Lecture 21: Immunology

Question 1

what is immunology

Answer 1

Branch of biomedical science that deals with the study of the immune system

Question 2

what does immunology include

Answer 2

-Cell-mediated immunity
-Humoral immunity
-Immune responses

Question 3

what is immunity and its two intrinsic systems

Answer 3

-Ability to resist a particular disease and infection
-Immune system consist of two intrinsic systems: innate & adaptive

Question 4

what is innate immunity

Answer 4

innate (nonspecific resistance) defense system (immunity)
-Constitutes first and second lines of defense
-First line of defense: external body membranes (skin and mucosae)
-Second line of defense: antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders; inflammation most important mechanism)

Question 5

what is adaptive immunity

Answer 5

adaptive (specific immunity) defense system (immunity)
-Third line of defense: attacks particular foreign substances (takes longer to react than innate)
-Involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance
-Adjusts to fight against specific microbes

Question 6

describe the immune system

Answer 6

-Immune system is a functional system rather than organ system
-Innate and adaptive defenses are intertwined:
*Both release and recognize many of the same defensive molecules
*Innate responses release proteins that alert cells of adaptive system to foreign molecules
*Innate defenses do have specific pathways for certain substances

Question 7

innate immunity and the immune system

Answer 7

-a variety of responses that protect the body against invasion by a wide variety of pathogens and thier toxins
-two lines of denfense: 1. skin and mucous membranes. 2. internal defenses (phagocytes, natural killer cells, inflammation, antimicrobial protains, fever)

Question 8

how does intact skin epidermis impact immunity

Answer 8

forms mechanical barrier that prevents entry of pathogens and toher harmful substances into body
(has acid mantle on skin & keratin)

Question 9

how does acid mantle of skin impact immunity

Answer 9

skin secretions (sweat & sebum) make epidermal surface acidic, which inhibits bacterial growth; also contain various bactericidal chemicals

Question 10

how does keratin impact immunity

Answer 10

provides resistance against acids, alkalis, and bacterial enzymes

Question 11

how does intact mucous membranes impact immunity

Answer 11

form mechanical barrier that prevents entry of pathogens
(has mucus, nasal hairs, cilia, gastric juice, acid mantle of vagina, lacrimal secretion (tears), saliva, urine)

Question 12

how does mucus impact immunity

Answer 12

traps microorganisms in respiratory and digestive tracts

Question 13

how do nasal hairs impact immunity

Answer 13

filter and trap microorganisms in nasal passages

Question 14

how does cilia impact immunity

Answer 14

propel debris-laden mucus away from nasal cavity and lower respiratory passages

Question 15

how does gastric juice impact immunity

Answer 15

contains concentrated hydochloric acid and protein-digesting enzymes that destroy pathogens in stomach

Question 16

how does acid mantle of vagina impact immunity

Answer 16

inhibits growth of most bacteria and fungi

Question 17

how does lacrimal secretion (sweat) and saliva impact immunity

Answer 17

continuously lubricate and cleanse eyes (tears) and oral cavity (saliva); contain lysozyme and enzyme that destroys microorganisms

Question 18

how does urine impact immunity

Answer 18

normally acid pH inhibits bacterial growth; cleanses the lower urinary tract as it flushes from the body

Question 19

how does sebum impact immunity (chemical factor)

Answer 19

forms protective acidic film over skin surface that inhibits growth of many microorganisms

Question 20

how does lysozyme impact immunity (chemical factor)

Answer 20

antimicrobial substance in perspiration, tears, saliva, nasal secretions, and tissue fluids

Question 21

how do interferons (IFNs) impact immunity (2nd line of defense) (antimicrobial substance)

Answer 21

-Small proteins (cytokines) released by activated lymphocytes and macrophages
-Diffuse to adjacent healthy cells, and trigger production of antiviral proteins
-Do not kill viruses, block viral replication
protect uninfected host cells from viral infection

Question 22

how do the complement system impact immunity (2nd line of defense) (antimicrobial substance)

Answer 22

causes cytolysis of microbes; promotes phagocytosis; contributes to inflammation

Question 23

how do inron-binding proteins impact immunity (2nd line of defense) (antimicrobial substance)

Answer 23

inhibit growth of certain bacteria by reducing amount of available iron

Question 24

how do antimicrobial proteins (AMPs) impact immunity (2nd line of defense) (antimicrobial substance)

Answer 24

have broad-spectrum antimicrobial activities and attract dendritic cells nad mast cells

Question 25

how do natural killer cells impact immunity (2nd line of defense) (antimicrobial substance)

Answer 25

kill infected target cells by releasing granules that contain perforin and granzymes; phagocytes then kill released microbes

Question 26

how do phagocytes impact immunity (2nd line of defense) (antimicrobial substance)

Answer 26

ingest foreign particulate matter

Question 27

how does inflammation impact immunity (2nd line of defense) (antimicrobial substance)

Answer 27

confines and destroys microbes; initiates tissue repair

Question 28

how does fever impact immunity (2nd line of defense) (antimicrobial substance)

Answer 28

intensifies effects of interferons, inhibits growth of some microbes, speeds up body reactions that aid repair

Question 29

what are antimicrobial aubstances

Answer 29

Enhance innate defense by:
* Attacking microorganisms directly, or
* Hindering microorganisms’ ability to reproduce
-Include:
* Interferons
* Complement system
* Iron-binding proteins
* Antimicrobial proteins (AMPs)

Question 30

what are the types of interferons and the antiviral mechanism of them

Answer 30

they can be alpha, beta, and gamma
1. virus inters cell and replicates
2. interferon genes swiths on
3. cell produces interferon molecules
4. interferon binging stimulates cell to turn on genes for antiviral proteins
5. antiviral proteins block viral reproduction

Question 31

describe the complement system

Answer 31

Group of proteins in plasma, work in cascade, circulate in blood in inactive form
-Includes proteins C1–C9, factors B, D, and P, and regulatory proteins
-Provides major mechanism for destroying foreign substances
-Activation enhances inflammation, and also directly destroys bacteria
-Enhances both innate and adaptive defenses
-Activated by three different pathways:
-Classical pathway; Lectin pathway; Alternative pathway
-All three pathways involve conversion of inactive C3 into C3b and C3a
for microbial destruction

Question 32

review slide 14 complement activation

Question 33

describe antimicrobial proteins

Answer 33

-Broad spectrum agents; bactericidal
-Can attract APCs (dendritic and mast cells) for immune response
-Ex. thrombocidin, defensins, dermcidin, etc.

Question 34

describe inro-binding proteins

Answer 34

Suppresses bacterial activities by reducing iron moiety
* Ex. Ferritin, transferrin, lactoferrin etc.

Question 35

describe natural killer (NK) cells

Answer 35

-Nonphagocytic, large granular lymphocytes that “police” blood and lymph
-Perforin-containing granules: bore hole on target cells
-Kill cancer- and virus-infected cells by releasing granzymes → induce apoptosis
-Attack cells that lack “self” cell-surface receptors
-Secrete potent chemicals that enhance inflammatory response

Question 36

describe phagocytosis and the two types

Answer 36

-Phagocytes: WBCs that ingest and digest (eat) foreign invaders
Main Phagocytes – neutrophils and macrophages
-Two Types of Macrophages:
* Fixed macrophages – histiocytes, microglia,
Kupffer cells, etc.
* Free (Wandering) macrophages – actively
travel throughout the body

Question 37

what are the events of phagocytosis

Answer 37

1. phagocyte adheres to pathogens or debris (using receptors)
2. phagocyte forms pseudopods that eventually engulf the particles forming a phagosome
3. lysosome fuses with the phagocytic vesicle forming a phagolysosome
4. toxic compounds and lysosomal enzymes destroy pathogens
5. sometimes exocytosis of the vesicle removes indigestible and residual material

Question 38

describe inflammation

Answer 38

-Triggered whenever body tissues are injured due to trauma, heat, irritating chemicals, or infections by microorganisms
MAST CELL
1. increases blood flow
2. activates macrophages
3. increases capillary permeability
4. activates complement
5. stimulates regional clotting reaction
6. increases regional temperature
7. activates adaptive defense

Question 39

what are the signs and symptoms of inflammation

Answer 39

redness, swelling, heat, pain, immobility

Question 40

what are the mechanisms of inflammation

Answer 40

1.leukocytosis: neutrophils enter blood from bone marrow
2. margination: neutrophils cling to capillary wall
3. diapedesis: neutrophils flatten and squeeze out of capillaries
4. chemotaxis: neutrophils follow chemical traiil

Question 41

what are the products of inflammation

Answer 41

-Necrosis – local tissue destruction in area of injury
-Pus – mixture of debris, fluid, dead and dying cells, and necrotic tissue
-Abscess – accumulation of pus in an enclosed space

Question 42

describe adaptive (specific) immunity

Answer 42

-Ability to defend against specific invading agents
-Activities of T cells and B cells; Exposure to antigen
-Antigens – substances recognized as foreign that provoke immune responses

Question 43

what are the properties of adaptive immunity

Answer 43

-Specificity – each T or B cell responds only to a specific antigen and ignores all others
-Memory – inactive lymphocytes (memory cells) stay in circulation. Provide immunity against new exposure
-Tolerance – immune system ignores “normal” antigens (self-antigens)

Question 44

describe exogenous antigen processing (specific immunity)

Answer 44

1. phagocytosis or endocytosis of antigen
2. digestions of antigen into peptide fragments
3. synthesis of MCH-II molecules
4. packaging of MHC-II molecules into a vesicle
5. vesicles containing anitgen peptide fragments and MHC-II molecules fuse
6. antigen peptide fragments bind to MHC-II molecules
7. vesciels undergo exocytosis and antigen-MHC-II cpmplexes are inserted into plasma membrane

Question 45

describe endogenous antigen processing (specific immunity)

Answer 45

1. digestion of antigen into peptide fragments
2. synthesis of MHC-I molecules
3. antigen peptide fragments bind to MHC-I molecules
4. packaging of antigen-MHC-I molecules into a vescile
5. vesicles undergoes exocytosis and antigen-MHC-I complexes are inserted into plasma membrane

Question 46

what are the types of adaptive immunity

Answer 46

cell-mediated immunity and anti-body immunity

Question 47

review slide 23

Question 48

descibe cell-mediated adaptive immunity

Answer 48

By T-cells, against intracellular antigens
* Bacteria, viruses, fungi inside cells; defective cells (tumor cells)
* Two Population of T cells – based on surface glycoproteins: CD4 cells & CD8 cells

Question 49

review slide 25 T cell education

Question 50

review sldie 26 clonal selection