Muscle Physiology - Anatomy
Card 0 of 280
Which of the following is NOT characteristic of cardiac muscle?
Which of the following is NOT characteristic of cardiac muscle?
Skeletal muscle is the only muscle type that is multinucleated. Both cardiac and smooth muscle cells have only one nucleus.
Smooth muscle is under involuntary control, innervated by the autonomic nervous system, and contains mononucleated cells. Skeletal muscle is striated, multinucleated, and under voluntary control. Cardiac muscle is striated, mononucleated, and under involuntary control.
Cardiac muscle also uses intercalated discs, specialized cellular junctions, to facilitate electrical conduction between cardiomyocytes. This helps coordinate the contraction of the heart.
Skeletal muscle is the only muscle type that is multinucleated. Both cardiac and smooth muscle cells have only one nucleus.
Smooth muscle is under involuntary control, innervated by the autonomic nervous system, and contains mononucleated cells. Skeletal muscle is striated, multinucleated, and under voluntary control. Cardiac muscle is striated, mononucleated, and under involuntary control.
Cardiac muscle also uses intercalated discs, specialized cellular junctions, to facilitate electrical conduction between cardiomyocytes. This helps coordinate the contraction of the heart.
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Three muscle cells are placed side by side.
In muscle cell 1, striations are clearly visible.
In muscle cell 2, striations are also present, with sharp discs periodically found along muscle fibers. Further examination shows gap junctions between adjacent cells.
In muscle cell 3, no striations are present.
Which of the above types of muscle cell is most likely to be found in the myocardium?
Three muscle cells are placed side by side.
In muscle cell 1, striations are clearly visible.
In muscle cell 2, striations are also present, with sharp discs periodically found along muscle fibers. Further examination shows gap junctions between adjacent cells.
In muscle cell 3, no striations are present.
Which of the above types of muscle cell is most likely to be found in the myocardium?
Cardiac muscle is physiologically and morphologically distinct from skeletal and smooth muscle. Instead of using myosin light chain kinase (like smooth muscle), cardiac muscle uses the same sarcomere pattern of skeletal muscle. This explains the presence of striations in both types of tissue.
Cardiac muscle is unique, however, in that it has gap junctions that allow the exchange of ions between individual cells. This allows the myocardium, or muscular portion of heart tissue, to beat in a coordinated fashion, as cells are depolarizing alongside one another. Additionally, intercalated discs are present at the ends of sarcomeres, but are not present in skeletal muscle.
These two characteristics allow us to conclude that muscle cell type 2 is cardiac muscle, and will be found in the myocardium.
Cardiac muscle is physiologically and morphologically distinct from skeletal and smooth muscle. Instead of using myosin light chain kinase (like smooth muscle), cardiac muscle uses the same sarcomere pattern of skeletal muscle. This explains the presence of striations in both types of tissue.
Cardiac muscle is unique, however, in that it has gap junctions that allow the exchange of ions between individual cells. This allows the myocardium, or muscular portion of heart tissue, to beat in a coordinated fashion, as cells are depolarizing alongside one another. Additionally, intercalated discs are present at the ends of sarcomeres, but are not present in skeletal muscle.
These two characteristics allow us to conclude that muscle cell type 2 is cardiac muscle, and will be found in the myocardium.
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Which of the following cellular structures allows the heart to operate as a functional syncytium?
Which of the following cellular structures allows the heart to operate as a functional syncytium?
The presence of gap junctions within the intercalated discs of contractile cardiac myocytes allows for the rapid passage of ions from one cell to another. Once pacemaker cells in the sinoatrial node of the heart spontaneously generate action potentials, this wave of depolarization spreads into neighboring contractile myocytes via gap junctions. These gap junction connections are crucial to the heart operating in a unified and coordinated fashion, and are responsible for the characteristic wavelike contraction of the heart from the apex to the base.
The presence of gap junctions within the intercalated discs of contractile cardiac myocytes allows for the rapid passage of ions from one cell to another. Once pacemaker cells in the sinoatrial node of the heart spontaneously generate action potentials, this wave of depolarization spreads into neighboring contractile myocytes via gap junctions. These gap junction connections are crucial to the heart operating in a unified and coordinated fashion, and are responsible for the characteristic wavelike contraction of the heart from the apex to the base.
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What is the pericardial membrane?
What is the pericardial membrane?
The pericardial membrane is the tissue that surrounds the heart. The easiest way to determine the answer in this problem is to understand that "cardial" indicates pertinence heart and that "peri" is a prefix meaning "around."
The pericardial membrane is the tissue that surrounds the heart. The easiest way to determine the answer in this problem is to understand that "cardial" indicates pertinence heart and that "peri" is a prefix meaning "around."
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What is the correct sequence of the cardiac impulse as it transverses through the heart?
What is the correct sequence of the cardiac impulse as it transverses through the heart?
Cardiac contraction begins in the sinoatrial node. The impulse travels through both atria then followed by arriving at the atrioventricular node, which slows the impulse to allow for complete atrial contraction and ventricular filling. Then the impulse travels through the bundle of His, which branches into the right and left bundle branches and through the Purkinje fibers in the walls of both ventricles generating a strong contraction.
Cardiac contraction begins in the sinoatrial node. The impulse travels through both atria then followed by arriving at the atrioventricular node, which slows the impulse to allow for complete atrial contraction and ventricular filling. Then the impulse travels through the bundle of His, which branches into the right and left bundle branches and through the Purkinje fibers in the walls of both ventricles generating a strong contraction.
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A patient is shown to have a cardiac output of 
and a stroke volume of 
. What is his pulse (in beats per minutes)?
A patient is shown to have a cardiac output of
Cardiac output (CO) is defined as:
Rearrange to solve for heart rate.
Cardiac output (CO) is defined as:
Rearrange to solve for heart rate.
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Which of the following is NOT characteristic of cardiac muscle?
Which of the following is NOT characteristic of cardiac muscle?
Skeletal muscle is the only muscle type that is multinucleated. Both cardiac and smooth muscle cells have only one nucleus.
Smooth muscle is under involuntary control, innervated by the autonomic nervous system, and contains mononucleated cells. Skeletal muscle is striated, multinucleated, and under voluntary control. Cardiac muscle is striated, mononucleated, and under involuntary control.
Cardiac muscle also uses intercalated discs, specialized cellular junctions, to facilitate electrical conduction between cardiomyocytes. This helps coordinate the contraction of the heart.
Skeletal muscle is the only muscle type that is multinucleated. Both cardiac and smooth muscle cells have only one nucleus.
Smooth muscle is under involuntary control, innervated by the autonomic nervous system, and contains mononucleated cells. Skeletal muscle is striated, multinucleated, and under voluntary control. Cardiac muscle is striated, mononucleated, and under involuntary control.
Cardiac muscle also uses intercalated discs, specialized cellular junctions, to facilitate electrical conduction between cardiomyocytes. This helps coordinate the contraction of the heart.
Compare your answer with the correct one above
Three muscle cells are placed side by side.
In muscle cell 1, striations are clearly visible.
In muscle cell 2, striations are also present, with sharp discs periodically found along muscle fibers. Further examination shows gap junctions between adjacent cells.
In muscle cell 3, no striations are present.
Which of the above types of muscle cell is most likely to be found in the myocardium?
Three muscle cells are placed side by side.
In muscle cell 1, striations are clearly visible.
In muscle cell 2, striations are also present, with sharp discs periodically found along muscle fibers. Further examination shows gap junctions between adjacent cells.
In muscle cell 3, no striations are present.
Which of the above types of muscle cell is most likely to be found in the myocardium?
Cardiac muscle is physiologically and morphologically distinct from skeletal and smooth muscle. Instead of using myosin light chain kinase (like smooth muscle), cardiac muscle uses the same sarcomere pattern of skeletal muscle. This explains the presence of striations in both types of tissue.
Cardiac muscle is unique, however, in that it has gap junctions that allow the exchange of ions between individual cells. This allows the myocardium, or muscular portion of heart tissue, to beat in a coordinated fashion, as cells are depolarizing alongside one another. Additionally, intercalated discs are present at the ends of sarcomeres, but are not present in skeletal muscle.
These two characteristics allow us to conclude that muscle cell type 2 is cardiac muscle, and will be found in the myocardium.
Cardiac muscle is physiologically and morphologically distinct from skeletal and smooth muscle. Instead of using myosin light chain kinase (like smooth muscle), cardiac muscle uses the same sarcomere pattern of skeletal muscle. This explains the presence of striations in both types of tissue.
Cardiac muscle is unique, however, in that it has gap junctions that allow the exchange of ions between individual cells. This allows the myocardium, or muscular portion of heart tissue, to beat in a coordinated fashion, as cells are depolarizing alongside one another. Additionally, intercalated discs are present at the ends of sarcomeres, but are not present in skeletal muscle.
These two characteristics allow us to conclude that muscle cell type 2 is cardiac muscle, and will be found in the myocardium.
Compare your answer with the correct one above
Which of the following cellular structures allows the heart to operate as a functional syncytium?
Which of the following cellular structures allows the heart to operate as a functional syncytium?
The presence of gap junctions within the intercalated discs of contractile cardiac myocytes allows for the rapid passage of ions from one cell to another. Once pacemaker cells in the sinoatrial node of the heart spontaneously generate action potentials, this wave of depolarization spreads into neighboring contractile myocytes via gap junctions. These gap junction connections are crucial to the heart operating in a unified and coordinated fashion, and are responsible for the characteristic wavelike contraction of the heart from the apex to the base.
The presence of gap junctions within the intercalated discs of contractile cardiac myocytes allows for the rapid passage of ions from one cell to another. Once pacemaker cells in the sinoatrial node of the heart spontaneously generate action potentials, this wave of depolarization spreads into neighboring contractile myocytes via gap junctions. These gap junction connections are crucial to the heart operating in a unified and coordinated fashion, and are responsible for the characteristic wavelike contraction of the heart from the apex to the base.
Compare your answer with the correct one above
What is the pericardial membrane?
What is the pericardial membrane?
The pericardial membrane is the tissue that surrounds the heart. The easiest way to determine the answer in this problem is to understand that "cardial" indicates pertinence heart and that "peri" is a prefix meaning "around."
The pericardial membrane is the tissue that surrounds the heart. The easiest way to determine the answer in this problem is to understand that "cardial" indicates pertinence heart and that "peri" is a prefix meaning "around."
Compare your answer with the correct one above
What is the correct sequence of the cardiac impulse as it transverses through the heart?
What is the correct sequence of the cardiac impulse as it transverses through the heart?
Cardiac contraction begins in the sinoatrial node. The impulse travels through both atria then followed by arriving at the atrioventricular node, which slows the impulse to allow for complete atrial contraction and ventricular filling. Then the impulse travels through the bundle of His, which branches into the right and left bundle branches and through the Purkinje fibers in the walls of both ventricles generating a strong contraction.
Cardiac contraction begins in the sinoatrial node. The impulse travels through both atria then followed by arriving at the atrioventricular node, which slows the impulse to allow for complete atrial contraction and ventricular filling. Then the impulse travels through the bundle of His, which branches into the right and left bundle branches and through the Purkinje fibers in the walls of both ventricles generating a strong contraction.
Compare your answer with the correct one above
A patient is shown to have a cardiac output of and a stroke volume of . What is his pulse (in beats per minutes)?
A patient is shown to have a cardiac output of
Cardiac output (CO) is defined as:
Rearrange to solve for heart rate.
Cardiac output (CO) is defined as:
Rearrange to solve for heart rate.
Compare your answer with the correct one above
Which of the following sarcomere portions does not decrease in length during muscular contraction?
Which of the following sarcomere portions does not decrease in length during muscular contraction?
During muscular contraction, the myosin heads pull the actin filaments toward one another resulting in a shortened sarcomere. While the I band and H zone will disappear or shorten, the A band length will remain unchanged. This is because the A band corresponds to the full length of the myosin filament, or thick filament. Since the myosin filament does not actually change length, the A band remains constant.
The I band corresponds to the region of action that does not overlap with myosin. The length of the actin filament does not change during contraction, but the region of overlap increases. This results in a decrease of the non-overlapped I band.
The H zone refers to the region of myosin that is not overlapped by action. As the region of overlap grows, the H zone shrinks.
During muscular contraction, the myosin heads pull the actin filaments toward one another resulting in a shortened sarcomere. While the I band and H zone will disappear or shorten, the A band length will remain unchanged. This is because the A band corresponds to the full length of the myosin filament, or thick filament. Since the myosin filament does not actually change length, the A band remains constant.
The I band corresponds to the region of action that does not overlap with myosin. The length of the actin filament does not change during contraction, but the region of overlap increases. This results in a decrease of the non-overlapped I band.
The H zone refers to the region of myosin that is not overlapped by action. As the region of overlap grows, the H zone shrinks.
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An investigational drug prevents skeletal muscle contraction by preventing ATP hydrolysis at the active site in muscle tissue. Where is this drug most likely to act?
An investigational drug prevents skeletal muscle contraction by preventing ATP hydrolysis at the active site in muscle tissue. Where is this drug most likely to act?
ATP binds to myosin head regions and is hydrolyzed to ADP and inorganic phosphate when muscle relaxes. The release of these products allows the contraction to occur as the myosin head changes position. The binding of new ATP releases the myosin head from actin, and allows the muscle to relax prior to another round of hydrolysis. This explains why, in the absence of adequate ATP, muscle can remain in a contracted state. This phenomenon, when seen in the deceased, is called rigor mortis.
ATP binds to myosin head regions and is hydrolyzed to ADP and inorganic phosphate when muscle relaxes. The release of these products allows the contraction to occur as the myosin head changes position. The binding of new ATP releases the myosin head from actin, and allows the muscle to relax prior to another round of hydrolysis. This explains why, in the absence of adequate ATP, muscle can remain in a contracted state. This phenomenon, when seen in the deceased, is called rigor mortis.
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Ions are key in mediating muscle contraction. Which of the following structures interacts directly with ions to expose actin binding sites in contracting muscle?
Ions are key in mediating muscle contraction. Which of the following structures interacts directly with ions to expose actin binding sites in contracting muscle?
Troponin (also called troponin C) is the most direct structure that interacts with ions involved in initiating muscle contractions. Once bound to calcium ions, troponin facilitates the movement of tropomyosin away from actin binding sites, allowing myosin to bind and, ultimately, contract. Without the binding of calcium ions to troponin, the myosin-binding site on actin remains obscured by tropomyosin and contraction cannot occur.
Troponin (also called troponin C) is the most direct structure that interacts with ions involved in initiating muscle contractions. Once bound to calcium ions, troponin facilitates the movement of tropomyosin away from actin binding sites, allowing myosin to bind and, ultimately, contract. Without the binding of calcium ions to troponin, the myosin-binding site on actin remains obscured by tropomyosin and contraction cannot occur.
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In excitation-contraction coupling in skeletal muscle, the calcium released from the smooth endoplasmic reticulum binds to which of the following?
In excitation-contraction coupling in skeletal muscle, the calcium released from the smooth endoplasmic reticulum binds to which of the following?
When calcium is released in muscle cells, it binds to troponin. This binding allows tropomyosin to change its orientation, exposing the myosin-binding sites on actin. Myosin heads can then bind to actin, and contraction can occur.
Calmodulin is a molecule that can bind calcium; however, it plays important roles in cell signal cascades and is not involved in skeletal muscle contraction.
When calcium is released in muscle cells, it binds to troponin. This binding allows tropomyosin to change its orientation, exposing the myosin-binding sites on actin. Myosin heads can then bind to actin, and contraction can occur.
Calmodulin is a molecule that can bind calcium; however, it plays important roles in cell signal cascades and is not involved in skeletal muscle contraction.
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In a muscle cell, the H-zone has .
In a muscle cell, the H-zone has .
The H-zone is an area made up of only thick filaments (myosin). The I-band is thin filaments (actin) only, and the A-band is where there are thick and thin filaments. The Z-disc is dividing feature between sarcomeres and appears as dark lines in electron micrographs.
The H-zone is an area made up of only thick filaments (myosin). The I-band is thin filaments (actin) only, and the A-band is where there are thick and thin filaments. The Z-disc is dividing feature between sarcomeres and appears as dark lines in electron micrographs.
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During muscle contraction, which band(s) of the sarcomere shorten(s)?
During muscle contraction, which band(s) of the sarcomere shorten(s)?
Muscle contraction results in both the H-band and I-bands shortening, but the A-band remains the same length (A band is Always the same). The Z-band is a static structure and doesn't change size.
Muscle contraction results in both the H-band and I-bands shortening, but the A-band remains the same length (A band is Always the same). The Z-band is a static structure and doesn't change size.
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Where within the sarcomere is myosin contained?
Where within the sarcomere is myosin contained?
Thick filaments contain myosin. Thick filaments are present in the A band in the center of the sarcomere. Myosin has six polypeptide chains, including one pair of heavy chains and two pair if light chains. Each myosin molecule has two “heads” attached to a single “tail.” The myosin heads are capable of ATP hydrolysis and bind ATP and actin, and are involved in cross bridge formation.
Thick filaments contain myosin. Thick filaments are present in the A band in the center of the sarcomere. Myosin has six polypeptide chains, including one pair of heavy chains and two pair if light chains. Each myosin molecule has two “heads” attached to a single “tail.” The myosin heads are capable of ATP hydrolysis and bind ATP and actin, and are involved in cross bridge formation.
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Troponin binds with which ion?
Troponin binds with which ion?
Troponin is the regulatory protein that permits cross bridge formation when it binds 
. Troponin is a complex of three globular proteins. Troponin C (
) is the 
binding protein, that when bound to 
, permits the interaction of actin and myosin via conformational change that reveals the myosin binding site on actin, and thus muscular contraction.
Troponin is the regulatory protein that permits cross bridge formation when it binds
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