Ch 14: Immune System / Lymphoid Tissues & Q Bank

Question 1

BASIC IMMUNITY

2 types:

Answer 1

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.

Question 2

BASIC IMMUNOLOGY

Immune cells communicate with one another by….

Answer 2

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

Question 3

BASIC IMMUNOLOGY

What are Antigens?

Answer 3

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

Question 4

BASIC IMMUNOLOGY

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

Answer 4

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

Question 5

BASIC IMMUNOLOGY

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

Answer 5

on major histocompatibility complex (MHC) class I molecules.

Question 6

BASIC IMMUNOLOGY

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

Answer 6

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

Question 7

LYMPHOCYTE ORIGINS AND DIFFERENTIATION

There are 2 kinds:

Where do they originate from?

Answer 7

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

Question 8

Lymphocyte Origins and Differentiation

While B cells produce antibodies for humoral immunity

Answer 8

T cells function in cell-mediated immunity.

Question 9

Lymphocyte Origins and Differentiation

How do T Cells work?

Answer 9

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.

Question 10

Lymphocyte Origins and Differentiation

There 4 class’s of T cells

List them:

Answer 10

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.

Question 11

Lymphocyte Origins and Differentiation

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

Answer 11

bind specific antigens whenever they contact them.

Question 12

Lymphocyte Origins and Differentiation

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

Answer 12

1. the lymph nodes,
2. all mucosa-associated lymphoid tissue (MALT),
3. and the spleen.

Question 13

Lymphocyte Origins and Differentiation

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

Answer 13

fibroblastic reticular cells,

and most APCs are dendritic cells with many processes.

Question 14

Lymphocyte Origins and Differentiation

In secondary lymphoid tissues, BCRs bind antigen not

Answer 14

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

Question 15

Lymphocyte Origins and Differentiation

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

Answer 15

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

Question 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…

Answer 16

respond and proliferate quickly if their specific antigen reappears.

Question 17

Thymus

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

Answer 17

cytoreticulum composed of interconnected thymic epithelial cells (TECs).

Question 18

Thymus

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

Answer 18

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

Question 19

Thymus:

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

Answer 19

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

Question 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,

Answer 20

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

Question 21

Thymus

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

Answer 21

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

Question 22

Thymus

Peripheral immune tolerance occurs throughout the body when….

Answer 22

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

Question 23

Thymus:

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

Answer 23

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

Question 24

Mucosa-Associated Lymphoid Tissue (MALT)

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

Answer 24

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

Question 25

Mucosa-Associated Lymphoid Tissue (MALT) Unlike MALT, **lymph nodes** are completely **encapsulated** and occur

Answer 25

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

Question 26

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

Answer 26

differentiation to antibody-secreting **plasma cells.**

Question 27

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

Answer 27

an **outer cortex**, a underlying **paracortex,** and an **inner medulla** adjacent to the hilum and efferent lymphatic.

Question 28

Lymph Nodes Lymphatics enter at the **cortex** of a node, where B cells encounter antigens, and then

Answer 28

proliferate into **lymphoid nodules**, and then move into the deeper regions of the lymph node.

Question 29

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

Answer 29

most lymphocytes in this region are **T helper cells.**

Question 30

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

Answer 30

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

Question 31

Spleen The spleen is a large lymphoid organ without a cortex/medulla structure; instead, it has

Answer 31

two intermingled but functionally different regions: **white pulp** and **red pulp.**

Question 32

Spleen **White pulp**, only 20% of the spleen, is **secondary lymphoid tissue** associated with

Answer 32

_small central arterioles_ that are also enclosed by **periarteriolar lymphoid sheaths** (PALS) of T cells.

Question 33

Spleen **Red pulp**, which filters blood, removes defective erythrocytes, and recycles hemoglobin iron, consists of

Answer 33

**splenic cords** with macrophages and blood cells of all kinds and **splenic sinusoids.**

Question 34

Spleen Red Pulp has **Splenic cords** and **Splenic Sinusoids**: which are lined by unusual endothelial cells called

Answer 34

**stave cells** that are elongated and aligned parallel to the blood flow, with open slits between the cells.

Question 35

Spleen Blood flow in red pulp is either a **closed circulation**, moving from capillaries into the venous sinusoids, or

Answer 35

an **open circulation**, with capillaries opening directly into the splenic cords.

Question 36

Spleen **Blood filtration** in the open circulation involves interaction with splenic cord **macrophages** that remove....

Answer 36

old, swollen RBCs unable to slip between stave cells to reenter the venous blood flow.

Question 37

Q Bank 1 - 3 1. Which function is carried out by all lymphoid tissues and organs? d. Production of lymphocytes 2. Which structure is partly encapsulated and covered by nonkeratinized stratified squamous epithelium? c. Palatine tonsil 3. Which cell type gives rise to both memory and effector cells and is primarily associated with humoral immunity? a. B lymphocyte**​**

Answer 37

Q Bank 4 -6 4. Recycling of iron and heme, the major complex containing iron, occurs most actively in which lymphoid organ(s)/tissue(s)? d. Spleen 5. Which description is true of all secondary (peripheral) lymphoid organs?  e. Contain lymphoid nodules 6. Which structure would be most heavily labeled by an immunohistochemical method targeting the CD8 surface antigen? b. Paracortex

Question 38

Q bank 7 7. A baby is born with a cleft palate and a condition called DiGeorge syndrome, which involves failure of third and fourth pharyngeal pouch derivatives to develop properly. The palate defect is corrected surgically, but regarding the pharyngeal pouch defect the parents are advised that the growing child may expect which of the following health problems? e. Conditions related to autoimmunity

Answer 38

Qbank 8 8. Many immune-related cellular activities are often impaired in aged patients. Which lymphoid organ(s) normally develop less functionality and increasing amounts of adipose tissue with age?  c. Thymus

Question 39

Q bank 9 9. A 12-year-old African-American girl presents with anemia and a large percentage of her peripheral erythrocytes appear sickle-shaped. Genetic testing reveals homozygosity for sickle cell disease. In which of the following sites will the abnormal RBCs be removed from the circulation?  e. Splenic cords (of Billroth)

Answer 39

Q bank 10 10. A 6-year-old boy is brought to the clinic where his mother reports that was bitten by a neighbor’s dog two days earlier. The child’s right hand is lacerated between the thumb and index finger and this area is inflamed but healing. The doctor’s examination reveals small but painless swellings beneath the skin inside the right elbow and arm pit and he explains to the mother that these are active lymph nodes enlarged in response to the infection in the hand. What has produced the swelling? b. Formation of germinal centers for B-cell proliferation in each node’s cortex