MoD lectures 8-12 Flashcards
What are the two ways cells heal after inflammation?
regeneration and repair
What is regeneration?
damaged cells replaced by like so tissue returns to normal –> restitution of specialist function
What is repair?
damaged cells cannot be replaced by like so fibrosis and scarring –> loss of specialized function
What are the properties of labile cell populations and name some examples
- high normal cell turnover so maintain their integrity
- active cell populations sitting in the basal zone
- e.g. epithelia
What are the properties of stabile cell populations and name some examples
- low physiological turnover but can switch on turn over when the need arises
- e.g. liver and renal tubules
What are the properties of permanant cell populations and name some examples
- no physiological turnover, very long life cells
- e.g. neuron and muscle cells
Which type of cells are best at regeneration and which are worst?
best: labile
stabile
worst: permanant
What are adult stem cell niches?
reservoirs of adult stem cells present in adult tissues in specific anatomical places–> the survival of this is crucial to regeneration
What does uncontrolled cell division lead to?
neoplasia
Name some examples for how regeneration is controlled
contact inhibition (cells proliferate until they touch each other) and using growth factors, cell-cell and cell-matrix interactions
What is granulation tissue?
new connective tissue that forms on the surfaces of wounds during healing
it matures into a fibrous scar
What 3 components make up granulation tissue?
- new capillary loops
- phagocytic cells to remove dead tissue (neutrophils and macrophages)
- (myo)fibroblasts to lay down matrix components (e.g. collagen)
What is a catabolic state?
state of breaking down larger molecules to smaller ones proteins- amino acids fats- fatty acids glycogen- gluose e.g. corticol steroids. This interacts with the healing process
What is primary intention healing?
-healing of a clean, uninfected surgical wound with good haemostasis with edges apposed
What is organisation?
The formation of a fibrous scar and converting to a fibrous scar
What is secondary intention healing?
the wound edges are not opposed causing more extensive scarring
What cells form a callus?
osteoblasts which lay down woven bone (callus) which is then replaced by lamellar bone
What is the supporting tissue in the brain?
glial cells instead of collagen and fibroblasts etc
What does damaged tissue form in the brain?
a cyst
What is gliosis?
proliferating of astrocytes in the brain (instead of scarring)
Name some local factors which inhibit healing
infection, haematoma, blood supply, foreign bodies, mechanical stress
Name some systemic factors which inhibit healing
age, drugs, anaemia, diabetes, malnutrition, catabolic states, vit c deficiency, trace metal deficiency
What is an akaryote?
cell without a nucleus e.g. RBC
What is a prokaryote?
microscopic single-celled organism which has neither a distinct nucleus with a membrane nor other specialized organelles
What is a eukaryote?
organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus
What are virulent micro-organisms?
microorganisms which cause disease
What is Koch’s postulates?
criteria used to describe if a microorganism caused disease
1 the causative organism must be isolated from every individual suffering from the disease in question
2. the causative organism must be cultivated artificially in pure culture
3. When the causative organism, is inoculated from pure culture, the typical symptoms of the infection must result
4. the causative organism must be recoverable from individuals who are infected experimentally
What organism causes syphilis?
treponema pallidum
What causes typhoid fever?
salmonella typhi
What is the protein coat that surround the nucleic acid core of a virus made up of?
capsomeres
What is a virus envelope made up of?
lipid and usually derived from the cell in which they grow
What is the nucleic acid core of a virus made up of?
DNA or RNA but not both
How are retroviruses different from normal ones?
the virion carries an RNA copy of the genome but upon infection of a host cell a cDNA copy of the virus genome is made using reverse trancriptase
what are bacteriophages?
special class of bacteria which attacks viruses
What are viroids?
naked, infectious RNA molecules that are not associated with any proteins, commonly attack plants
What are prions?
a small infectious particle that is a disease-causing form of a protein called cellular prion protein (PrPc)
What is another name for prion diseases?
transmissible spongiform encephalopathies (TSE’s)
including: CJD, scarpie and BSE
What is a microfungi cell wall made up of?
chitin: a polymer of N-acetyl glucosamine that is found in the cell wall of the majority of fungi
What are two superficial infections that mould causes?
ringworm and athletes foot
What is thrush caused by?
candida albicans
What are moulds?
fungi that grow inmats of tiny filaments known as hyphae or myselia. They may be subdivided into separate compartments by corss walls known as septa
What are protists?
unicellular eukaryotes
What are the 4 classes of protista?
apicomplexa
flagellate protista
ciliate protista
amoebae
What are the 3 basic shapes that a bacteria can adopt?
round- cocci
rod-shaped bacilli
spiral
How does the gram stain affect gram pos and gram neg bacteria?
gram pos retain the purple iodine dye complex when treated with acetone or alcohol and gram neg don’t so turn pink
What does the envelope of gram positive comprise of?
peptidoglycan
interlinked sugar molecules and short peptides containing both D- and L- amino acids
teichoic and teichuronic acides
What is responsible for gram negative shock?
lipid A which acts as an endotoxin
What is dental caries caused by?
streptococcus mutans
it produces extracellular slime to allow it to stick to teeth
What GI infections are spread through the faecal oral route?
typhoid, scholera, dysentry, hep A and poliomyelitis
What is a zoonosis?
disease which can be spread from animals to human
What are fomites?
objects or materials which are likely to carry infection
How do bacteria stick to surfaces?
pili and fimbrae
define symbiosis
two or more organisms co-exist in a close physical association
define mutalism
both organisms benefit from symbiosis
define commensalism
one organisms benefits, the other derives no harm or benefit
define neutralism
neither organism derives harm or benefit
define parasitism
one organism benefits are the expense of the other
define tissue tropism
propensity for a particular organism to grow in a particular habitat
What is the difference in normal flora between breast fed babies and bottle-fed babies
breast-fed: predominanttly bifidobacteria and lactobacillus
bottle-fed: more enterobacteriacae
Name some skin flora
coagulose negative staphylococci (staphylococcus epidermis)
staphylococcus aureus
propionibacterium acnes
Name some pharynx flora
streptococcus pyogene (gorup A) haemophilus influenzae streptococcus pneumoniae neisseria meningitidis s. aureus
What bacteria are in the stomach or small intestine?
acid tolerant lactobacilli
helicobacter pylori
predominantly aoerobic, low gastric pH inhibits bacterial growth
What is the most common type of bacteria in the large intestine?
anaerobes: bacteriodes spp, clostridium spp, bifidobacteria spp
What secretes vit b12 and k?
enteric bacteria
What is the best treatment for C.difficile?
faecal transplants (+/- vancomyacin)
What are 3 ways that normal flora can cause disease?
- overgrowth e.g. vaginal thrush
- translocation e.g. conjunctivitis
- cross infrection e.g. MRSA
What clinical conditions are caused by normal flora?
abscesses, pneumonia, gastroenteritis, peritonitis, urogenital infections, endocarditis, dental caries, peridontal disease, pharyngitis
What is pathogenicity?
the capacity of a micro-organism to cause an infection.
It requires: transmissibility, establishment in or on a host, harmful effect, oresistence
What is a pathogenic organism?
organisms of sufficient virulence
What is infectivity?
the ability of a micro-organism to become established in/on a host
What are virulence factors?
components of micro-organisms that result in the harmful effects
What is the dose of an organism that would cause death?
LD50
What is the dose of an organism that would cause infection?
ID50
define colonisation
the process of an organism becoming maintained on or in a host
Name 3 receptor-ligand interactions between a micro-organism and a host cell that causing colonisation
E.coli P fimbrae: glyoclipids on human uroepithelial cells
S pyogenes protein- F : fibronectin 1 in connective tissue
influenza haemagglutin : respiratory epithelial sialic acid receptors
What is the active component in endotoxins?
lipopolysaccharide- LPS. Consists of lipid A, oligosaccharide cor and polysaccharide “o” antigen
lipid A causes harm
What is systemic inflammatory response syndrome? (SIRS)
the host response to endotoxin, emcompases imprecise terms like septic shock and endotoxic shock
causes: uncontrolled cytokine release, hypotension, fever, cardiac and/or renal failure, uncontrolled activation of clotting cascade, DIC
what are exotoxins produced by?
living bacteria
What is botulism caused by?
clostridium botulinum (gram pos baccilus, anaerobe)
What are the clinical presentations of botulism? (5 D’s)
diplopia dysphagia dystharia dry mouth death (due to respiratory failure)
What is tetanus caused by?
clostridium tetani
How does the clinical presentation differ between tetanus and botulism?
botulism causes flaccid paralysis and tetanus causes rigid paralysis ‘opisthotonis’
Name the causes of these exotoxin-mediated infections
a) cholera
b) diphtheria
c) whooping cough
d) scarlet fever
a) vibrio cholerae
b) corynebacterium diptheriae
c) bordetella pertussis
d) streptococcus pyogenes
Name s.pyogenes virulence factors (5)
- hyaluronidas and streptokinase (breaks down connective tissue)
- C5a peptidase (inactivates C5a)
- erythrogenic toxin (causes rash of scarlet fever)
- toxic shock syndrome toxin
Which micro-organisms evade the immune system by inhibit phagocytosis?
s. pyogenes and s. pneumoniae
Which micro-organisms evade the immune system by hiding in host cells?
mycobacterium tuberculosis, salmonella typhi and listeria monocytogenes
