Lymphoid

Question 1

Body defense mechanisms

Answer 1

Physical/biochemical barriers, innate immunity, and adaptive immunity

Question 2

Physical barriers

Answer 2

First line of defense. Skin, ciliary action, fluid movement, normal flora.

Question 3

Biochemical barriers

Answer 3

First line of defense. Tears, saliva, mucus, stomach acidity, spermine.

Question 4

Innate immunity

Answer 4

Non-specific immunity that prevents infection or penetration of the body. It lacks immunologic memory and the responses remain unchanged despite encountering a pathogen. Cells involved are mastocytes, granulocytes and agranulocytes.

Question 5

Natural killer cells

Answer 5

Lymphocyte that contribute to the innate immunity by destroying unhealthy host cells. They lack CD3. CD4. and CD8 surface markers, don’t require antigen processing or MHC recognition, don’t have immunologic memory, and they can kill target cells coated with IgG.

*Surgery or other trauma like experiences reduces there NK cell count.

Question 6

Acquired immunity

Answer 6

Specific immunity that protects the internal environment of the body by producing specific responses to antigens. 3 characteristics are specificity, diversity, and memory.

Question 7

Antigen

Answer 7

Substances typically foreign to the host (Ex/microorganisms)

Question 8

Antigen recognition

Answer 8

Component of adaptive immunity where a lymphocyte must recognize and distinguish non-self vs. self.

Question 9

Immune response

Answer 9

Component of adaptive immunity. It is the inactivation/elimination of foreign antigens such as, microorganisms, foreign material, cancer cells, and organ transplants.

Question 10

Antigen encounter

Answer 10

Antigen recognition is enhanced by the circulation and recirculation of lymphocytes through the tissues.

Question 11

Antigen presenting cells (APC)

Answer 11

Cells found in most tissues that process antigens and present them at their cell surface for T lymphocyte recognition. These include macrophages, dendritic cells, B lymphocytes and Langerhans cells. Associated with MHC-II

Question 12

B cell lymphocytes

Answer 12

Humoral immunity cells. They are antibody forming cells of the lymphoid system and provide indirect antigen recognition. They differentiate into plasma cells which secrete antibodies. They undergo differentiation in the fetal liver and bone marrow.

Question 13

T cell lymphocytes

Answer 13

They are the primary effector cells of cell mediated immunity and immunoregulation. They provide recognition though T cell receptors (TCR) and the MHC-I molecules on the surface. They originate in the thymus.

Question 14

Anamnestic response

Answer 14

Memory cell defense for future exposures to same antigen. A secondary anamnestic response occurs after the primary response, where the expanded population of memory cells allows for a greater specific response upon re‑exposure to the antigen.

Question 15

Memory cells

Answer 15

They provide an expanded population of cells which retain ability to divide and respond if exposed to the same antigen. Differentiated from B cells.

Question 16

Antibody (Immunoglobulins)

Answer 16

Proteins which interact specifically with an antigen. Antibody can be found in serum, tissue fluids, and secretions. They contain 2 pairs of identical light chains and heavy chains connected by disulfide bonds, each one a polypeptide with a variable region and a constant region.

Question 17

IgG

Answer 17

Activates phagocytosis and neutralizes antigens. Only Ig that can cross the placenta. Located in the blood and lymph intestinal fluid. Most abundant class of Ig.

Question 18

IgM

Answer 18

They are the 1st antibodies produced in an initial immune response. Located on the surface of B lymphocytes. It has a pentamer structure which is confined intravascular spaces.

Question 19

IgD

Answer 19

Acts as receptor to antigens that trigger B cell activation

Question 20

IgE

Answer 20

Participates in allergy response and lyses parasitic worms. Located on the cell membrane surface of mast cells and basophils

Question 21

IgA

Answer 21

Main Ig found in secretions & mucosal fluids (GI and respiratory tract) because they protect the surface from these fluids by resisting proteolysis.

Question 22

Opsonization

Answer 22

Binding of antibodies to a microorganism facilitates phagocytosis

Question 23

Agglutination

Answer 23

Antibodies bind to antigens forming aggregates and reducing the number of free antigens

Question 24

Neutralization

Answer 24

Binding of an antibody to a microorganism blocks their adhesion to cells and inactivates toxins

Question 25

Cytotoxicity

Answer 25

Antibodies adhere to the surface of worms (pathogens) and stimulate the release of cells from the immune system (eosinophils and macrophages). This induces them to release chemical agents to destroy the pathogen.

Question 26

Complement activation

Answer 26

Antibody binding to the initial protein of the complement system triggers the complement cascade which produces the membrane attack complex. This complex forms transmembrane channels and cause cell lysis on a pathogen.

Question 27

Cytokines (Lymphokines)

Answer 27

Polypeptide mediators which are involved with the production and regulation of the immune response. They amplify the response to an antigen non-specifically. Major types include: Interleukins, chemokines, interferons, and colony stimulating factors

Question 28

3 types of T cells

Answer 28

Cytotoxic (CTL), helper, and memory T cells

Question 29

T cell receptors (TCR)

Answer 29

Surface receptors uniquely specific for antigen. They ONLY recognize processed antigens if it is incorporated with MHC molecules.

Question 30

Major histocompatibility complex (MHC) molecules

Answer 30

Special integral membrane molecules that recognize self from non-self cells. Strictly associated with TCR.

Question 31

MHC-I

Answer 31

Present on all cells and interacts with CD8+ T cells. Does not pass through endosome/lysosome vesicles (Ex/ viruses).

Question 32

MHC-II

Answer 32

Present on antigen presenting cells and interact with CD4+ T cells. They pass through endosome/lysosome vesicles (Ex/ phagocytosis)

Question 33

Helper T cells (CD4+)

Answer 33

General inducers of effector cells for cell mediated and humoral immunity. They help to produce memory B cells and plasma cells. They are associated with MHC-II molecules and secrete cytokines.

Question 34

Cytotoxic T cells (CD8+)

Answer 34

Kill target cells by releasing perforins, inducing apoptosis (fas induction), and releasing granzymes. They are associated with MHC-I molecules.

Question 35

Perforins

Answer 35

Protein that targets a cell’s membrane.

Question 36

Granzymes

Answer 36

Serine proteases that kill intracellular microbes directly through apoptosis