Chapt 7 (diseases) Flashcards
define pathogens
disease causing organism
define communicable disease
diseases that are transmitted from and infected person to a non infected person
compare bacteria and viruses in terms of size, level of harm, nucleic acid, ability to survive out of host, and living or non-living
bacteria: 1-10micrometres, light microscope
harmful or harmless
DNA and RNA
can survive outside host
prokaryotic, unicellular
Virus: 20-750nanometres, electron microscope
always harmful
DNA or RNA
needs host to survive
non-living
list the compulsory components of bacteria
- DNA: floats freely/ plasmids
- Cytoplasm: granulated due to ribosomes, no membrane bound organelles
- Cell membrane: phospholipid bilayer
- Cell wall: usually peptidoglycan, a protein-carbohydrate
list the optional parts of bacteria
- capsule: made of carbohydrates for protection
- slime layer
-flagella: movement
List all the components of viruses
- DNA or RNA (nucleic acid)
- protein coat surrounding the nucleic acid
- (optional) lipid or lipoprotein envelope
state how viruses infect living cells
- virus bind to host cell
- insert nucleic acid into host cell
- replication of virus nucleic acid within cell
- manufacture virus proteins using viral RNA/DNA polymerase
- burst out of cell, killing it
- goes to infect more cells
describe bacteriophages
viruses that multiply in bacterial cells
state 4 types of bacteria
cocci, bacilli, spirilla, vibrio
define contagious disease
diseases transmitted directly from an infected person to a non infected person
state 6 modes of transmission
contact, ingestion, body fluids, droplets, airborne, vectors
contact
direct (touching an infected person) or indirect (touching an object that was touched by an infected person)
ingestion
food or drink contaminated by pathogens
body fluids
body fluids of an infected person come in contact with the bloodstream or mucous membranes of an uninfected person
droplets
droplets of moisture containing pathogenic organisms emitted when talking breathing coughing sneezing
airborne transmission
moisture in droplets evaporate, some bacteria die, but viruses and some bacteria still remain viable for a longer distance because they are lighter
vectors
intermediate hosts of a pathogen
purpose of non-specific defence
defence of the body that acts against all pathogens
purpose of external defence
prevent pathogens from entering the bloodstream
name 7 external defenses
skin, mucus, cilia, acids, lysozyme, cerumen, flushing action
skin
- impervious barrier
- large amount of skin bacteria, difficult for microorganisms to become established
- sebum secreted from sebaceous glands kills some bacteria
- sweat contains salts, fatty acids, and lysozymes, preventing the growth of microorganisms
mucous membranes
-mucous membranes line body cavities that open to the exterior
-mucus traps particles because its sticky, inhibits entry of microorganisms
cilia
-tiny hair-like projections from cells capable of a rhythmic beating motion
- moves mucus up and out of the trachea into the throat to cough or swallow
acids
- HCl in stomach kills most microbes
- vagina is slightly acidic, hostile environment for microorganisms
- urine, sweat are slightly acidic
cerumen
protects the outer ear against infection from some bacteria
lysozyme (6)
- enzyme which kills bacteria
- cerumen, saliva, sweat, tears, nose secretions, tissue fluid
flushing action
-urination, urethra is flushed out, kept relatively free of pathogens
-blinking, eyes are flushed out, kept relatively free of pathogens
internal defenses function
work to eliminate all types of pathogens
define phagocytes
specialised leucocytes that engulf, ingest and digest microorganisms and cell debris
describe monocytes and macrophages
non-granulated leucocytes, monocytes leave the bloodstream and enter the tissues, differentiate into macrophages
how and what do macrophages phagocytose
- either move through the tissue looking for and phagocytose pathogens OR
- fixed in one place and phagocytose pathogens that come to them
- remove microbes and dying cells
describe neutrophils
granulated leucocytes with lobulated nucleus
- when they die they form pus
how and what do neutrophils phagocytose
- first cells to move into tissues to phagocytose pathogens
- primarily kill pathogens inside cells
define a fever
elevation in the body temperature >37°C
what causes a fever?
- pyrogens are released by leucocytes during the inflammatory response
- act on the hypothalamus, causing it to reset body’s set temperature to a higher level than normal (>36.8°C)
what happens before crisis?
- thermoreceptors detect that the body temperature is below set point
- vasoconstriction of blood vessels in the skin reduce blood flowing through them, decrease heat loss through skin from blood
- shivering, involuntary rhythymic contraction of muscles generate heat
- these increase body’s temperature to new set point
what happens after crisis?
- during the crisis, the fever breaks, hypothalamus resets set temperature back to normal
- thermoreceptors detect that body temperature is higher than set point
- person feels hot starts to sweat increasing heat loss
- vasodilation of blood vessels in the skin, increase amount of blood flowing through them, increase heat loss through skin from blood, person appears flushed
- decreases body temperature down to normal set point
purpose of fever
- inhibit growth of bacteria and virus replication
- increase rate of chemical reactions
define inflammatory response
response to any damage in the tissues, causing heat, redness, swelling, and pain
3 purposes of inflammation
- decrease the spread and prevent additional entry of pathogens
- remove damaged tissue and cell debris
- begin repair of damaged tissue
also its assisted by proteins in the complement system
How, why do mast cells release chemicals?
- when there is abnormal damage to tissues like mechanical damage or chemical changes,
- mast cells will be activated with complement proteins and release histamine, heparin and other chemicals
what do histamine and heparin do?
histamine: increases blood flow to damaged tissues through vasodilation AND increases permeability of capillary walls
heparin: prevents clotting at the immediate area of injury, BUT a clot of fluid forms around the damaged area, decreasing spread of pathogens to healthy tissues
How is phagocytosis involved?
complement proteins and chemicals released by mast cells attract phagocytes to phagocytose pathogens and cell debris, dead phagocytes form pus
what happens after inflammation?
mitosis to produce new cells, repair of damaged tissues
how is there heat and redness in inflammation?
increased blood flow due to vasodilation of blood vessels caused by histamine
how is there swelling in inflammation?
escape of fluid out of blood into tissues due to increased permeability of capillary walls caused by histamine
how is there pain in inflammation?
abnormal conditions like damaged tissues stimulate pain receptors
specific defense
defense of the body against a specific pathogen
immune system
different types of cells present in most organs of the body that protects against foreign organisms, alien chemicals and abnormal cells in the body
immune response
response triggered by foreign substances or microorganisms entering the body
define antigen
any substance capable of triggering an immune response and production of antibodies
- large molecules like main 4
self-antigens
antigens produced in the persons own body such that it does not trigger an immune response
antibodies
Y shaped specialised proteins released by plasma cells produced in reponse to a non-self antigen
- type of immunoglobulin
antigen-antibody complex
2 conditions
compound formed when an antibody combines with an antigen
- antigen has a specific active site with a particular shape, antibodies has the complementary shape
- each antibody can only combine with 1 particular antigen
how antibodies work (non phagocytosis)
- inactivate foreign enzymes or toxins by combining with them or inhibiting their reaction with other cells or compounds
- bind to surfaces of viruses, preventing them from entering cells
- dissolve organisms
how antibodies work (phagocytosis)
- coat bacteria to make them easier to phagocytose
- cause agglutination
- react with soluble substances to make them less soluble
what do antigen presenting cells do
- Detect presence of non-self antigen
- Engulf pathogen
- Digest the pathogen, producing small fragments that move to the surface of the cell
- Present the antigen to the lymphocytes
dendritic cells, macrophages, undifferentiated B cells
antibody mediated immunity function and definition
production and release of antibodies by plasma cells into the blood and lymph
provides resistance against virus, bacteria, bacterial toxins before these microorganisms or substances enter body cells
describe B cells
produced and mature in the bone marrow, occur in the lymphoid tissue
have a receptor for a particular antigen, capable of responding to the particular antigen
antibody mediated process
- antigen presenting cell presents antigen to helper T cell
- helper T cell releases cytokines, which activate B cells
- B cells undergo mitosis and form a group of cells called a clone
- differentiate into plasma cells and memory cells
what do plasma cells do
produce and release antibodies able to bind with the the active site of antigen, antibodies circulate through blood lymph extracellular fluid to reach site of infection
what do memory B and T cells do
spread throughout the tissue, allow response to occur more rapidly next time pathogen enters body
Cell mediated immunity function
provides resistance against the intercellular phase of bacterial and viral infections, whole cells, cancer cells
T cells description
produced in the bone marrow, mature in the thymus, occur in the same lymphoid tissue as B cells, but occupy different areas of lymphoid tissue
each type of T cell responds to 1 particular antigen
Cell mediated immunity process
antigen presenting cell present antigen to T lymphocytes, causing them to become sensitised
enlarge and divide into a group of identical T cells, differentiate into 4 types
Killer T
migrate to site of infection to deal with invading antigen
attaches to an infected cell and secretes a chemical that destroys the antigen, then goes in search of more antigens
Helper T
binds to antigen on antigen presenting cell, stimulating secretion of cytokines which
- sensitises lymphocytes, intensifying response
- intensify phagocytosis of macrophages
- attract lymphocytes and macrophages to site of infection
- promotes action of killer T cells
define cytokine
protein released in response to non-self antigen and act as messengers in the immune response
Suppressor T
when immune activity has become excessive or infection has been dealt with successfully, release substances that inhibit B and T cells activity, slows down immune response
primary response
first exposure to antigen
takes several days for B cells to multiply and differentiate into plasma cells to secrete antibodies, level of antibodies reaches a peak, then declines over time
secondary response
second exposure to same antigen,
memory cells recognise antigen more quickly,
plasma cells form quickly, antibody levels in plasma rising rapidly to a higher level that lasts longer
antigen has little opportunity to exert effect on body, no illness
immunity
resistance to infection from invading microorganisms
natural vs artifical
no human intervention vs being given antibody or antigen
passive vs active
body receives antibodies from another source vs body produces its own antibodies in response to non-self antigens
vaccine
antigen preparation for artificial immunisation
living attentuated
produced with microorganisms with a reduced virulence (ability to cause disease)
often prepared by recombinant DNA
inactivated
made with a dead organism, not as long lasting
toxoid
inactivated toxins produced by bacteria so they do not cause illness
sub unit
fragment of microorganism to trigger immune response
herd immunity
high proportion of population are immunised, those who are not immune are protected
health reasons
allergic reaction to medium in which vaccine was cultured, experienced reactions before
social reasons
ethical concerns with use of human tissue to produce vaccines
ethical concerns with use of animal tissue to produce vaccines
ethical concerns with animal testing to produce vaccines
ethical concerns with informed consent
availability
economic reasons
expensive
commercialisation, interests of commercial vaccine production affects its use
immunisation
prepare immune system to respond to pathogens/become immune to a pathogen
antibiotics
drugs used to fight infections caused by bacteria
narrow/broad spectrum
wide range of different types/specific types
bacteriocidal
kills bacteria directly by changing nature of the cell wall/cell membrane or disrupting action of essential enzymes
bacteriostatic
stops bacteria from reproducing by preventing protein synthesis
multiple/total drug resistance
resistance of some strains of bacteria to most/all available antibiotics
antivirals
treatment of infections caused by viruses, inhibit development of virus
