Skeletal Muscle Mechanics Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is a motor unit?

A

Single Neuron and all muscle fibers innervated by it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What determines strength of muscle contraction?

A
  • # Number of fibers
  • Number motor units
  • Frequency of stimulation
  • Fiber length
  • Fiber thickness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How long is the lag phase of a muscle contraction?

A

2-4 ms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does tension and load resistance determine contraction?

A

If tension > load resistance, result is isotonic contraction

Tension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does summation play into contraction?

A

The muscle can be activated again before it has fully relaxed
and if a second action potential occurs during relaxation, the
force it produces adds to that remaining from the first action
potential - this is called summation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the titanic fusion frequency?

A

the action potentials will occur so rapidly that no relaxation
occurs, this produces a smooth or fused rise in tension to a
plateau that is several (3-8) times that produced during a
single twitch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the role of the Golgi tendon organ?

A

Sends information to het CNA about muscle tension and rate of change of tension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are NM spindles?

A
  • Stretch receptor organs in skeletal muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the structure of a muscle spindle?

A
  • 2-10 nifedipine skeletal muscle fibers (intrafusal) which are innervated by gamma motor neurons.
  • Anulospiral an flower spray sensory neurons end information to CNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is the hamstring an example of excitatory and inhibitory synaptic mediation of the stretch reflex?

A

The stretch receptor sensor y neuron of the quadriceps muscle makes a monosynaptic excitator y connection with the extensor motor neuron of the same muscle and a disynaptic inhibitor y inter neuron projecting to flexor motor neurons supplying the antagonistic hamstring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are load and velocity related?

A

• The Velocity of contraction depends on the load on the
muscle and is inversely propor tional to the amount of load
• Maximum velocity is achieved at zero load (no weight) and
corresponds to the maximal cross-bridge cycling rate which
is deter mined by the ATPase activity of the myosin present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is phosphlamban?

A
  • In unphosphorylated state, inhibits cardiac muscle SR Ca ATPase
  • When phosphorylation, increases Ca uptake into SR contributing to lusitropic response elicited in heart by beta adrenergic agonists
  • key regulator of diastolic function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe pathology of Muscular dystrophy

A
  • X-linked
  • Muscle degeneration
  • Defect or lack of dystrophin, a cytoskeleton Anchoring protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe pathology of malignant hyperthermia

A
  • Autosomal dominant

- abnormal release of Ca from SR from anesthetics and strenuous exercise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is dantrolene sodium?

A
  • Muscle relaxant which acts of Ryanodine channels to decrease excesssice contraction
  • Mostly for malignant hyperthermia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly