Muscle Physiology - Human Anatomy and Physiology
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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.
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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 accurately describes a characteristic of fast twitch fibers located within a muscle?
Which of the following accurately describes a characteristic of fast twitch fibers located within a muscle?
Slow twitch fibers are located within muscles used for endurance and posture. They have a red coloring due to an abundance of myoglobin and participate in aerobic glycolysis. Slow twitch fibers contain large amounts of mitochondria and fewer glycolytic enzymes in order to enhance ATP production and maintain contractions for longe periods of time. Slow twitch fibers are associated with endurance fitness, such as running a marathon, and prolonged postural contractions, such as the muscles that keep the spine and neck erect.
Fast twitch fibers are located within muscles used for spurt and explosive excercises. They have a white coloring due to a lack in myoglobin and participate in anaerobic glycolysis. Fast twitch fibers contain fewer mitochondria and more glycolytic enzymes, aiding in rapid (but unsastainable) energy production. Fast twitch fibers are associated with speed and agility fitness, such as a sprinting a short distance.
Slow twitch fibers are located within muscles used for endurance and posture. They have a red coloring due to an abundance of myoglobin and participate in aerobic glycolysis. Slow twitch fibers contain large amounts of mitochondria and fewer glycolytic enzymes in order to enhance ATP production and maintain contractions for longe periods of time. Slow twitch fibers are associated with endurance fitness, such as running a marathon, and prolonged postural contractions, such as the muscles that keep the spine and neck erect.
Fast twitch fibers are located within muscles used for spurt and explosive excercises. They have a white coloring due to a lack in myoglobin and participate in anaerobic glycolysis. Fast twitch fibers contain fewer mitochondria and more glycolytic enzymes, aiding in rapid (but unsastainable) energy production. Fast twitch fibers are associated with speed and agility fitness, such as a sprinting a short distance.
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Which of the following correctly relates a muscle's origin and insertion?
Which of the following correctly relates a muscle's origin and insertion?
Most skeletal muscles have origins closer to the midline than their insertions. The bone from which the muscle originates is typically held steady, while the bone onto which the muscle inserts is pulled toward the origin point of the muscle during flexion. For example, the biceps brachii originate on the scapula and insert on the radius. When activated, the biceps brachii pull the radius toward the scapula.
Most skeletal muscles have origins closer to the midline than their insertions. The bone from which the muscle originates is typically held steady, while the bone onto which the muscle inserts is pulled toward the origin point of the muscle during flexion. For example, the biceps brachii originate on the scapula and insert on the radius. When activated, the biceps brachii pull the radius toward the scapula.
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Which of the following is not a characteristic of skeletal muscle?
Which of the following is not a characteristic of skeletal muscle?
Gap junctions only occur in skeletal and smooth muscle. Through gap junctions, the signal from the neuron to contract may diffuse throughout the muscle, causing wave-like contraction of smooth and/or cardiac muscle.
Gap junctions only occur in skeletal and smooth muscle. Through gap junctions, the signal from the neuron to contract may diffuse throughout the muscle, causing wave-like contraction of smooth and/or cardiac muscle.
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Cardiac and skeletal muscle have some similarities, but some important differences too. Which of these features are found in cardiac muscle, but not skeletal muscle?
Cardiac and skeletal muscle have some similarities, but some important differences too. Which of these features are found in cardiac muscle, but not skeletal muscle?
Intercalated discs are found only in cardiac muscle; they add structural stability to cardiac muscle, and help the propagation of action potentials due to gap junctions. The other features listed are features common to both skeletal and cardiac muscle.
Intercalated discs are found only in cardiac muscle; they add structural stability to cardiac muscle, and help the propagation of action potentials due to gap junctions. The other features listed are features common to both skeletal and cardiac muscle.
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Type I muscle fibers __________.
Type I muscle fibers __________.
Type I muscle (slow oxidative) consists of slow-twitch muscle fibers. Its fibers are red due to high concentrations of myoglobin, and it has a high density of mitochondria (and thus increased oxidative phosphorylation). This leads to a sustained contraction, and resistance to fatigue. Think "one slow red ox."
Type I muscle (slow oxidative) consists of slow-twitch muscle fibers. Its fibers are red due to high concentrations of myoglobin, and it has a high density of mitochondria (and thus increased oxidative phosphorylation). This leads to a sustained contraction, and resistance to fatigue. Think "one slow red ox."
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Which of the following is correct in regards to individual skeletal muscle fibers?
Which of the following is correct in regards to individual skeletal muscle fibers?
Individual skeletal muscle fibers are multinucleate and behave as single units. They contain bundles of myofibrils which are surrounded by a sarcoplasmic reticulum and is invaginated by transverse tubules. Each myofibril contains interdigitating thick and thin filaments arranged longitudinally in sarcomeres. Repeating units of sarcomeres account for the unique banding pattern in striated muscle.
Individual skeletal muscle fibers are multinucleate and behave as single units. They contain bundles of myofibrils which are surrounded by a sarcoplasmic reticulum and is invaginated by transverse tubules. Each myofibril contains interdigitating thick and thin filaments arranged longitudinally in sarcomeres. Repeating units of sarcomeres account for the unique banding pattern in striated muscle.
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The perimysium surrounds which of the following parts of a skeletal muscle fiber?
The perimysium surrounds which of the following parts of a skeletal muscle fiber?
The perimysium surrounds the fascicles in a skeletal muscle fiber. From largest to smallest, the sequence goes as follows: the Epimysium surrounds the entire muscle; the Perimysium surrounds the fascicles inside the muscle; the Endomysium surrounds the myofiber (muscle cell).
The perimysium surrounds the fascicles in a skeletal muscle fiber. From largest to smallest, the sequence goes as follows: the Epimysium surrounds the entire muscle; the Perimysium surrounds the fascicles inside the muscle; the Endomysium surrounds the myofiber (muscle cell).
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The vastus medialis is supplied by __________.
The vastus medialis is supplied by __________.
The vastus medialis, one of the quadricep muscles is located in the anterior compartment of the thigh and is supplied by the femoral artery.
The vastus medialis, one of the quadricep muscles is located in the anterior compartment of the thigh and is supplied by the femoral artery.
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__________, __________, and __________ are examples of pennate muscles, because __________.
__________, __________, and __________ are examples of pennate muscles, because __________.
The term pennate describes muscles whose fibers insert obliquely into the tendon. The vastus medialis, rectus femoris, and deltoid are all examples of this type of muscle.
The term pennate describes muscles whose fibers insert obliquely into the tendon. The vastus medialis, rectus femoris, and deltoid are all examples of this type of muscle.
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Which of the following statements is false?
Which of the following statements is false?
The fibularis longus is supplied by the fibular artery, a branch of the posterior tibial artery. All other statements are true.
The fibularis longus is supplied by the fibular artery, a branch of the posterior tibial artery. All other statements are true.
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Which of the following muscles attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5?
Which of the following muscles attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5?
The extensor digitorum longus attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5.
The extensor digitorum longus attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5.
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Which of the following are characteristics of only skeletal muscle?
Which of the following are characteristics of only skeletal muscle?
Characteristics of smooth muscle include: striated, somatic innervation, multinucleated, and requiring calcium for contraction. Furthermore, similar characteristics are seen in cardiac muscle such as: striations, autonomic innervation, 1-2 nuclei, requires calcium for contraction. Finally, smooth muscle is nonstriated, has autonomic innervation, mononucleated, and requiring calcium for contraction.
Characteristics of smooth muscle include: striated, somatic innervation, multinucleated, and requiring calcium for contraction. Furthermore, similar characteristics are seen in cardiac muscle such as: striations, autonomic innervation, 1-2 nuclei, requires calcium for contraction. Finally, smooth muscle is nonstriated, has autonomic innervation, mononucleated, and requiring calcium for contraction.
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To which of the following molecules does calcium released from the sarcoplasmic reticulum bind?
To which of the following molecules does calcium released from the sarcoplasmic reticulum bind?
Calcium is released from the sarcoplasmic reticulum into the the sarcoplasm. It binds the troponin molecules on the thin filaments, causing the strands of tropomyosin to shift, exposing the myosin-binding sites on the thin filaments.
Calcium is released from the sarcoplasmic reticulum into the the sarcoplasm. It binds the troponin molecules on the thin filaments, causing the strands of tropomyosin to shift, exposing the myosin-binding sites on the thin filaments.
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Where is calcium stored in the skeletal muscle cell?
Where is calcium stored in the skeletal muscle cell?
Calcium is stored in the sarcoplasmic reticulum at high concentrations. When neurons signal the contraction of muscle, calcium is released from the sarcoplasmic reticulum, and facilitates the contraction of muscle fibers and ATP hydrolysis, to generate muscle contraction force.
Calcium is stored in the sarcoplasmic reticulum at high concentrations. When neurons signal the contraction of muscle, calcium is released from the sarcoplasmic reticulum, and facilitates the contraction of muscle fibers and ATP hydrolysis, to generate muscle contraction force.
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