Lecture 4 Flashcards

1
Q

myofilaments

A

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

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2
Q

components of skeletal muscle

A

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

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3
Q

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

A

movement

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4
Q

innervation is referred to as:

A

the nerve which sends signals to a specific muscle.

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5
Q

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

A

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

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6
Q

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

A

some can be non-obligatory

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7
Q

Neuromuscular Synapse

A
  • neurotransmitter: acetylcholine (ACh)
  • always excitatory
  • obligatory
  • no multiple innervation
  • AChesterase quickly destroysACh in the synaptic cleft
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8
Q

MEPP’s

A

Moter End Plate Potential

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9
Q

Where to MEPP’s occur?

A

MEPP’s spontaneously occur on the postsynaptic muscle membrane

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10
Q

Functional meaning of MEPP’s?

A

Functional meaning unclear

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11
Q

presynaptic nerves and MEPP’s

A

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

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12
Q

Direct Effects of the Muscle Action Potential

A

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

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13
Q

Sliding Filament Theory

A

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.

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14
Q

A ________ of a muscle in response to a single stimulus

A

typical twitch

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15
Q

Under neurological stimulation. Muscle ONLY _______.

A

contracts.

It does not extend or flex.

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16
Q

Temporal Summation

A

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
Q

How does a tetanus happen?

A

A sequence of action potentials may lead to a tetanus

18
Q

Smooth tetanus happens from?

A

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