BBB, Neurotransmitters, Dermatomes B&B

Question 1

what are the 4 major circumventricular organs (CVOs)?

Answer 1

1. area postrema
2. OVLT (organum vasculosum of the lamina terminalis)
3. subfornical organ (SFO)
4. median eminence of the hypothalamus

Question 2

where is the area postrema found, and what is this area known for?

Answer 2

caudal end of the 4th ventricle in the medulla

circumventricular organ (CVO) - “chemoreceptor trigger zone” (chemo agents affect this area, cause signaling to the vomiting center in the medulla)

Question 3

where is the OVLT found, and what kind of neurons does it contain?

Answer 3

OVLT (organum vasculosum of the lamina terminalis): circumventricular organ (CVO) found in anterior wall of third ventricle

contains osmosensory neurons

Question 4

where is the subfornical organ (SFO) found?

Answer 4

circumventricular organ (CVO, no BBB)

found in anterior wall of third ventricle

Question 5

what is the main source of norepinephrine in the brain?

Answer 5

locus ceruleus in the posterior pons, near the 4th ventricle

Question 6

where are the 2 locations within the brain in which dopamine is synthesized?

Answer 6

1. ventral tegmentum
2. substantia nigra

both in midbrain

Question 7

how do dopamine levels differ in schizophrenia vs Parkinson’s?

Answer 7

schizophrenia - increased dopamine
Parkinson’s - decreased dopamine

Question 8

where is GABA synthesized in the brain? which enzyme is required? which vitamin is required as a cofactor for this reaction?

Answer 8

(gamma-aminobutyric acid)

synthesized in nucleus accumbens (pleasure/reward center) via glutamate decarboxylase (requires B6!)

Question 9

activation of GABA receptors allow which ion to flow into the cell? where are GABA(A) vs GABA(B) vs GABA(C) receptors found?

Answer 9

GABA receptor activation —> chloride influx

GABA(A/B) found in brain, GABA(C) found in retina

Question 10

where is serotonin synthesized in the brain?

Answer 10

raphe nucleus (pons)

Question 11

what is the classic triad of serotonin syndrome?

Answer 11

(aka too much serotonin)

1. mental status change
2. autonomic hyperactivity (tachycardia, hyperthermia, diaphoresis)
3. neuromuscular abnormalities (tremor, clonus, hyperreflexia, bilateral Babinski sign)

Question 12

how can neuroleptic malignant syndrome (NMS) be differentiated from serotonin syndrome?

Answer 12

both —> muscle rigidity, fever, change in mental status, autonomic instability

NMS (rxn to neuroleptic medications) —> “lead pipe” rigidity, high creatine kinase (CK) levels

serotonin syndrome —> clonus (rhythmic muscle spasms)

Question 13

Pt presents to the ED with fever, confusion, and rigid muscles. PMH is significant for depression. What drug will you administer to reverse these symptoms?

Answer 13

patient is experiencing serotonin syndrome from anti-depressants

treat with cyproheptadine (5-HT antagonist, also anti-histamine)

Question 14

where is acetylcholine synthesized in the brain?

Answer 14

basal nucleus of Meynert (subcortex)

Question 15

the symptoms of Huntington’s are due to neuronal death from _____ toxicity

Answer 15

glutamate toxicity - binds NMDA (N-methyl-D-aspartate) receptor, excessive calcium influx

glutamate = major excitatory neurotransmitter

Question 16

to which receptor does phencyclidine (PCP, “angel dust”) bind?

Answer 16

antagonist of NMDA (N-methyl-D-aspartate) receptor for glutamate (major excitatory NT)

—> violent behavior, hallucinations, ataxia, nystagmus (uncontrolled, repetitive eye movements), HTN, tachycardia, diaphoresis, seizures, coma

Question 17

damage to spinal nerve T10 causes referred pain to where? where does this pain actually originate?

Answer 17

T10 = umbilicus, referred pain for appendicitis

common first symptom of appendicitis is pain in the belly button

Question 18

which spinal nerves are being tested by the following reflexes?
a. biceps
b. triceps
c. patella
d. achilles

Answer 18

a. biceps - C5
b. triceps - C7
c. patella - L4
d. achilles - S1

Question 19

how can nerve root syndromes originating in L5 vs S1 be differentiated (2 most common)?

Answer 19

L5 (L4/L5 disc) —> back pain down lateral leg, foot strength reduced, reflexes normal

S1 (L5/S1 disc) —> pain down back of leg, weak plantar flexion, ankle reflex lost

Question 20

what is the Babinski sign

Answer 20

aka plantar reflex - rubbing bottom of foot should cause downward pointing toes (plantar flexion)

“upward going toes” (dorsiflexion) is a positive Babinski sign, indicates UMN damage (but normal in infants, due to incomplete myelination)

Question 21

what are the 6 primitive reflexes (present in babies)?

Answer 21

1. moro reflex: baby dropped slightly on back will spread arms, then retract them, then cry
2. rooting: baby turns cheek towards side of stroke
3. sucking: baby sucks anything touching roof of mouth
4. palmar: baby will grasp anything stroking palm
5. plantar: Babinski reflex, “upward going toes”
6. galant: baby swings legs side to side if stroked on their back

Question 22

how does CSF sampling differ between bacterial and viral meningitis?

Answer 22

bacterial: high protein, low glucose, HIGH WBC

viral: mildly high protein, normal glucose, normal/mildly high WBC (lymphocytes)

Question 23

what are the 3 components of the BBB?

Answer 23

1. endothelial tight junctions
2. perivascular pericytes
3. astrocyte foot processes