Module 11

Question 0

What does the motor unit consist of?

Answer 0

Alpha motor neurons and all fibers it innervates

Question 1

What two ways is the skeletal muscle innervated?

Answer 1

Motor unit

Neuromuscular junction

Question 2

What is the muscle to nerve ratio of the motor unit?

Answer 2

Small 1:5 in tongue muscles; small ratio if if needs to be more precise

Large 1:900 in leg; for gross movements

Question 3

What is the neuromuscular junction?

Answer 3

Termination of a peripheral nerve fiber on skeletal muscles

Question 4

Where is the motor end-plate?

Answer 4

Where the axon terminal synapses with the muscle fiber

Question 5

Is the motor end plate part of the post synaptic membrane?

Answer 5

Yes!

Question 6

What is the ratio of motor end plates per muscle fiber?

Answer 6

1:1; one end plate to EVERY fiber

Question 7

What is the mV of the membrane potential in a neuro at rest?

Answer 7

-70 mV

Question 8

What is membrane potential?

Answer 8

Measure of voltage between two points: the voltage across the membrane

Question 9

How is MP (membrane potential) created?

Answer 9

Metabolic activity that:

Continuously diffuses potassium (K+)
and
SELECTIVE transport of substances through cell membrane using gating mechanisms

Question 10

Inside of the cell there is a HIGH concentration of…

Answer 10

Anions (An-)
Potassium ions (K+)

Question 11

Outside of the cell there is a HIGH concentration of…

Answer 11

Sodium ions (Na+)
Chloride ions (Cl-)

Question 12

The resting cell is permeable and impermeable to what ions?

Answer 12

Impermeable to Na+

Permeable to K+ (so they leak out leaving An- which cause the cell to remain negative)

Question 13

What is neuron excitability?

Answer 13

Allows neuron to respond to stimulus

Sends signals in electrical forms

Question 14

What is it called when the signal is transmitted over a nerve fiber and the MP goes through a series of changes?

Answer 14

Action potential

Question 15

What is an action potential?

Answer 15

Nerve impulse

Question 16

How are AP elicited?

Answer 16

By anything that suddenly increases the permeability of the cell membrane to Na+

Question 17

What two types of stimulus can elicit an action potential?

Answer 17

Physical

Chemical

Question 18

How much membrane potential increase is needed to evoke an AP?

Answer 18

+10 mV or more

Question 19

How do transmission of neural signals occur?

Answer 19

Release of chemical stimulus (neurotransmitter)

Physical stimulus (pressure/pain/temperature)

Question 20

What is the difference between polarization, depolarization and repolarization?

Answer 20

Polarization- resting state

Depolarization- positive change

Repolarization- return to resting state

Question 21

How is AP conducted in myelinated axons?

Answer 21

Via saltatory conduction

Axon jumps from node to node (fasted conduction)

Question 22

How is AP conducted in unmyelinated axons?

Answer 22

General spread of AP

Gradual depolarization (slower conduction)

Question 23

How does AP Code information?

Answer 23

By response frequency

Question 24

What is a refractory period?

Answer 24

Period IMMEDIATELY after the AP is triggered

Question 25

Name the 2 components of a refractory period

Answer 25

Absolute refractory period | Relative refractory period

Question 26

Is a refractory period shorter in smaller diameter neurons?

Answer 26

No!! It's shorter in longer diameter neurons

Question 27

What is the absolute refractory period?

Answer 27

Neuron said to be hyperpolarized AP can not be generated Last for 2 msec

Question 28

What is the relative refractory period?

Answer 28

Membrane is NOT fully repolarized | AP can be produced with a STRONG stimulus

Question 29

what is the ALL or nothing principle?

Answer 29

Adequate stimulus fires to AP; it can not be partially fired

Question 30

What two things can neurotransmitters influence the post-synaptic membrane to do?

Answer 30

Excite Or Inhibit

Question 31

What's a generator potential?

Answer 31

Grades depolarization response

Question 32

Is the GP an ALL OR NOTHING event?

Answer 32

NO! Relies on summation, collective effect of multiple arriving stimuli

Question 33

What is the difference between the AP release and neurotransmitter release?

Answer 33

AP reaches terminal bouton neurotransmitter released from vesicles (acts on post synaptic membrane)

Question 34

How do generator potential create an action potential?

Answer 34

Stimulus must reach the axon hillock and receive neural summation

Question 35

What are the two types of neural summation for generator potential?

Answer 35

Temporal summation Spatial summation

Question 36

What is a temporal summation?

Answer 36

Sub-threshold stimuli must occur within a critical period of time

Question 37

What is a spatial summation?

Answer 37

Multiple stimuli converge on post synaptic membrane at the same time

Question 38

How to generator potential code responses?

Answer 38

According to the intensity of the stimulus Weak stimulus; small potential (voltage change) Strong stimulus; large potential (voltage change)

Question 39

What is an EPSP (excitatory post-synaptic potential)?

Answer 39

Excitation of receptor (soma/dendrite) Neurotransmitter partially depolarizes post synaptic membrane Generates GP CREATES likelihood of new AP

Question 40

What is an IPSP (Inhibitory post-synaptic potential)?

Answer 40

Neurotransmitter hyperpolarizes the receptor (makes negative) Prevents neuron from firing Prevents development of GP DECREASE likelihood of new AP