Chapter 7 - Specific Defenses

differences between viruses and bacteria

viruses non living, req host cell to multiply, genetic material is DNA or RNA, NO cell wall and NO organelles

bacteria living cell, dont req host cell, MAIN genetic material is DNA(altho still contain RNA), cell wall made of peptidoglycan, have organelles

gram staining

• gram positive bacteria(THICKER peptidoglycan layer) retain crystal violet stain

• gram negative lose crystal violet stain, stained by safranin

transmissable diseases

infectious disease that can be passed from one person to another by infection with microorganisms

direct VS indirect transmission

• contact

• body fluids

• droplet

• airborne

• ingestion

• vectors

contact

• direct: infected individual pustules burst and non infected individual touch pustule and touch own face

• indirect: infected individual sneeze on hand, transfer virus to doorknob and non infected individual touch doorknob and touch face

body fluids

• direct: exchange of fluids during sex

• indirect: sharing of needles

droplet

• direct: individual sneeze and pathogens remain SUSPECTED IN AIR ON DROPLETS OF SALIVA and is inhaled by uninfected individual

• indirect: individual sneeze and pathogens remain on INANIMATE OBJECTS and uninfected touch object and touch face

airborne

• indirect: individual sneeze and pathogens remain SUSPENDED IN AIR ON DUST PARTICLES and is inhaled by uninfected

ingestion

• indirect: food products contaminated with pathogen during preparation by an infected individual and is consumed by uninfected individual

vectors

• indirect: insect not affected by pathogen transfers pathogen from infected to uninfected individual

body defense mechanisms

• non specific

• specific

non specific response

• dont target specific pathogens, first line of defense

• external defenses, protective reflexes, internal non specific defenses

external defenses

• skin

• mucous membrane

• hair

• cilia

skin

• physical barrier to prevent entry of pathogens

• sweat have flushing action and is acidic to inhibit growth

• prescence of harmless bacteria as part of normal bacterial flora

hair

• traps dust particles and prevent entry into body

cilia

• move like waves to sweep away mucus and pathogens trapped in mucus

mucous membranes

• trap bacteria and dust particles in mucus secreted by cells

protective reflexes

• forceful expulsion of large quantities of pathogen or fluid containing those pathogens

• rapid removal of pathogens

• EG: sneezing, coughing, vomiting

non specific internal defenses

• phagocytosis

• fever

• inflammation

self antigen

• antigen that is recognised by immune sytem as belonging to host body and wont stimulate further immune response

non self antigen

• antigen that is not recognised by immune system as belonging to host body and will stimulate a further immune response

phagocytosis

• macrophages migrate to site of infection due to release of histamine by Mast cells

• macrophages recognize non self antigens and extend their cytoplasm to engulf pathogen

• forms a phagosome

• phagosome fuses with lysosome to form phagolysosome

• lysozymes in the phagolysosome breakdown the pathogen

inflammatory responses(swelling, redness, heat)

• histamine released by Mast cells promotes vasodilation, hence more blood flow to site of injury, lead to redness

• more warm blood at site of injury lead to heat

• increased permeability of capillaries, thus more plasma enters tissue, thus swelling restricts movement of damaged areas

• heparin released by Mast cells acts as anticoagulant to prevent blood at site of injury, blood clots form surrounding the site of injury instead

role of inflammatory responses

• prevent damage from spreading

• begin tissue repair mechanisms

• remove damaged tissue and cell debris

fever cause

• caused by cytokine induced upward displacement of set point

pyrogens

• substances which cause a fever

• exogenous pyrogens: microbes of their products, release endogenous pyrogens like interleukin-1

benefits of fever

• inhibit bacterial growth

• increase rate of tissue repair by increasing rate of reactiona

• increase blood flow so lymphocytes reach infection site fast

development and process of fever

antibody mediated immunity

• provide resistence to virus, bacteria and bacterial toxins BEFORE they enter our cells

process of antibody mediated immunity

cell mediated immunity

• provide resistence once pathogens already invaded cells, INTRACELLULAR PHASE

process of cell mediated immunity

types of response

• primary response

• secondary response

primary response

• immune response to FIRST exposure to an antigen

• takses time for B cells to multiply and differenciate into plasma cells(makes antibodies)

secondary response

• response to SUBSEQUENT exposure to an antigen

• faster stronger response, involves memory cells

• plasma cells form quickly, antibody levels rise quickly

immunity

resistence to infection by invading microoganisms

natural immunity

• occurs without human intervention

artificial immunity

• results from giving people an antibody or antigen

active immunity

• long lasting immunity when body manufactures antibodies against foreign antigen

• presence of memory cells

• can be naturally acquired(actual attack)or artificially acquired(vaccine)

• during subsequent infection, antibody production faster, and at higher conc

passive immunity

• short term immunity produced by introduction of antibodies from another person

• naturally acquired(from mother through placenta or breast milk) or artificially acquired(injection of antibodies)

vaccines

• antigen preparation

• antigen strong enough to provoke immune response but not product symptoms

types of vaccines

how do vaccines work?

• biological standpoint: stimulate immune system to produce memory cells

• social standpoint: provide herd immunity, protect those that cant be vaccinated

factors considered with vaccines

• social - use of animals to make vaccine

• health issues - allergic

• cultural - religious objections

• economic - cost

antibodies

• antibodies combine with specific antigen to form antigen antibody complex

• coats bacterian so bacteria can be easily consumed by phagocytes and enhance phagocytosis

antibiotics

• drugs used to fight infection of microorganisms

• cant treat virus

types of antibiotics

• bactericidal

• bacteriostatic

• broad spectrum

• narrow spectrum

bactericidal

• cause death of bacteria by disrupting cell membrane

• cause cells to lyse

bacteriostatic

• slow down population growth by disrupting protein synthesis

broad spectrum

• affects wide eange of different bacteria

narrow spectrum

• effective only against specific bacteria

examples of antibiotics

• penicillin - prevent synthesis of bacterial cell wall

• streptomycin - interfere with protein synthesis

• cephalosporin - interfere with synthesis of bacterial cell wall

over/under prescription of antibiotics

• some bacteria have natural resistsnce to antibiotics due to genetic mutation

• some bacteria will survive and pass resistent allele to offspring

• increase population of resistant strains

antivirals

• treat viral infections

• drug interferes with virus replication insids host cells