusoidal vessels lined by rod-shaped endothelial cells

137
Q

In splenic sinus Basal lamina is

A

present but incomplete.

138
Q

Central artery branches→

A

penicillar arterioles→enter red pulp and continue as arterial capillaries.

139
Q

The splenic artery branches many times in trabeculae to form

A

trabecular arteries.

140
Q

sheathed capillaries are:

A

arterial capillaries are surrounded by aggregations of macrophages

141
Q

macrophage in red pulp function:

A

function is to remove particulate matter and senescent cells from blood.

142
Q

In the open circulation, which occurs in humans, penicillar arterioles empty directly into

A

reticular meshwork of the cords rather than connect to the endothelium-lined splenic sinuses

143
Q

the only route by which blood returns to the venous circulation.

A

open circulation

144
Q

Hemopoietic function of spleen:

A
  • Removal and destruction of senescent, damaged, and abnormal erythrocytes and platelets.
  • Retrieval of iron from erythrocyte hemoglobin.
  • Formation of erythrocytes during early fetal life.
  • Storage of blood, especially red blood cells, in some species.
  • These functions are accomplished by the macrophages embedded in the reticular meshwork of the red pulp
145
Q

Immune system functions of spleen include:

A

Antigen presentation by APCs and initiation of immune response
* Activation and proliferation of B and T lymphocytes
* Production of antibodies against antigens present in blood
* Removal of macromolecular antigens from blood.
* Proliferation of B- lymphocytes and plasma cells (White pulp). Production and secretion of antibodies