Unit 5 - Chapter 22 Flashcards
(43 cards)
structure and significance of blood-brain barrier
prevents:
capillaries are:
drugs must be:
special carrier mechanisms for:
barrier which prevents many substances, including antibiotics, from entering the brain.
Capillaries are less permeable than others within the body, and more selective in passing materials.
Drugs cannot cross blood-brain barrier unless they are lipid soluble.
There are special carrier mechanisms for glucose and some amino acids
inflammation and the blood-brain barrier
tends to alter blood-brain barrier to allow antibiotics to cross that would not be able to cross if there were no infection
chloramphenicol w/ respect to the blood-brain barrier
antibiotic that enters brain readily b/c it is lipid soluble
penicillin w/ respect to the blood-brain barrier
only slightly lipid-soluble, but if taken in large enough doses, may cross the barrier to be effective
how do microorganisms invade the CNS?
- through trauma (skull fracture or fracture of the vertebral column);
- by a medical procedure (spinal tap);
- microorgs can move along peripheral nerves; and
- via bloodstream or lymphatic system when inflammation alters the permeability of the blood-brain barrier.
bacterial meningitis: bacterias that cause 70% of the cases and 70% of the related deaths
- gram+ diplococcus Streptococcus pneumoniae;
- Gram- Haemophilus influenzae;
- Gram- neisseria meningitidis
How do those 3 cause meningitis?
last part: they might enter:
All 3 possess a capsule that protects them from phagocytosis as they replicate rapidly in the bloodstream from which they might enter the cerebrospinal fluid.
Death & meningitis
speed at which it occurs
due to what symptoms
caused by release of what
Death from bacterial meningitis often occurs very quickly, probably from shock and inflammation caused by release of endotoxins of the gram-negative pathogens or the release of cell wall fragments (peptidoglycan and teichoic acids) of gram-positive bacteria.
meningitis symptoms
fever, headache, stiff neck… followed by nausea and vomiting
meningitis diagnosis
diagnosis based on gram stain and serological tests of the bacteria in CSF
meningitis treatment
cephalosporins may be administered before identification of the pathogen.
Tetanus cause
endospore status
gram status
aerobic status
shape
local infection of a would by Clostridium tetani. Obligate anaerobe grows in deep, unclean wounds. It is endospore-forming, gram+, and rod-shaped (bacillus)
Clostridium tetani pathogenic effects
invasiveness pathogenic effects due to: neurotoxin produced: spreads via: causes:
C. tetani is not invasive, does not spread from the site – pathogenic effects are due to toxicity. C. tetani produces the neurotoxin tetanospasmin–spreads via neural cells and causes spastic paralysis, which causes the symptoms of tetanus
Tetanus symptoms
spasms
lockjaw
death
C. tetani toxin
exotoxin, A-B toxin, blocks nerve impulses to muscle relaxation pathway, results in noncontrollable muscle contractions
Muscle contraction normal vs tetanus
normal: inhibitory interneuron releases glycine that binds to motor neuron and blocks excitation signals from CNS and stops release of acetylcholine so muscles relax.
tetanus: toxin binds to interneuron and inhibits release of glycine so motor neuron continues to release acetylcholine, thus muscle contractions continue
Tetanus immunization, unimmunized people, and control of infection
acquired immunity results from DPT immunization and booster (every 10 years). unimmunized persons can get tetanus immune globulin. Debridement (removal of tissue) and antibiotics may be used to control infection.
Botulism cause
aerobic
causative agent
spores
toxin (endo/exo) inhibits:
Anaerobe Clostridium botulinum that grows in canned goods under anaerobic conditions - has endospores
exotoxin (neurotoxin) that inhibits transmission of nerve impulses.
Botulism symptoms
blurred vision for 1-2 days;
progressive flacid paralysis follows for 1-10 days,
possibly resulting in death from respiratory and cardiac failure
Botulism diagnosis
diagnosed by inoculating mice with samples from patient serum, stool, or vomit specimins. Different sets of mice are immunized with type A, B, or E antitoxin. All the mice are innoculated w/ test toxin; if those protected w/ type A antitoxin are the only survivor, then the toxin is type A.
botox
toxin of C. botulinum used to decrease wrinkles
viral diseases of the nervous system
most enter via:
some can enter:
most enter by circulation of the blood or lymph; some viruses can enter peripheral nerve axons and move along them toward the CNS
poliomyelitis symptom
old people vs young people
best known for causing paralysis, which only affects 1% of those infected w/ polio. most cases are asymptomatic or exhibit mild symptoms such as headache, sore throat, and nausea, and happens in young people. older people will exhibit more of the paralytic form of the disease.
poliomyelitis invasion
1st
2nd
transmitted by ingestion of contaminated feces water.
first invades lymph nodes of neck and small intestine.
viremia and spinal cord involvement may follow
