BAB 3a

Question 1

What is the corticospinal tract?

Answer 1

Descending axons of upper motor neurons from the primary and supplementary motor area, and primary somatosensory area. They pass through the internal capsule, cerebral pedundle, basilar pons and form pyramids on the ventral surface of medulla. Most of these fibers cross at the lower part of medulla (motor Decussation) to form lateral corticospinal tract, which controls the movements of limb musculature. Some fibers remain on the ipsilateral side, form anterior corticospinal tract, and contribute to the control of axial musculature.

Question 2

What is the easy way to say the corticospinal tract?

Answer 2

a. white matter of hemispheres
b. internal capsule
c. cerebral peduncles (midbrain)
d. basilar pons and pyramids (medulla)

Question 3

Does the basal ganglia attach to the ipsi- or contralateral side of the cortex?

Answer 3

ipsilateral

Question 4

What can cause malignant hyperthermia?

Answer 4

Anesthetics (halothanes) and succinylocholine. (treat with dantrolene)

Question 5

What does Ketamine target?

Answer 5

NMDA receptor

Question 6

What do the following mean?

a. General anesthesia
b. Conscious sedation
c. Neurolept analgesia
d. Local anesthesia
e. Dissociative anesthesia

Answer 6

a. unrousable but reversible unconsciousness
b. anxiolysis and sedationn with arousal retained
c. opiate analgesia, disinterst and psychomotor retardation
d. local analgesia
e. catatonia, analgesia, amnesia, but w/o true unconsciouness

Question 7

What are clinical uses of local anesthetics?

Answer 7

a. reversible block of neural conduction
b. relax vascular smooth muscle
c. modest block of NMJ
d. increase AP duration and refractory period in Purkinje fibers and ventricular myocardium
e. mixed stim/depression of CNS

Question 8

What are some anesthetics that work by activating more GABAa?

What are some anesthetics that work by inhibiting NMDA receptors?

Answer 8

GABAa: Propofol, Etomidate, Midazolam

NMDA-R: Ketamine, Xenon, N2O

Question 9

What is the order of sensation loss with local anesthetics?

Answer 9

1. pain
2. temp
3. touch
4. pressure

Question 10

What is the big side effect of bupivicaine?

Answer 10

Severe ventricular arrhythmias

Question 11

What are the 4 stages of general anesthesia?

Answer 11

a. analgesia: pain sensation down
b. delirium: unconscious, irrational mov’t, pharyngeal muscles are intact
c. surgical anesthesia: loss of pharyngeal, muscle relaxation
d. medullary depression: CV collapse, marked CNS depression

Question 12

What are some qualities of the following:

a. thiopental
b. midazolam
c. ketamine
d. propofol

Answer 12

a. thiopental: quick onset, long half-life, hangover
b. midazolam: slower onset, cardio stable, sedation/amnesia
c. ketamine: bronchodilator, cardio stimulant, salivation
d. propofol: rapid onset/offset, easy titration, pain on injection

Question 13

What are the 5 characteristics of the “ideal drug”?

Answer 13

a. H20 soluble
b. sleep in one “arm-brain” cycle
c. rapid recovery with little accumulation
d. no metabolic effects
e. no immunologic or inflammatory effects

Question 14

Where are Amides metabolized?

Answer 14

liver

Question 15

Which inhalants are good for people with asthma? Which are bad?

Answer 15

good: halothane
bad: desflurane (lung irritant), enflurane (pungent)

Question 16

What is the main target of inhalation anesthetics? Local?

Answer 16

Inhalation: GABAa Cl- channels
Local: Na+ channels

Question 17

What is a Renshaw cell? What NT excites it?

Answer 17

It is the inhibitory cell used in Collateral Inhibition.

ACh.

Question 18

Neurons from the muscles spindle are excitatory or inhibitory? What is the shortest pathway for inhibition? What is the only known monosynaptic spinal reflex?

Answer 18

a. always excitatory
b. disynaptic
c. the sensory fibers from the muscle spindle (go to lamina IX with 1a afferent axons and synapse of alpha-motor neurons)

Question 19

The annulospiral ending (spindle fiber) is sensitive to what aspects of stretch?

Answer 19

rate and degree of stretch

Question 20

Where do the Gamma Motor Neurons work? What is their primary job?

Answer 20

On the end of the spindle fibers. They work to keep the length of the muscle constant.

Question 21

Compare and contrast golgi vs. spindle fibers.

Answer 21

Golgi: AP proportional to degree of stretch, 1b afferent, at least disynaptic, inhibitory (excites antag. muscle), slower to respond, responds to both stretch and contraction (tension)

Spindle: AP proportional to degree and rate of stretch, 1a afferent, monosynaptic excitatory (inhibits antag. muscle), quicker to respond, responds to stretch only

Question 22

What are the two tests for of motor system in the spinal cord and higher levels?

Answer 22

a. tendon reflexes: No rxn = lesion in sensory or motor neuron, spinal cord or muscle. Hyperreflexia = damage at higher levels
b. tone: Spasticity (Clasp knife) = hyperactivity of stretch reflexes… can be caused by collateral sprouting onto denervated synaptic sites.

Question 23

What is the primary pathway for voluntary mov’t in the spinal cord?

Answer 23

Lateral corticospinal tract.

Question 24

What type of cells are characteristic of the 5th cortical layer?

Answer 24

Betz cells

Question 25

What is the classic triad for an uncal hernia?

Answer 25

a. blown pupil (compression of CNIII)
b. hemiparesis
d. lethargy, obtundation, stupor, coma

Question 26

Is buprenorphine a partial mu agonist?

Answer 26

Yes. And a kappa antagonist.

Question 27

What are the 7 things assessed in the clinical evaluation of cognition?

Answer 27

a. level of consciousness
b. attention
c. language
d. memory
e. constructional ability
f. higher cognitive fxns
g. related cognitive fxns

Question 28

What percent of neurons in the striatum are medium spiny?

Answer 28

> 90%

Question 29

Is the STN hyper- or hypoactive in PD? What effect does deep brain stim have?

Answer 29

Hyperactive.

DBS blocks activity of STN and reduces the amount of GLU released. (Thalamus, cortex and STN are the only things that use GLU in the basal ganglia.)

Question 30

Where do the neurons from the GPi/SN-R mainly project?

Answer 30

Neurons from the GPi/SN-R project mainly to VA and a bit to VL, too.