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Cell Bio And Histology > Skeletal Muscle Contraction > Flashcards

Skeletal Muscle Contraction Flashcards

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0
Q

This is made up of multiple fascicles…

A

Muscle

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1
Q

What is the Epimysium?

A

Connective tissue surrounding the entire muscle

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2
Q

Perimysium

A

Connective tissue surrounding individual fascicle

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3
Q

What is a fascicle?

A

A bundle of myofibers

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4
Q

The delicate connective tissue surrounding each myofiber

A

Endomysium

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5
Q

What is the sarcolemma?

A

Cell membrane of muscle fiber

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6
Q

What is the myofiber?

A

Individual multinucleated muscle cell

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7
Q

A chain of sarcomere within a myofiber is?…

A

Myofibril

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8
Q

What is a Myofilament?

A

Actin and myosin filaments that make up a sarcomere

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9
Q

Invaginations of the sarcolemma, two per sarcomere, lie close to the cisternae of sarcoplasmic reticulum, and form triads with cisternae. I am?…

A

the T-tubules

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10
Q

Located at each end of the sarcomere that anchor actin filaments

A

Z discs

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11
Q

Composed entirely of actin and width changes during contraction

A

I-band

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12
Q

Composed of actin and myosin and the width does Not change during contraction

A

A-band

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13
Q

Composed entirely of myosin and width changes during contraction

A

H-band

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14
Q

Characteristic of skeletal muscle, sarcomeres are aligned to produce what?

A

A banding pattern

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15
Q

Excitation coupling of the muscle include which events?

A

1) action potential causing release of calcium ions

2) reuptake of calcium ions in repolarization

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16
Q

Voltage sensitive L type calcium channels arranged in quadruplets

A

Dihydropyridine receptors (DHP)

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17
Q

Causes a conformational change in the ryanodine receptor

A

DHP receptor

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18
Q

DHP receptors are located where?

A

Sarcolemma T-tubules

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19
Q

Opens in response to a conformational change by the DHP receptor

A

Ryanodine receptor

20
Q

Ryanodine receptors are located?…

A

On the terminal cisternae of the sarcoplasmic reticulum

21
Q

Ryanodine receptors release which ion into the cytosol from the SR?

A

Calcium

22
Q

T/F is ATP required to pump calcium back into the SR?

A

True, using the SR calcium ATPase.

23
Q

Which protein maintains an optimum concentration of Calcium in the SR?

A

Calsequestrin

24
Q

What are the three uses of ATP required for muscle contraction?

A
  • pump calcium back into the Sarcoplasmic reticulum
  • pump sodium and potassium through the sarcolemma to reestablish resting potential
  • used for the sliding filament mechanism
25
Q

What is the concentration of ATP in a muscle fiber?

A

~4mmol, enough to maintain contraction for 1-2 seconds

26
Q

There are three energies of rephosphorylation. What are they?

A

Oxidative metabolism

Glycolysis

Phosphocreatine

27
Q

Provides energy for ~ 95% of all energy needed for long term contraction

A

Oxidative metabolism

28
Q

Causes a lactic acid build up and can sustain contraction for up to 1min.

A

Glycolysis

29
Q

Rapid release of energy using ATP to provide enough energy for 5-8 seconds of contraction

A

Phosphocreatine

30
Q

What are the two types of muscle contractions?

A

Isometric and isotonic

31
Q

When does isometric contraction occur?

A

When there is an increase in tension but not in length.

Ex: pushing against a brick wall

32
Q

In isotonic contraction, the muscle length changes. What are the two definitions to describe this type?

A

Eccentric-occurs when muscle lengthens

Concentric- occurs when muscle shortens

33
Q

Fiber types are classified mainly on?…

A

Endurance (resistance to fatigue) and speed of contraction

34
Q

What are the two types of fibers?

A

Dark, slow fibers (red)

Light, fast fibers (white)

35
Q

Myofiber types are determined by?

A

The innervating neuron

36
Q

Contract rapidly, less endurance, fewer mitochondria, uses primarily anaerobic respiration, larger concentration of ATPases, little myoglobin

A

Fast twitch fibers

37
Q

Contract slowly, more endurance, aerobic respiration, more mitochondria, less concentration of ATPase, more myoglobin

A

Slow twitch fibers

38
Q

Lost muscle tissue is replaced by?

A

Scar tissue (fibrous connective)

39
Q

Some muscles are almost entirely of one fiber type.

Soleus muscle is predominately? Gastrocnemius muscle is predominately?

A

Dark. Light

40
Q

A neuron and the myofibers it innervates constitutes?…

A

A motor unit.

41
Q

T/F all or none response refers to a motor unit.

A

True

42
Q

Describe tetany?

A

The frequency of spikes is fast enough in which there is no time for relaxation. The muscle remains at maximal contraction

43
Q

When electrical events occur faster than mechanical events. Additional spike can occur before previous Ca ions have been returned to the SR

A

Summation

44
Q

This electrical event increases the total amt of Ca ions in the cytosol and increases the rate of cycling between the myosin and actin cross bridges thereby increasing muscle tension.

A

Summation

45
Q

Lever systems are classified according to position of the fulcrum in relation to the in-force and the out-force. What is the first class? There are three total. Give an example

A

Fulcrum is in middle. In and out forces move in opposite directions.

Ex. Raising your chin using sternocleidomastoid or similar muscles.

Fulcrum= atlas/axis complex.

46
Q

What is the second class lever system?

A

Resistance (out force) is in the middle

In and out force is on the same side of the fulcrum

Ex: raising the body on the ball of the foot
Fulcrum: ball of foot

47
Q

Third class lever system?

A

Effort (in force) is in the middle

In and out force in on the same side of the fulcrum
Both forces move in the same direction

Ex: lifting a weight in the palm of your hand

Cell Bio And Histology (17 decks)

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