introduction to immunology

Question 1

define immunology

Answer 1

study of structure and function of immune system

Question 2

define immune system

Answer 2

cells, tissues and molecules that mediate resistance to infections

Question 3

define immune response

Answer 3

collective and coordinated response to the introduction of foreign substances in an individual mediated by cells and molecules of the immune system

Question 4

define immunity

Answer 4

resistance of a host to pathogens and their toxic effects

Question 5

what are the 3 main roles of the immune system

Answer 5

1. defence against microbes
2. defence against growth of tumor cells
3. homeostasis (destruction of abnormal/dead cells)

Question 6

what are the 3 components of the immune system

Answer 6

organs
cells
molecules

Question 7

what are the 8 organs of the immune system

Answer 7

tonsils and adenoids
thymus
lymph nodes
spleen
peyer’s patches
appendix lymphatic vessels
bone marrow

Question 8

what are the 3 forms of cells in immune system

Answer 8

lymphocytes
monocytes/macrophages
granulocytes

Question 9

what are the 5 types of molecules in the immune system

Answer 9

antibodies
complement
cytokines
interleukins
interferons

Question 10

what are the 2 types of immunity

Answer 10

innate (non-adaptive)
acquired (adaptive)

Question 11

what is innate immunity

Answer 11

• first line of immune response
• relies on mechanisms that exist before infection
• uses granulocytes, macrophages etc
  (immunity acquired from birth)

Question 12

what is acquired immunity

Answer 12

• second line of response (if innate fails)
• relies on mechanisms that adapt after infection
• mediated by T and B lymphocytes
  (immunity acquired from interaction with pathogen)

Question 13

describe some features of innate immunity

Answer 13

• rapid response
• not specific (same molecules/cells respond to range of pathogens)
• no memory
• no clonal expansion

Question 14

describe some features of adaptive immunity

Answer 14

• responds more slowly, over days
• is specific (each cell responds to single epitope on antigen)
• has anamnestic memory (repeated exposure leads to faster, stronger response)
• leads to clonal expansion

Question 15

what subsections of immunity fall under adaptive immunity

Answer 15

natural and artificial active immunity
natural and artificial passive immunity

Question 16

give examples of natural and artificial active immunity

Answer 16

natural = clinical infection
artificial = vaccination

Question 17

give examples of natural and artificial passive immunity

Answer 17

natural = breast milk, placenta
artificial = immune serum

Question 18

what are the 2 mechanisms in adaptive immunity

Answer 18

cell mediated immune response
humoral immune response

Question 19

what is the CMIR

Answer 19

• t-lymphocytes
• eliminates intracellular microbes that survive within phagocyte of infected cells

Question 20

what is the HIR

Answer 20

• b-lymphocytes
• mediated by antibodies
• eliminates extra-cellular microbes and their toxins

Question 21

explain how CMIR works

Answer 21

• t-cell recognises peptide antigen on macrophage
• identifies molecules on cell surfaces
• helps body distinguish self from non-self
• t-cells differentiate into effector cells that are capable to kill infected cells

Question 22

what are the 2 types of t-lymphocytes and their funcition

Answer 22

helper t-lymphocytes, CD4+ T cells activate phagocytes to kill microbes

cytolytic t-lymphocytes, CD8+ T cells destroy infected cells containing microbes or microbial proteins

Question 23

explain how HIR works

Answer 23

• b-lymphocytes recognise specific antigens (proliferate and differentiate into anti-body secreting plasma cells)
• antibodies bind to specific antigens on microbes and destroy them via specific mechanism
• some b lymphocytes evolve into resting state-memory cells

Question 24

describe the structure of antibodies (immunoglobulins)

Answer 24

y shaped polypeptides
2 identical heavy chains
2 identical light chains
consists of variable regions (where it binds to antigens) and constant regions (same in all antibodies)

Question 25

what are the 5 kinds of immunoglobulins (antibodies)

Answer 25

IgG, IgM, IgA, IgD, IgE

Question 26

where is IgG, IgM, IgA secreted

Answer 26

G= secreted in high quantities in SECONDARY EXPOSURE A= lumen of GI tract and respiratory tract M= during PRIMARY infection

Question 27

what is the function of IgG

Answer 27

- neutralise microbes and toxins - opsonise antigens for phagocytosis - activate the complement - protect newborn (as it crosses placenta)

Question 28

what the function of IgM

Answer 28

- activates complement - used as marker of recent infection

Question 29

function of IgA

Answer 29

neutralizes micros and toxins

Question 30

function of IgD

Answer 30

- present on surface of B lymphocytes - functions as membrane receptor - has role in antigen stimulated lymphocyte differenciation

Question 31

function of IgE

Answer 31

- associated with anaphylaxis (allergic reaction) - plays role in immunity to helminthic parasites (worm)

Question 32

what is immunodeficiency

Answer 32

loss/inadequate function of various components of the immune system (can occur in any part of system e.g phagocyte, b or T cells)

Question 33

what is an immune-compromised host

Answer 33

patient who due to impaired function of immune system is at high risk of infection

Question 34

how do hypersensitive reactions affect the immune system

Answer 34

cause cell damage through excessive immune response to antigens

Question 35

what are 3 types of hypersensitive reaction + explain

Answer 35

hypersensitivity (overreaction to agents) allergy (overreaction to substance) autoimmunity (overreaction to self)

Question 36

what is intravenous contrast used for

Answer 36

enhance and improve visibility of internal organs/body structure on CT.

Question 37

what is the difference between the characteristics of ionic and non-ionic iodine contrast

Answer 37

ionic = higher osmolarity, more side effects non-ionic = bound to organic compound, fewer side effects as it doesnt dissociate into component molecules

Question 38

what contrast agent is mostly used in MRI

Answer 38

gadolinium (paramagnetic, weakly magnetised)

Question 39

what are some adverse reactions of contrast media

Answer 39

- causes direct release of histamine (chemical that immune system releases) - contrast molecule causes effect on antigen binding sites on IgE of mast cells - severity of reaction-quantity of circulating IgE and mast cells - due to direct contact with blood vessel endothelium, it leads to activation of factor X11 etc (similar to histamine)

Question 40

examples of mild contrast reactions

Answer 40

nausea cough warmth dizziness itching hives sweats swelling in face

Question 41

examples of moderate contrast reactions

Answer 41

hypertension hypotension dyspnea (SOB) wheezing laryngeal edemaex

Question 42

examples of severe contrast reactions

Answer 42

arrythmia profound hypotension seizures cardiac arrest anaphylaxis

Question 43

what are the treatments u give to mild, moderate and severe contrast reaction

Answer 43

mild = medication or support moderate = O2, IV fluids, Benadryl, corticosteroids severe = (if anaphylaxis) stop contrast injection, secure airway, restore BP (IV fluids, raising feet) (if not) O2, antihistamine, corticosteroid, Epipen