Animal defences against pathogens - Non-specific Flashcards
What are non-specific responses?
Always present pr activated rapidly defending the body against pathogens
What are specific responses?
Specific to each pathogen but much slower to respond due to this
What are examples of non-specific animal defences?
Skin, lysozymes, mucous membrane, explusive reflexes, blood clotting + wound repair, inflammatory response, fever, phagocytosis
How is the skin a defence?
It has skin flora of healthy microorganisms that outcompete pathogens for space on body surface
Produces sebum + inhibits pathogen growth
Where are lysozymes?
In tears + urine and in stomach acid
How is mucous membrane a defence?
Secretes mucus, traps microorganisms that destroy bacterial + fungal cell walls
How are expulsive reflexes a defence?
Cough, sneeze, vomiting, diarrhoea = Ejects pathogens from gas exchange system + gut
How does blood clotting + wound repair work?
- Damaged tissues activate platelets
- Platelets secrete thromboplastin, which triggers many reactions resulting in formation of blood clot
- Clot dries out, forming a scab
- Epidermal cells beneath scab start to grow, sealing wound permenantly
Describe the inflammatory response:
- Injury + invasion of pathogens, WBCs release histamines
- Vasodilation = increased blood supply
- Capillaries become leaky
- Antibodies move into tissue causing pain
- Monocytes mature in macrograph, leaves blood stream, + ingest bacteria by phagocytosis
Describe a fever:
- Average body temp is 37*C, maintained by hypothalamus
- When pathogen invades, cytokines stimulate hypothalamus to reset thermostat, temp goes up
- Pathogens reproduce best at 37*C, higher temp
What are the 2 types of specialised WBCs that engulf + destroy pathogens?
Neutrophils + macrophages
What is the process of phagocytosis?
- Pathogens produce chemicals that attract phagocytes
- Phagocytes recognise non-human proteins on pathogen
- The phagocyte engulfs the pathogen + encloses it in a vacuole (phagosome)
- The phagosome combines with a lysosome to form a phagolysosome
- Enzymes from the lysosome digest + destroy the pathogen
What can phagocytes be helped by?
Opsonins and cytokines
What are opsonins?
Chemicals that bind to pathogen + ‘tag’ them so they are easier to recognise
Phagocytes have receptors that are common to opsonins on cell surface membrane so will bind to these + engulfs pathogen
What are cytokines?
Phagocytes release cytokines which attract other phagocytes to the area
How can u see whether a specific or non-specific response is occurring?
By looking at blood sample down microscope + counting types of blood cells there are
What are the types of blood cells u may see?
- Neutrophils
- Lymphocytes = small with large round nucleus
- Monocytes = develop into macrophages
- Eosinphils = allergies
- Basophils = Release histamine during inflammatory response
What are the 2 main groups of lymphocytes u might find?
T cells (CMI) and B cells (humoral)
