Unit 5 - Chapter 22 Flashcards Preview

Uncategorized > Unit 5 - Chapter 22 > Flashcards

Flashcards in Unit 5 - Chapter 22 Deck (43)
1

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

2

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

3

chloramphenicol w/ respect to the blood-brain barrier

antibiotic that enters brain readily b/c it is lipid soluble

4

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

5

how do microorganisms invade the CNS?

1. through trauma (skull fracture or fracture of the vertebral column);
2. by a medical procedure (spinal tap);
3. microorgs can move along peripheral nerves; and
4. via bloodstream or lymphatic system when inflammation alters the permeability of the blood-brain barrier.

6

bacterial meningitis: bacterias that cause 70% of the cases and 70% of the related deaths

1. gram+ diplococcus Streptococcus pneumoniae;
2. Gram- Haemophilus influenzae;
3. Gram- neisseria meningitidis

7

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.

8

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.

9

meningitis symptoms

fever, headache, stiff neck... followed by nausea and vomiting

10

meningitis diagnosis

diagnosis based on gram stain and serological tests of the bacteria in CSF

11

meningitis treatment

cephalosporins may be administered before identification of the pathogen.

12

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)

13

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

14

Tetanus symptoms

spasms
lockjaw
death

15

C. tetani toxin

exotoxin, A-B toxin, blocks nerve impulses to muscle relaxation pathway, results in noncontrollable muscle contractions

16

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

17

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.

18

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.

19

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

20

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.

21

botox

toxin of C. botulinum used to decrease wrinkles

22

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

23

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.

24

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

25

poliomyelitis diagnosis

based on isolation of the virus in feces and throat secretions

26

poliomyelitis treatment

S: IPV
S: OPV

Salk vaccine (inactive polio vaccine, or IPV) involves injection of formalin-inactivated viruses and boosters every few years.

Sabin vaccine (oral polio vaccine, or OPV) contains three live, attenuated strains of poliovirus and is administered orally.

27

rabies symptoms

spasms of mouth and throat muscles,

virus multiples in skeletal muscles and connective tissue. results in fatal encephalitis when virus moves along peripheral nerves to the CNS.

extensive brain and spinal cord damage and death

28

rabies contraction

through bite of rabid animal (esp dangerous when bitten in areas rich in nerve fibers (hands/face));

by inhalation of aerosols when macerating infected tissue in a laboratory blender;

invasion through minute skin abrasions.

Mostly from dogs, cats, domestic cattle; but also happens by bats, skunks, foxes, raccoons, silver-haired bats and vampire bats.

Never in squirrels, rabbits, rats, or mice.

29

rabies diagnosis

alive
dead

When patient/animal is alive, diagnosis is sometimes confirmed by immunofluorescent studies, in which viral antibodies are detected in saliva, serum, or CSF.

After death, diagnosis is confimed by fluorescent-antibody (F-A) test performed on brain tissue.

30

rabies treatment
post
pre

postexposure: PEP (postexposure prophylaxis -- administration of human rabies immune globin (RIG) along with multiple intramuscular injections of vaccine. Preexposure consists of vaccination, but only for high-risk individuals (lab workers, animal control professionals, veterinarians) are routinely vaccinated before known exposure.

31

Arboviral encephalitis causative agent

mosquito borne viruses (arboviruses)

32

Arboviral encephalitis symptoms

encephalitis (brain swolls); increases in summer months when mosquitos are more prevalent

33

most notable arboviral infections

eastern equine encephalitis (EEE); western equine encephalitis (WEE), St. Louis encephalitis (SLE); California encephalitis (CE); west nile virus (WNV)

34

arboviral encephalitis diagnosis

serological tests

35

arboviral encephalitis control

control of the mosquito vector is the most effective way to control encephalitis

36

prions

abnormally folded self-replicated proteins with no detectable nucleic acid that can induce change in the shape of a normal protein, causing proteins to clump

37

nervous system diseases caused by prions

incubation time, measured in (unit of time)
Damage is:
Symptoms:

have long incubation times, measured in years. CNS damage is insidious and slowly progressive, with the fever and inflammation seen in encephalitis.

38

prion autopsies shows what characteristics?

show characteristic spongiform (porous, like a sponge) degeneration of the brain, as well as characteristic fibrils in brain tissue.

39

transmissible spongiform encephalopathies (TSE)

disease caused by prions

40

sheep scrapie

occurs in animals, infected animal scrapes itself against fences and walls until areas of its body are raw. Animal gradually loses motor control and dies. Infection can be experimentally passed to other animals by injection of brain tissue from one animal to the next.

41

Creutzfeldt-Jakob disease (CJD)

who suffers?
caused by what?
some cases traced to injection of what:

TSE disease that humans suffer from that is similar to scrapie. Transmission is via corneal transplants and accidental scalpel nicks from a surgeon during autopsy. Some cases are traced to injection of growth hormone derived from human tissue.

42

Kuru

TSE disease of humans in new guinea, Transmission is related to cannabalistic rituals

43

Bovine spongiform encephalitis (BSE)

aka mad cow disease, origin is from feed supplements contaminated with prions from sheep infected w/ scrapie