IM 1+2

Question 1

what is the immune system?

Answer 1

a collection of things in the body that provide immunity

Question 2

what is immunity?

Answer 2

the ability to resist or eliminate

Question 3

what is susceptibility?

Answer 3

lack of resistance

Question 4

what are pathogens?

Answer 4

viruses, and microbes such as parasites, fungi, and bacteria

Question 5

what are the actions of the immune system?

Answer 5

defending against invading pathogens, removing worn out and damaged cells, facilitating wound healing and tissue repair, immune surveillance

undesired functions: allergies, rejection of transplants and grafts

Question 6

what is the first line of defense?

Answer 6

external factors that act as BARRIERS, NOT a response

Question 7

what are the physical barriers?

Answer 7

skin, hairs, mucus, reflexes

Question 8

what are the chemical barriers?

Answer 8

sebum, lysozymes, stomach acid

Question 9

where are lysozymes found?

Answer 9

sweat, tears, nasal secretions, tissue fluids

Question 10

what are the two types of immune responses?

Answer 10

innate and adaptive

Question 11

what is the encounter stage?

Answer 11

when the pathogen comes into contact with an immune cell

Question 12

where can the encounter stage take place?

Answer 12

in a resident cell population in the spleen, lymph nodes, and lymphatic tissue, or in blood/lymphatic circulation

Question 13

what is the recognition stage?

Answer 13

the pathogen and the immune cell bind together

Question 14

how does the recognition stage work (innate)?

Answer 14

toll proteins on the surface of the immune cell bind to carbohydrates and lipids on the surface of the pathogen and recognize the specific arrangements

Question 15

how do lysozymes function?

Answer 15

they break the cell wall of bacteria

Question 16

what is the function of inflammation?

Answer 16

destroy/inactivate foreign invaders, and set the stage for tissue repair/healing

Question 17

what are the usual signs of inflammation?

Answer 17

redness, swelling, heat, pain

Question 18

what are the common causes of inflammation?

Answer 18

pathogens, chemical irritants, abrasions, extreme temperatures, cell distortion/disturbance

Question 19

what happens in the first stage of inflammation?

Answer 19

a) chemical mediators are released to perform two functions
i) vasodilate microcirculation vessels to increase delivery of plasma proteins, leukocytes, O2 and nutrients
ii) endothelial cells of the blood vessels contract to increase permeability
iii) release of stored immune cells from spleen/lymph nodes
iv) proliferation of immune cells in bone marrow

Question 20

what happens in the second stage of inflammation?

Answer 20

a) margination: phagocytes and endothelial cells bind to form adhesion molecules
b) diapedesis: phagocyte migration through blood vessel walls
c) chemotaxis: phagocyte migration to site of tissue damage, guided by cytokines (chemoattraction), fluid follows cell migration causing edema

Question 21

what happens in the third stage of inflammation?

Answer 21

• worn out/dead/damaged cells are replaced
• new blood vessels may form (angiogenesis)
• tissue repair may leave scars
• remodelling may continue after initial repair

Question 22

how does scar tissue differ from undamaged tissue?

Answer 22

denser collagen leads to decreased elasticity and blood flow to the tissue, less functional

Question 23

how can we distinguish adaptive from innate responses?

Answer 23

adaptive cells (lymphocytes) recognize the specific threat, and can store memory of previously encountered markers

Question 24

what are antigens?

Answer 24

any molecule that can bind to an antibody or lymphocyte receptor and trigger an immune response

Question 25

what are antigens?

Answer 25

any molecule that can bind to an antibody or lymphocyte and triggers a specific immune response against itself

Question 26

what do adaptive immune cells detect and bind to on pathogen cell surfaces?

Answer 26

proteins

Question 27

what are the two types of lymphocytes (in this course)

Answer 27

B-cells and T-cells

Question 28

where do B-cells originate?

Answer 28

B-cells arise and mature in the bone marrow

Question 29

where do T-cells originate?

Answer 29

T-cells arise in the bone marrow, and migrate to the thymus to mature

Question 30

what do T-cells mature to?

Answer 30

helper, regulatory, and cytotoxic cells

Question 31

what are the primary lymphoid organs?

Answer 31

the bone marrow and the thymus

Question 32

what are the secondary lymphoid organs?

Answer 32

lymph nodes, spleen, tonsils, lymphocyte accumulations in the intestinal, respiratory, urinary, and genital tracts

Question 33

after maturation, what do B and T cells do?

Answer 33

they migrate to secondary lymphoid structures and form clonal populations

Question 34

what is a naive lymphocyte?

Answer 34

a lymphocyte that has newly migrated, has not been exposed to any antigen, have only one specific type of surface receptors, and are genetically developed

Question 35

what is an immunoglobulin?

Answer 35

receptors/antibodies that can bind to an antigen

Question 36

what is the structure of an immunoglobulin?

Answer 36

4 chains- 2 heavy/2 light
the end of each will vary within classes, but with two of the same specific antigen bonding sites

Question 37

what is the IgG class?

Answer 37

bacteria and virus, largest class

Question 38

what is the IgA class?

Answer 38

sweat, saliva, breast milk, tears, mucus, gastrointestinal secretions

Question 39

what is the IgM class?

Answer 39

bacteria and virus- these appear first, very short lived

Question 40

what is the IgE class?

Answer 40

allergic reactions, parasites

Question 41

what is the IgD class?

Answer 41

B cell activation

Question 42

how do type 1 interferons work?

Answer 42

i) when a cell is infected, it releases type 1 interferons into the IST fluid
ii) interferons bind to uninfected cells and cause them to start producing antiviral proteins, preventing viral replication

Question 43

how do type 2 interferons work?

Answer 43

i) they are released from infected cells and helper T-cells
ii) they increase the effectiveness of type 1 interferons
iii) help release cytokines which proliferates immune cells in bone marrow

Question 44

what are the four phases of phagocytosis?

Answer 44

1) recognition: binding of pathogen on cell membrane of phagocyte
2) ingestion: phago/endocytosis to bring pathogen inside the cell, forming a phagosome
3) digestion: lysosome binds to phagosome, forming a phagolysosome
4) kill: pathogen is rendered nonfunctional, remains will be excreted

Question 45

what are complement proteins?

Answer 45

proteins released from the liver that circulate inactive, such as C3

Question 46

how do C3 and C3B work?

Answer 46

C3 binds to a pathogen and triggers a cascade of activations

C3B is part of C3, and flags the pathogen

Question 47

what do C5-C9 do?

Answer 47

forms the MAC, which creates a hole in the cell membrane of the pathogen