Immune System

Question 2

what is the purpose of the immune system

Answer 2

to protect organisms against harmful pathgens or in response to other physical attacks in a nuber of ways

Question 3

3 lines of defence

Answer 3

physical
general cellular/protein
specific/targeted

Question 4

3 broad phases which are from convergent or parallel evolution in different species

Answer 4

recognition phase
activating phase
effector phase

Question 5

recognition phase

Answer 5

has to be able to tell the difference between self and non-self

pattern recognition receptors on the surface of cells detect the general feature so fgroups of micro-organisms and pthogens (Microbe associaed molecular patterns, or pathogen associated molecular patterns)

patterns are specific to the microorganisms and are different to the host, and can be used to recognise non-self cells

Question 6

activating phase

Answer 6

mobilisation of cells and molecules to fight an invader
binding of Microbe associated molecular patterns to pattern recognition proteins causes the activation of this phase

can include:
defensins (antimicrobial peptides)
cytokine signal production, resulting in further immune responses

Question 7

effector phase

Answer 7

mobilised cells or molecules destroy the invading microorganisms

defensins disrupt pathogen membranes leading to cell deth

macrophages
destroy pathogens through phagocytosis

also causes regulated cell death

Question 8

how to macrophages work?

Answer 8

destroy pathogens through phagocytosis

engulf pathogens and encase it in a vacuole

lysosomes fuse with the vacuole and digest the bacterium

the antigens from the bacterium are presented on teh cell surface

T cells can use antigens to further fight infection

Question 9

How does regulated cell death occur?

Answer 9

disruption of membranes and lysis of the cell itself

examples found in fungi
apoptosis-like death (apoptosis bodies)
heterokaryon incompatability-induced death (membrane disruption)
ferroptosis (lipid peroxidation)

Question 10

what is the innate immune system

Answer 10

first line of defence
skin and associated mucus
physical and chemical barriers
all organisms have an innate immune ststem
it is quick
it is indescriminate

Question 11

second line of defence?

Answer 11

when the first line is corrupted, the second line kicks in

macrophages and mast cells mount an inflammatory response to prevent infection

Question 12

third line of defence

Answer 12

adaptive
lymphocytes destroy the infectious agents themselves or through circulating antibodies
in order for this to occur, it must have previously encountered the pathogen, forming a memory to produce a stronger attack

Question 13

what is acquired immunity

Answer 13

higher order animals like mammals
lacking in plants
more targeted
slower
replication of specific immune cells which act as memory in case the pathogen is reincountered

Question 14

What is inflammation?

Answer 14

second line of defence
non-specific but effective

isolates the damaged area to stop the spread of damage

recruits molecules and cells to promote the destruction of the damage and promote healing

it is lead by mast cells in invertebrates
- secretes cytokines to activate immune cells
- increase of blood flow and permeability of blood cells
- blood clotting

Question 15

Plants innate defenses

Answer 15

structural defences
- epidermis
- thorns
- hairs
- chemicals to deter plant eating animals

membrane bound receptors recognise molecular patterns that signal pathogen prescence

triggers a signalling cascade, triggering the immune response including
- closing of the stomata
- strengthening of the cell wall
- secretion of antimicrobial agents

Question 16

what is the hypersensitive response?

Answer 16

some pathogens try to overcome the plants innate immune system, and plants have developed resistance proteins that detect effector proteins

these proteins trigger another cascade that results in the expression of pathogenesis genes that trigger the hypersensitive response
- rapid programmed cell death
- rapidly limits the spread of the pathogen by reinforcing the cell walls of other cells and systemic acquired resistance

Question 17

what is systemic acquired resistance?

Answer 17

long term resistance for parts of the plants that are removed from the initial site of infection

Question 18

what is teh adaptive cell-mediated response?

Answer 18

innate immune system actives the adaptive immune system

phagoytic cells of the innate immune system such as macrophages and dendritic cells

major histocompatability complex (MHC) proteins bind to the antigens of foreign bodies and protrude from the phagocyte

the MHC-antigen complex activates cells of the adaptive immune system

Question 19

T cells as the cell mediated immune response

Answer 19

main cellular response of the adaptive immune ststem

only set into action by single specific antigen

memory T cells will only activate when this particular antigen is reencountered

the more antigens an organism encounters in its life, the larger its arsenal of T cells

A type of WBC

rapidly multiples to produce specialised cells

Question 20

what is cell mediated immunity

Answer 20

adapted cellular response to prevent infection

Question 21

How to antigen presenting cells work?

Answer 21

macrophages engulf and digest harmful pathogens through phagocytosis

the pathogen antigen is fragmented by a phagolysosome and transported to the macrophages surface

antigen is then presented on the surface

major histocompatability class moelcule embed the fragments for presentation on teh surface on APC

these can then be detected by T cells

Question 22

helper t cells

Answer 22

secrete chemicals to stimulate growth and differentiation of cytotoxic t cells

Question 23

cytotoxic t cells

Answer 23

kills damaged cells

Question 24

memory t cells

Answer 24

remsin in the host after the infection is cleared, just in case there is reinfection

Question 25

suppressor t cells

Answer 25

inhibit the immune ststem to prevent further destruction to the host tissues

Question 26

what is the adaptive humoral immune response?

Answer 26

also known as antibody-mediated immune response

targets pathogens circulating in the ‘humors’ or extracellular fluids, such as blood and lymph

antibodies target invading pathogens for destruction

Question 27

what are the 3 ways antibodies target invading pathogens

Answer 27

neutralisation
opsonisation
activation of the complement system

Question 28

neutralisation

Answer 28

antibodies neutralise a pathogen by interfering with its ability to infect host cells

not able to bond to host cells and enter etc.

Question 29

opsonisation

Answer 29

antibodies function as opsonins, which tag pathogens for destruction

the formation of the antigen antibody complex attracts and stimulates phagocytic cells that engulf and destroy the pathogen

Question 30

complement cascade

Answer 30

sequential cascade of more then 30 proteins

proteins opsonise pathogens for destruction of macrophages and neutrophils, induce the inflammatory response with the recruitment of immune cells and promote lysis of the pethogen