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((archived year 1 med)) > Immunology > Flashcards

Immunology Flashcards

1
Q

what is another good way to learn immunology ?

A

use the quizzes linked to the lectures

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2
Q

describe origin of B cells and maturation stages

A
  • originate in bone marrow or lymph nodes
  • become activated when antigen (from T cell / antigen presenting cell) binds to receptor
  • B memory cells retain the and keep comminucating with T cells for more help
  • B plasma cells remove membrane anchor and secrete immunoglobulins
  • cytokines from the T cell determine type of Ig IgA, IgE, IgM, IgG
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3
Q

describe structure of antibody

A

Y shaped structure
four polypeptides : 2 heavy chains, 2 light chains
tips of the Y variable specific to antigen

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4
Q

what are the primary immune organs and what do they make

A

Thymus : T cells
Bone marrow : B cells

development and maturation of immune cells

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5
Q

describe action of T 1 helper cells

A

recognise MHC II complexes on macrophages and help macrophages digest pathogens

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6
Q

describe action TH 2 cells

A

recognise MHC II / antigen complexes on beta cells and help them to become plasma cells to secrete antibodies

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7
Q

describe action cytotoxic T cells

A

recognise MHC I / Ag complexes on virus infected cells and kill them via release of perforins and granzymes

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8
Q

name some secondary immune tissues

A

adenoids, peyers patches , mucosa associated lymph tissue ( MALT ), appendix, spleen, lymph nodes

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9
Q

what are the features of the innate immune system and give some examples

A

fast response, non specific, no memory

epithelial barriers, dendritic cells, mast cells, phagocytes, complement, NK cells

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10
Q

what are the features of the adaptive immune system and give examples

A

slower ( days ) , specific and have memory

T cells and B cells ( produce abs )

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11
Q

what cell is the precursor to macrophages

A

monocytes

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12
Q

macrophages have specific types in different tissues - name some

A

bone - osteoclasts
lung : alveolar macrophage
brain : microglial cells
liver : kupffer cells

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13
Q

name cells involved in the innate immune system ( there are 6 )

A

Natural Killer Cells
neutrophils - have enzymes to excrete
macrophages - phagocytose and present ags to T cells

dendritic cells - phagocytose and present ags to T cells
mast cells
eosinophils

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14
Q

how do macrophages and dendritic cells recognise pathogens

A

DAMPS ( damage ), PAMPS ( pathogen ) and MAMPS ( microbe ) associated protein structure
by Toll like receptors

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15
Q

What is the term used to describe a rounded aggregate of activated macrophages/giant cells?

A

A granuloma

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16
Q

what is the complement pathway ?

A

30 proteins which can destroy bacteria within seconds, eg lectin responds to microbial sugars, can respond to lipids from bacteria ( fast )

classical pathway activated by antibodies ( if met before ie memory )

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17
Q

What is the function of lysosomes?

A
  • Lysosomes are membrane-bound organelles that contain enzymes capable of breaking down (digesting) proteins, nucleic acids, carbohydrates and lipids
  • destroy pathogens
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18
Q

In cell membranes, phosphotidylserine normally faces inwards. What happens if this molecule flips to face outwards?

A

It becomes an ‘eat me’ signal for phagocytes (a cell which can gobble other cells or particles), in the setting of apoptosis (programmed cell death).

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19
Q

How specific is the immediate response to a pathogen?

A

The immediate response activates the innate immune system and therefore has limited specificity.

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20
Q

What is the main cytokine produced by sentinel cells when they are activated by DAMPs and PAMPs?

A

Interleukin 1 (IL-1).

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21
Q

Name the 3 complement system activation pathways and explain how they are activated.

A
  1. Classical pathway. Activated by antigen binding to IgG or IgM which activates C1.
  2. Alternative pathway. Activated by microbial components directly.
  3. Mannose-binding lectin pathway. Activated by mannose-binding lectin binding to mannose on the surface of a bacterium.
22
Q

What is the Complement System?

A

A system of pro-inflammatory proteins produced by the liver which circulate as inactive precursors until they are activated by 1 of 3 pathways.

23
Q

List 4 consequences of complement system activation.

A
  1. Formation of anaphylatoxins (C3a, C4a + C5a) which cause histamine to be released from mast cells. C5a is a chemotactic + activation agent for neutrophils, monocytes, eosinophils and basophils.
  2. Opsonisation. C3b is the main opsonin (an ‘eat-me’ signal for neutrophils and macrophages which have C3b receptors).
  3. Cell lysis. The final stage of the complement cascade results in the formation of a membrane attack complex (C5b, C6, C7, C8 and C9) flooding the cell with water and ions and causing lysis.
  4. Immunoglobulin clearance. Removal of immune complexes from the circulation
24
Q

Describe the consequences of mast cell activation

A
  • Mast cells contain pre-formed histamine granules which can be quickly released causing blood vessels to dilate and to leak.
  • Mast cells also cause a delayed response by producing leukotrienes.
25
Q

What is produced when 5-lipooxygnease acts on Arachidonic acid?

A

Leukotrienes

26
Q

List 4 effects of prostaglandin production in the context of acute inflammation

A
  1. Vasodilation.
  2. Increased vascular permeability.
  3. Pain (PGE2).
  4. Fever (PGE2).
27
Q

List 4 consequences of leukotriene production in the context of acute inflammation

A
  1. Vasoconstriction.
  2. Bronchospasm.
  3. Increased vascular permeability.
  4. Attraction and activation of neutrophils (LTB4).
28
Q

What are the 3 main functions of bradykinin?

A
  1. Vasodilation.
  2. Increased vascular permeability.
  3. Pain.
29
Q

What are Toll-like receptors?

A
  • These are receptors that present on macrophages and dendritic cells which can be activated by PAMPs.
  • TLR activates immune response genes producing cytokines.
  • TLRs are also present on cells of adaptive immunity (lymphocytes).
30
Q

describe steps in phagocytosis ( 6 )

A
  • activation of phagocytic cell / chemotaxis
  • recognition of invading microbes ( PAMPs )
  • ingestion and form phagosomes
  • fusion with lysosome ( phagolysome )
  • microbe killing and form residual bodies
  • elimination of digested contents ( exocytosis )

( a diagram would be nice )

31
Q

_______________________________

A

___________________________________________________

32
Q

where are immune cells made?

A
  • within bone marrow during haematopoiesis
33
Q

where do lymphocytes mature and receive their immunological ‘education’ before being released into the bloodstream?

A
  • thymus gland
34
Q

once lymphocytes mature in the thymus gland, where do they migrate to?

A
  • lymph nodes
35
Q

other than lymph nodes, what 2 other organs play a role in the immune system?

A
  • spleen (massive lymph node): site of antigen presentation
  • liver: contains its own cohort of phagocytes and lymphocytes, it also synthesises acute phase proteins such as CRP in response to infection
36
Q

what are some physical and chemical barrier mechanisms in humans to prevent the invasion of infective organisms?

A
  • intrinsic epithelial barriers exist between the body and outside world: epithelial cell walls have tight junctions between them and are hard to penetrate (eg. lining of mouth, lungs)
  • the continuous longitudinal flow of air or fluid through most body systems: creates a flushing action which prevents bacteria from adhering to structures
  • movement of mucus by cilia in lungs: prevents bacteria from adhering to structures
  • desquamation of skin and epithelial cells: prevents adherence of microorganisms
  • natural acids in parts of the body: eg. lysozymes in saliva, hydrochloric acid in stomach
  • natural antibacterial peptides on the skin and surface linings of lungs and gut (eg. defensins, chemokines)
  • normal bacterial flora colonise parts of body: compete with infective microorganisms (eg. vaginal lactobacilli produce lactate- creates acidic environment and destroys infective organisms)
37
Q

what cells are granulocytes?

A
  • neutrophils: first line of defence against all infections
  • eosinophils: involved in IgE mediated allergic disorders such as asthma
  • basophils (or mast cells): have a role in type 1 hypersensitivity reactions through their binding with IgE antibodies
38
Q

what do macrophages derive from?

A
  • blood monocytes
39
Q

what are the main roles of tissue macrophages?

A
  • they ‘tidy up’ any pathogens, foreign debris, and any old/dead cells using phagocytosis
  • they also perform antigen presentation and can activate memory cells
40
Q

describe the process by which a tissue macrophage would destroy a pathogen/foreign piece of debris/old or dead cell

A
  • tissue macrophages have processes on their cell membranes called pseudopodia which extend around the unlucky item they’re about to eat
  • once internalised, the engulfed material is contained within a phagosome
  • the phagosome then fuses with a lysosome which contains either reactive oxygen species or enzymes which break down its contents
41
Q

give an example of a macrophage found in bone

A
  • osteoclasts
42
Q

what is the role of dendritic cells?

A
  • once formed in bone marrow they circulate in the bloodstream until they reach their target tissues, where they are activated by pathogens and differentiate into their mature forms
  • they phagocytose pathogens before migrating to lymph nodes, where they present antigens on their cell surfaces with the costimulatory molecules required to activate the adaptive immune response
  • they have numerous dendritic processes
43
Q

what cells are lymphocytes?

A
  • B cells
  • T cells
  • Natural killer cells
44
Q

what are the 2 types of B cells?

A
  • plasma cells (mature B cells) that secrete antibodies
  • memory B cells
  • B cells surface markers include CD19, CD20, CD21, MHC II
45
Q

what are the 4 types of T cell?

A
  • helper T cells (CD4): facilitate the activation of the immune response and stimulate effector cells
  • cytotoxic T cells (CD8): also known as killer T cells or effector T cells, provide cell-mediated immunity
  • regulatory T cells (CD25+FOXP3): also known as suppressor T cells, provide role of limiting the immune response to prevent excessive damage to tissues and organs
  • memory T cells (CD62+CCR7): remember what happened to allow immune system to mount a faster and more effective response if the infective organism enters body again
46
Q

what are natural killer cells also known as, what do they express, and what is their role?

A
  • also known as large granular lymphocytes
  • they express CD16, CD56, and CD8
  • NK cells form part of both the innate and adaptive immune systems and are able to destroy pathogens without the need to prior activation by specific antigens
47
Q

what are the 4 main parts of the immune response?

A
  1. the innate immune system
  2. the acute inflammatory response
  3. antigen presentation
    4a. humoral immunity
    4b. cell-mediated immunity
48
Q

what are the key features of the innate immune response? (not cellular level)

A
  • very fast
  • non-specific
  • no memory
49
Q

what does the innate immune response consist of?

A
  • innate cellular response

- innate chemical response

50
Q

describe the innate cellular response

A

PHAGOCYTES (eg. dendritic cells, tissue macrophages, neutrophils):

  • phagocytes identify pathogens by recognising pathogen-associated molecular patterns (PAMPs) using pathogen recognition receptors (PRRs)
  • (toll-like receptors (TLRs) are an example of a PRR)
  • phagocytes identify, internalise, kill, and digest pathogens into their component proteins
  • phagocytes then present the digested protein antigens to the cells of the adaptive immune system via major histocompatibility complexes (MHCs)

((archived year 1 med)) (15 decks)

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