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Histology > Lymphatic System Part III > Flashcards

Lymphatic System Part III Flashcards

1
Q

Regulate and carry out adaptive immunity

A

LYMPHOCYTES

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2
Q

In adult stem cells for all lymphocytes are located in the ____

A

red bone marrow

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3
Q

cells of the major lymphoid lineages mature and become functional in two different central or primary lymphoid organs:

A

B lymphocytes
T lymphocytes

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4
Q

remains and differentiate further in the bone marrow

A

B lymphocytes

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5
Q

progenitors move via circulation into the developing thymus

A

T lymphocytes

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6
Q

Long lived lymphocytes, 75% of the circulating lymphocytes

A

T LYMPHOCYTES

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7
Q

Recognize antigenic epitopes via surface protein complexes termed T-cell receptors (TCRs) which include two glycoproteins called alpha and beta chains, each of which are with variable regions produced similarly to those of immunoglobulins.

A

T LYMPHOCYTES

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8
Q

Surface receptors for antigens are monomers of IgM or IgD

A

B LYMPHOCYTES

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9
Q

Covered by about 150,000 B-cell receptors (BCRs)

A

B LYMPHOCYTES

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10
Q

Produced antibodies

A

B LYMPHOCYTES

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11
Q

A main function of the _____is induction of central tolerance, which along with regulatory T cells prevents autoimmunity.

A

THYMUS

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12
Q

has a vascularized connective tissue capsule that extends septa into the parenchyma, dividing the organ into many incompletely separated lobules. Each lobule has an outer darkly basophilic cortex surrounding a more lightly stained medulla

A

THYMUS

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13
Q

contains an extensive population of T lymphoblasts (or thymocytes), some newly arrived via venules, located among numerous macrophages and associated with the unique thymic epithelial cells (TECs) that have certain features of both epithelial and reticular cells.

A

thymic cortex

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14
Q

three major types of TECs in the cortex of the thymus:

form a layer, joined by desmosomes and occluding junctions, line the connective tissue of the capsule and septa and surround the microvasculature. This creates an isolated cortical compartment and, together with the vascular endothelial cells and pericytes, forms a blood-thymus barrier preventing unregulated exposure of thymocytes to antigens.

A

Squamous TECs

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15
Q

three major types of TECs in the cortex of the thymus:

with processes containing keratin tonofilaments joined by desmosomes, form a cytoreticulum to which macrophages and developing lymphocytes attach instead of to reticulin fibers. Importantly, these cells are APCs,
expressing MHC class II molecules in addition to MHC class I. They also secrete numerous cytokines for T-cell development and other immune functions, justifying this organ’s inclusion among endocrine glands.

A

stellate TECs

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16
Q

three major types of TECs in the cortex of the thymus:

express MHC class II molecules but form a sheetlike structure contributing to a functional corticomedullary barrier between these two regions of each lobule.

A

squamous cortical TECs

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17
Q

bean-shaped, encapsulated structures, generally only 10 mm by 2.5 cm in size, distributed throughout the body along the lymphatic vessels

A

LYMPH NODES

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18
Q

A total of _____ lymph nodes are present in the axillae (armpits) and groin, along the major vessels of the neck, and in the thorax and abdomen, and especially in the visceral mesenteries.

A

400-450

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19
Q

constitute a series of in-line filters of lymph that defend against the spread of microorganisms and tumor cells and provide enclosed environments for antigen presentation and the development of plasma cells secreting non-IgA antibodies.

A

Lymph nodes

20
Q

Before merging with the bloodstream, all lymph is filtered and has antibodies added by at least _____.

A

one lymph node

21
Q

three major regions within each lymph node:

A
  1. OUTER CORTEX
  2. PARACORTEX
  3. MEDULLA
22
Q

three major regions within each lymph node:

containing the nodules

A

OUTER CORTEX

23
Q

three major regions within each lymph node:

a deeper extension of cortex

A

PARACORTEX

24
Q

three major regions within each lymph node:

lacks nodules

A

PARACORTEX

25
Q

three major regions within each lymph node:

with prominent draining sinusoids adjacent to the hilum

A

MEDULLA

26
Q

The CORTEX includes the following components:

A

Subcapsular sinus
Lymphoid nodules

27
Q

immediately inside the capsule, receives lymph from the afferent lymphatics. From this space cortical sinuses (or trabecular sinuses) branch internally among the lymphoid nodules along trabeculae

A

Subcapsular sinus

28
Q

These sinuses are lined by a very thin, discontinuous endothelium penetrated by reticulin fibers and processes of dendritic cells.

A

Subcapsular sinus

29
Q

Lymph containing antigens, lymphocytes, and APCs passes through these sinuses and percolates easily into the surrounding lymphoid tissue

A

Subcapsular sinus

30
Q

with or without germinal centers, consist largely of developing B lymphocytes and occupy much of the cortex not filled with helper T lymphocytes

A

Lymphoid nodules

31
Q

Each nodule is organized around the long, interdigitating processes of FDCs, but these are not readily seen by routine light microscopy

A

Lymphoid nodules

32
Q

Numerous macrophages are also present for removal of newly formed defective B cells that undergo apoptosis.

A

Lymphoid nodules,

33
Q

does not have precise boundaries but can be distinguished from the outer cortex by its lack of nodules

A

paracortex

34
Q

Unlike the superficial cortex, the ____ contains lymphoid tissue rich in T cells distinguishable by immunohistochemistry

A

paracortex

35
Q

The medulla of a lymph node has two major components:

A

Medullary cords
Medullary sinuses

36
Q

are branched cordlike masses of lymphoid tissue extending from the paracortex. They contain T and B lymphocytes and many plasma cells.

A

Medullary cords

37
Q

are dilated spaces lined by discontinuous endothelium that separate the medullary cords

A

Medullary sinuses

38
Q

The lumens of these sinuses include a meshwork of processes from reticular cells, which represent a final lymph filter.

A

Medullary sinuses

39
Q

These sinuses contain many macrophages and sometimes neutrophils if the lymph node is draining an infected region.

A

Medullary sinuses

40
Q

They are continuous with the cortical sinuses and converge at the hilum as the efferent lymphatic vessel .

A

Medullary sinuses

41
Q

contains the largest single accumulation of lymphoid tissue in the body and is the only lymphoid organ involved in filtration of blood, making it an important organ in defense against blood-borne antigens

A

SPLEEN

42
Q

It is also the main site of old erythrocyte destruction

A

SPLEEN

43
Q

As is true of other secondary lymphoid organs, the _____is a production site of antibodies and activated lymphocytes, which here are delivered directly into the blood.

A

spleen

44
Q

Located high in the left upper quadrant of the abdomen and typically about 12 × 7 × 3 cm in size

A

Spleen

45
Q

Its volume varies with its content of blood and tends to decrease very slowly after puberty.

A

Spleen

46
Q

The spleen is surrounded by a capsule of dense connective tissue from which emerge trabeculae to penetrate the parenchyma or ___

A

splenic pulp

47
Q

_____ originate at the hilum, on the medial surface of the spleen, and carry branches of the splenic artery, vein, lymphatics, and nerves into the splenic pulp

A

Large trabeculae

Histology (37 decks)

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