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From Flashcardlet > Muscle tissue and organization > Flashcards

Muscle tissue and organization Flashcards

This flashcard deck was created using Flashcardlet's card creator

0
Q

1 muscle fiber = ?

A

1 muscle cell

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1
Q

What are the three types of muscle in the body?

A
  1. Smooth
  2. Cardiac
  3. Skeletal
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2
Q

What are the four unique properties of muscle tissue?

A
  1. Excitability
  2. Contractibility
  3. Elasticity
  4. Extensibility
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3
Q

What is Excitability?

A

Outside stimuli initiates electrical charges in muscle fibers.

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4
Q

What is Contractibility?

A

Shortening of muscle fibers.

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5
Q

What is Elasticity?

A

The muscle fiber’s ability to return to it’s original length following a contraction.

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6
Q

What is Extensibility?

A

The ability to be stretched beyond it’s released length.

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7
Q

A skeletal muscle is an _________ because it contains multiple __________.

A

Organ; tissue types

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8
Q

What tissue types are contained in a muscle?

A

Muscle, epithelial, nervous and connective tissue

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9
Q

Miuscle fibers are ________ when observed under a microscope.

A

striated (striped)

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10
Q

What are the five functions of skeletal muscle?

A
  1. Body movement - must cross a joint to provide movement
  2. Maintenance of posture - back/neck muscles
  3. Temperature regulation - shivering
  4. Storage and movement of materials - sphincters
  5. Support - abdominal wall
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11
Q

List the five organizational levels of skeletal muscle, largest to smallest.

A
  1. Muscle
  2. Fascicles
  3. Muscle fiber
  4. Myofibrils
  5. Myofilaments
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12
Q

Describe a muscle.

A

Multiple fascicles bundled together, surrounded by epimysium.

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13
Q

Describe a fascicle.

A

A bundle of muscle fibers surrounded by perimysium

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14
Q

Describe a muscle fiber.

A

Elongated, multinucleated, cylindrical cell, containing myofibrils, surrounded by endomysium

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15
Q

Describe myofibrils.

A

Long, cylindrical contractile element within a muscle fiber, composed of myofilaments. Exhibits striations. Organized into repeating units of sarcomeres.

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16
Q

Describe myofilaments.

A

Short, contractile proteins of two types, thick and thin, within a sarcomere.

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17
Q

Each muscle has _______ layers of ___________ connective tissue that is comprised mainly of _________ and __________ fibers.

A

three; concentric; collagen; elastic

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18
Q

What are the four functions of this connective tissue?

A
  1. Protection
  2. Blood vessels and nerve distribution
  3. Means of attaching the muscle to the skeleton
  4. Electrical isolation
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19
Q

List the layers of connective tissue from deep to superficial.

A
  1. Endomysium
  2. Perimysium
  3. Epimysium
  4. Deep and superficial fascia
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20
Q

What does the endomysium surround?

A

Muscle fiber

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21
Q

What does the perimysium surround?

A

Fascicle

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22
Q

What does the epimysium surround?

A

Muscle

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23
Q

What is the function of the deep fascia? What is it made of?

A

It surrounds the epimysium, separates individual muscles, binds muscles with similar functions and distributes nerves and blood vessels. It’s made of dense irregular connective tissue.

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24
Q

What is another name for the superficial fascia? What is it made of?

A

Subcutaneous layer, hypodermis; areolar and adipose connective tissue

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25
Q

At the ends of each muscle, all of the connective tissue merge to form a _________, which attaches the muscle to the bone.

A

tendon

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26
Q

Tendons are usually ______-like in appearance but sometimes they are ______.

A

cord; flat

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27
Q

What is tendonitis?

A

Inflammation of a tendon, or it’s covering sheath.

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28
Q

What causes tendonitis?

A

Overuse, age, rheumatoid arthritis

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29
Q

What is the treatment for tendonitis?

A

Rest, ice, anti-inflammatory medication, stretching and strengthening of the muscles in the affected area.

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30
Q

What is the plasma cell membrane called in a muscle fiber (cell)?

A

Sarcolemma

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31
Q

What is the cytoplasm called in a muscle fiber (cell)?

A

Sarcoplasm

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32
Q

What is the smooth endoplasmic reticulum called in a muscle fiber (cell)?

A

Sarcoplasmic reticulum

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33
Q

What mineral needs to be present in order for a muscle to contract?

A

Calcium

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34
Q

What are two main structures that are unique to a muscle fiber (cell)?

A

Transverse tubules (t-tubules)

Terminal cisternae

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35
Q

Define Transverse tubules.

A

Deep invaginations of the sarcolemma that extend into the sarcoplasm.

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36
Q

Define Terminal cisternae.

A

Blind sacs at the end of the sarcoplasmic reticulum, adjacent to each t-tubule.

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37
Q

Why are skeletal muscle fibers multinucleated?

A

The skeletal muscle fibers are made of fused myoblasts, therefore they are multinucleated.

38
Q

Relative to a muscle fiber, how long is a myofibril? How many make up a muscle fiber?

A

The entire length of the muscle fiber; 100s

39
Q

Myofibrils have the ability to __________ resulting in contraction of the muscle.

A

Shorten

40
Q

Relative to a muscle fiber, how long is a myofilament? What are the two types of myofilament?

A

My filaments do not run the entire length of the muscle fiber, but are organized into repeating elements called sarcomeres.

Thick and thin

41
Q

Myofibrils are composed of short bundles of ______________.

A

Myofilaments

42
Q

Thin filament = ________, plus what two regulatory proteins?

A

Actin; tropomyosin, troponin complex

43
Q

What is the function of tropomyosin?

A

It covers the active sites of the actin.

44
Q

What is the function of troponin complex?

A

Its three sub units move tropomyosin off the active sites.

45
Q

What is G-Actin?

A

1 bead of actin

46
Q

What is F-Actin?

A

1 strand of actin beads

47
Q

Thick filaments = ________. They are _______ as thick as thin filaments.

A

Myosin; twice

48
Q

A myosin molecule has a _______ and an elongated ________.

A

Head; tail

49
Q

The heads of myosin form _____________ with thin filaments during contraction.

A

Crossbridges

50
Q

What is the functional contractile unit of a skeletal muscle fiber?

A

A sarcomere

51
Q

What is an A-band?

A

A dark band containing the entire myosin molecule and overlapping portion of actin.

52
Q

What is an I-band?

A

A light band containing thin filaments but no thick filaments.

53
Q

What is the function of titin?

A

It helps return my filaments to their original position after contraction.

54
Q

What is an H-zone?

A

A light central region of the a-band where there are no thin filaments.

55
Q

What is an M-line?

A

A protein meshwork in the h-zone that keeps thick filaments aligned.

56
Q

What is the Z disc (z-band)?

A

A protein structure in the middle of the I-band that serves for the attachment site for one end of the thin filament.

57
Q

What theory explains the mechanism for muscle contraction?

A

Sliding filament theory

58
Q

Which bands/zones shorten when a sarcomere shortens?

A

H-zone, I-band

59
Q

Does the length of the thick and thin filaments ever change when miscue contracts or relaxes?

A

No

60
Q

Muscle contraction begins when a __________ impulse stimulates an impulse in a __________.

A

Motor neuron; muscle fiber

61
Q

What is a neuromuscular junction (NMJ)?

A

The region where the motor neuron comes into close proximity to the muscle fiber.

62
Q

What are the six components of a neuromuscular junction?

A
  1. Synaptic knob
  2. Synaptic vesicles
  3. Motor end plate
  4. Synaptic cleft
  5. ACh receptors
  6. Acetylcholinesterase (AchE)
63
Q

What is a synaptic knob?

A

The expanded tip of an axon that covers a large area of the sarcolemma.

64
Q

What is a synaptic vesicle?

A

A small membrane sac filled with acetylcholine (ACh) located within the synaptic knob.

65
Q

What is the motor end plate?

A

A specialized region of the sarcolemma. It has folds and indentations to increase the membrane surface area covered by the synaptic knob.

66
Q

What is the synaptic cleft?

A

A narrow space separating the synaptic knob from the motor end plate.

67
Q

What are ACh receptors?

A

They are located in the motor end plate and act as doors that normally remain closed. ACh (acetylcholine) is the key that opens these doors.

68
Q

What is acetylcholinesterase?

A

An enzyme that resides in the synaptic cleft that rapidly breaks down ACh molecules. Thus, AChE is needed to stop ACh from continuously stimulating the muscle.

69
Q

Summarize the six steps involved in muscle contraction.

A
  1. A nerve impulse causes ACh release into the synaptic cleft.
  2. ACh binds to ACh receptors in the motor end plate, initiating a muscle impulse along the sarcolemma and the t-tubule membranes.
  3. Calcium is released from the terminal cisterae into the sarcoplasm.
  4. Calcium ions cause the uncovering of activation sites on the actin.
  5. Myosin heads bind to the actin and form crossbridges.
  6. In the presence of ATP the sliding of the filaments is activated.
70
Q

What is a motor unit?

A

A single motor neuron and the muscle fibers it innervates.

71
Q

Does each motor neuron control only one muscle fiber?

A

No

72
Q

Does each muscle consists of multiple motor units? Why?

A

Yes; for different degrees of control

73
Q

Can a muscle fiber have an “intermediate” amount of contraction?

A

No

74
Q

Can a muscle have an “intermediate” amount of contraction?

A

Yes

75
Q

What is muscle atrophy?

A

A wasting of tissue that results in reduction of muscle size, tone and power.

76
Q

What is muscle hypertrophy?

A

An increase in the number of myofibrils per fiber in fast fibers.

77
Q

What are the two types of muscle contraction?

A

Isometric and isotonic

78
Q

What is isometric contraction?

A

During contraction the length of the muscle does not change because the resistance is greater than the tension produced by the contracting muscle.

79
Q

What is isotonic contraction?

A

During contraction the tension produced by the contracting muscle is greater than or equal to the resistance, which shorten the muscle fibers, causing movement.

80
Q

What are the two types of isotonic contractions?

A

Concentric and eccentric

81
Q

What is a concentric contraction?

A

Actively shortening the muscle.

82
Q

What is eccentric contraction?

A

Actively lengthening the muscle.

83
Q

What are the three types of muscle fibers?

A
  1. Slow (type I, slow aerobic)
  2. Intermediate (type IIa, fast aerobic)
  3. Fast (type IIb, fast anaerobic)
84
Q

What type of muscle fiber is red? Why?

A

Slow; stores oxygen

85
Q

What is myoglobin?

A

An oxygen-binding, reddish appearing protein.

86
Q

Describe the four organizational patterns in fascicles.

A
  1. Circular - concentric around an opening
  2. Convergent - converging on a central tendon
  3. Parallel - most common
  4. Pennate - feather-like; one or more tendons running through a muscle; strongest
87
Q

What are the three actions of skeletal muscles?

A
  1. Agonist
  2. Antagonist
  3. Synergist
88
Q

What is an agonist muscle?

A

A prime mover that produces a specific movement when it contracts.

89
Q

What is an antagonist muscle?

A

A muscle whose action opposes that of the agonist.

90
Q

What is a synergist muscle?

A

A muscle that assists the agonist.

91
Q

Compare and contrast cardiac and skeletal muscle fibers.

A

Both are striated, and have sarcomeres

Cardiac muscle fiber:

Has only 1 or two nuclei
Are short and branch
Cells meet each at intercalated discs
They have gap junctions
No motor neurons, autorhythmic
92
Q

Compare and contrast smooth and skeletal muscle fibers.

A

Found in walls of viscera and blood vessels, hollow organs
Cells are short and fusiform shaped
1 nucleus
No striations
Has thick and thin filaments
No z discs, the filaments attach to dense bodies

From Flashcardlet (118 decks)

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