Ch 19 Pt 1cd

Question 1

A motor neuron pool is 1 motor neuronal excitability CNS and many muscle fibres ?

Answer 1

False
-many motor neurons/ units

Question 2

A motor unit innervates a variety of fibre types?

Answer 2

False
-a motor unit only innervates the same fiber type as it

Question 3

Small motor units are typically involved in complex movements?

Answer 3

True

Question 4

Alpha motor neurons are Afferent neurons?

Answer 4

False
-would be efferent because they send signals to the muscle, not away from it

Question 5

At rest Inside the Muscle Fibers (cell): (3)

Answer 5

More Na+ on outside of cell
More K+ inside the cell
Controlled b y membrane permeability
Thus, fiber cell more negatively charged on the inside

Question 6

RMP

Answer 6

Resting membrane potential
-around -70mV

Question 7

Depolarization of a cell

Answer 7

Membrane potential becomes more positive
-70 closer to 0 or above

Question 8

Repolarization

Answer 8

Membrane potential becomes more negative (back towards RMP)

Question 9

Hyperpolarization

Answer 9

Membrane potential becomes more negative than resting membrane potential (-70)

Question 10

Signals

Answer 10

Electrical currents created by movements of ions

Question 11

Types of Signals: Endpoint Potential

Answer 11

Depolarization of hyperpolarization of membrane potential

Question 12

Types of signals: Action Potential

Answer 12

Substantial (high) depolarization of membrane potential becomes

Question 13

EPSP

Answer 13

Excitatory input from one neuron to another
Depolarizations of postsynaptic membrane
-facilitates (may lead to) AP

Question 14

IPSP

Answer 14

Inhibitory input from one neuron to another
Hyperpolarizations of postsynaptic membrane
-inhibits AP (doesn’t happen)

Question 15

Action Potentials can be generated by: (2)

Answer 15

Temporal Summation: one or few neurons can deliver REPETITIVE subthreshold stimulus over a short period of time -SAME NEURONS

Spatial Summation: a bunch of EPSPs can be delivered from DIFFERENT pre synaptic terminals

Question 16

AP

Answer 16

Action Potential: substantial depolarization (subthreshold level) that will result in muscle contraction

Question 17

EPP

Answer 17

End Point Potential: depolarization or hyperpolarization that does NOT result in muscle contraction

Question 18

Initiation the AP

Answer 18

Impulse travels down axon terminal
Calcium channels open, calcium diffuses into axon
Causes fusion of synpatic vesicles -carnations ACh with membrane of axon
Vesicles release ACh into synpatic cleft
ACh binds on receptors on muscle membrane, excites membrane, changes permeability
Channels open to allow Na in and K out

Question 19

Initial opening of sodium and potassium due to:

Answer 19

Binding of acetylcholine with muscle membrane

Question 20

Open of adjacent channels on the muscle due to:

Answer 20

Spread of electrical charge (voltage gated)

Question 21

Muscle Fiber Stimulation/ Excitation

Answer 21

1. Impulse (AP)- moves down axon of motor neurons
2. Ca channels open and calcium moves into terminal
3. ACh primes for release
4. ACh transverse the synapse and binds to ACh receptors on postsynaptic terminal
5. Changes permeability of membrane (influx/ efluxx of Na and K)
6. Depolarization generates EPP, if at threshold an AP
7. AP depolarization wave spreads throughout the T-Tubule network into muscle fiber

Question 22

Ending Excitation

Answer 22

AP- prepares muscle fiber for contraction by travelling down T-Tubule
ACh hydrolysis -broken down by cholinesterase to depolarize postsynaptic membrane
Axon resynthesizes acetic acid to form ACh to process can repeat