Big exam Flashcards
(83 cards)
1
Q
Muscular System
Composed of more than ___ndividual skeletal muscles
A
600
2
Q
3 types of muscle tissue:
A
1.Skeletal
2.Smooth
3.Cardiac
3
Q
The primary functions of skeletal muscle are to:
A
Facilitate locomotion and breathing by generating force
–Support posture through static and dynamic force generation
–Produce heat by causing shivering during periods of cold stress
4
Q
Muscle fibers are held in place by thin sheets of connective tissue membranes called __
A
fasciae.
5
Q
Epimysium
A
is fascia that encases the entire muscle.
6
Q
perimysium.
A
–Within the epimysium are bundles of muscle fibers grouped together in a fibrous sheath of fascia known as the
7
Q
endomysium.
A
Within the perimysium are individual muscle fibers wrapped in a fascia called
8
Q
Myofibrils run_1.___to each other and extend lengthwise rods throughout the cell.
Myofibrils contain many _2.__ or basic contractile units.
Sarcomeres contain 3.___ or overlapping protein filaments.
A
parallel
sarcomeres
myofilaments
9
Q
What causes the striations in muscle fibers?
A
Striations in muscle fibers are caused by the alternating dark and light bands formed by the arrangement of actin (thin) and myosin (thick) filaments in the sarcomere.
10
Q
What are A bands, and what protein are they primarily made of?
A
A bands are the dark areas in muscle fibers that contain thick filaments, which are primarily made of the protein myosin, twisted together.
11
Q
What protein attaches at the Z line and at either end of the thick filament?
A
The protein titin attaches at the Z line and at either end of the thick filament.
12
Q
How is a cross-bridge formed between myosin and actin?
A
A cross-bridge is formed when myosin heads bind to the active receptor sites on the actin filament, linking the two myofilaments together.
13
Q
: What are I bands, and what protein are they primarily made of?
A
I bands are the light areas in muscle fibers where the thin filaments are located, primarily made up of the protein actin.
14
Q
where do thin filaments extend, and what do they overlap with?
A
Thin filaments extend into the A bands, where they overlap with the thick filaments.
15
Q
What three protein molecules make up the thin filament?
A
The thin filament is made up of actin, tropomyosin, and troponin.
16
Q
What are the receptor sites on thin filaments called, and what binds to them?
A
he receptor sites on thin filaments are called active sites, and myosin binds to them.
17
Q
How does the thin filament affect the length of the muscle fiber?
A
The thin filament slides over the thick filament, causing a change in the length of the muscle fiber.
18
Q
How is a muscle fiber stimulated to contract?
A
A muscle fiber is stimulated by an action potential at the neuromuscular junction, which causes the release of the neurotransmitter acetylcholine from the end of the motor neuron into the synaptic cleft.
19
Q
What effect does acetylcholine have on the muscle fiber?
A
Acetylcholine excites (or depolarizes) the muscle fiber.
20
Q
What happens when the action potential reaches the T-tubules?
A
The arrival of the action potential to the T-tubules signals the release of calcium from the terminal cisternae.
21
Q
What happens when calcium binds to troponin?
A
When calcium binds to troponin, it causes tropomyosin to shift its position, exposing binding sites on the thin filament.
22
Q
What are the characteristics of fast-twitch muscle fibers?
A
ast-twitch muscle fibers (also known as Type 2, with subtypes IIx and IIa) have fast shortening speeds, high maximal shortening velocity, and produce 10%-20% more force than slow-twitch fibers. They are better suited for activities such as sprinting and weightlifting.
23
Q
What are the characteristics of slow-twitch muscle fibers?
A
Slow-twitch muscle fibers (also known as slow-oxidative or Type 1) contain large amounts of mitochondria, are surrounded by more capillaries than fast-twitch fibers, have higher concentrations of myoglobin, are more resistant to fatigue, and are more efficient at using oxygen to generate ATP for sustained muscle contractions.
24
Q
What is responsible for the strength gains experienced after prolonged resistance training?
A
Muscle growth, or hypertrophy, is responsible for the strength gains experienced after a prolonged period of resistance training.
25
What is chronic hypertrophy associated with?
Chronic hypertrophy is associated with fiber hypertrophy, fiber hyperplasia, or both.
26
What mechanism is responsible for fiber hypertrophy in trained individuals?
The increase in muscle protein synthesis stimulated by resistance training appears to be the mechanism responsible for fiber hypertrophy in trained individuals.
27
What are the two main reasons for muscle atrophy?
The two main reasons for muscle atrophy are disuse and aging.
28
Can muscle mass and strength lost due to disuse atrophy be regained?
Yes, both muscle mass and strength lost with disuse atrophy can be regained by returning the muscle to normal use.
29
What is atrophy due to the aging process called?
Atrophy due to the aging process is called sarcopenia.
30
What protein is commonly found in connective tissue?
Connective tissue is made up of dozens of proteins, including collagen.
31
What are the physical properties of collagen, and where is it mainly found?
Collagen has tensile strength and relative inextensibility. It is a main constituent of ligaments and tendons.
32
What role do elastic fibers play in connective tissue?
Elastic fibers in connective tissue are responsible for determining the possible range of extensibility of muscle cells.
33
What are the roles of elastic fibers in skeletal muscle?
Elastic fibers in skeletal muscle play several roles, including disseminating mechanical stress, enhancing coordination, maintaining tone during muscular relaxation, and defending against excessive forces.
34
What are the characteristics and functions of tendons?
Tendons are cord-like tissues that connect muscles to bones. Their functions include transmitting force from the muscle to the bone, thereby producing motion, and resisting movement in the direction opposite of the force that causes joint movement.
35
What are the characteristics and functions of ligaments?
Ligaments attach bone to bone at the joints. They support the joints by allowing freedom of movement while being strong, tough, and inextensible, preventing them from yielding easily to applied forces.
36
What are the characteristics and functions of fasciae?
Fasciae are sheath-like substances that encase body cavities, muscles, and organs. They support the innermost body cavities and organs, enable the safe and effective transmission of forces within the body, and provide lubricated surfaces between muscle fibers, allowing muscles to change shape during contraction and elongation.
37
Central Nervous System (CNS)
–Brain and spinal cord
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Peripheral Nervous System (PNS)
All the nervous structures located outside of the CNS, namely nerves and ganglia
39
Step-by-Step Process from Cell Depolarization to Muscular Contraction:
1. **Action Potential Generation:**
- A nerve impulse (action potential) is generated in the motor neuron.
2. **Neuromuscular Junction:**
- The action potential travels along the motor neuron to the neuromuscular junction (the synapse between the motor neuron and muscle fiber).
3. **Release of Acetylcholine:**
- The action potential triggers the release of the neurotransmitter acetylcholine (ACh) from the motor neuron into the synaptic cleft.
4. **Muscle Fiber Depolarization:**
- Acetylcholine binds to receptors on the muscle fiber’s sarcolemma (cell membrane), leading to the depolarization of the muscle fiber (generation of an action potential).
5. **Action Potential Spreads:**
- The muscle fiber action potential travels along the sarcolemma and into the T-tubules, which are extensions of the sarcolemma.
6. **Calcium Release:**
- The action potential reaches the T-tubules, which signals the release of calcium ions (Ca²⁺) from the terminal cisternae of the sarcoplasmic reticulum.
7. **Calcium Binding to Troponin:**
- The released calcium ions bind to troponin, a regulatory protein on the thin actin filament.
8. **Tropomyosin Shift:**
- The binding of calcium to troponin causes tropomyosin to shift its position on the actin filament, exposing the active binding sites for myosin.
9. **Cross-Bridge Formation:**
- The myosin heads bind to the exposed active sites on the actin filament, forming cross-bridges between the actin and myosin filaments.
10. **Power Stroke:**
- The myosin heads pivot, pulling the actin filaments toward the center of the sarcomere, resulting in the contraction of the muscle fiber. This movement is called the power stroke.
11. **ATP Hydrolysis and Cross-Bridge Detachment:**
- ATP binds to the myosin head, causing it to detach from the actin filament. The ATP is then hydrolyzed into ADP and inorganic phosphate, which re-energizes the myosin head for another cycle of contraction.
12. **Muscle Contraction:**
- This process repeats, with myosin heads continually forming cross-bridges, pulling actin, and detaching until the muscle fiber contracts fully.
13. **Muscle Relaxation:**
- When the action potential stops, calcium ions are pumped back into the sarcoplasmic reticulum, and tropomyosin covers the active sites on actin again, causing the muscle fiber to relax.
This cycle of contraction and relaxation is what allows muscles to contract in response to neural stimulation.
40
What is a reflex?
A reflex is a response to a certain stimulus that is not under conscious control.
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Where are simple reflexes processed?
Simple reflexes are processed at the level of the spinal cord.
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Where are complex responses processed?
Complex responses are processed by the higher brain centers
43
What is proprioception largely a result of?
Proprioception is largely a result of reflexive responses.
Helps to protect us by responding to outside stimuli
44
What does a typical reflex consist of?
A typical reflex consists of a nerve pathway from a sensory receptor to the central nervous system (CNS) and from the CNS along a motor pathway to an effector organ.
45
How do sensory and motor neurons function in a reflex?
The sensory neuron identifies the senses and transmits them to the spinal cord via the dorsal root, where the information is processed. Then, the motor neuron sends a signal to the muscle, telling it what to do.
46
What is the pathway for a reflex arc involving pain?
The pathway for this reflex arc is as follows:
A sensory pain receptor (nociceptor) sends an impulse to the spinal cord.
Interneurons, which relay sensory information within the central nervous system, are stimulated and excite motor neurons.
The stimulated interneurons cause depolarization of specific motor neurons, which control the skeletal muscles necessary to withdraw the limb from the pain stimulus.
47
What is sensory-motor integration, and how does it work?
Sensory-motor integration involves somatosensory receptors, which are nervous system structures that report afferent feedback needed to perform movement. These receptors include muscle spindles, Golgi tendon organs (GTOs), joint receptors, cutaneous mechanoreceptors, and thermal sensors. The integration center, located in the spinal cord or brain, interprets the sensory input and links it to the motor system. Efferent signals then trigger depolarization, leading to muscle contraction.
48
How do efferent signals lead to skeletal muscle contractions?
efferent signals are sent from the CNS to the peripheral nervous system (PNS) to produce skeletal muscle contractions, carried along alpha (α) motor neurons. The cell bodies of these neurons are located in the gray matter of the spinal cord, and their axons extend outward to the skeletal muscle fibers they innervate, forming a motor unit. Once a motor neuron is stimulated, it transmits its signal away from the CNS to the associated muscle fibers, leading to muscle contraction.
49
What is the integration center in the CNS?
he integration center is the area within the CNS where sensory information terminates. It is also where sensory input is interpreted and linked to the motor system.
50
How does the pain withdrawal response work in the case of a sprained ankle?
In the case of a sprained ankle, the pain withdrawal response works as follows:
Sensory: Swelling and pain from the injury are detected by sensory receptors.
CNS: The sensory information is integrated in the CNS, where it is processed and interpreted.
Effector: The motor system activates muscles to withdraw the ankle from the painful stimulus, minimizing further injury.
51
How do muscle spindles function in monitoring muscle length and stretch?
Muscle spindles are receptors within skeletal muscle that monitor muscle length and changes in length, such as stretch. They contain two types of fibers:
Intrafusal fibers: Located within the spindle and sensitive to stretch.
Extrafusal fibers: Surround the spindle and are responsible for muscle contraction.
Information about the extent and speed of the stretch is sent from the muscle spindle to the spinal cord via primary afferent (Ia) pathways. The afferent neuron synapses with an α-motor neuron (efferent pathway), which sends excitatory stimuli to the muscle, summing with voluntary movement stimuli
52
How do Golgi tendon organs (GTOs) function in response to muscle tension?
Golgi tendon organs (GTOs) produce an inhibitory reflex action in the muscles they supply. When there is a change in tension within a muscle fiber, the collagen fibers surrounding the GTO are pinched. This sends action potentials to the CNS, indicating the level of tension in the muscle.
53
What is autogenic inhibition, and how does it work?
Autogenic inhibition occurs when excessive tension is detected in the musculotendinous unit. The afferent signals from the Ib nerve fibers of the Golgi tendon organ (GTO) synapse with inhibitory interneurons in the spinal cord. These interneurons then inhibit the α motor neurons, reducing muscle contraction to prevent injury from excessive tension.
54
What is the role of joint receptors?
joint receptors are located in the joint capsules and surrounding ligaments. They transmit sensory information related to the position, velocity, and acceleration occurring at the joints.
55
What are Pacinian corpuscles and what do they detect?
Pacinian corpuscles are joint receptors that detect changes in movement or pressure. They are located close to the Golgi tendon organs (GTOs).
56
What do Golgi-Mazzoni corpuscles respond to, and where are they located?
Golgi-Mazzoni corpuscles are located within the joint capsule and are responsive to joint compression. They play a role in sensing changes such as edema, swelling, and pain.
57
What is the function of free nerve endings?
Free nerve endings are nociceptive in nature, meaning they detect painful stimuli.
58
What is a motor unit, and what does it consist of?
A motor unit is defined as an α motor neuron and all of the skeletal muscle fibers it innervates.
59
What are the characteristics of Type I muscle fibers?
Type I fibers contain myosin heavy chain (MHC) isoforms related to "slow twitch" fibers. They have slow contractile speed, determined by ATPase activity, and use oxidative metabolic pathways for energy production.
60
What are the characteristics of the α-motor neuron in Type I muscle fibers?
The α-motor neuron in Type I muscle fibers has a relatively small cell body and a small diameter axon. It typically innervates fewer than 300 muscle fibers, resulting in smaller activation because less muscular activity is needed.
61
Why do Type II motor units reach peak tension more rapidly than Type I motor units?
Type II motor units reach peak tension more rapidly than Type I motor units because they contain faster isoforms of myosin heavy chain (MHC) and have faster myosin ATPase activity.
62
What are the characteristics of Type IIa fibers?
Type IIa fibers contain myosin heavy chain (MHC) isoforms of one subtype of "fast twitch" fibers. They have fast contractile characteristics, fast ATPase enzyme activity, and use a combination of oxidative and glycolytic metabolic pathways for energy production
63
What are the characteristics of Type IIx fibers?
rype IIx fibers contain myosin heavy chain (MHC) isoforms of another subtype of "fast twitch" fibers. They have fast contractile characteristics, even faster ATPase activity, and primarily use glycolytic metabolic pathways for energy production.
64
How does the CNS regulate force production in muscles?
the CNS regulates force production by determining the number and size of the motor units that are activated to participate in the muscle's force production
65
What is rate coding, and how does the CNS adjust force production?
Rate coding is the process by which the CNS adjusts the firing rate of motor neurons. Once all signals are recruited, the firing rate traveling down the motor neuron to the fibers within the motor unit can be adjusted, which leads to an increase or decrease in force production within the motor unit.
66
What is the Size Principle in relation to force production?
he Size Principle states that less force requires less activation. Smaller motor units are recruited first for low-force activities, while larger motor units are recruited as more force is needed.
67
What is the optimal muscle length for force production according to the Length-Tension Relationship?
The optimal muscle length for force production is between 100% and 120% of the muscle's resting length. At this length, the ends of the thin filaments are near the center of the thick filament, producing the greatest overlap and allowing the maximum number of cross-bridge attachment
68
What is the Stretch-Shortening Cycle (SSC) and how does it affect muscle function?
The Stretch-Shortening Cycle (SSC) involves an eccentric contraction immediately followed by a concentric contraction. This cycle is apparent in activities such as walking, running, and hopping. SSC leads to increased neural responses from the CNS, and training reactive abilities within the neuromuscular system improves muscle stiffness, rate of force development, and peak velocity of muscle contraction.
69
What is the difference between a countermovement jump and a squat jump in terms of jump height?
The difference in jump height is attributed to the countermovement, which allows more force production at the start of the concentric phase of the jump compared to starting from a static position. This results in higher ground reaction forces, leading to greater jump heights.
70
What are the possible secondary mechanisms that contribute to increased jump height in a countermovement jump?
The possible secondary mechanisms contributing to increased jump height in a countermovement jump include the recovery of stored elastic energy in the muscles and tendons and the activation of the stretch reflex.
71
How is muscle fatigue defined?
Muscle fatigue is defined as an exercise-induced reduction in the ability of a muscle to maintain force or power.
72
How does a lack of blood glucose (hypoglycemia) affect muscle function and motor output?
A lack of blood glucose (hypoglycemia) during sustained exertion not only disturbs muscle function but also interferes with the motor output of the cerebral cortex, impairing overall performance.
73
How do ammonia and low blood glucose affect an endurance exerciser’s performance?
Active muscles release ammonia into the bloodstream, and in combination with low blood glucose, excess ammonia can impair an endurance exerciser's ability to sustain muscle activation, negatively affecting performance.
74
What happens to the sense of effort during sustained submaximal exertion?
during sustained submaximal exertion, there is an increase in the sense of effort from when the task began to when it ended, making the task feel more challenging as time progresses.
75
When does Delayed Onset Muscle Soreness (DOMS) typically occur?
Delayed Onset Muscle Soreness (DOMS) generally appears 24 to 48 hours after strenuous exercise and peaks between 2 to 3 days post-exercise.
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What is the likely cause of Delayed Onset Muscle Soreness (DOMS)?
Evidence suggests that DOMS is likely caused by tissue injury from excessive mechanical force, particularly eccentric force, exerted on muscle and connective tissue.
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What are the chronic neuromuscular adaptations to exercise?
Chronic neuromuscular adaptations to exercise include an increase in muscle strength and fiber adaptation, leading to improved performance and muscle function over time.
78
What accounts for the strength differences among individuals?
About 50% of the strength differences among individuals can be accounted for by muscle size, as muscle fibers with the greatest surface area are capable of producing the most force.
79
What factors could explain early strength gains in muscle training?
early strength gains:
-increases in neural drive to the exercising muscle
-changes in the coordination of the muscles involved in the task
-increased synchronization of motor unit activation.
- faster tetanic firing rates
- increased motor unit synchronization have been demonstrated following strength training.
80
How do muscle fibers adapt to strength training?
Most research shows that Type II motor units hypertrophy to a greater relative amount than Type I units. While fiber type adaptations were once believed to only occur from type IIx to IIa, a change from type I to type IIa has also been observed.
81
What is the principle of training reversibility, or detraining?
The principle of training reversibility, or detraining, suggests that the stoppage or marked reduction of training leads to a partial or complete reversal of training-induced adaptations.
82
What factors influence the degree of strength loss after complete cessation of strength training?
The degree of strength loss after complete cessation of strength training seems to depend on:
-training experienc
-the length of the cessation period
-age.
83
How do muscle fibers adapt to strength training?
Most research shows that Type II motor units hypertrophy to a greater relative amount than Type I units. While fiber type adaptations were previously thought to occur only from type IIx to IIa, a change from type I to type IIa has also been observed.
