EMS lectures 7,8,9, 10 Flashcards
What is healing by regeneration
tissue returns to normal as damage is replaced by same cells
restituation of specialised function
what is healing by repair
tissue replaced by fibrosis and scaring
loss of specialised function
Describe a labile cell population
High cell turnover
active stem cell population
excellent regenerative capacity
e.g. epithelia
Describe a stable cell population
low cell turnover - can be inc
good regenerative capacity
liver/renal tubules
Describe a permanent cell population
No cell turnover
long life cells
NO regenerative capacity
e.g. neurones, muscle cells
what is crucial to regeneration?
survival of stem cells
tissue kinetics and architecture
explain the formation of granulation tissue
endothelial proliferation > new vessels > macrophage debridement > proliferation of myofibroblasts > collagen and EMC synthesised> myofibrils gain contractile ability –> wound contraction
what are factors inhibiting healing
Local
- blood supply
- haematomoa
- forgein body
- mechanical stress
- infection
Systemic
- diabetes
- anaemia
- malnutrition
- trace metal deficiet
- Vit C deficit
- catabolic state
- drugs
- age
what is healing by 1st intention
clean uninfected surgical wound,
wound edges apposed
good haemostats
= neat scar in a couple of weeks
what is healing by second intention
wound not apposable
increased granulation reaction
extensive scarring
how does wound strength progress
day 7 =10% sutures out
week 4 = 70%
week 12 = 80%
How does fracture healing occur
1) organised haematoma
2) removal of necrotic fragments
3) osteoblasts deposit woven bone - callus
4) callus remodelled by mechanical stress
5) callus replaced by lamella bone
How does healing occur in the brain
Neurons = terminally differentiated
cyst formation
Gliosis = proliferation of astrocytes (not scarring)
what is the commensal microbiota
the 90% of cells in the human body that are not of human origin
- flora associated varies depending on anatomical site
What are Koch’s postulates
1) causative organism can be isolated from every individual with disease
2) organism can be cultured artificually in lab
3) cultured organism causes disease when inoculated into person
4) cultured organism can be extracted from person inoculated
Koch’s postulates with regards to genes
Gene encode virulence factors
1) gene encoding train of interest must be presents and translated in a virulent strain
2) if gene not present or silent - strain should not cause disease
3) disruption of gene in virulent strain - incapable of causing disease
4) introduction into previously non pathogen stain causes transformation to virulence
5) gene is expressed during infection
6) antibodies raised against gene are protective against disease
Explain a Virus
obligate intracellular parasite
- nucleic acid core (RNA or DNA)
- protein coat - made of capsomeres
- retroviruses - rare
- plant viruses = viroids
Explain Microfungi
- eukaryotic
- cell walls made of chitin
- hairy growths = mould
- filaments of mould = hypae
- group of hypae = mycelia
- moulds = ringworm, atheletes foot
unicellular fungi - yeast
what are the protista
unicellular eukaryotes
1) apicoplxa (sporoza)
2) flagella protista
3) ciliate prostae
4) Amoebae
What is caused by Trichomonas vaginalis
foul smelling vaginal discharge and vaginal infection
What type of microorganism is Pneumocystis jiroveci (carinii)
FUNGUS
what does streptococcus mutants produce to help stick to teeth?
thick slime - helps to form plaque and eventually leads to dental cavities
what do “coagulase negative staphylococci” produce and where do they live?
on the skin
produce slime that enable them to stick to plastic
- associated with infection from implanted plastic medical devices
Explain bacteria
prokaryotes
- cocci = round,
- bacilli = rod
- gram -ve = pink = 2 membranes
- gram +ve = purple = 1 membrane
if encapsulated = protective from phagocytes
Routes by which infection can be spread
faecal oral Sexually direct innoculation airborne animal to human
What is a Zoonoses?
A bacterial reservoir in an animal that is disease causing
What is a Fomite
inanimate object used as a vector for the spread of disease
What is an intoxication illness
disease caused by exposure to a toxin not a microorganism
- tetanus, botulism
What type of toxins are produced by bacteria
endotoxin
exotoxin
Define normal flora
organisms found in a given location in a state of health
define colonisation
establishment at a site in the bodt
define symobiosis
two or more organisms coexist in close physical association
what are the types of symbiosis
Mutualism
Neutralism
Commensalism
Parasitism
Difference between non sterile and sterile sites?
non sterile = have normal flora
- exposed to environment
- no mechanism to maintain sterility
- conjunctiva, GI tract, vagina, skin, nasopharynx
sterile - no normal flora
- maintained by surface cleaning
lower respiratory tract
- maintained by unidirectional flow created by barriers
cervix, urethra, eustachian tube
- maintained by physical separation from non sterile sites
plural cavity, spinal cord meninges
what is tissue tropism
the propensity that a specific organism grows in an area
what are the physical variables that affect microenvironment?
moisture, temperature, pH, o2 availability, nature of surface
What are the normal skin flora
Coagulase-negative staphylococci (staph. epidermis)
- staph aureas (nasal)
- propionibacterium acnes
normal mouth flora
viridans
oral streptococci
anaerobes
+ many others
common flora of nasopharyngeal
Nostrils - skin flora, Staph aureus
Pharynx - respiratory and pathogens
- strep pyogenes group A
- haemophilus influenzae
- step pnuemoniae
- neisseria meningitidis
- s. aureus
Normal Vaginal flora
Prepuberty - skin flora, lower GI flora
Post puberty
- oestrogens produce glycogen changes environment
- Lactobacillus Spp = maintains pH 3
- skin flora
- candida albicans
GI - stomach and small intestine flora
low pH prevens bacterial growth
- acid tolerant lactobacilli
- helicobacter pylori
GI large intestine flora
10(9)-10(11) organisms/gram
95% anaerobes
areobic bacteria - Enteric gram -ve bacilli (E.coli, enterobacter spp, proteus spp)
benefits of normal flora
synthesis and excretion of vitamins (K and B12 from enteric bacteria)
- colonisation resistance (environmental manipulation e.g. pH)
- Induction of cross reactive antibodies - protective effect
C diff - infection
-hospital acquired
-usually affects >60yo
-antibiotic treatment = RISK
(inhibition of colonization resistance)
-toxin produces - diarrhoea
pseudomembranous colitis
What can be used to treat C diff
Vancomyocin
Faecal transplant
Pathology of normal flora
- Types
Overgrowth - Thrush
Translocation - conjunctivitis
Cross Infection - MRSA
conditions caused by normal flora
dental cavities, pharyngitis, endocarditis, abscesses, pneumonia
