communicable diseases Flashcards
define disease
departure from good health caused by malfunction of the mind/body
define communicable disease
caused by infectious agent
define parasite
organism tha loves on/within another- causing harm to the host
define pathogen
MICROORGANISM that causes disease
how do bacteria cause diseases differently to other pathogens
b- produce toxins which damage host tissue
other- damage host tissues directly
describe bacteria and how they cause disease
prokaryotic cells
many aren’t pathogens
gram positive- purple- blue under light microscope when stained
gram negative- red under light microscope
secrete toxins that damage cells by breaking down membranes
describe viruses and how they cause disease
non-living
have DNA/RNA
intracellular parasites
-invade living cells
-insert own genetic material into hosts DNA
-use host cell to reproduce new viruses rapidly
-burst out of cell, destroying it and spreading to others
describe protoctists and how they cause disease
eukaryotic only few are pathogens often need vectors to transfer take over cells and break them open -digest contents
describe fungi and how they cause disease
eukaryotic
can be uni/multicellular
can’t photosynthesise
secrete enzymes to extracellularly digest food and absorb nutrients
name an describe a direct method of transmission
physical contact
name and describe indirect forms of transmission
droplet infection -contact with bodily fluids contact with fomites -things infected ppl have touched vectors
name and describe plant defences to disease
recognition
- receptors in cells respond to mol.s on pathogens
- signalling mol.s released that with on genes
- triggering cell responses e.g. strengthening walls, producing defensive chemicals
physical defences
- cells next infected one produce high levels of callose
- synthesised and deposits between cell membrane + wall
- prevents pathogen entering
- lignin added to make barter stronger
chemical defenders
- repel insect vectors
- kill invading pathogens
describe defences in the skin
dead, out cells full of keratin- difficult to penetrate
dead cells flake off with pathogens
sebum from sweat gland has low pH which inhibits pathogen growth
harmless microorganisms reduce pathogen N due to competition
describe defences of the gut wall
saliva has lysozyme which digests bacteria walls
stomach has hydrochloric acid which destroys bacteria
describe defences of the urinary tract
mucus traps pathogens
harmless microorganisms
lysozyme in urine
describe defences of the gas exchange surface
mucus
cilia sweep the away to mouth to be expelled
describe the inflammatory response
tissue damage activates mast cells which secrete histamine and cytokines
describe the effects of histamines
dilate blood vessels -increases blood flow + body temp increase permeability of blood vessels -easier for WBCs to leave vessels -plasma forced out- causing swelling
describe the effects of cytokines
attract phagocytes to engulf pathogens
cause hypothalamous to raise body temp (fever)
describe the process of blood clotting
platelets become sticky secrete thombroplastin activates prothrombin into thombrin converts fibrinogen (soluble) to fibrin (insoluble) forms mesh that traps RBCs
describe phagocytosis
neutrophils and macrophages phagocytes recognise non-human proteins engulf pathogen into phagosomes phagosome combines with lysosome to form phagolysosome enzymes from lysosome direct pathogen
describe the specific immune response
antigens= protein/ polysaccharide on pathogen surface antibodies= proteins secreted by b lymphocytes in response to non-self antigens- neutralise pathogens
describe the structure of antibodies
hinge region
-provide flexibility so can attach to antigens
variable region
-different primary (and tertiary) structure in different antibodies
-specific to antigens
constant region
-binds to phagocyte receptors
describe b cells
mature in bone marrow
produce antibodies with some binding site as receptor
used outside pathogen cells
