Chapter 11 Muscular Tissue
Again, SOME questions from chapter 11 that WILL be on the exam. :D
- 1.
Which of the following is not a purpose of the excess post excercise oxygen consumption in muscle?
- A.
To replenish the phosphagen system
- B.
To oxidize lactic acid
- C.
To neutralize carbon dioxide buildup
- D.
To restore resting levels of ATP and CP
- E.
To serve elevated metabolic rate
Correct Answer
C. To neutralize carbon dioxide buildupExplanation
The purpose of excess post-exercise oxygen consumption (EPOC) in muscles is to replenish the phosphagen system, oxidize lactic acid, restore resting levels of ATP and CP, and serve elevated metabolic rate. However, it is not a purpose of EPOC to neutralize carbon dioxide buildup.Rate this question:
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- 2.
Which muscle(s) can contract without the need for the nervous stimulation?
- A.
Smooth and cardiac muscle
- B.
Skeletal muscle
- C.
Cardiac muscle
- D.
Smooth muscle
- E.
Skeletal, smooth and cardiac muscle
Correct Answer
A. Smooth and cardiac muscleExplanation
Smooth and cardiac muscles can contract without the need for nervous stimulation. Unlike skeletal muscles, which require nervous input to initiate contraction, smooth and cardiac muscles have intrinsic electrical activity that allows them to contract on their own. This is why smooth muscles can be found in organs like the intestines and blood vessels, and cardiac muscles make up the heart, both of which need to contract regularly without conscious control.Rate this question:
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- 3.
Where is lactic acid converted to pyruvic acid?
- A.
In the liver
- B.
In the muscle tissue
- C.
In the small intestine
- D.
In the neuromuscular junction
- E.
In the sarcoplasmic reticulum
Correct Answer
C. In the small intestineExplanation
Lactic acid is converted to pyruvic acid in the small intestine. This conversion occurs during the process of digestion and absorption of carbohydrates. Lactic acid is produced in the muscles during intense exercise when there is not enough oxygen available. It is then transported to the liver where it is converted back to pyruvic acid. However, this conversion can also take place in the small intestine, where lactate is metabolized by the intestinal mucosa.Rate this question:
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- 4.
During muscle contraction, a single myosin head consumes ATP at a rate of about
- A.
9 ATP per second
- B.
7 ATP per second
- C.
5 ATP per second
- D.
1 ATP per second
- E.
3 ATP per second
Correct Answer
C. 5 ATP per secondExplanation
During muscle contraction, a single myosin head consumes ATP at a rate of about 5 ATP per second. This is because ATP is required for the myosin head to detach from the actin filament, reset its position, and reattach to the next actin binding site. This process is repeated multiple times during muscle contraction, and each time ATP is hydrolyzed to provide the energy needed for the myosin head to perform its function. Therefore, the rate of ATP consumption by a single myosin head is approximately 5 ATP per second.Rate this question:
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- 5.
The term for shortening of a muscle while maintaining constant tension is
- A.
Isometric contraction
- B.
Isotonic contraction
- C.
Treppe
- D.
Tetanus
- E.
Isokinetic contraction
Correct Answer
B. Isotonic contractionExplanation
Isotonic contraction refers to the shortening of a muscle while maintaining a constant tension. This means that the muscle is able to generate enough force to overcome the resistance and move a load. During isotonic contraction, the muscle length changes, resulting in movement of the body part. This is different from isometric contraction, where the muscle contracts but does not change length, and from other options such as treppe, tetanus, and isokinetic contraction, which do not specifically describe the shortening of a muscle while maintaining constant tension.Rate this question:
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- 6.
Which fibers are primarily responsible for producing lactic acid?
- A.
Type I slow oxidative fibers
- B.
Type IIA intermediate glycoytic fibers
- C.
Type IIB fast glycolytic fibers
- D.
Type I slow-twitch fibers
- E.
Red fibers
Correct Answer
C. Type IIB fast glycolytic fibersExplanation
Type IIB fast glycolytic fibers are primarily responsible for producing lactic acid. These fibers are characterized by their ability to contract quickly and generate a high amount of force. They primarily rely on anaerobic metabolism, which produces lactic acid as a byproduct. This allows them to generate energy rapidly but for a short duration. Lactic acid buildup in these fibers can lead to fatigue and muscle soreness.Rate this question:
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- 7.
Michael Jordan was arguably the best player in pofesional basketball history. Scientifically one would expect him to have highly developed
- A.
Red fibers
- B.
Intermediate fibers
- C.
Fast-twitch fibers
- D.
White fibers
- E.
Slow oxidative fibers
Correct Answer
D. White fibersExplanation
Michael Jordan's exceptional skills and dominance in professional basketball suggest that he possessed highly developed white fibers. White fibers, also known as fast-twitch fibers, are responsible for generating explosive bursts of power and speed. These fibers are essential for activities that require quick movements, such as sprinting, jumping, and making rapid changes in direction. Given Jordan's incredible athleticism and ability to perform high-intensity movements with precision, it is reasonable to assume that his muscular composition included a significant proportion of white fibers.Rate this question:
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- 8.
Where would you expect to find numerous gap junctions in muscular tissue?
- A.
Multiunit smooth muscle
- B.
The sarcoplasmic reticulum of skeletal muscle
- C.
The A bands of skeletal and cardiac muscle
- D.
Intercalated discs of cardiac muscle
- E.
The sarcolemma of skeletal muscle
Correct Answer
D. Intercalated discs of cardiac muscleExplanation
Intercalated discs are specialized structures found in cardiac muscle tissue. These discs contain numerous gap junctions, which are protein channels that allow for direct electrical and chemical communication between adjacent cardiac muscle cells. This allows for synchronized contractions of the heart, ensuring efficient pumping of blood. Therefore, it is expected to find numerous gap junctions in intercalated discs of cardiac muscle.Rate this question:
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- 9.
The contraction strength of smooth muscle is relatively independent of its resting length partly because
- A.
It does not have Z disc
- B.
It gets nearly all of its Ca2+ from the extracellular fluid
- C.
It does not have intercalated discs
- D.
It is regulated by a length-tension relationship
- E.
It is voluntary muscle
Correct Answer
A. It does not have Z discExplanation
Smooth muscle does not have Z discs, which are structures found in striated muscle that anchor the thin filaments. In striated muscle, the contraction strength is dependent on the resting length due to the sliding filament mechanism, where the overlap between thick and thin filaments determines the force generated. However, smooth muscle lacks this mechanism and instead relies on other factors such as the phosphorylation of myosin light chains. Therefore, the contraction strength of smooth muscle is relatively independent of its resting length.Rate this question:
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- 10.
In comparison to skeletal muscle, smooth muscle
- A.
None of them
- B.
contracts more slowly but relaxes more rapidly
- C.
Contracts more rapidly but relaxes more slowly
- D.
Contracts more slowly
- E.
Contracts and relaxes more slowly
Correct Answer
D. Contracts more slowlyExplanation
Smooth muscle contracts more slowly compared to skeletal muscle. This is because smooth muscle cells have a different structure and arrangement of contractile proteins, which causes a slower contraction. Smooth muscle also has a slower rate of relaxation compared to skeletal muscle. This difference in contraction and relaxation speed allows smooth muscle to perform its functions, such as regulating blood flow, digestion, and other involuntary movements, in a controlled and coordinated manner.Rate this question:
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- 11.
Which of the following is very important for muscle to continue contraction during anaerobic respiration?
- A.
Protease
- B.
Myokinase
- C.
Cholinesterase
- D.
Acetylvholinesterase
- E.
Acid phosphatase
Correct Answer
B. MyokinaseExplanation
Myokinase is very important for muscles to continue contraction during anaerobic respiration. Myokinase is an enzyme that helps in the conversion of adenosine monophosphate (AMP) to adenosine diphosphate (ADP), which is a crucial step in the production of ATP (adenosine triphosphate) during anaerobic respiration. ATP is the main source of energy for muscle contractions, and myokinase plays a vital role in replenishing ATP levels in the muscles, allowing them to continue contracting even in the absence of oxygen.Rate this question:
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- 12.
The minimum stimulus needed to cause muscle contraction is called
- A.
The latent period
- B.
The threshold
- C.
Twitch
- D.
Recruitment
- E.
Innervation
Correct Answer
B. The thresholdExplanation
The threshold refers to the minimum stimulus required to initiate a muscle contraction. It is the point at which the muscle fibers are stimulated enough to generate an action potential and contract. Below this threshold, no contraction occurs. The threshold can vary depending on factors such as muscle type, individual muscle fiber characteristics, and the state of the muscle (resting or fatigued).Rate this question:
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- 13.
If one nerve stimulus arrives at a muscle fiber so soon that the fibers has only partially relaxed from the previos twitvh, the most likely result will be
- A.
Fatigue
- B.
Treppe
- C.
Complete tetanus
- D.
Incomplete tetanus
- E.
Flaccid paralysis
Correct Answer
D. Incomplete tetanusExplanation
If a nerve stimulus arrives at a muscle fiber before it has fully relaxed from the previous twitch, the muscle fiber will not have enough time to fully relax and will contract again. This repeated, rapid contraction without complete relaxation is known as incomplete tetanus. This is different from complete tetanus, where the muscle fiber is stimulated at such a high frequency that it remains in a state of sustained contraction without any relaxation. Fatigue refers to a decrease in muscle performance due to prolonged or intense activity. Treppe refers to the phenomenon where subsequent contractions of a muscle increase in strength. Flaccid paralysis is a condition where the muscles are limp and cannot contract.Rate this question:
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- 14.
Which of the following is true concerning isotonic eccentric contraction?
- A.
The muscle lengthens but tension remains constant
- B.
The muscle shortens but tension remains constant
- C.
The muscle tenses and shortens
- D.
The muscle tenses but length remains unchanged
- E.
The muscle lengthens and tension declines
Correct Answer
A. The muscle lengthens but tension remains constantExplanation
Isotonic eccentric contraction refers to a type of muscle contraction where the muscle lengthens while maintaining a constant tension. This means that the muscle is actively contracting and generating force, but the force produced is not enough to overcome the external load or resistance. As a result, the muscle lengthens as it contracts, but the tension within the muscle fibers remains constant. This type of contraction is often seen during activities such as lowering a weight slowly or descending stairs.Rate this question:
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- 15.
Which of the following has the largest mitochondria?
- A.
Intermediate fibers
- B.
Smooth muscle
- C.
Cardiac muscle
- D.
Fast glycolytic fibers
- E.
Slow oxidative fibers
Correct Answer
C. Cardiac muscleExplanation
Cardiac muscle has the largest mitochondria compared to the other options listed. Mitochondria are responsible for producing energy in cells through aerobic respiration, and cardiac muscle requires a constant supply of energy to sustain its continuous contractions. Therefore, it makes sense for cardiac muscle to have larger mitochondria to meet its high energy demands.Rate this question:
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- 16.
One somatic motor neuron is stimulated by how many muscle fibers
- A.
0
- B.
1
- C.
4
- D.
2
- E.
3
Correct Answer
A. 0Explanation
A somatic motor neuron is responsible for transmitting signals from the central nervous system to skeletal muscles. Each somatic motor neuron can innervate multiple muscle fibers, meaning it can stimulate more than one muscle fiber. Therefore, the correct answer cannot be 0.Rate this question:
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- 17.
To stimulate muscle contraction, acetycholine is released from the into the synaptic cleft.
- A.
Juctional folds
- B.
Terminal cisterna
- C.
Synaptic knob
- D.
Sarcolemma
- E.
Sarcoplasmic reticulum
Correct Answer
C. Synaptic knob -
- 18.
The absence or inhibition of AChE at a synapse would lead to which of the following?
- A.
Atrophy
- B.
Tetanus
- C.
Muscle wasting
- D.
Numbness
- E.
Flaccid paralysis
Correct Answer
B. TetanusExplanation
The absence or inhibition of AChE (Acetylcholinesterase) at a synapse would lead to tetanus. AChE is responsible for breaking down the neurotransmitter acetylcholine, allowing the muscles to relax after contraction. When AChE is absent or inhibited, acetylcholine cannot be broken down, leading to continuous muscle contraction and spasms, which is characteristic of tetanus.Rate this question:
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- 19.
Which statement best describes the goal of medications used to treat myasthenia gravis?
- A.
To inhibit Ca2+ release from the sarcoplasmic reticulum
- B.
To inhibit the function of cholinesterase
- C.
To decrease the number of synaptic vesicles
- D.
To increase the number of ACh receptors
- E.
To promote multiple motor unit summation
Correct Answer
B. To inhibit the function of cholinesteraseExplanation
The goal of medications used to treat myasthenia gravis is to inhibit the function of cholinesterase. Cholinesterase is an enzyme that breaks down acetylcholine (ACh), a neurotransmitter involved in muscle contractions. In myasthenia gravis, there is a decrease in the number of ACh receptors at the neuromuscular junction, leading to muscle weakness and fatigue. By inhibiting cholinesterase, more ACh is available in the synaptic cleft to bind to the remaining receptors, improving muscle function.Rate this question:
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- 20.
A single high voltage stimulation of a muscle will result in
- A.
Treppe
- B.
Wave summation
- C.
Recruitment
- D.
Incomplete tetanus
- E.
Complete tetanus
Correct Answer
C. RecruitmentExplanation
Recruitment refers to the process of activating additional motor units in a muscle in order to generate a stronger contraction. A single high voltage stimulation of a muscle is not sufficient to produce a complete tetanus (a sustained contraction), but it can lead to recruitment where more motor units are recruited to generate a stronger contraction. This allows the muscle to generate more force by increasing the number of active muscle fibers. Therefore, the correct answer is recruitment.Rate this question:
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- 21.
Aerobic respiration produces approximately more ATPs per glucose molecule than glycolysis does
- A.
24
- B.
48
- C.
12
- D.
36
- E.
100
Correct Answer
D. 36Explanation
Aerobic respiration produces approximately 36 more ATPs per glucose molecule than glycolysis does. This is because aerobic respiration involves the complete breakdown of glucose in the presence of oxygen, which allows for the production of a larger amount of ATP through the electron transport chain. In contrast, glycolysis is the initial step in both aerobic and anaerobic respiration, and it only produces a small amount of ATP. Therefore, aerobic respiration is more efficient in generating ATP from glucose compared to glycolysis.Rate this question:
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- 22.
Athletes who train at high altitudes increase their red blood cell count and thus increase their oxygen supply during exercise. Increase oxygen supply results in
- A.
Longer aerobic respiration
- B.
Increased glycolysis
- C.
Increased use of myokinase
- D.
Longer anaerobic fermentation
- E.
Reduced ATP consumption
Correct Answer
A. Longer aerobic respirationExplanation
When athletes train at high altitudes, the decrease in oxygen levels stimulates their bodies to produce more red blood cells. This increase in red blood cells allows for a higher oxygen supply during exercise. With more oxygen available, the body can engage in longer periods of aerobic respiration, which is the process that produces energy using oxygen. This is why the correct answer is longer aerobic respiration.Rate this question:
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- 23.
Cardiac muscle has very little capacity for regeneration because it lacks
- A.
Endomysium
- B.
Sarcomeres
- C.
Satellite cells
- D.
Dense bodies
- E.
Somatic nerve fibers
Correct Answer
C. Satellite cellsExplanation
Cardiac muscle has very little capacity for regeneration because it lacks satellite cells. Satellite cells are a type of stem cell that are present in skeletal muscle and play a crucial role in muscle regeneration and repair. In contrast, cardiac muscle does not have a significant population of satellite cells, which limits its ability to regenerate and repair damaged tissue. This is one of the reasons why cardiac muscle injuries, such as heart attacks, can have long-lasting and sometimes irreversible effects.Rate this question:
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- 24.
Which of the following would be caused by contraction of smooth muscle?
- A.
Deep respiration
- B.
Goose bumps
- C.
Blood leaving the left ventricle of the heart
- D.
Blinking of the eyelids
- E.
Elevating the eyebrows
Correct Answer
B. Goose bumpsExplanation
Contraction of smooth muscle can cause goose bumps. When the smooth muscle in the skin contracts, it causes the hair follicles to stand upright, resulting in the appearance of goose bumps. This response is often triggered by cold temperatures or emotional stimuli, such as fear or excitement. The contraction of smooth muscle in other parts of the body, such as the respiratory system or the cardiovascular system, would not directly cause goose bumps.Rate this question:
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- 25.
The triads of a muscle fiber consist of
- A.
Two thin myofilaments and one thick myofilament
- B.
Two terminal cisternae and one T tubule
- C.
To thick myofilaments and one thin myofilament
- D.
Two A bands and one I band
- E.
Two T tubules and one terminal cisternae
Correct Answer
B. Two terminal cisternae and one T tubuleExplanation
The triads of a muscle fiber consist of two terminal cisternae and one T tubule. Terminal cisternae are enlarged areas of the sarcoplasmic reticulum that store calcium ions, while T tubules are invaginations of the sarcolemma that allow for the conduction of electrical impulses deep into the muscle fiber. Together, these structures play a crucial role in the excitation-contraction coupling process, where the electrical signal triggers the release of calcium ions from the terminal cisternae, leading to muscle contraction.Rate this question:
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- 26.
As you are lifting a box someone places extra weight on top of it. For your muscle to continue contracting and lifting a box, the muscle must
- A.
Recruit more muscle fibers
- B.
Lower threshold
- C.
Reduce its wave summation
- D.
Shift from isometric to isotonic contraction
- E.
Shift from slow-twitch to fast-twitch mde
Correct Answer
A. Recruit more muscle fibersExplanation
When extra weight is placed on top of the box, the muscle needs to generate more force in order to continue contracting and lift the box. To achieve this, the muscle recruits more muscle fibers. By activating additional muscle fibers, the muscle can generate a greater force and overcome the increased load. This recruitment of more muscle fibers allows the muscle to adapt and meet the increased demand placed upon it.Rate this question:
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- 27.
The protein that acts as a calcium receptor in skeletal is
- A.
F actin
- B.
Tropomyosin
- C.
Troponin
- D.
Titin
- E.
Dystrophin
Correct Answer
C. TroponinExplanation
Troponin is a protein that acts as a calcium receptor in skeletal muscle. When calcium binds to troponin, it causes a conformational change that allows for the interaction between actin and myosin, leading to muscle contraction. This interaction is essential for the regulation of muscle contraction and relaxation. Therefore, troponin is the correct answer as it specifically functions as the calcium receptor in skeletal muscle.Rate this question:
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- 28.
Drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. These drugs
- A.
Prevent calcium from entering cardiac muscle, thus slowing down the heart rate.
- B.
Prevent calcium from exiting the sarcoplasmic reticulum in skeletal muscle
- C.
Prevent calcium from entering the sarcoplasmic reticulum of the smooth muscle.
- D.
Prevent calcium from entering smooth muscle, thuse allowing the muscle to relax.
- E.
Stimulate the calcium pump in smooth muscle, thus removing calcium from the calmodulin
Correct Answer
D. Prevent calcium from entering smooth muscle, thuse allowing the muscle to relax.Explanation
Calcium channel blockers work by preventing calcium from entering smooth muscle, which allows the muscle to relax. When calcium enters smooth muscle, it causes the muscle to contract. By blocking the entry of calcium, these drugs help to lower blood pressure by promoting relaxation of the smooth muscle in the arteries, leading to vasodilation and improved blood flow.Rate this question:
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- 29.
Exposure to Clostridium tetani causes continuous release of ACh. What effect does this have on smooth muscle?
- A.
No effect
- B.
Myocardial atrophy
- C.
Lockjaw
- D.
Spastic paralysis
- E.
Flaccid paralysis
Correct Answer
A. No effectExplanation
Exposure to Clostridium tetani, which causes continuous release of ACh, does not have any effect on smooth muscle. This is because ACh primarily acts on skeletal muscle, not smooth muscle. Smooth muscle is primarily regulated by other neurotransmitters and hormones, such as norepinephrine and acetylcholine released by the autonomic nervous system. Therefore, the continuous release of ACh by Clostridium tetani would not directly affect smooth muscle.Rate this question:
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- 30.
Dystrophin, the protein that is defective in muscular dystrophy, is normally found
- A.
Between the thin myofilaments and the sarcolemma of a muscle fiber
- B.
As a transmembrane protein of the sarcolemma
- C.
In the Z discs of skeletal and cardiac muscle
- D.
In the dense bodies of smooth muscle
- E.
Bridging the gap between the sarcolemma and synaptic knob
Correct Answer
A. Between the thin myofilaments and the sarcolemma of a muscle fiberExplanation
Dystrophin, the protein that is defective in muscular dystrophy, is normally found between the thin myofilaments and the sarcolemma of a muscle fiber. This positioning allows dystrophin to provide structural support and stability to the muscle fiber, linking the contractile elements (thin myofilaments) to the cell membrane (sarcolemma). This interaction is crucial for maintaining the integrity and function of the muscle fiber.Rate this question:
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- 31.
A reason that muscle twitches become progressively stronger in treppe is
- A.
ATP is regenerated faster than it is consumed
- B.
Myosin heads show faster and faster power strokes
- C.
Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it.
- D.
More and more ACh is released with each stimulus
- E.
As the muscle warms up, aerobic respiration is accelerated
Correct Answer
C. Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it.Explanation
In treppe, muscle twitches become progressively stronger because Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it. This leads to an increased availability of Ca2+ ions, which are necessary for muscle contraction. As a result, more cross-bridges can form between actin and myosin filaments, leading to stronger and more forceful muscle contractions.Rate this question:
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- 32.
The purpose of varicosities in muscle physiology is
- A.
To prevent single-unit smooth muscle cells from pulling apart
- B.
To release norepinephrine
- C.
To reabsorb the decomposition products of ACh after AChE breaks it down
- D.
To link the thin filaments to the inside of the sarcolemma in smooth muscle
- E.
To enable each cardiac myocyte to directly stimulate its neighbors
Correct Answer
B. To release norepinephrineExplanation
Varicosities in muscle physiology serve the purpose of releasing norepinephrine. Norepinephrine is a neurotransmitter that is released by varicosities in response to nerve impulses. It acts as a chemical messenger, transmitting signals between nerve cells and muscle cells. The release of norepinephrine allows for the regulation of various physiological processes, including the contraction and relaxation of smooth muscles. Therefore, varicosities play a crucial role in facilitating the communication between nerves and muscles through the release of norepinephrine.Rate this question:
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- 33.
Creatine kinase
- A.
Donates one of its phosphate groups to ADP
- B.
Phosphorylates and activates certain enzymes in the sarcoplasm
- C.
Catalyze the transfer of phosphate from CP to ADP
- D.
Functions as a substitute for ATP during anaerobic fermentation
- E.
Acts as a second messenger in muscle fibers.
Correct Answer
C. Catalyze the transfer of phosphate from CP to ADPExplanation
Creatine kinase is an enzyme that catalyzes the transfer of a phosphate group from creatine phosphate (CP) to adenosine diphosphate (ADP). This reaction results in the formation of adenosine triphosphate (ATP), which is the primary energy source for cellular processes. By transferring the phosphate group, creatine kinase helps replenish ATP levels in cells, allowing them to continue carrying out their functions. Therefore, the correct answer is that creatine kinase catalyzes the transfer of phosphate from CP to ADP.Rate this question:
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- 34.
Release of ACh
- A.
Increases permability of the sarcolemma
- B.
Lowers the threshold of the muscle fiber
- C.
Overrides the inhibitory effect of AChE
- D.
Decreases the positive charge on the sarcolemma
- E.
Decreases the release of Ca2+ from the sarcolemma
Correct Answer
A. Increases permability of the sarcolemmaExplanation
The release of ACh increases the permeability of the sarcolemma. ACh is a neurotransmitter that is released at the neuromuscular junction and binds to receptors on the sarcolemma. This binding causes ion channels to open, allowing ions to move in and out of the muscle fiber. The increased permeability of the sarcolemma allows for the movement of ions, such as sodium and potassium, which are important for generating an action potential and initiating muscle contraction.Rate this question:
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- 35.
Which of the following best describe the resting membrane potential (RMP)?
- A.
The intracellular environment has more positively charged sodium
- B.
It has a voltage of about +75 mV
- C.
It depends on the muscle fiber absorbing potassium ions fro the ECF
- D.
The intracellular environment is negatively charged
- E.
The extracellular environment is negatively charged
Correct Answer
D. The intracellular environment is negatively chargedExplanation
The resting membrane potential (RMP) refers to the electrical charge difference across the cell membrane when the cell is at rest. The correct answer states that the intracellular environment is negatively charged, which accurately describes the RMP. This negative charge is maintained by the unequal distribution of ions, with more negatively charged ions inside the cell compared to the outside. This creates an electrical potential across the membrane, typically around -70 mV in most cells.Rate this question:
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- 36.
The sarcolemma of a resting muscle fiber is most permeable to
- A.
Potassium
- B.
Calcium
- C.
Sodium
- D.
Magnesium
- E.
Lithium
Correct Answer
A. PotassiumExplanation
The sarcolemma of a resting muscle fiber is most permeable to potassium. This is because the resting membrane potential of a muscle fiber is mainly determined by the movement of potassium ions. At rest, the sarcolemma has more open potassium channels compared to other ions, allowing potassium to diffuse out of the cell more easily. This creates a negative charge inside the cell, maintaining the resting membrane potential.Rate this question:
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- 37.
What is the purpose of a triad?
- A.
The triad removes ACh from the synaptic cleft
- B.
The triad allows for a Ca2+ release when a muscle fiber is excites
- C.
The triad maintains the resting membrane potential
- D.
The triad synthesizes ATP
- E.
The triad stores sodium
Correct Answer
B. The triad allows for a Ca2+ release when a muscle fiber is excitesExplanation
The triad is a specialized structure found in muscle fibers and is responsible for the release of calcium ions (Ca2+) during muscle contraction. When a muscle fiber is excited, an action potential travels along the transverse tubules of the triad, causing the release of Ca2+ from the sarcoplasmic reticulum. This Ca2+ release is essential for muscle contraction as it triggers the interaction between actin and myosin, leading to the sliding of muscle filaments and subsequent muscle contraction. Therefore, the purpose of the triad is to allow for the Ca2+ release necessary for muscle fiber excitation and contraction.Rate this question:
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- 38.
Which of the following systems would improve energy for a racquetball player?
- A.
The respiratory system
- B.
The glycolysis system
- C.
The anaerobic system
- D.
Phosphagen system
- E.
Glycogen-lactic acid system
Correct Answer
D. Phosphagen systemExplanation
The phosphagen system is the primary energy system used for short bursts of high-intensity activity, such as sprinting or explosive movements in racquetball. It provides immediate energy through the breakdown of stored phosphocreatine, which can be rapidly converted to ATP, the body's main source of energy. This system allows racquetball players to generate quick and powerful movements on the court, improving their overall energy and performance during the game.Rate this question:
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- 39.
Loss of muscle mass from lack of activity is termed
- A.
Myopathy
- B.
Dystrophy
- C.
Atrophy
- D.
Apathy
- E.
Treppe
Correct Answer
C. AtrophyExplanation
Atrophy refers to the loss of muscle mass that occurs due to lack of physical activity. When muscles are not used regularly, they can become weaker and smaller in size. This can happen as a result of various factors such as injury, illness, or prolonged immobilization. Atrophy can affect any muscle in the body and can lead to muscle weakness and decreased functionality. Therefore, atrophy is the correct term to describe the loss of muscle mass from lack of activity.Rate this question:
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- 40.
Which of the following is not a characteristic of a muscle cell?
- A.
Plasticity
- B.
Contractility
- C.
Conductivity
- D.
Extensibility
- E.
Excitability
Correct Answer
A. PlasticityExplanation
Plasticity is not a characteristic of a muscle cell. Muscle cells have the ability to contract (contractility), conduct electrical signals (conductivity), stretch (extensibility), and respond to stimuli (excitability). However, plasticity refers to the ability of a cell or tissue to change its structure or function in response to external stimuli, which is not a characteristic of muscle cells.Rate this question:
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- 41.
Collagen is
- A.
Excitable
- B.
Impermeable
- C.
Elastic
- D.
Expendable
- E.
Contractile
Correct Answer
C. ElasticExplanation
Collagen is a fibrous protein found in connective tissues that provides strength and support to various structures in the body. It is known for its elastic properties, allowing it to stretch and recoil without losing its shape. This elasticity is crucial for maintaining the integrity and flexibility of tissues such as skin, tendons, and blood vessels.Rate this question:
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- 42.
A myofilament that flanks a thick filament and anchors it to a Z disc is called
- A.
A myofibril
- B.
A thin filament
- C.
A myoglobin
- D.
An elastic filament
- E.
a sarcoplasm
Correct Answer
D. An elastic filamentExplanation
An elastic filament is a myofilament that flanks a thick filament and anchors it to a Z disc. It provides stability and helps in maintaining the alignment of the thick filament within the muscle fiber. It allows for the stretching and contraction of the muscle during movement, providing elasticity and flexibility to the muscle fibers.Rate this question:
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- 43.
The bladder's ability to greatly distend and return to normal tension is due to the of the smooth muscles
- A.
Longevity
- B.
Plasticity
- C.
Tone
- D.
Tensile strength
- E.
Elasticity
Correct Answer
B. PlasticityExplanation
The bladder's ability to greatly distend and return to normal tension is due to the plasticity of the smooth muscles. Plasticity refers to the ability of a material or tissue to undergo deformation without breaking or permanently changing its shape. In the case of the bladder, the smooth muscles can stretch and expand to accommodate urine, and then contract back to their original size and shape once the urine is expelled. This flexibility and adaptability of the smooth muscles allow the bladder to function properly in storing and releasing urine.Rate this question:
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- 44.
A skeletal muscle generates the greatest tension when it is
- A.
Fully relaxed before being stimulated.
- B.
In a state of treppe.
- C.
Well-rested and low in creatine phosphate.
- D.
Partially stretched before being stimulated.
- E.
Greatly stretched before being stimulated.
Correct Answer
D. Partially stretched before being stimulated.Explanation
When a skeletal muscle is partially stretched before being stimulated, it is in an optimal position to generate the greatest tension. This is because when a muscle is partially stretched, it allows for an optimal overlap of actin and myosin filaments, which leads to an increased number of cross-bridges being formed. This increased number of cross-bridges results in a greater force of contraction and therefore greater tension.Rate this question:
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- 45.
A volleyball player depends on the gastrocnemius for plantar flexion, where as marathon runner depends more on the soleus muscles for the same action. This is because the soleus muscles
- A.
have a smaller mitochondria
- B.
Have more glycogen in them
- C.
Make more use of aerobic respiration
- D.
Do not have as many blood capillaries per gram of tissue
- E.
Break ATP down to ADP and Pi faster
Correct Answer
C. Make more use of aerobic respirationExplanation
The correct answer is that the soleus muscles make more use of aerobic respiration. This means that they rely more on oxygen to produce energy for muscle contractions, which is important for endurance activities like marathon running. Aerobic respiration is more efficient and sustainable than anaerobic respiration, which is why marathon runners, who require prolonged muscle activity, rely more on this energy-producing process.Rate this question:
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- 46.
Ina relaxed muscle fiber, the active sites of actin are blocked by
- A.
Tropomyosin
- B.
F actin
- C.
Dystrophin
- D.
G actin
- E.
Myosin
Correct Answer
A. TropomyosinExplanation
In a relaxed muscle fiber, the active sites of actin are blocked by tropomyosin. Tropomyosin is a protein that wraps around the actin filament, preventing the binding of myosin. When the muscle fiber is stimulated, calcium ions bind to troponin, causing a conformational change in tropomyosin, which exposes the active sites on actin. This allows myosin to bind to actin and initiate muscle contraction. F actin, dystrophin, and G actin are not directly involved in blocking the active sites of actin in a relaxed muscle fiber.Rate this question:
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- 47.
In skeletal muscle, alternating light and dark bands are termed
- A.
Treppe
- B.
Striations
- C.
Myofibrils
- D.
Strabisums
- E.
Myoblasts
Correct Answer
B. StriationsExplanation
In skeletal muscle, alternating light and dark bands are termed striations. These striations are caused by the arrangement of contractile proteins within the muscle fibers. The two types of contractile proteins, actin and myosin, are organized in a repeating pattern, creating the striated appearance. This organization allows for the contraction and relaxation of the muscle, enabling movement and function.Rate this question:
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- 48.
The training regimen of a competitive weight lifter is designed partly to
- A.
Convert certain parallel muscles into stronger pennate muscles
- B.
Lower the threshold for muscle excitation
- C.
Increase the size of his motor units
- D.
Increase the average number of myofibrils per muscle fiber
- E.
Convert white muscle tissue to red muscle
Correct Answer
D. Increase the average number of myofibrils per muscle fiberExplanation
The training regimen of a competitive weight lifter is designed to increase the average number of myofibrils per muscle fiber. Myofibrils are the contractile units of muscle fibers, and increasing their number within each fiber allows for greater force production and muscle strength. By subjecting the muscles to progressively heavier loads and challenging exercises, weightlifting training stimulates the growth and development of myofibrils, resulting in increased muscle fiber size and strength. This adaptation is crucial for weightlifters as it allows them to generate more force and lift heavier weights.Rate this question:
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Mar 16, 2023Quiz Edited by
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Mar 25, 2010Quiz Created by
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