Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
59 Cards in this Set
- Front
- Back
|
T/F Neurotransmitters do not cross the blood brain barrier easily
|
True
|
|
|
T/F Astrocyte foot processes surround cerebral capillaries to produce the physical properties of the BBB
|
False - Astrocytes do surround cerebral capillaries but their role is:
1) directing formation of tight junctions 2) regulating transporter expression 3) ion and neutrotrans homeostasis 4) producing immune mediators |
|
|
What type of junction produces the physical properties of the BBB
|
Continuous tight junction
|
|
|
Which areas of the brain are not equipped with the barrier structure?
|
Pituitary gland, some hypothalamus, area postrema and pineal gland
|
|
|
T/F: Substances with a high oil:water partition coefficient cross the BBB readily
|
True - A high O:W coefficient implies the substance is lipid soluble
|
|
|
Which glucose transporter is present in brain capillaries?
|
Glut-1
It is insulin insenstive |
|
|
Why is L-Dopa relatively more penetrating to the BBB than dopamine?
|
There is an L-Dopa transporter
|
|
|
Name 4 situations where BBB may fail
|
Stroke
Trauma Tumours Infectious AI Neurodegenerative Epilepsy |
|
|
T/F Penicillin cross the BBB effectively
|
False
It may do so during bacterial meningitis though when the BBB is breached |
|
|
T/F Carbon dioxide, nicotine and ethanol cross the BBB easily
|
True
|
|
|
What is the circadian variation in temperature?
|
Around 1 degree C
|
|
|
What is the cause of most heat loss at rest?
|
Radiation (~60%)
|
|
|
T/F Dehydration, humidity, clothing and capacity to redistribute cardiac output determine heat radiation
|
False - these factors contribute to evaporative heat loss
|
|
|
Which hormones may increase metabolic rate?
|
Thyroxine and adrenaline
|
|
|
Which area of the CNS detects deep temperature and responds to an increase or decrease in activity
|
Hypothalamic control centre
|
|
|
T/F Sweating is the principal mechanism of reducing temperature in exercise
|
False - Heat transfer from the core to the skin is the principal mechanism
|
|
|
T/F In fever, blankets and shivering are an attempt to reach set point
|
True - setpoint is elevated in fever causing shivering and behavioural responses
|
|
|
What is the mechanism of confusion in heat stroke?
|
Core temp rises > skin vasodilation > reduced blood pressure > reduced cerebral perfusion
|
|
|
Which areas are responsible for a) controlling heat loss in warm environments and b) conserving heat in cold
|
Hypothalamus
a) Preoptic area b) Posterior hypothalamus |
|
|
What are the three areas that afferent thermoreceptors may project to?
|
1) Sensory cortex
or via raphe pallidus to 2) Preoptic area (hypothal) 3) Dorsomedial hypothalamus |
|
|
What are the three main thermoregulatory outputs via raphe pallidus?
|
Sweat
Blood vessels Muscles |
|
|
What are the common organisms that cause acute bacterial meningitis
|
Meningococcus (nasal), Pneumococcus (blood),
HiB |
|
|
What would you expect to find in CSF following acute bacterial meningitis?
|
cloudy, neutrophils, low glucose, high protein
|
|
|
What organisms commonly cause acute viral meningitis?
|
Echo, coxsackie, mumps, measles
|
|
|
What CSF findings would you expect following acute viral meningitis?
|
Lymphocytes, normal glucose, protein normal or raised
|
|
|
What organisms commonly cause chronic viral meningitis?
|
Tuberculosis, cryptococcus
|
|
|
Meningitis generally occurs in which meningeal space?
|
Subarachnoid space
|
|
|
Herpes simplex encephalitis has a predilection for which area of cortex?
|
Temporal lobes
|
|
|
Acyclovir is used in which flavour encephalitis/es?
|
Herpes simplex, varicella-zoster,
|
|
|
Which vector spreads the Murray Valley encephalits?
|
Mosquitoes
(>birds>humans) |
|
|
Which organisms commonly cause CNS infection in immunosuppression?
|
CMV, toxoplasmosis, cryptococcus...
|
|
|
What is the name for a CNS infection involving brain AND spinal cord? Give one example.
|
Encephalomyelitis
e.g. poliomyelitis (motor neurons) varicella-zoster (DRG) |
|
|
Which parasite is commonly spread by cats?
Which virus is commonly spread flying foxes? |
cats - toxoplasma
flying fox - lyssa virus |
|
|
What is empyema?
|
Spread of infection through a natural (c.f. pathological) space
|
|
|
What are the four layers of abscess?
|
pus, macrophages, granulation tissue, astrocytes
|
|
|
What is the most common route of bacterial entrance in meningitis?
|
Spread from a contiguous focus
|
|
|
What is the most common organism responsible for meningitis following trauma?
|
Staphylococci
|
|
|
What are some examples of encapsulated bacteria and how does the body fight them?
|
HiB, Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes
Complement-mediated antibody response is important (requires spleen) because they are antiphagocytic. |
|
|
T/F Aminoglycosides are generally used to treat brain abcess
|
False - generally use 3'GC + metronidazole
The accumulation of lactate in the purulent abscess reduces pH and reduces their bactericidal activity. Aminoglycosides are water soluble and therefore also do not cross the BBB well. |
|
|
What are the typical meningitis A/B's and how are they administered?
|
Penicillins, 3rd generation cephalosporins (e.g. cefotaxime, ceftriaxome, ceftazidime) and carbapenems
Administered by high dose IV |
|
|
Quinolones, chloramphenicol, antifungal, antiretroviral and anti-TB drugs readily reach therapeutic CSF levels using standard doses and routes
|
True
|
|
|
What are the principles of beta-lactam therapy (related to MIC)?
|
1) Levels should exceed MIC for >40% of dosing interval and
2) Should ideally exceed ~5x MIC |
|
|
What percentage of organisms causing meningitis are resistant to penicillin?
|
~30%
|
|
|
What is the empirical therapy for meningitis of unknown cause?
|
7-10 days IV
1) Cefotaxime/Ceftriaxome (3rd generation cephalosporin) + 2) Penicillin (covers listeria) + 3) Vancomycin 4) Corticosteroids until organism identified and susceptibility available N.b. penicillin not required if 3mnths - 15 years old (listeria uncommon) |
|
|
What are the principle signs of a CNS infection in children?
|
Fever and altered consciousness
|
|
|
The sphenoid sinus may provide a route of intracranial spread to which areas?
|
Middle cranial fossa and cavernous sinus
|
|
|
What are the characteristic signs of coning?
|
CNIII paresis
Ipsilateral CsT signs (by cerebral peduncle compression) Coma |
|
|
Which cranial nerve is often compressed in tentorial herniation?
|
CNIII
|
|
|
Which cranial nerve is most likely to be effected by raised ICP?
|
CNVI
|
|
|
Which organisms are most common in neonatal (0-3mnths) CNS infections?
|
E.coli
Listeria Strep agalactiae |
|
|
What is the most common means of infectious organism entry in meningitis?
|
Hematogenous
|
|
|
Neural signals from vestibular receptors result in which three major effects?
|
Proprioception
Oculomotor responses Postural responses |
|
|
Otoliths sense what type of force?
|
Linear force
|
|
|
Semicircular canals sense what type of force?
|
Angular force
|
|
|
T/F Utricles are sensitive to horizontal movement and saccules are sensitive to vertical
|
True
|
|
|
Which centre is responsible for saccade movement generation?
|
Pontine paramedian reticular formation
(PPRF) |
|
|
Disordered pursuit (eye movement) is the result of what sort of lesion?
|
Central lesion
|
|
|
What are the two main types of cerebral edema? Which type causes intracellular fluid collection?
|
Vasogenic and toxogenic
Toxogenic |
|
|
Which type of herniation is most life threatening?
|
Cerebellar tonsillar - compresses brainstem
|
