L01: Neuroanatomy/Neuro Exam (Carrera)

Question 1

Nernst Potential

Answer 1

diffusion potential level across a membrane that exactly opposes the net diffusion of a particular ion through the membrane

• determined by the ratio of the concs. of an ion on the 2 sides of the membrane
• helps establish resting membrane potential

Question 2

K/Na “leak” channels are most permeable to:

Answer 2

K+

Question 3

membrane potential must be what to depolarize?

Answer 3

0

Question 4

what happens during depolarization

Answer 4

• increase in Na permeability, influx of positive

- potential may approach 0 or greater

Question 5

what happens during repolarization

Answer 5

• Na channels begin to close
• K channels open more
• re-establishment of RMP

Question 6

Ca deficit –> Na channels

Answer 6

activates them with little increases in membrane potential, leading to a very excitable nerve (tetany)

Question 7

action potential threshold is reached when:

Answer 7

Na ions entering the fiber >K+ leaving the fiber

Question 8

AP propagation

Answer 8

AP elicited at any point on an excitable membrane exites adjacent portions of the membrane

Question 9

Refractory period due to:

Answer 9

Na channels becoming inactivated

Question 10

how is excitation inhibited?

Answer 10

high extracellular Ca (dec. permeability to Na)

local anesthetics to block Na channels

Question 11

perikaryon

Answer 11

cell body of a neuron

Question 12

myelin sheath composed of what in PNS

Answer 12

Schwann cells

Question 13

larger diameter fiber has faster or slower conduction?

Answer 13

faster

Question 14

how are postsynaptic receptors excited?

Answer 14

opening of Na channels

dec. conduction through Cl/K channels

Question 15

how are postsynaptic receptors inhibited?

Answer 15

opening of Cl channels

inc. K+ out of the neuron

Question 16

which NT excitatory

Answer 16

Ach (usually)

Question 17

Where NE synthesized

Answer 17

adrenergic n. terminal

-reuptake into adrenergic endings, diffused away, or enzymatically destroyed

Question 18

presynaptic inhibition

Answer 18

release of inhibitory substance (GABA) onto presynaptic fibrils

• cancels effect of Na influx
• occurs in many sensory pathways to minimize sideways spread

Question 19

where do APs begin?

Answer 19

Axon initial segment (loaded with Na channels)

Question 20

alkalosis inc./dec. excitability for synaptic transmission?

Answer 20

increases

Question 21

end plate potential

Answer 21

local positive potential in the muscle fiber created by inlux of Na into m. fiber

Question 22

sarcoplasm

Answer 22

fluid filling spaces b/w myofibrils in a m. fiber

Question 23

sarcolemma

Answer 23

true cell membrane in muscle

Question 24

myofibrils

Answer 24

make up muscle fiber; actin and myosin filaments

-myosin heads controlled by ATP-ase

Question 25

what activates actin and myosin sliding?

Answer 25

Ca influx

Question 26

transverse tubules

Answer 26

penetrate through muscle fibers to communicats APs deep into muscle

Question 27

can APs be generated by stretch?

Answer 27

yes

Question 28

which fibers secrete Ach?

Answer 28

cholinergic

Question 29

which fibers secrete NE?

Answer 29

adrenergic

Question 30

all preganglionic neurons are ____

Answer 30

cholinergic

Question 31

Most parasympathetic postganglionic neurons are ___

Answer 31

cholinergic

Question 32

most sympathetic postganglionic neurons are ____

Answer 32

adrenergic

Question 33

where are muscarinic receptors found

Answer 33

on all effector cells stim. by postganglionic cholinergic neurons of sympathetic or PS systems

Question 34

where are nicotinic receptors found

Answer 34

- found in autonomic ganglia at synapses b/w pre and postganglionic neurons of sympathtic and PS systems - NMJ

Question 35

NE excites mainly alpha/beta receptors

Answer 35

alpha

Question 36

what detects m. stretch

Answer 36

muscle spindle

Question 37

golgi tendon organs

Answer 37

- detect m. tension - sensory - locally inhibitory to a single muscle

Question 38

alpha motor neuron fx

Answer 38

innervate skeletal m.

Question 39

gamma motor neuron fx

Answer 39

- transmit impulses through smaller nerves | - controls m. tone

Question 40

Renshaw cells

Answer 40

prevent neurons from firing inappropriately (inhibited in Strychnine poisoning)

Question 41

Forebrain = ***

Answer 41

cerebrum (cerebral cortex, hippocampu, basal nuclei) | diencephalon (thalamus, hypothalamus)

Question 42

Midbrain = ***

Answer 42

(mesencephalon) cn3,4 rostral and caudal colliculi

Question 43

Cerebellum = ***

Answer 43

cn5-12 motor tracts proprioceptive tracts

Question 44

Brainstem = ***

Answer 44

connection to cn8 unconscious proprioception (inhibitory)

Question 45

Ascending Reticular Activating System fx

Answer 45

receives sensory info from the spinal cord and cranial nerves. Projects, through thalamic relays, diffusely to the cerebral cortex, thus maintaining consciousness

Question 46

superficial to deep on spinal cord: proprioceptive tracts --> motor tracts --> pain

Answer 46

:)