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immunology Flashcards

1
Q

what is the lymphatic system comprised of

A

-lymphatic vessels
-lymph
-lymphoid [immune] cells, tissues and organs

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2
Q

what are the functions of the lymphatic system

A

captures lost fluid from blood
transports dietary lipids
transports foreign substances and immune cells from tissues to lymphoid organs

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3
Q

where does lymphatic drainage empty

A

into venous system [right lymphatic duct and thoracic duct]

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4
Q

what is lymph

A

captured lost fluid [IF] and transports it back to the blood

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5
Q

what are the innate system defences

A

-surface barriers [skin and mucous membranes]
-internal defences [phagocytes, NK cells, inflammation, antimicrobial proteins and fever]

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6
Q

what are the adaptive immune system defences

A

-humoral immunity [B cells]
-cellular immunity [T cells]
[both lymphocytes]

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7
Q

what are the cells of the immune system

A

-neutrophils
-eosinophils
-basophils/mast cells
-macrophages
-dendritic cells
-NK cells
-lymphocytes [B/T cells]

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8
Q

Neutrophils

A

-aka polymorphonuclear neutrophils [PMNs]
-most abundant phagocyte [up to 70% of WBCs]
-first cell to arrive at site of infection
-chemotactic [attracted by chemical gradients]
-major defence against bacterial infection
-generate ROS vis ‘respiratory burst’

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9
Q

eosinophils

A

-granulocyte
-contains granules packed with digestive enzymes
-key role in defence against parasitic worms

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10
Q

basophils

A

-granulocyte
-granules contain histamine and heparin
-major role in inflammation together with mast cells

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11
Q
A
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12
Q

macrophages

A

-large agranular cells derived from monocytes that have entered tissue
-actively phagocytic [engulf foreign particles]
-deploy weapons [lysozymes, ROS]
-component of innate but play large role in adaptive [involved in activation of lymphocytes, present antigens]

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13
Q

Dendritic cells

A

-located in epithelia and most organs with characteristic long ‘arms’
-migrate to lymphatic system once antigen is internalised
-present antigen to T cells in lymph nodes
-major link between innate and adaptive

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14
Q

NK cells

A

-cytotoxic against some cancer cells and virally-infected cells
-lack specific antigen receptors [recognise defected self antigens [MHC]
-release perforins and granzymes [innate cell destruction by apoptosis]

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15
Q

lymphocytes of adaptive immune system

A

-mature in primary lymphoid organs [bone marrow or thymus]
-migrate between secondary lymphoid tissues
-able to recognise specific antigens

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16
Q

B cells

A

-possess cell surface receptors [immunoglobulin bound to surface] [specific for only one type of antigens, produce antibody immunoglobulin]
-differentiate in plasma cells producing large amounts of antibodies

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17
Q

T cells

A

-each cell expresses a unique antigen specific receptor
-perform both effector and regulatory roles
-helper t-cells [antigen specific t cell receptor, co-receptor molecule CD4]
-cytotoxic t cells [antigen specific, co-receptor molecule CD8]

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18
Q

primary lymphoid organs

A

bone marrow and thymus
[sites at which lymphocytes mature and develop antigen specificity]

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19
Q

secondary lymphoid organs

A

lymph nodes, spleen, mucosa-associated lymphoid tissue [MALT]
[site at which lymphocytes are activated when they recognise their specific antigen]

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20
Q

thymus

A

-site of T-cell maturation [immunocompetence]
-highly active after birth
-atrophies after puberty [involution]
-remains active but rate declines with age

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21
Q

lymph nodes

A

-bulbous kidney shaped organs up to 25mm in diameter
-large collections of nodes present throughout body [cervical, axillary and inguinal regions, around 600 in total]
-perform two major functions [filtration, immune activation]

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22
Q

spleen regions

A

-2 distinct regions
-red pulp [contains vascular sinuses filled with RBCs and macrophages
-white pulp [contains lymphocytes on reticular fibres

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23
Q

what are the spleen functions

A

-cleanses blood [removes old and defective blood cells and platelets, resident macrophages remove foreign particles and debris]
-recycles breakdown products [inro from RBCs stored for use in making haemoglobin]
-stored monocytes and platelets

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24
Q

mucosa-associated lymphoid tissue [MALT]

A

-lymphoid tissue found in mucous membranes in different parts of body
-tonsils [palatine, lingual, pharyngeal]
-peyer’s patches [wall of small intestine]
-appendix

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25
Q

innate system -skin layers

A

-epidermis [renewable mechanical barrier]
-dermis/hypodermis [contains sweat glands, sebaceous glands]
-secretion of various anti bacterial chemicals

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26
Q

innate system -mucous membrane

A

-goblet cells secrete mucus
-various anti bacterial chemicals
-first point of contact with pathogens from external environment

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27
Q

commensal bacteria

A

-normal microbiota may inhibit pathogen colonisation in several ways
-formation of bacterial layer [prevents more pathogenic bacteria from forming large colonies]
-compete for nutrients and space
-production of bactericides [inhibit other bacteria]

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28
Q

inflammation

A

-causes pain, redness, heat and swelling
-attempt to rid area of pathogens and accelerate recovery

29
Q

what are the three stages of inflammation

A

-vasodilation and increased permeability of blood vessels
-accumulation of phagocytes and antimicrobial proteins in area
-clearance of pathogens and accelerated tissue repair

30
Q

mobilising phagocytes

A

-leukocytosis
-margination
-diapedesis
-chemotaxis

31
Q

what is leukocytosis

A

injured cells releases factors that increase the number of circulating WBCs

32
Q

what is margination

A

Expression of cell adhesion molecules (CAMs) that
enables phagocytes to adhere to capillary walls

33
Q

what is diapedesis

A

Phagocytes pass through capillary wall into injured
tissues

34
Q

what are chemotaxis

A

Cells are attracted to site of injury along chemical
gradients

35
Q

chemical mediators of acute inflammation

A

-proteins/enzyme cascades [kinins and complement proteins]
-lipid-derived mediators [prostaglandins and leukotrienes]
-vasoactive amines [histamine released by mast cells/basophils]
-cytokines [signalling proteins involved in communication and control of immune repsonses]

36
Q

antimicrobial proteins

A

-collection of cellular and plasma proteins that enhance immunity
-includes
-interferons
-complement
-other antimicrobials

37
Q

what are interferons

A

-antiviral proteins produced by virally infected cells
-able to protect neighbouring cells
-some also exert control over inflammation and activate NK cells and macrophages

38
Q

what are complement antimicrobial proteins

A

-collection of over 20 plasma proteins
-normally present in an inactive state
-when activated, enhance inflammation and phagocytosis and directly kill bacteria
major mechanism for destroying pathogens
-contributes to both innate and adaptive immune responses

39
Q

complement activation

A

-classical pathway [initiated by binding of antibody to antigen and activation of C1]
-Mannose-binding lectin [MBL] [activated by lectin binding to mannose of micro-org surface]
-alternative pathway [initiated by activation of C3 and factors B,D,P through interaction with microbe surface]

40
Q

complement functions

A

-C3a enhances inflammation [reduces release of other chemical signals]
-C3b promotes phagocytosis through opsonisation [coats microbe with C3b molecules, promotes uptake of microbe by phagocytes]
-C5a enhances inflammation
-C5b forms membrane attack complex with C6,7,8,9

41
Q

other antimicrobial proteins

A

-lysozyme [present in some body fluids and phagocytic granules [enzymatically degrades peptidogylcan in bacterial cell walls]]
-various peptides including defensins and cathelicidins [disrupt microbial membranes, inhibit nucleic acid or protein synth in numerous bacteria, viruses and fungi]

42
Q

divisions of adaptive immunity

A

-humoral
-cellular

43
Q

humoral immunity

A

-antibody-mediated
-immune function performed by release of immunoglobulin [antibodies]
-blocks entry of pathogen or target pathogen for destruction

44
Q

cellular immunity

A

-cell-mediated immunity
-immune function performed by cells
-causes death of infected cells and pathogens within them

45
Q

antigen specificity meaning

A

antigen-toxin or foreign substance which induces an immune response
specificity-ability to bind one but not another member of a family of related substances

46
Q

antigens - clonal selection theory

A

-proposed by McFarlane Burnett to explain diversity in antibodies
-name derived from antibody generator [antigen]

47
Q

response of antigen binding to receptor

A

-activation of B cells [release of immunoglobulin]
-activation of T cells [killing of infected cells/release of cytokines]

48
Q

where can antigens be found

A

foreign organisms or particles such as
-bacteria
-viruses
-toxins
-foreign tissue [transplant organs etc]

also found on our own cells [posses their own self antigens, e.g. A,B,Rh antigens on RBCs]

49
Q

immunocompetence

A
  • Lymphocytes must be able to recognise and respond a large
    number of foreign antigens
    -Must not respond to normal self antigens (self tolerance)
50
Q

lymphocyte development

A

-lymphocytes develop immunocompetence in primary lymphoid organs
-b cells mature in bone marrow
-t cells in thymus
-mature lymphocytes circulate between secondary lymphoid organs where they encounter antigen

51
Q

human self-antigen

A

major histocompatibility complex [MCH] moles
[key molecules to match in organ transplantation]

52
Q

role of MHC molecules

A

-incorporate and present antigens to T cells [forms antigen/MHC complex, antigen presented as a peptide sequence, recognised by T cell receptor]

53
Q

types of MHC molecules

A

class 1 [displayed by all nucleated cells, incorporate foreign peptides generated within cell, present peptide-MHC 1 to CD8+ Tcells]
class 2 [displayed by professional antigen presenting cells, engulf and break down antigens into peptide, present peptide-MHC 2 to CD4+ Tcells]

54
Q

antigen presenting cells

A

-professional APC include dendritic cells, macrophages, and B cells
-engulf and destroy foreign pathogens [phagocytosis]
-package foreign peptide sequence onto MCH2 molecules
-display or present antigen-MHC 2 complex to CD4+ T cells

55
Q

b cell activation process

A

-antigen binds to B cell receptor [immunoglobulin on cell surface]
-activation [via helper CD4+ T cell]
-proliferation [division] and differentiation

56
Q

B cell activation -proliferation and differentiation

A

-divide into many daughter cells [proliferation]
-differentiate to produce 2 distinct cell types
-plasma cells [secrete large quantities of immunoglobulin]
-memory B cells [tailored antibody response to pathogen]

57
Q

antibody IgM

A

-first class secreted by plasma cells during primary response
-readily fixes and activated complement
-exists in monomer/pentamer forms
-serves as an antigen receptor on B cell surface
-numerous antigen binding sites make it a potent agglutinating agent

58
Q

antibody IgA

A

-dimer, secretory IgA found in body secretions [saliva, sweat, intestinal juice and milk]
-helps stop pathogens from attaching to epithelial cell surfaces [including mucous membranes and epidermis]

59
Q

antibody IgD

A

-found on B cell surface
-functions as a b cell antigen receptor

60
Q

antibody IgG

A

-most abundant antibody in plasma, accounting for 75-85% of circulating antibodies
-main antibody of both secondary and late primary responses
-readily fixes and activates complement
-protects against bacteria, viruses, and toxins circulating in blood and lymph
-crosses placenta and confers passive immunity from mother to foetus

61
Q

antibody IgE

A

-stem end binds to mast cells/basophils, antigen binding to its receptor end triggers cells to release histamine and other chemicals that mediate inflammation and allergic reaction
-secreted by plasma cells in skin, mucosae of GI and respiratory tracts, and tonsils

62
Q

antibody effectiveness

A

antibodies are effective against extracellular antigens
-some pathogens [viruses and some bacteria] enter the cell and not accessed by antibodies [cell mediated immunity most important in these circumstances]

63
Q

cell-mediated immunity

A

-t-cells undergo clonal selection [recognise antigen via t cell receptor [TCR]]
-t-cells recognise peptide bound to MHC molecules
[CD4+T-cells-MHC class 2
CD8+T-cells-MHC class 1]

64
Q

helper T cell function in humoral immunity

A

1 - T(h)cells binds with self-nonself complexes of a B cell has encountered its antigen and is displaying it on MHC 2 on its surface
2 - T(h)cell releases interleukins as costimulatory signals to complete B cell activation

65
Q

helper T cell function in cellular immunity

A

1 - T(h)cell binds dendritic cell
2 - T(h)cell stimulates dendritic cell to express co-stimulatory molecules
3 - dendritic cell can now activate CD8 cell with help of interleukin 2 secreted by T(h)cell

66
Q

role of CD4+ helper cells

A

-T(h)1 against intracellular bacteria and protozoa
-T(h)2 against extracellular parasites
-T(h)9 promote inflammation -allergic inflammation
-T(h)17 protective and pathogenic
-T(fh) [identified by CXCR5] role in selection and survival of B cells
-T(regs) natural development and emigrate from thymus

67
Q

cytotoxic CD8+ T cells

A

induce cell death [apoptosis]by releasing perforin and granzymes

68
Q

innate chemical defenses

A

-inflammation
-antimicrobial proteins [interferons, complement, others]
-fever

biomed (9 decks)

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