FIRST LINE DEFENCE BIO

what does the immune system recognise (2)

self: body material

non self: foreign material

what is the marking for identifying a first line of defence

a type of barrier, explicitly mention that it is a physical/chemical/microbiological barrier, function

physical barriers (3)

intact skin

mucous

cilia

intact skin

tightly joined epithelial cells prevent pathogen entry

mucous

viscous fluid that traps bacteria / virus

like a honey trap for an ant

cilia

thin membranous hair - like projections beat mucous up the bronchi and trachea towards the throat

like an escalator, protrudes from eukaryotic cells

chemical barriers (2)

natural secretions

skin glands

natural secretions

contain bactericidal agents

example of natural secretions (3)

saliva / tear

stomache

lungs

saliva / tear (2)

lysozyme - physically flushes away the debris

delivers antimicrobial agents to neutralise invading pathogens

stomache

has hcl acid

highly corrosive barrier, sterilises digestive track

lungs

surfactant

microbiological barriers (1)

microbiota (natural flora )

microbiota (natural flora)

non-pathogenic bacteria

- trains system to recognise friend and foe

- physically crowds out harmful pathogen

microbiological barriers locations (3)

skin

mouth

large intestine

* occupies a niche

innate immune system

a component of the immune system that is composed of generalised and non-specific defences and/or responses to pathogens. Also known as the non-specific immune system.

first line of defence

a component of the innate immune system characterised by the presence of physical, chemical, and microbiological barriers to keep pathogens out of the host organism

non specific

describes a component of the immune system that responds the same way to all pathogens

physical barrier definition

a component of the first line of defence that features solid or fluid obstacles that block pathogen entry such as skin or mucus

chemical barrier definition

a component of the first line of defence that features the use of enzymes, toxins, and acids to protect against pathogen invasion

microbiological barrier definition

microbiological barrier definition a component of the first line of defence in which the presence of normal flora limits the growth of pathogenic bacteria. Also known as microbiota barrier

flora definition

naturally occurring, nonpathogenic bacteria present in an organism

what form of defence does a plant have

only first line

physical barrier

structures of substances that physically prevent pathogens from causing disease

physical barriers (4)

cell walls

intact bark

trichomes

leaf position

cell walls

surround cells and prevent pathogens from coming in contact with the cell membrane

intact bark

thick cuticle layer on the leaves of bark further deterring pathogens

trichomes

leaf hairs brush away or trap larger pathogens

leaf positioning

plants may also position their leaves so they face downwards, preventing pathogens from accumulating on the surface

chemical barrier

chemically react with pathogens to prevent them from causing disease

chemical barriers (3)

saponin

caffeine

defensins

saponin

disrupts membrane of fungi

caffeine

toxic to insects and fungi

defensins

toxic to microbes

what do chemical barriers release and how does it act as a barrier (3)

antimicrobial peptides

chemical enzymes

digestive enzymes

toxic to the pathogen or organism

microbiome

microbiota does resource competition ie starving and out crowding pathogens