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Anatomy & Physiology > Ch9 Muscles and Muscle Tissues > Flashcards

Ch9 Muscles and Muscle Tissues Flashcards

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1
Q

What are the 3 types of muscle tissue?

A

Skeletal, cardiac, and smooth

These muscle tissues have distinct structures and functions.

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2
Q

What do the prefixes myo, mys, and sarco refer to?

A

Muscle

These prefixes are commonly used in anatomical terminology.

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3
Q

What type of muscle is striated and voluntary?

A

Skeletal muscle

This muscle type is under conscious control.

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4
Q

What is voluntary muscle?

A

Muscle with conscious control

This allows for intentional movement.

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5
Q

What are striations?

A

Stripes seen along muscle cells

These are visible in the microscopic structure of skeletal muscle.

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6
Q

What is the role of skeletal muscle?

A

Responsible for overall body motility

It enables movements such as walking, running, and lifting.

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7
Q

Where is skeletal muscle attached?

A

To and covers the skeleton (bone)

This attachment allows for movement of the skeletal system.

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8
Q

What type of muscle is striated and involuntary?

A

Cardiac muscles

Cardiac muscles are unique to the heart.

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9
Q

Where does cardiac muscle tissue occur?

A

Only in the heart

Cardiac muscle contracts at a steady rate.

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10
Q

What are the characteristics of smooth muscle?

A

Visceral, nonstriated, and involuntary

Smooth muscle is found in hollow visceral organs.

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11
Q

In which locations is smooth muscle found?

A

Hollow visceral organs, valves, and arrector pili muscles

Smooth muscle helps in various involuntary functions.

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12
Q

What are the four key characteristics that allow muscle tissue to function?

A

Excitability, contractility, extensibility, and elasticity

These characteristics are essential for muscle performance.

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13
Q

Define excitability in muscle tissue.

A

The ability of a cell to receive and respond to a stimulus by changing its membrane potential

This responsiveness is crucial for muscle activation.

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14
Q

What is contractility in muscle tissue?

A

The ability to shorten forcibly when adequately stimulated

This characteristic is essential for muscle contraction.

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15
Q

What does extensibility mean in the context of muscle tissue?

A

The ability to extend or stretch

Muscle cells shorten when contracting and stretch when relaxing.

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16
Q

What is elasticity in muscle tissue?

A

The ability of a muscle cell to recoil and resume its resting length after stretching

This property helps muscles return to their original state.

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17
Q

What are the 4 functions of muscles in the body?

A
  • Produce movement
  • Maintain posture/body position
  • Stabilize joints
  • Generate heat
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18
Q

What typically serves each muscle in terms of blood and neural supply?

A

One nerve, artery, and one or more veins

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19
Q

What is fascia?

A

A type of connective tissue that surrounds and supports muscles, organs, and other structures in the body

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20
Q

What are the roles of fascia?

A
  • Maintains structural integrity
  • Reduces friction between tissues
  • Plays a role in movement and flexibility
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21
Q

What are the 3 connective tissue sheaths in muscle fibers?

A
  • Epimysium
  • Perimysium
  • Endomysium
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22
Q

What is the function of the epimysium?

A

It is the outermost ‘overcoat’ of dense irregular connective tissue that surrounds the whole muscle

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23
Q

What is the function of the perimysium?

A

A layer of dense irregular connective tissue that surrounds each fascicle; it is the middle layer

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24
Q

What is the function of the endomysium?

A

A wispy sheath of connective tissue that surrounds each individual muscle fiber; it is the innermost layer

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25
What are fascicles?
Grouped muscle fibers surrounded by the perimysium, resembling a bundle of sticks
26
Fill in the blank: The outermost layer of connective tissue surrounding a muscle is called the _______.
[epimysium]
27
True or False: The perimysium surrounds individual muscle fibers.
False
28
Fill in the blank: The innermost layer of connective tissue surrounding a muscle fiber is called the _______.
[endomysium]
29
What is the origin of a muscle?
The fixed attachment point of a muscle (proximal); it remains stationary during muscle contraction. ## Footnote The origin is typically located proximal to the insertion.
30
What is the insertion of a muscle?
The movable attachment point (distal); it moves toward the origin when the muscle contracts. ## Footnote The insertion is usually located distal to the origin.
31
How do muscle attachments differ in terms of origin and insertion?
The origin typically lies proximal to the insertion. ## Footnote This means the origin is closer to the center of the body than the insertion.
32
What are the two types of muscle attachments?
Direct and indirect attachments. ## Footnote Each type has distinct structural characteristics.
33
What characterizes direct muscle attachments?
The epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage. ## Footnote This type of attachment allows for a direct connection between muscle and bone.
34
What characterizes indirect muscle attachments?
Muscles connective tissue wrappings extend beyond the muscle to either a ropelike tendon or sheetlike aponeurosis. ## Footnote This allows the muscle to anchor to connective tissue covering of a skeletal element or to the fascia of other muscles.
35
Why are indirect attachments more common than direct attachments?
Because of their durability and small size. ## Footnote Indirect attachments provide greater flexibility and strength.
36
What is the sarcoplasm?
The cytoplasm of a muscle cell ## Footnote It contains large amounts of glycosomes and myoglobin.
37
What do glycosomes do?
They provide glucose during muscle cell activity for ATP production ## Footnote Glycosomes are granules of stored glycogen.
38
What is myoglobin?
A red pigment that stores oxygen ## Footnote It is found in muscle cells.
39
Name the three specialized structures contained in muscle cells.
* Myofibrils * Sarcoplasmic reticulum * T tubules ## Footnote These structures are essential for muscle function.
40
What is contained within a single muscle fiber?
Hundreds to thousands of rodlike myofibrils that run parallel to each other ## Footnote Myofibrils are essential for muscle contraction.
41
What are myofibrils made up of?
A chain of sarcomeres linked end to end ## Footnote Sarcomeres are the basic contractile units of muscle fibers.
42
What do sarcomeres contain?
Even smaller rodlike structures called myofilaments ## Footnote Myofilaments are composed of actin and myosin proteins.
43
What is the organizational level of muscle from largest to smallest?
Muscle, Fascicle, Muscle fiber, Myofibril, Sarcomere, Myofilament ## Footnote This hierarchy shows the structural organization of muscle tissue.
44
What are striations in muscle cells?
A repeating series of dark A bands and light I bands ## Footnote Striations are visible under a microscope and are characteristic of skeletal and cardiac muscle.
45
What is the H zone?
A lighter region in the midsection of each dark A band ## Footnote The H zone appears during muscle contraction when the actin filaments are pulled away from the myosin filaments.
46
What is the M line?
A dark line that bisects each H zone vertically ## Footnote The M line is formed by molecules of the protein myomesin, which helps stabilize the position of thick filaments.
47
What is the Z disc (or Z line)?
A darker area that serves as a midline interruption in each light I band ## Footnote The Z disc anchors the thin filaments and defines the boundaries of a sarcomere.
48
What is the region of a myofibril between two successive Z discs called?
Sarcomere
49
What is the smallest contractile unit of a muscle fiber?
Sarcomere
50
What is the functional unit of skeletal muscle?
Sarcomere
51
What does each sarcomere contain?
An A band flanked by half an I band at each end
52
True or False: The A band is located at the center of the sarcomere.
True
53
Fill in the blank: Sarcomeres contain an A band flanked by ______ at each end.
half an I band
54
What are myofilaments?
Muscle equivalents of actin-containing microfilaments and myosin motor proteins ## Footnote Myofilaments are essential components of muscle contraction.
55
What are the two types of contractile myofilaments in a sarcomere?
Thick filaments (myosin) and thin filaments (actin) ## Footnote These filaments work together to facilitate muscle contraction.
56
Where do the central thick filaments containing myosin extend?
The entire length of the A band ## Footnote The A band is the dark region of the sarcomere where thick filaments are located.
57
What connects the thick filaments in the middle of the sarcomere?
The M line ## Footnote The M line is crucial for the structural integrity of the sarcomere.
58
Where do lateral thin filaments containing actin extend?
Across the I band and partway into the A band ## Footnote This arrangement is important for the overall function of the muscle.
59
What does the Z disc do?
Anchors the thin filaments ## Footnote The Z disc serves as a boundary for sarcomeres.
60
What does the I band contain?
Thin filaments only ## Footnote The I band appears lighter under a microscope due to the absence of thick filaments.
61
What does the H zone contain?
Thick filaments only ## Footnote The H zone is a lighter region within the A band.
62
What is the role of the accessory proteins at the M line?
Link thick filaments together ## Footnote These proteins provide stability to the sarcomere structure.
63
What holds adjacent thick filaments together?
The M line ## Footnote This connection is essential for coordinated muscle contraction.
64
How are myofilaments held in alignment?
At the Z discs and the M lines ## Footnote Proper alignment is crucial for effective muscle contraction.
65
To what are myofilaments anchored?
To the sarcolemma at the Z discs ## Footnote This anchoring helps transmit the force generated by muscle contractions.
66
What are the components of each myosin molecule?
Each myosin molecule consists of six polypeptide chains: 2 heavy chains and 4 light chains. ## Footnote Myosin is a motor protein essential for muscle contraction and movement.
67
What forms the rodlike tail of myosin?
The two heavy chains twist together to form myosin's rodlike tail. ## Footnote The structure of myosin is vital for its function in muscle contraction.
68
What is located at the end of each heavy chain of myosin?
Each heavy chain ends in a globular head that is attached to the tail. ## Footnote The globular heads play a crucial role in muscle contraction.
69
What do myosin's globular heads link together during contractions?
Myosin's globular heads link the thick and thin filaments together, forming cross bridges. ## Footnote Cross bridges are essential for the sliding filament model of muscle contraction.
70
What do myosin's globular heads do during muscle contractions?
They swivel around their point of attachment, acting as motors to generate force. ## Footnote This swiveling mechanism is critical for the contraction process.
71
What role does myosin play in ATP metabolism?
Myosin splits ATP and acts as an ATPase. ## Footnote The energy released from ATP hydrolysis is used to drive muscle contraction.
72
Fill in the blank: Myosin itself splits _______ and uses the released energy to drive movement.
ATP
73
What are the kidney-shaped polypeptide subunits of actin called?
G actin (globular actin) ## Footnote G actin is the monomeric form of actin that polymerizes to form filaments.
74
What feature does each G actin possess that is crucial for muscle contraction?
Myosin binding site (active site) ## Footnote This site is where myosin heads attach during the contraction process.
75
What do G-actin subunits polymerize to form?
F-actin (filamentous actin) ## Footnote F-actin is the polymerized form of G-actin.
76
Describe the structure of F-actin.
Two intertwined actin filaments resembling a twisted double strand of pearls ## Footnote This structure forms the backbone of each thin filament in muscle fibers.
77
Fill in the blank: G actin subunits polymerize into long actin filaments called _______.
F-actin
78
True or False: Each G actin molecule has a binding site for myosin.
True
79
What is the shape of G actin?
Kidney-shaped ## Footnote This shape contributes to its ability to polymerize and form filaments.
80
What are the four regulatory proteins found in thin filaments?
Tropomyosin, troponin, elastic filament, dystrophin ## Footnote These proteins play crucial roles in muscle contraction and regulation.
81
What is the function of tropomyosin in muscle fibers?
Helps stiffen and stabilize the actin core ## Footnote Tropomyosin spirals about the actin core.
82
In a relaxed muscle fiber, what does tropomyosin block?
Myosin binding sites on actin ## Footnote This prevents myosin heads from binding to thin filaments.
83
Describe the structure of troponin.
A globular protein with 4 polypeptide subunits ## Footnote Each subunit has a specific function related to muscle contraction.
84
What are the three functions of the subunits in troponin?
* Attaches troponin to actin * Binds tropomyosin and positions it on actin * Binds calcium ions
85
How do troponin and tropomyosin interact in muscle contraction?
They help control the myosin-actin interactions involved in contraction ## Footnote This interaction is essential for muscle contraction to occur.
86
What is the composition of the elastic filament?
The elastic filament is composed of the giant protein titin
87
From where does the elastic filament extend?
The elastic filament extends from the Z disc to the thick filament
88
What is the role of the elastic filament in muscle organization?
The elastic filament holds the thick filament in place, maintaining the organization of the A band
89
How does the elastic filament assist muscle cells after stretching?
The elastic filament helps the muscle cell spring back into shape after stretching
90
What happens to titin when it is stretched?
Titin does not resist stretching in the ordinary range of extension but stiffens as it uncoils
91
What is the function of titin in muscle tissue?
Titin helps the muscle resist excessive stretching
92
What does dystrophin link to the sarcolemma?
Dystrophin links the thin filaments to the integral proteins of the sarcolemma
93
What are the two sets of intracellular tubules in skeletal muscle fibers?
Sarcoplasmic reticulum and T tubules ## Footnote These structures help regulate muscle contraction.

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