Ch 14: Immune System / Lymphoid Tissues & Q Bank Flashcards Preview

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Flashcards in Ch 14: Immune System / Lymphoid Tissues & Q Bank Deck (39)
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1

BASIC IMMUNITY

2 types:

Innate immunity is present from birth and involves leukocytes (mainly granulocytes), and proteins such as defensins, complement, lysozyme, and interferons; adaptive immunity develops more slowly and is based on antigen presentation to lymphocytes.

2

BASIC IMMUNOLOGY

 

Immune cells communicate with one another by....

 and regulate one another’s activities via polypeptide hormones called cytokines.

3

BASIC IMMUNOLOGY

 

What are Antigens?

They are the regions of macromolecules, usually proteins, that are recognized by lymphocytes to elicit a specific immune response against them.

4

BASIC IMMUNOLOGY

 

Antibodies are immunoglobulins produced by plasma cells after a progenitor B cell is activated by....

a specific antigen and rearranges its immunoglobulin genes so the antibody matches the antigen.

5

BASIC IMMUNOLOGY

 

Surfaces of all nucleated cells bear fragments of their constituent proteins and placed on...

on major histocompatibility complex (MHC) class I molecules.

6

BASIC IMMUNOLOGY

 

Only antigen-presenting cells (APCs), mostly derived from monocytes, also present...

 fragments of endocytosed foreign (usually from microorganisms) proteins on surface MHC class II molecules.

7

LYMPHOCYTE ORIGINS AND DIFFERENTIATION

There are 2 kinds:

Where do they originate from?

Lymphocytes originate in the primary lymphoid organs: bone marrow for B lymphocytes and the thymus for T lymphocytes.

8

Lymphocyte Origins and Differentiation

 

While B cells produce antibodies for humoral immunity

 

T cells function in cell-mediated immunity.

9

Lymphocyte Origins and Differentiation

How do T Cells work?

 

T cells develop receptors (TCRs), usually containing α and β chains, that bind antigen along with another surface protein designated by a CD (“cluster of differentiation”) numbering system.

10

Lymphocyte Origins and Differentiation

 

There 4 class's of T cells

List them:

1. CD4+ T helper cells;

2. CD8+ cytotoxic T cells; 

3. CD4+CD25+ regulatory T cells;

4. and γδ T cells, which have those TCR chains and are mainly in epithelia.

11

Lymphocyte Origins and Differentiation

B-cell receptors (BCRs) are IgM or IgD antibodies on the cell surface that 

 

bind specific antigens whenever they contact them.

12

Lymphocyte Origins and Differentiation

 

B and T cells are often activated, proliferate, and begin to function in the secondary lymphoid organs:  Which are:

1. the lymph nodes,

2. all mucosa-associated lymphoid tissue (MALT),

3. and the spleen.

13

Lymphocyte Origins and Differentiation

 

In these organs, lymphocytes are distributed within a meshwork of reticulin produced by

 fibroblastic reticular cells,

and most APCs are dendritic cells with many processes.

14

Lymphocyte Origins and Differentiation

 

 

In secondary lymphoid tissues, BCRs bind antigen not 

presented in MHC class II molecules of another cell, which are the follicular dendritic cell (FDC).

15

Lymphocyte Origins and Differentiation

 

 

With cytokines from helper T cells, a FDC-activated B cell proliferates clonally to

produce temporarily a large lymphoid nodule (or follicle), which develops a pale germinal center.

16

Lymphocyte Origins and Differentiation

 

From lymphoid nodules cells produced, there dispersed as plasma cells, various T cells, and B and T memory cells that...

respond and proliferate quickly if their specific antigen reappears.

17

Thymus

 

T lymphoblasts, or thymocytes, attach in the thymus to a 

cytoreticulum composed of interconnected thymic epithelial cells (TECs).

18

Thymus

 

The thymic epithelial cells (TECs) also secrete many cytokines, and compartmentalize the thymus into a cortex and a medulla, and 

 in the cortex, surround blood vessels in the blood-thymus barrier.

19

Thymus:

Developing T cells with nonfunctional TCRs are detected and removed in the thymic cortex by

 a process of positive selection; cells with functional TCRs move into the thymic medulla.

20

Thymus

 

In the thymic medulla, T cells whose TCRs bind strongly to “self-proteins,” including proteins of many nonthymus cell types made by thymic epithelial cells expressing the Airegene

 are induced to undergo apoptosis there in a process of negative selection.

21

Thymus

This two-stage thymic selection leads to central immune tolerance, that 

produces functional T cells that do not bind to proteins of the host.

22

Thymus

Peripheral immune tolerance occurs throughout the body when....

 specific immune reactions are suppressed by regulatory T cells that also originate largely in the thymic medulla.

23

Thymus:

 

Regulatory T cells form in the thymus upon interacting with dendritic cells presenting self-antigens in a process promoted by cytokines from

thymic epithelial cell (TEC) aggregates called Hassall corpuscles, found only in the thymic medulla.

24

Mucosa-Associated Lymphoid Tissue (MALT)

 

MALT is found in the mucosa of most tracts but is concentrated  most in

 the palatine, lingual and pharyngeal tonsils, Peyer patches, and the appendix.

25

Mucosa-Associated Lymphoid Tissue (MALT)

 

Unlike MALT, lymph nodes are completely encapsulated and occur

 along the lymphatic vessels; each has several afferent lymphatics and one efferent lymphatic.

26

Lymph Nodes

 

Each lymph node filters lymph and provides a site for B-cell activation and

differentiation to antibody-secreting plasma cells.

27

Lymph Nodes

 

A lymph node has three functional but not physically separate compartments:

an outer cortex,

a underlying paracortex,

and an inner medulla adjacent to the hilum and efferent lymphatic.

28

Lymph Nodes

 

Lymphatics enter at the cortex of a node,

where B cells encounter antigens, and then

 proliferate into  lymphoid nodules, and then

move into the deeper regions of the lymph node.

29

Lymph Nodes

 

Most lymphocytes enter at the paracortex of the lymph node via high endothelial venules (HEVs) located there only;

 most lymphocytes in this region are T helper cells.

30

Lymph Nodes

 

The medulla has medullary cords containing reticular fibers with many plasma cells, macrophages, and other leukocytes; between the cords are

 lymph-filled medullary sinuses that converge at the efferent lymphatic.