second line of defence

what is the second line

attack

properties of the second line of defence

innate, rapid, active, no memory / fixed/ response, respond to infections

leukocyte second name

white blood cells

leukocyte special thing

have pattern recognition receptors on their cell membrane (PRR)

PRR

pattern recognition receptor

what are the receptors on a leukocyte complementary to

pathogen associated molecular patterns (PAMP)

PAMP

pathogen associated molecular patterns

what does a leukocyte recognise

common pathogens

phagocyte

performs phagocytosis of foreign agents (pathogens) and materials

types of leukocytes (6)

neutrophils (small and mobile)

dendritic cells

macrophages (big eater)

natural killer

mast cell

eosinophil

phagocytosis steps (5)

pathogen detection / binding (PRR binds complementary to PAMPs)

engulfment

phagosome (vacuole) formation

lysosome phagosome fusion

enzymatic digestion

APC

antigen presenting cell

when does APC occur

after phagocytosis

what types of cells do APC

macrophages and dendritic cells

APC process (2)

process antigen after phagocytosis

display antigen on MHC2 markers to T cells

2nd line chemical damage

complement cascade

-> form MACs

-> opsonisation

-> chemoattractant

cytokines

what does an infection mean

it got past the first line of defence

natural killer cells purpose

kill virally infected/ cancerous cells

what is wrong with a infected cell

missing / damaged MHC1 markers

what do NK cells secrete

perforin and granzyme

what do NK cells do to destroy the cell

triggering apoptosis

attacks intracellular pathogen

what does an eosinophil interact with

large pathogens

multicellular parasites

what does an eosinophil perform

exocytosis

what does an eosinophil contain

granules (small enzyme vesicles)

what does an eosinophil granule contain

enzymes and other cytotoxic molecules and cytokines that are secreted via exocytes

what does an eosinophil attack

extracellular pathogen

what does a neutrophil do (3 steps)

phagocytosis

degranulation

neutrophic extracellular traps (NETs)

how abundant is a neutrophil

most abundant WBC (40-70%)

characteristics of the neutrophil

highly mobile phagocyte, small

what does a neutrophil secrete

anti-microbial proteins

where does complement protein fatal attraction circulate

in the blood

what does a complement protein purposes (3)

form membrane attack complexes (MAC's) to lyse cells

opsonisation - bind to bacteria promoting phagocytosis

chemo attractant: attract phagocytes to the infection

what is a cytokine

signalling molecules secreted by all immune cells

what does a cytokine do

immune cell to cell communication (some body cells)

properties of cytokines (2)

immunogenic, apoptotic

what is an interferon

secreted by infected cells

what do neighbouring cells

have complementary interferon receptors

what does a cytokine stimulate

antiviral protein production

what does mast cell do

big and waits for things to happen

what do granules in a mast cell do

they are signalling molecules

what is inflammation iniatated by

trauma (cellular debris) or infection (PAMPs)

inflammation steps (4)

1. mast cell releases histamine via exocytosis, triggering vasodilation and increasing permeability, cytokine secretion attracting phagocytes

2a. complement protein activation

2b. platelets wall of the site with activated fibrin, slowing movement and spread of pathogen

3. macrophages and neutrophils migrate from blood to phagocytose pathogen (N= release antimicrobial defensins )

where are mast cells located

in the tissue

what do mast cells act as

guard phagocytes

how does vasodilation and increased permeability

increases fluids

-> delivery of 2nd line defences

-> want everything to stay where it is

what do debris and injured cells contribute to

releasing cytokines

second line of defence

a component of the innate immune system characterised by the nonspecific response to injury and/or pathogens by a variety of cells and molecules

leukocyte definition

a group of blood cells responsible for protecting the body against pathogens and foreign material. Also known as white blood cells

phagocyte definition

a group of leukocytes responsible for the endocytosis and destruction of pathogens, foreign material, and cell debris

neutrophil definition

the most common type of leukocyte in the body. Engages in phagocytosis of pathogens and foreign material, as well as the release of cytokines

macrophage definition

a type of leukocyte found throughout the body that engages in phagocytosis and antigen presentation

dendritic cell definition

a type of leukocytes that engages in phagocytosis and antigen presentation

antigen presenting cell definition

a subgroup of phagocytes that display antigens from consumed pathogens on their surface and interact with the adaptive immune system. Also known as professional antigen presenting cell

cytokine definition

a signalling molecule released by cells (typically in the immune system) which aids in communication between immune cells and helps protect against pathogens

NK cell definition

a type of leukocyte responsible for the recognition and destruction of damaged and / or infected host cells

mast cell definition

a type of leukocyte responsible for releasing histamine during allergic and inflammatory responses

degranulation definition

the release of granule contents from a cell

histamine definition

a molecule released by mast cells that plays a key role in inflammation

inflammatory response definition

a series of biochemical events that occur in the body as a result of infection and/or trauma. Characterised by swelling, redness, pain, and heat in the affected tissue

eosinophil definition

a large granular leukocyte responsible for the release of toxic chemical mediators

interferon definition

a cytokine released by virally infected cells that increases the viral resistance of neighbouring uninfected cells

complement proteins definition

a number of different types of proteins found in the blood that opsonise, cause lysis, and attract phagocytes to invading pathogens

complement cascade definition

a complex sequence of events which occurs after the activation of complement proteins

opsonisation definition

the mechanism by which complement proteins attach to the surface of pathogens, making them easier to phagocytose

chemotaxis definition

the attraction of phagocytes towards a pathogen

lysis definition

the disintegration or rupturing of a cell

membrane attack complex

a pore formed by complement proteins in the cell membranes of a pathogen, disrupting the membrane and leading to the pathogen's destruction

steps of inflammation simple (3)

initiation

vasodilation

migration

initiation (2)

Macrophages activate and along with damaged cells release cytokines

Mast cells degranulate, releasing histamine

vasodilation - step of inflammation (3)

Histamine travels to nearby blood vessels, binding to specific receptors, causing vasodilation

Causes blood vessels to widen, increasing blood flow to the injury site (reason behind swelling, redness and warmth)

Formation of gaps in the vessel wall increases its permeability to cells of the immune system

migration (3)

Allows for number of innate immune system components to leave the bloodstream and enter the site of the injury

eg Phagocytes Phagocytose pathogens and digest them using enzymes like lysozymes

Complement proteins are attracted to the pathogens to make it easier for phagocytes to destroy them

Response continues until the site has been cleared of pathogens and debris, then the site of injury is healed and returns to normal

NK cell receptors (2)

Killer inhibitory receptor -> examines the surface of cells for MHC class I markers

Killer activation receptor -> binds to certain molecules which appear on cells undergoing cellular stress (eg infected or cancerous cells)

complement proteins 3 major outcomes

opsonisation

chemotaxis

lysis

opsonisation

Complement proteins stick on the outside of pathogens and make it easier for immune system cells to recognize them as foreign

chemotaxis

Complement pathogens gather near a pathogen and attract phagocytes to it, making it more likely to be destroyed

lysis

Complement proteins can join together on the surface of pathogens, forming a membrane attack complex (MAC), which creates pores in their membrane, this destroys the pathogen by causing lysis - sudden influx of fluid into the pathogen causes it to burst

what is the purpose of a fever

increase metabolic rate to get better faster, also may kill off some of the infecting pathogens with the increase in temperature

stuff like shivering or heat conserving behaviour eg put on a jacket