Response to infection Flashcards
Methods of Transfer of Pathogens
Contact
Body Fluids
Airbourne Transmission
Vectors
Ingestion
Droplets
Structure of a bacteria
Slime Layer*
Cell Wall
Cell Membrane
DNA and RNA (NO NUCLEUS)
Plasmids
Flagella*
Cytoplasm
Capsule
*Some may have this
meausred in micrometers
Structure of a virus
DNA or RNA
Protein Coat
Lipoprotein Coat
measured in nanometers
Cocci Bacteria
Spherical Cells that can occur singulary, in pairs or in clusters
e.g. staph infection
Bacilli Bacteria
Rod shaped cells with flagella for movement
e.g. Salmonella
Spirila Bacteria
Twisted cells
Vibrio Bacteria
Curved rods (comma shaped)
e.g. Cholera
Non-specific Defences
Work against all pathogens
Specific Defences
Work against a particular pathogen
External non-specific defences
Skin - a physical barrier
- sebum; an oily substance secreted from the subaceous glands which contain substances which kill some pathogenic bacteria
- Sweat; contains salts and fatty acids which inhibit growth of microorganisms
Mucous Membranes - line the body cavities and secretes mucous which traps particles and inhibits their entry into the cell
Hair - in the nose and ear, traps 90% of bacteria before it can enter the respiratory system
Cilia - hair like projections from cells which stop the entry of pathogens and send them back to the throat with a beating action
Acids - kills pathogens e.g. stomach or vagina
Lyzozyme - An enzyme which kills the bacteria by weakening the cell wall e.g. tears
Cerumen (Wax) - Slightly acidic, contains lyzozymes which protect the inner ear
Fluid Movement - a flushing action which removes the pathogen from the body e.g. urine, sweat, tears
Protective Reflexes
Vomiting
Sneezing
Coughing
Diarrhoea
Internal non-specific defences
Phagocytes - cells which can ingulf and digest microorganisms and cell debris
Leucocyetes - cells which can leave blood capillaries to migrate through tissues finding the source of the infection.
Macrophages - developed from leucocytes, can either be fized or wander around, and secrete substances which kill bacteria.
Inflammation - Signs of swelling, redness, heat, pain, which is the result of a response to infection
Fever - elevation of the body temperature due to an increase in the body’s thermostat. Prevents the growth of pathogens, and increases the rate of chemical reactions, which speeds up the rate of repair of cells
Pyrogens - chemicals released by white blood cells during an inflammatory response. Act directly on the hypothalamus to increase body temperature.
Cell Mediated Response
Production and release of three different cells during the intracllular phase of infection
1. Macrophage engulfs the virus, releasing cytokines to help helper t-cells
2. Antigen is presented to a specific t-cell
3. T-cell is sensitised; dividing it into a clone
- memory cells
Further developed into:
Killer T-cells - destroy the invading pathogen by attaching to it and secreting substances which kill it
Helper T-cells - Secrete substances to further sensitise the T-cell; attracting macrophages to the point of infection, increasing phagocytic activity
Suppressor T-cells - Secrete substances that inhibit the actions of t-cells once the infection is dealt with.
Antibody Mediated (Humoral Response)
Production and release of an antibody into body fluids before a pathogen enters the body cells
1. Pathogen enters the body
2. Macrophage engulfs the virus, and presents a non-self antigen
3. B-cells are sensitised and divide into clones
- most are plasma cells
- some are memory cells
4. Plasma cells secrete an anitbody which travels in the bloodstream to destroy antigens.
Natural Passive Immunity
Antibodies are passed from mother to foetus via breast milk and placenta
