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Flashcards in Lecture 4 Deck (18):
1

myofilaments

actin and myosin are two filaments which have a structure referred to as cross-bridges. This structure forms the smallest unit of skeletal muscle, the sarcomere

2

components of skeletal muscle

the sarcolemma is a membrane which has within its structure the sarcoplasm which contains myofilaments and sarcoplasmic reticulum

3

__________ is created when a signal is sent from the CNS to the muscle intended to move.

movement

4

innervation is referred to as:

the nerve which sends signals to a specific muscle.

5

How does the action potential travel during communication between axon and muscle in the neuromuscular synapse (junction)

The action potential travels down the axon and arrives at the neuromuscular junction and muscle contraction occurs due to obligatory nature of neuromuscular synapses

6

How is the neuromuscular synapse (junction) different from other synapse?

some can be non-obligatory

7

Neuromuscular Synapse

-neurotransmitter: acetylcholine (ACh)
-always excitatory
-obligatory
-no multiple innervation
-AChesterase quickly destroysACh in the synaptic cleft

8

MEPP's

Moter End Plate Potential

9

Where to MEPP's occur?

MEPP's spontaneously occur on the postsynaptic muscle membrane

10

Functional meaning of MEPP's?

Functional meaning unclear

11

presynaptic nerves and MEPP's

A presynaptic nerve action potential always reaches the depolarization threshold and induces a msucle action potneital

12

Direct Effects of the Muscle Action Potential

Muscle action potential travels along the sarcolemma enters T-tubules, and leads to a release of Ca++ ions from the sarcoplasmic reticulum.

Sliding Filament Theory

13

Sliding Filament Theory

Ca++ ions remove tropomyosin and free a site for myosin to bind to troponin (this process uses the energy from ATP). A ratchet motion occurs, moving the filaments with respect to each other.

14

A ________ of a muscle in response to a single stimulus

typical twitch

15

Under neurological stimulation. Muscle ONLY _______.

contracts.
It does not extend or flex.

16

Temporal Summation

two action potentials come at a short interval and induce two twitch contractions. Their mechanical effects are superimposed leading to a higher level of muscle force.

17

How does a tetanus happen?

A sequence of action potentials may lead to a tetanus

18

Smooth tetanus happens from?

At a high frequency of action potentials, individual contractions may fuse, leading to smooth tetanus