Immunology Physio

Question 1

Describe the 2 intrinsic immune systems

Answer 1

• innate (nonspecific - born with it)
• adaptive (specific - after exposure)

Question 2

What are the two lines of defense of the innate immune system

Answer 2

• 1st: external membranes (contain: keratin, enzymes, toxins, acidity, lipids, lysozyme, mucus)
• 2nd: antimicrobial proteins, phagocytes, etc. that inhibit spread and drive inflammation

Question 3

Describe the line of defense of the adaptive immune system

Answer 3

• takes longer than innate
• attacks particular foreign substances
• Humoral immunity: B cells
• Cellular immunity: T cells

Question 4

Describe macrophages in the immune system

Answer 4

• chief phagocytic cells
• free macrophages wander through tissues
• fixed macrophages in some organs (Langerhan’s of skin, Kuppfer of liver, Microglia of brain)

Question 5

When do neutrophils become phagocytic

Answer 5

When meeting infectious material in tissues

Question 6

What are lysosomes responsible for in phagocytosis

Answer 6

enzymes that digest particles engulfed in a phagocyte

Question 7

Describe natural killer cells

Answer 7

• large granular lymphocytes
• in spleen, LNs, bone marrow, blood
• lyse virus infected cells & Ab coated cells
• enhance inflammatory response

Question 8

List the 5 cardinal signs of acute inflammation

Answer 8

• redness (rubor)
• heat (calor)
• swelling (tumor)
• pain (dolor)
• impaired function (functio laesa)

Question 9

List some inflammatory mediators/cytokines

Answer 9

• histamine from mast cells
• blood proteins
• kinins, prostaglandins, leukotrienes, complements

Question 10

Describe interferons

Answer 10

complement proteins
- secreted by virus infected cells which enter neighboring cells and produce antiviral proteins to block reproduction
- produced in lymphocytes, WBCs, fibroblasts
- reduce inflammation, activate macrophages & NK cells

Question 11

Describe complement proteins

Answer 11

• cascade of 20+ serum proteins/glycoproteins that circulate in inactive forms
• destroy foreign substances & amplify inflammation
• cell lysis (opsonization)

Question 12

What are the two complement activation pathways

Answer 12

• classical: activated by Ag-Ab complexes
• alternative: activated by components of pathogen surfaces

Question 13

What is the cellular mechanism of fever

Answer 13

leukocytes & macrophages exposed to foreign substances secrete pyrogens which increase body’s temp

Question 14

What are the benefits of moderate fever

Answer 14

• causes liver & spleen to sequester iron & zinc
• increases metabolic rate & repair rate

(high fevers can denature important enzymes)

Question 15

What are the functions of the adaptive/acquired immune system

Answer 15

• protect against infectious agents/abnormal cells
• amplifies inflammatory response
• activates complement systems

Question 16

Define antigens

Answer 16

substances that mobilize the adaptive defenses and provoke an immune response

Question 17

Define immunogens

Answer 17

substance that always gives an immune response (foreign protein, polysacc., lipids, nucleic acids)

Question 18

Define haptens

Answer 18

incomplete/baby antigens that are only immunogenic when attached to body proteins (poison ivy, animal dander, detergents, cosmetics, drugs)

Question 19

Define Epitope/Antigenic determinants

Answer 19

certain parts of an entire antigen that are immunogenic
- Abs & lymphocyte receptors bind to them

Question 20

What are MHC proteins (major histocompatibility complex)

Answer 20

• self antigen
• Class I: found in all body cells (nucleated cells & platelets)
• Class II: found on certain immune cells (dendritic cells, macrophages)

Question 21

Where are B cells and T cells matured

Answer 21

B: red bone marrow
T: thymus
(Naive/Unexposed B & T cells exported to LNs, spleen, lymphoid organs)

Question 22

Describe the 2 cells that T cells differentiate into

Answer 22

• CD4: helper T, aid in humoral & cell-mediated immunity
• CD8: cytotoxic T, cell mediated response against viral/tumor cells

Question 23

Describe Ag Presenting cells (APCs)

Answer 23

Engulf Ags & present fragments to be recognized by T cells
- dendritic cells in connective tissue & epidermis
- macrophages in connective tissue & lymphoid organs
- B cells

Question 24

Define antigen challenge

Answer 24

first encounter between an antigen and a naive immunocompetent lymphocyte (usually in spleen or LN)

(If B cell, will trigger Abs & immune response)

Question 25

Define clonal selection

Answer 25

Stimulated B cell grows to form a clone of identical cells bearing the same Ag specific receptors (usually requires T cell help)

Question 26

Define naturally acquired active humoral immunity

Answer 26

infection or contact with a pathogen

Question 27

Define artificially acquired active humoral immunity

Answer 27

vaccination or dead/attenuated pathogens

Question 28

Define naturally acquired passive humoral immunity

Answer 28

Abs passed from mom to fetus via placenta or breast milk

Question 29

Define artificially acquired passive humoral immunity

Answer 29

injection of immune serum (gamma globulin/antibodies)

Question 30

Describe IgM

Answer 30

IgM: pentamer, **first Ab released**, acute

Question 31

Describe IgA

Answer 31

IgA: monomer/dimer in mucus/secretions

Question 32

Describe IgD

Answer 32

IgD: monomer attached to B cell surfaces

Question 33

Describe IgG

Answer 33

IgG: monomer, 80% of Abs in plasma, from chronic/late infection, **can cross placenta**

Question 34

Describe IgE

Answer 34

IgE: monomer, allergies & parasitic infections

Question 35

CD4 cells become ____ when activated and CD8 cells become _____ when activated

Answer 35

CD4 = helper T CD8 = cytotoxic

Question 36

Describe severe combined immunodeficiency syndrome (SCID)

Answer 36

- genetic defect with deficiency of B and T cells - abnormalities in interleukin receptors - fatal, treat with bone marrow transplant

Question 37

Describe Hodgekin's disease

Answer 37

- acquired immunodeficiency from cancer of B cells - depresses lymph node cells & immunity

Question 38

Describe AIDS

Answer 38

- crippling of immune system by interfering with helper T activity (CD4) - susceptible to opportunistic infection

Question 39

Describe autoimmune diseases

Answer 39

- immune system loses ability to distinguish self from foreign - autoantibodies & cytotoxic T cells attack body tissue

Question 40

Describe Type 1/Acute hypersensitivity (allergy)

Answer 40

- immediate immune response after contact with allergen - asymptomatic initially but becomes sensitized (local or systemic) - involves **IL-4** secreted by T cells which stimulates B cells to secrete **IgE**

Question 41

Describe anaphylactic shock (Type 1 hypersensitivity)

Answer 41

systemic response to allergen directly entering blood - systemic histamine release causing: constriction of bronchioles, sudden vasodilation, HoTN - treat with epi

Question 42

Describe Type 2/cytotoxic hypersensitivity

Answer 42

- subacute - **Ab mediated hypersensitivity against our own cells/receptors/membranes - mediated by IgG or IgM - slow onset with long duration **(ex. transfusion reaction, autoimmune hemolytic anemia (Graves, MG, Goodpasture))**

Question 43

Describe Type 3 hypersensitivity

Answer 43

- subacute - complexes deposted in various tissues - high levels of circulating IgG or IgM - intense inflammation, local cell lysis **(SLE, RA, PSGN)**

Question 44

Describe Type 4 delayed hypersensitivity

Answer 44

- onset extremely slow (days) - involves helper T cells, activated macrophages, cytotoxic T cells **(allergic contact dermatitis, poison ivy, Mantoux test)**