APII: Muscle System Flashcards
(72 cards)
1
Q
What is the first type of muscle tissue?
A
Skeletal muscle
2
Q
What type of muscle is under voluntary control?
A
Skeletal muscle
3
Q
What is the characteristic appearance of skeletal muscle?
A
Striated
4
Q
What is the second type of muscle tissue?
A
Smooth muscle
5
Q
What type of muscle is involuntary?
A
Smooth muscle
6
Q
What does smooth muscle primarily control?
A
Organ and blood vessel muscle
7
Q
What is the third type of muscle tissue?
A
Cardiac muscle
8
Q
What type of muscle is found only in the heart?
A
Cardiac muscle
9
Q
Is cardiac muscle under voluntary or involuntary control?
A
Involuntary
10
Q
What are skeletal muscle cells called?
A
Muscle fibers
11
Q
What is a characteristic of skeletal muscle that refers to its ability to receive and respond to stimulus?
A
Excitability
12
Q
What is the ability of skeletal muscle to shorten or contract called?
A
Contractility
13
Q
What characteristic of skeletal muscle allows it to be stretched or extended?
A
Extensibility
14
Q
What is the ability of skeletal muscle to recoil or return to its original shape after contraction or extension?
A
Elasticity
15
Q
What percentage of body weight do skeletal muscles account for?
A
40%
16
Q
List the four functions of skeletal muscle.
A
- Movement
- Posture
- Joint stability
- Heat production
17
Q
What are the two main types of protein filaments in myofilaments?
A
- Myosin
- Actin
18
Q
What are myofibrils?
A
Tubes of myofilaments
19
Q
What are the functional units of muscle contraction called?
A
Sarcomeres
20
Q
What is the connective tissue covering surrounding every muscle fiber called?
A
Endomysium
21
Q
What is a fasciculus?
A
A bundle of muscle fibers
22
Q
What connective tissue surrounds each fasciculus?
A
Perimysium
23
Q
What covers the entire muscle?
A
Epimysium
24
Q
What is fascia?
A
A tougher, thicker layer of connective tissue above epimysium
25
What is compartmental fascia?
A very tough, thick layer of connective tissue surrounding certain functional muscle groups
26
What do connective tissue coverings extend past to become tendons?
The gaster (belly) of muscle
27
What is the energy demand of muscle and its requirement?
Very high; needs adequate blood supply to deliver nutrients & O2 and to remove metabolic wastes & CO2
## Footnote
Muscle cells require a constant supply of blood due to their high metabolic activity.
28
What is a motor unit?
A single motor neuron and all the muscle fibers it stimulates
## Footnote
Motor units are essential for muscle contraction and coordination.
29
What is the sarcolemma?
Cell membrane that physically conducts the action potential
## Footnote
The sarcolemma is crucial for the transmission of nerve impulses to muscle fibers.
30
What is the sarcoplasm?
Cytoplasm of muscle cells
## Footnote
Sarcoplasm contains various organelles and is involved in metabolic processes.
31
What is the function of the sarcoplasmic reticulum?
Stores and releases calcium ions causing muscle contraction
## Footnote
Calcium ions play a key role in the contraction mechanism of muscle fibers.
32
What are T-tubules?
Inward projections of sarcolemma that carry nerve impulses to the sarcoplasmic reticulum
## Footnote
T-tubules ensure that the action potential reaches deep into the muscle fiber.
33
What is a sarcomere?
Functional unit of muscle contraction; lengthwise segments of myofibrils
## Footnote
A typical myofibril contains over 10,000 sarcomeres.
34
What are the two types of myofilaments?
Thin myofilaments (actin) and thick myofilaments (myosin)
## Footnote
The interaction between these myofilaments is responsible for muscle contraction.
35
What do actin filaments attach to?
The Z-line on each side
## Footnote
Actin filaments are essential for the structural integrity of the sarcomere.
36
What is the role of myosin heads?
Attach onto actin myofilaments to perform actual contraction
## Footnote
Myosin heads play a crucial role in the sliding filament theory of muscle contraction.
37
What causes the characteristic striations of skeletal muscle cells?
Arrangement of myosin and actin filaments
## Footnote
Striations are visible under a microscope and are indicative of the organized structure of muscle fibers.
38
What is the Z-line?
Protein disc to which the actin filaments attach
## Footnote
The Z-line marks the boundary of each sarcomere.
39
What is the I band?
Region where there are only actin filaments
## Footnote
The I band appears light under a microscope due to the absence of thick filaments.
40
Fill in the blank: One sarcomere extends from one _____ to another Z-line.
Z-line
## Footnote
This definition is crucial for understanding the structure of muscle fibers.
41
What are the two types of filaments in muscle structure?
Thin filaments (actin) and thick filaments
## Footnote
Thin filaments are primarily composed of actin, while thick filaments are mainly made up of myosin.
42
What does the A band in muscle fibers extend over?
The entire length of thick filaments
## Footnote
The A band includes both thick and overlapping thin filaments.
43
What is the zone of interlap?
Where the myosin overlaps the actin
## Footnote
This area is crucial for muscle contraction as it facilitates the interaction between actin and myosin.
44
What is the H-zone?
The area where only myosin is present
## Footnote
The H-zone is visible in the A band and indicates the region of thick filaments without thin filaments.
45
What is the M-line?
Where the myosin filaments connect
## Footnote
The M-line provides structural support for the thick filaments.
46
What is the neuromuscular junction?
The region where an axon terminal meets a muscle fiber
## Footnote
This junction is critical for transmitting nerve impulses to muscles.
47
What is the synaptic cleft?
The fluid-filled space between the axon terminal and the sarcolemma
## Footnote
The synaptic cleft allows for the diffusion of neurotransmitters.
48
What neurotransmitter crosses the synaptic cleft?
Acetylcholine
## Footnote
Acetylcholine is essential for muscle contraction signaling.
49
What is the function of acetylcholinesterase?
It rapidly breaks down acetylcholine
## Footnote
This process ensures that one nerve impulse causes only one contraction.
50
What happens after the action potential travels across the sarcolemma?
It travels down the t-tubules
## Footnote
This facilitates the spread of the signal deep into the muscle fiber.
51
Where are Ca²⁺ ions released from during muscle contraction?
Sarcoplasmic reticulum
## Footnote
The release of Ca²⁺ is crucial for muscle contraction as it triggers the interaction between actin and myosin.
52
What do Ca²⁺ ions bind to during muscle contraction?
Proteins covering the active sites on the actin filaments
## Footnote
This binding causes a shift that uncovers the active sites for myosin attachment.
53
What is the 'power stroke' in muscle contraction?
The pivoting of the myosin head that pulls the actin fiber towards the center of the sarcomere
## Footnote
This action is a key component of the contraction mechanism.
54
What happens when a new ATP binds to the myosin head?
It causes the myosin head to detach from the actin
## Footnote
The detachment is necessary for the cycle of muscle contraction to continue.
55
What occurs to ATP during the contraction cycle?
ATP breaks down into ADP and P, releasing energy
## Footnote
This energy is used to reposition the myosin head for the next contraction.
56
What must be present in the sarcoplasm for the contraction process to repeat?
Ca²⁺ ions
## Footnote
The presence of calcium ions is essential for muscle contraction to continue.
57
What happens to Ca²⁺ ions when action potentials stop?
They are actively transported back into the sarcoplasmic reticulum
## Footnote
This process leads to muscle relaxation.
58
What is the All or None Principle?
When a muscle fiber receives a sufficient stimulus to contract, all of its sarcomeres shorten at the same time, and it pulls as hard as it possibly can.
59
Does a stronger stimulus produce a stronger contraction in a muscle fiber?
No, a stronger stimulus will not produce a stronger contraction of the muscle fiber.
60
How are stronger muscle contractions produced?
By stimulating a greater number of muscle fibers.
61
What is a threshold (liminal) stimulus?
The minimum stimulus to produce a contraction.
62
What is a twitch in muscle contraction?
The way a muscle responds to a single threshold stimulus, only in laboratory conditions.
63
What is tetany in muscle contraction?
A smooth sustained contraction (or tetanus).
64
What does treppe refer to?
The staircase effect where each contraction is slightly stronger than the previous one due to rapid stimulation.
65
What is an isometric contraction?
A contraction where the tone of the muscle increases, but the muscle does not change length.
66
What does isotonic contraction mean?
A contraction where the length of the muscle changes.
67
What occurs during a concentric isotonic contraction?
The muscle shortens.
68
What occurs during an eccentric isotonic contraction?
The muscle lengthens.
69
What is a tonic contraction?
Subconscious, partial muscle contractions responsible for muscle tone.
70
Fill in the blank: In isometric contraction, the tone of the muscle increases, but the muscle does not change _______.
[length]
71
Fill in the blank: In concentric isotonic contraction, Effort > _______.
[Resistance]
72
Fill in the blank: In eccentric isotonic contraction, Effort < _______.
[Resistance]
