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Physl > Muscle 2 > Flashcards

Muscle 2 Flashcards

1
Q

What are muscles made up of?

A

Many single fibers

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2
Q

What is a single skeletal muscle cell also called?

A

A muscle fiber

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3
Q

What is the shape of a single skeletal muscle fiber?

A

More or less cylindrical with an elongated shape

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4
Q

What does each muscle fiber end in?

A

Tendons made up of fibrous inelastic tissue composed largely of collagen

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5
Q

How are skeletal muscles attached to bone?

A

By tendons

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6
Q

What do skeletal muscle fibers contain within them?

A

Smaller subunits arranged in bundles called rods or myofibrils

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7
Q

What are myofibrils found within?

A

Skeletal muscle cells

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8
Q

How are muscle fibers formed?

A

During development, undifferentiated or mononucleated cells called myblast that fuse into a single cylindrical muscle fiber

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9
Q

Why are skeletal muscles multinucleated?

A

Because they form from the fusion of multinucleated myoblasts into one muscle fiber

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10
Q

Why is it important for skeletal muscles to be multinucleated?

A

For gene expression and to meet the high protein synthesis requirements of muscle

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11
Q

What is each muscle fiber made of?

A

Many myofibrils that have a specialized intracellular structure

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12
Q

What are myofibrils that are found in skeletal muscle cells made of?

A

Thick and thin filaments

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13
Q

What are Cytoskeletal elements?

A

The thick and thin filaments that make up myofilaments

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14
Q

What are thick and thin filaments made up of?

A

Proteins myosin and actin

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15
Q

How are muscle fibers arranged in a whole muscle?

A

In functional units called motor units

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16
Q

What is a motor unit?

A

All the muscle fibers that a single motor nerve innervates

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17
Q

What is the number of muscle fibers controlled by a single motor axon determined by?

A

The dexterity of the movement controlled

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18
Q

What is the motor unit like in Gross movement?

A

One nerve controls hundreds of muscle fibers (ie. Posture)

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19
Q

What is a motor unit like in Fine movements?

A

1 nerve controls 5-6 muscle fibers ex. Changing eye position

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20
Q

Which nervous system is skeletal muscle innervated by?

A

The somatic nervous system

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21
Q

What is the Neuromuscular Junction?

A

The area where the somatic nervous system meets the musculature

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22
Q

What are nerve cells and muscle cells separated by?

A

The synaptic cleft or synapse

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23
Q

What is the Motor Endplate?

A

The area of little muscle directly below the synaptic terminal

24
Q

How does an action potential work in skeletal muscles?

A

An action potential travels down the motor neuron causing depolarization of the synaptic terminal causing opening of the voltage gated calcium channels. Calcium rushes into the synaptic terminal of the of the motor neuron causing the synaptic vesicle to fuse with the membrane and acetylcholine to be released into the synaptic cleft. Acetylcholine binds to ion channels allowing sodium to enter. The sodium causes voltage gated sodium channels to open and allow more sodium to enter the muscle fiber and a muscle fiber action potential is initiated

25
Q

What does the action potential of a muscle membrane move down?

A

Structures called T tubules

26
Q

What does each muscle cell need in order to contract?

A

To be stimulated by a process of a motor neuron

27
Q

What does a functional unit of a motor system represent?

A

The smallest increment of force that can be generated

28
Q

Is it possible to contract just one motor cell?

A

No

29
Q

What is the functional unit of the motor system?

A

A motor neuron, its axon and all the muscle fibers it activated

30
Q

What are Cross Striations?

A

The alternating light and dark bands seen in skeletal muscle

31
Q

What do Cross striations span?

A

The full length of the muscle fiber

32
Q

What do thick filaments interdigitate between?

A

The thin filaments

33
Q

What does the A band of muscle contain?

A

The overlapping portion of thick and thin filament

34
Q

What does the H zone contain?

A

Only thick filaments

35
Q

What is the M line?

A

The center line that thick filaments are anchored on

36
Q

What does the I band contain?

A

Only thin filaments

37
Q

What is the Z line?

A

The anchor for titin and thin filaments

38
Q

Where does a Sarcomere span?

A

From Z line to Z line

39
Q

What does titin connect to?

A

Thick filaments and the Z line

40
Q

What is the distance from Z line to Z line known as?

A

The sarcomere

41
Q

What is the functional unit of skeletal muscle?

A

The Sarcomere

42
Q

What is the functional unit of any organ?

A

The smallest unit component that can perform all the functions of that organ

43
Q

How does a muscle grow and increase in length?

A

By adding new sarcomeres to the myofibril

44
Q

Are the I bands light or dark regions?

A

Light regions

45
Q

How big is the distance from Z line to Z line?

A

About 2-3 micrometers

46
Q

What can you see if you look at a myofibril under magnification?

A

The myofilaments

47
Q

What are the two types of myofilaments?

A

Thick filaments and thin filaments

48
Q

What are Thick filaments composed of?

A

Myosin

49
Q

What are thin filaments composed of?

A

Actin

50
Q

What is the shape of Myosin?

A

Club-like shaped

51
Q

What is responsible for the striated appearance of skeletal and cardiac muscle?

A

The highly organized sarcomeres stacked end to end

52
Q

Why is smooth muscle non-striated?

A

Because the actin and myosin have a less regular pattern or organization

53
Q

What are Myofibrils made of?

A

Sarcomeres stacked end to end

54
Q

What is required in order for muscles to contract?

A
  • Actin
  • Myosin
  • Troponin
  • Tropomyosin
  • ATP
  • Trace Mg2+
  • Ca2+
55
Q

What does the presence of molecular participants in muscles allow for?

A

Cross bridge cycling

Physl (94 decks)

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