IMMUNOLOGY

Question 1

Immunity and the Immune System

Answer 1

-immunity = resistance to disease
-immune system is a functional system rather than organ system

Question 2

Lymphatic System:

Answer 2

-made of lymphatic tissue (bone marrow and thymus), lymphatic vessels and lymphfluid
-lymphatic tissue = connective tissue content in lymphocytes
-lymph = clear fluid, similar to interstitial fluid in lymphatic vessels and tissues
-system cirualtes fluids, drains excess interstitial fluid, traposnrts lipids, andinitates/coorsinates immune reposne

Question 3

Primary Lymphoid Organs:

Answer 3

-where pluripotent stem cells differentiate and become immunocompetent (when born and develop)
-red bone marrow (flat bones and long bone epiphyses), immunocompetent B and immature T cells
-thymus (on top of heart, bi-lobed) where t cells go to develop into mature T cells

Question 4

Secondary Lymphoid Organs/Tissues:

Answer 4

-where immune cells continue maturation and connect to initiate adaptive immune response (where most immune responses occur)
-lymph nodes (meet up spot, small organ), spleen (remove bad RBCs) , lymphatic nodules/follicles (mass of lymph tissue not surrounded by a capsule - mucosal surfaces such as tonsils)

Question 5

Innate Immune System:

Answer 5

-non specific
-1st and 2nd line of define
-surface barriers (skin, mucous membranes and microbiome)
-internal defences (phagocytes, NK cells, inflammation, neutrophils, mast cells, monocytes antimicrobial proteins, fever)

Question 6

1st Line of Defence

Answer 6

Skin:
-epidermis is packed-keratized cells which is hard for bacteria to get in
-sheds periodically

Mucous Membrane:
-viscous, traps things
-either propelled out or into acidic stomach

Hairs:
-trap and filter microbe

Cilia:
-propel pathogens

Tears:
-washing of eyes
-enzyme lysozyme breaks down cell walls of certain bacteria
-present in tears, saliva, sweat, other secretions

Fluids:
-propel/wash system
-can be acidic
-committing/defecation expels microbes

Question 7

2nd line of defense

Answer 7

-interferons: secreted proteins which interfere with viral replication
-complement: plasma proteins that make pathogen look yummy
-iron binding proteins: inhibit bacterial growth by binding iron
-antimicrobial proteins: attract dendritic cells and mast cells

Question 8

Natural Killer Cells:

Answer 8

-granular
-in blood and tissue
-perforin (make hole), granzyme (enter cells and cause apoptosis) and release cytonkins
-attack cells that display surface molecules

Question 9

Phagocytosis:

Answer 9

Chemotaxis (cells chemically stimulated to move to infected/damaged site)
Adherence (attachment of phacite to pathogen)
Ingestion (phagocyte engulfs pathogen so it becomes phagosome)
Digesting (phagosome fuses with lissome containing digestive enzymes)
Killing (microbe killed by lysozomes)

Question 10

Phagocytes:

Answer 10

-neutrophils (most abundant, 1st to move from blood to tissues, is pus)
-monocytes (monocytes in blood, mature to macrophage in tissues, big eaters - monocytes recruited to infections in response to chemokines and differentiate to macrophages)
-dendritic cells (specialised, tissue-resident macrophage, antigen presenting cells)

Question 11

Pattern Recognition Receptors (PRRs)

Answer 11

-used to see pathogen-associated molecular patterns (PAMPS)
-when PRR binds with PAMP, this stimulates phagocytosis

Question 12

Dendritic Cells:

Answer 12

-link innate to adaptive; use PRRS to recognize and phagocytose pathogens in tissues
-travel to lymph nodes to present pathogenic antigens to T cells
-then adaptive immune response is activated

Question 13

Inflammation:

Answer 13

-non-specific
-can be response to tissue damage so not always a pathogen response
-delivers effector molecules to infection site
-prepares site for tissue reading and prevents spread to other tissues
1. Vasodilation/increased permeability of blood vessel/decreased blood glow (mast vells release histamine, cytokines etc)
1. Emigration of phagocytes from blood to infected site (resident marrow becomes averaged PRRs, cytokines and chromium released)
3. Tissue repair

Question 14

Inflammation Signs:

Answer 14

Rubor/redness from increased blood flow
Calor/heat from increased blood flow
Tumour/swelling to increase vascular permeability so fluid begins to collect
Dolor/pain (with loss of function) due to swelling and release of neurotransmitters, immobilising are hearts to contain spread

Question 15

Fever:

Answer 15

-cytokines called pyrogens alter body temp (secreted by macrophages and leukocytes)
-mild/moderate increase metabolic rates/healing (heat is catalyst)
-causes sequestration (separating and hiding it from bacteria) of zinc and iron by liver/spleen as bacteria need these to multiple
-high fever is dangerous as it denatures enzymes

Question 16

Adaptive Immune System:

Answer 16

-specific cells/proteins for attacking foreign substances
-systemic - not restricted to initial infection site
-3rd line of defence
-has memory

Question 17

B and T Cells:

Answer 17

-both derived from bone marrow
-b cells derived and developed in bone marrow
-t cells go to Thymus
-naive B and T cells leave thymus/bone marrow to lymph nodes to await antigen exposure
-b cell receptors have 2 antigen recognition sites
-t cell receptors have 1 antigen recognition site

Question 18

CD4 T Cell:

Answer 18

-HELPer T cell
-recognizes antigens on MHC11
-helps activate B cells

Question 19

CD8 T Cells:

Answer 19

-cytotoxic t cells
-reconized antigen on MHC1
-kills infected/altered cells through perforin and granzyme

Question 20

Antigen:

Answer 20

-any molecule that can bind to an antibody
-made of proteins, polysaccharides or lipids
-may be foreign or self molecules presented at wrong place/time

Question 21

Epitope/antigenic determinants:

Answer 21

-small structure on antigen that can induce immune response by binding an antibody or receptor on a B or T cell

Question 22

Antigen Presenting Cells (APCs):

Answer 22

-proccess and displace antigenic peptides on cell surface molecules
-activate T cells
-denctic cells are best at being antigen presenting cells
-macrophages can be an APC but are better as phagocytes

Question 23

Major Histocompatibility Complex:

Answer 23

-self antigens (ark cells as your own)
-help T cells recognize self vs non-self

MHC 1: in plasma membrane of all nucleated cells ENDOGENOUS = present inside cell, CD8
MHC 2: on antigen presenting cells EXOGENOUS = brought into cell from outside, CD4

Question 24

Humoral Immunity

Answer 24

-B cells
-antibody mediated (antibody produced by B cell and float in blood and lymph or become memory B cell awaiting subsequent exposure)
-bind to pathogens/mark for destruction
-B cells can see antigen though their BCR, will need co-stimulation

Question 25

Cellular Immunity

Answer 25

-T cells
-cell on cell violence
-infected cells, cancer cells and foreign cells killed

Question 26

Making Effector T Cells:

Answer 26

-naive t cell gets activated by specific antigen
-once T cell is activated it proliferates and differentiates and is an effector to cell

-includes CD4 Helper, CD8 cytotoxic, memory t cells, regulatory t cells
-T cells cannot see antigen so antigens must be presented on MHC
-T cells need double activation, needs a co-stimulation (single ½ activates naive T cell, signal 3 tells it its purpose)

-activated apcs present antigen to T cell in lymph nodes
-starts primary cell mediated response when T cells can proliferate/differentiate or become memory T cells

Question 27

Antibody Isotopes:

Answer 27

IgM - first made, in breast milk, binds pathogens (pentamer/pentagin with 5 Ys)
IgA - in secretions, helps prevent attachment of pathogens to epithelial surfaces, lots in breastmilk (dimer/2 ys)
IgD - signals for B cells to be activated (monomer/Y shape)
IgG - most abundant, can cross placenta, long lasting (monomer)
IgE - mediates allergic responses (monomer)

Question 28

What do Antibodies do

Answer 28

-antibodies prevent attachment
-immobilise bacteria
-activate complement
-enhance phagocytosis

Question 29

Precipitation = makes soluble antigens insoluble to aid in elimination
Agglutinato = clumping
Neutralisation = mask dangers part of pathogen ex exotoxin
Inflammation = triggers histamine

Question 30

Active vs Passive Immunity

Answer 30

Active immunity = B/T cell response, production of memory cells (VACCINE)
Passive immunity = no memory cells made, short term, antibodies mop up antigens, transfer through placenta or breastmilk (WHINRO)