first line of defence

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