defensive barriers

defensive barrier examples

• physical barriers- skin

• physiological barriers- mucous membranes

• biochemical barriers- gastric acid

• chemical barriers- lysozyme

• cellular- macrophages

commensal flora

• colonise where harmful bacteria would be otherwise

physical barrier

keratinocytes replicate to generate stratified squamous keratinised epithelium.

they detect infection, toll like receptors, cascade reaction (antimicrobial peptides, cytokines, chemokines)

melanocytes protect from uv damage

langerhans cells

present particle to activate immune response

eg allergic dermatitis

sebaceous glands and sebum

• water repellent

• contains fatty acids

• anti microbial components

AMPs: beta defensins

• what are they

• what properties do they have

• what do they do

• small cationic peptides

• broad spec anti microbial properties

• disrupt microbial membranes or interferance of intercellular function

what does mucous contain

• water and electrolytes

• glycoproteins and lipids

• antimicrobial compounds (transferrin, lactoferrin, lysozyme)

• antibodies (IgA)

• antioxidants

implications of impairment of mucocliliary escalator

lung pathology such as

• virus infection

• trauma- dust

• toxins- ammonia

alveolar macrophages

• what are they derived from

• lifespan in alveoli

• main line of defence

• derived from blood monocytes and intersitital macrophages

• short lifespan in alveoli

oral cavity and oesophagus

• what type of epithelium

• barrier hw

• prehension, mastication, digestion

• protect against trauma and infectious agents

• physical barrier- stratified squamous epithelium

• biochemical berrier- lysozyme in saliva

stomach

• sterilisation and digestion of food

• HCl acid, pepsin, mucous, regulatory peptides

small intesistine

• what is the defence against bacteria and where and what are they synthesised by

cryptidins are toxic to bacteria and synthesised by paneth cells in intestinal crypts

GIT

• gut associated lymphoid tissue- factor where you make immune response eg peyers patches

• IgA

example of direct contact

greasy pig disease

staphylococcus bacteria

example of aerosol

kennel cough

example of oro faecal

clostridium perfringens- haemorrhagic enteritis

example of vector

• sandfly eg leishmaniosis

• tick lyme disease

example of transplacental

bovine virus diarrhoea

how can keratinocytes trigger inflammation

• produce cytokines- immunological hormones

• produce chemokines- cell migration factors

what is often a opportunistic infection

bacterial bronchopneumonia