Nerve Physiology

Question 1

At rest, is potential positive or negative intracellular vs extracellular?

Answer 1

Intracellular = negative 
Extracellular = positive

Question 2

At rest what does the sodium potassium ATP pump do

Answer 2

Pumps out three sodium ions while pumping in 2 potassium ions

Question 3

And rest what is the difference in sodium and potassium concentration intracellularly versus extracellularly

Answer 3

More sodium outside and more potassium inside

Question 4

Effect of decreased temperature on velocity, amplitude and latency

Answer 4

Decreased velocity, increased latency, increased amplitude for focal cooling and decreased amplitude for generalized cooling

Question 5

What does a decrease in temperature do to sodium channel gates?

Answer 5

Delays opening and closing of gates.

Question 6

Orthodromic versus antidromic

Answer 6

Orthodromic is in the direction of physiologic conduction and antidromic is opposite direction of physiologic conduction

Question 7

Orthodromic of motor and sensory fibers

Answer 7

Motor is away from spinal cord and sensory is toward spinal cord

Question 8

Antidromic of motor and sensory fibers

Answer 8

Motor is toward spinal cord and sensory is away from spinal

Question 9

MEPPs vs EPP vs MUAP

Answer 9

Miniature endplate potentials (MEPP) = spontaneous release of quanta at rest
Endplate potential (EPP) = multiple MEPP summate to make EPP
Motor Unit Action Potential (MUAP) = When EPP is high enough, it generates a MUAP

Question 10

What is the safety factor?

Answer 10

EPP’s amplitude is much larger than needed to create an action potential which allows time for Ach storage compartments to replenish

Question 11

Safety factor depends on what 2 factors

Answer 11

Quantal content and quantal response

Question 12

What is the quantal content

Answer 12

of Ach quanta release with each nerve depolarization

Question 13

What is quantal response

Answer 13

Ability of Ach receptors to respond to Ach

Question 14

What 2 main proteins make up skeletal muscle fibers

Answer 14

Actin and myosin

Question 15

Basic unit of a muscle myofibril

Answer 15

Sarcomere

Question 16

Z-lines

Answer 16

Length of sarcomere

Question 17

H zone

Answer 17

Actin to actin length

Question 18

I zone

Answer 18

Myosin to myosin

Question 19

A band

Answer 19

Length of myosin filament

Question 20

What happens to sarcomere length, Z lines, H zone, A band, I band during contraction?

Answer 20

Sarcomere length - decreases as Z lines move closer to each other.
H zone - gets smaller as actin filaments get closer.
A band - Stays the same because myosin length doesn’t change during contraction.
I band - gets smaller as myosin filaments get closer

Question 21

What is the only section of the sarcomere that does not change in size with contraction

Answer 21

A band

Question 22

Action potentials penetrate through the muscle through the _________

Answer 22

T-tubules

Question 23

Calcium binds to what to cause muscle contraction

Answer 23

Troponin-tropomyosin complex

Question 24

What is exposed when calcium binds to muscle filaments

Answer 24

Actin active sites

Question 25

What allows muscle relaxation

Answer 25

ATP pumps that pump calcium out