1. Defensive barriers Flashcards
(26 cards)
What are horizontal routes of transmission?
Direct contact
Aerosol
Oro-faecal
Vector borne
What are vertical routes of transmission?
Mother to embryo
- direct contact
Example of a direct contact disease
Greasy pig disease
- staphylococcus bacteria
- staphylococcus hyicus
Example of a aerosol transmission disease
Kennel cough
Example of a oro-faecal transmission disease
haemorrhagic enteritis
- Clostridium perfringens
Example of a vector transmitted disease
Pathogen uses an arthropod host to spread from animal to animal when it bites
- sandfly (e.g., Leishmaniosis)
- tick (e.g., Lyme disease)
Example of a transplacental transmission disease
Pathogen crosses the placental barrier to infect foetus e.g., Bovine virus diarrhoea (BVD)
What are commensal flora “friendly bacteria”?
- prevent pathogenic organisms from colonising
- provide competition
- may trigger a low level of functional immunity
What effect do antibiotics have on commensal flora?
Remove normal flora which can cause colonisation of pathogenic organisms
What do keratinocytes replicate to become?
Stratified squamous keratinised epithelium
What is the role of melanocytes?
Offer protection from UV damage
What are Langerhans cells?
Immune sentinels
- detect an antigen and take up the microbe
- migrate to lymph node and the lymph node where the immune cells reside and can generate an immune response
What is sebum?
Water repellant
Contains fatty acids (pH 5.5)
Anti-microbial components
How do keratinocytes detect and respond to infection?
When a microbe binds to a keratinocyte they express molecules on the cell surface that recognise microbes
What is the significance of toll like receptors?
Expressed on keratinocytes
- when microbes bind to these receptors a signalling cascade is triggered that can lead to the production of various soluble factors
- have anti-microbial properties
What are AMPs: Beta-defensins?
- small cationic peptides
- broad spectrum anti-microbial properties
- disruption of microbial membranes and/or interference with intracellular functions
What are the Beta-defensins expressed in humans?
- HBD1 constitutively expressed by keratinocytes
- HBD 2-4 Inducible in keratinocytes in response to infection
What are the Beta-defensins expressed in dogs?
3 genes have been identified
What does the triggering of inflammation by keratinocytes produce?
Cytokines = immunological hormones Chemokines = cell migration factors
What is mucous made up of?
Water + electrolytes Glycoproteins + lipids Antimicrobial compounds - transferrin - lactoferrin - lysozyme Antibodies (IgA) Antioxidants - superoxide dismutase - catalase - glutathione peroxidase
What is the mucocillary escalator?
Continual escalator of cilia that prevents microbes binding, adhering and colonising
- once infected host becomes immunocomprimised which can damage the escalator
What are alveolar macrophages?
Single celled - involved in phagocytosis
- main line of defence against inhaled microbial pathogens and inanimate particles
- derived from blood monocytes and interstitial macrophages
- short lifespan in alveoli
What are the phases of phagocytosis?
Binding Attachment phase Phagosome forming Phagolysosome forms Microbe destroyed
What are the physical and biochemical barriers in the oral cavity and oesophagus?
Physical = stratified squamous epithelium Biochemical = lysozyme in saliva
