essential immunology 1

Question 1

pathogen

Answer 1

any microorganism which causes harm to the body

Question 2

tolerance/self-tolerance

Answer 2

immunological unresponsiveness to an antigen.

self-tolerance means the body does not attack itself. this is because it is able to recognise its own antigens as self.

Question 3

innate vs adaptive immune response

Answer 3

innate:
- from birth
- same response to every pathogen
- involves phagocytosis
- first to come into action
- cellular and chemical barrier=skin, mucosal barrier
- cells-phagocytes and natural killer
- proteins: complement

adaptive:

• specific
• involves T-cells and B-cells
• immunological memory
• cellular response: lymphocytes in the epithelia
• proteins: antibodies
• cells: lymphocytes

Question 4

phagocytosis

Answer 4

1- phagocyte moves towards microbe due to difference in concentration-chemoosmosis
2-phagocyte engulfs microbe-phagosome
3-lysosome binds to phagocyte to form phagolysosome
4-lysosome releases digestive enzymes which break down phagolysosome
5-remants are either digested or discharged

Question 5

different cells involved in the innate system? and functions?

Answer 5

1- macrophages:
-Involved in phagocytosis
-constricts blood flow at site of infection-redness
-contracts epithelial cells- swollen
2-neutrophils:
-involved in phagocytosis
-biggest WBC
3-eosinophils:
-parasitic control
-contains many granules full of digestive enzymes
4-mast cells:
-parasitic control
-contain many granules of histamine- released onto foreign cell
-can be involved in anaphylactic reactions
5-basinophils: function unknown
6-natural killer cells :
-have two receptors. one which will cause death of target cell. one which will not.
-release perforin
-reacts to fungi, viruses, tumour cells, parasites
-release enzyme which causes autolysis of target cell

Question 6

complement system

Answer 6

group of about 20 serum proteins. 
function: 
-inflammation
-stimulates phagocytosis-opsonization
-stimulates cell lysis
different pathways:
-classic: 
C1 binds to antobody-antigen complex. C2 binds to C1 and C2 cleaves into C2a and C2b. C4 cleaves into C4a and C4b.  c2b and C4b combine to form C3 converts. C3 converts breaks down C3a and C3b. C3a causes inflammation. c3b can bind to microbes and make them more prone to be bound to phagocytes-opsonization.
c3 convertase can bind to properdin to form c5 converts-this breaks down c5 into c5a-inflammation and c5b which combines with other compliments to form a Membrane attack lysis-cell lysis.

Question 7

what are cytokine? what action can they have?

Answer 7

they are chemicals which allow communication between cells.
autocrine-self
paracrine-cells nearby
endocrine-cells far away.

Question 8

what is inflammation? what are the different types?

Answer 8

it refers to the action of neutrophils, macrophages and mast cells against an invader which allows cells and tissues to heal.
ACUTE= initial response against harmful stimuli
CHRONIC= gradual replacement of cells present at cell by co- replacement and destruction