Musculoskeletal System and Muscle Tissue - MCAT Biological and Biochemical Foundations of Living Systems
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Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
The “basal lamina” refers to .
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
The “basal lamina” refers to .
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The muscle fiber cytoplasm is the sarcoplasm. The outer covering of the muscle body is the epimysium. The region of the muscle closest to the tendon and the region of sarcolemma near the synapse do not have technical names that you need to know for the MCAT, nor do they make sense as answer choices; we are looking for something that the sarcolemma must be anchored to. The basal lamina is the extracellular matrix surrounding the muscle fiber, made up largely of collagen, that connects each muscle fiber to its neighbors and helps them contract in unison.
The muscle fiber cytoplasm is the sarcoplasm. The outer covering of the muscle body is the epimysium. The region of the muscle closest to the tendon and the region of sarcolemma near the synapse do not have technical names that you need to know for the MCAT, nor do they make sense as answer choices; we are looking for something that the sarcolemma must be anchored to. The basal lamina is the extracellular matrix surrounding the muscle fiber, made up largely of collagen, that connects each muscle fiber to its neighbors and helps them contract in unison.
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Which is not a function of muscle tissue?
Which is not a function of muscle tissue?
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The primary functions of muscle tissue are motion and locomotion (movement in relation to the body, and movement of the entire body). Muscle is also responsible for the shiver response, used in thermoregulation. Finally, smooth muscles move substances through the body in the process known as peristalsis.
Leverage is a function primarily accomplished by bone.
The primary functions of muscle tissue are motion and locomotion (movement in relation to the body, and movement of the entire body). Muscle is also responsible for the shiver response, used in thermoregulation. Finally, smooth muscles move substances through the body in the process known as peristalsis.
Leverage is a function primarily accomplished by bone.
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Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Which of the following would be true of a patient who has Duchenne Muscular Dystrophy?
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Which of the following would be true of a patient who has Duchenne Muscular Dystrophy?
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We know that the "innervation of the muscle is unaffected" in muscular dystrophy patients, so we are looking for the answer choice that is true of healthy muscle. A neuromuscular junction consists of one neuron and all the muscle fibers it innervates (not just one). The basal lamina does not interfere with action potentials; it just helps the fibers contract together by forming physical connections between fibers. The sarcoplasmic reticulum releases Ca2+, not Na+. Finally, epinephrine is not the neurotransmitter used at neuromuscular junctions.
All neuron-muscle interactions use acetylcholine as the neruotransmitter, thus vesicles at the neuromuscular junction will contain acetylcholine.
We know that the "innervation of the muscle is unaffected" in muscular dystrophy patients, so we are looking for the answer choice that is true of healthy muscle. A neuromuscular junction consists of one neuron and all the muscle fibers it innervates (not just one). The basal lamina does not interfere with action potentials; it just helps the fibers contract together by forming physical connections between fibers. The sarcoplasmic reticulum releases Ca2+, not Na+. Finally, epinephrine is not the neurotransmitter used at neuromuscular junctions.
All neuron-muscle interactions use acetylcholine as the neruotransmitter, thus vesicles at the neuromuscular junction will contain acetylcholine.
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Which of the following muscles is an antagonist for the biceps brachii?
Which of the following muscles is an antagonist for the biceps brachii?
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An antagonist is defined as the muscle that strecthes when another muscle (the agonist) is contracting. When the antagonist contracts, it will stretch the agonist and move the bone in the opposite direction.
The biceps brachii is responsible for flexion of the forearm, while the triceps brachii is responsible for the extension of the forearm. As a result, we say that the triceps brachii is the antagonist of the biceps brachii.
An antagonist is defined as the muscle that strecthes when another muscle (the agonist) is contracting. When the antagonist contracts, it will stretch the agonist and move the bone in the opposite direction.
The biceps brachii is responsible for flexion of the forearm, while the triceps brachii is responsible for the extension of the forearm. As a result, we say that the triceps brachii is the antagonist of the biceps brachii.
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The masseter is the most prominent muscle involved in eating food. It is responsible for elevating the jaw during mastication. The temporalis is a muscle located on the outside of the temporal bone. It also elevates the mandible during the chewing of food.
Based on this information, how would you describe the temporalis in relation to the masseter?
The masseter is the most prominent muscle involved in eating food. It is responsible for elevating the jaw during mastication. The temporalis is a muscle located on the outside of the temporal bone. It also elevates the mandible during the chewing of food.
Based on this information, how would you describe the temporalis in relation to the masseter?
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Synergistic muscles assist agonists by properly positioning the insertion bone or stabilizing the origin bone. This cooperation by multiple muscles allows for better movement and posture. Since the temporalis assists in raising the jaw with the masseter, we say that the temporalis is the synergist of the masseter.
Synergistic muscles assist agonists by properly positioning the insertion bone or stabilizing the origin bone. This cooperation by multiple muscles allows for better movement and posture. Since the temporalis assists in raising the jaw with the masseter, we say that the temporalis is the synergist of the masseter.
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During muscle contraction, which parts of a sarcomere change in length?
During muscle contraction, which parts of a sarcomere change in length?
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During muscle contraction, the H zone and I band contract, decreasing in length. The A band never changes in length. Also, while actin and myosin myofilaments slide over each other, their length does not change either.
During muscle contraction, the H zone and I band contract, decreasing in length. The A band never changes in length. Also, while actin and myosin myofilaments slide over each other, their length does not change either.
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Which type of muscle has both striations and multiple nuclei?
Which type of muscle has both striations and multiple nuclei?
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There are three primary types of muscle tissue: skeletal, smooth, and cardiac.
Skeletal muscle and cardiac muscle are highly organized, with their contractile filaments arranged into sarcomeres. This organization results in a "striped" look on the cells, known as striations. Smooth muscle contains the same contractile filaments, but lacks the sort of highly organized structure found in the other two muscle types. As a result, smooth muscle is not striated.
Smooth muscle and cardiac muscle are generally mononucleate, meaning that each cell has only on nucleus. In contrast, skeletal muscle cells contain multiple nuclei.
The correct answer is that skeletal muscle is striated and contains multiple nuclei per cell.
There are three primary types of muscle tissue: skeletal, smooth, and cardiac.
Skeletal muscle and cardiac muscle are highly organized, with their contractile filaments arranged into sarcomeres. This organization results in a "striped" look on the cells, known as striations. Smooth muscle contains the same contractile filaments, but lacks the sort of highly organized structure found in the other two muscle types. As a result, smooth muscle is not striated.
Smooth muscle and cardiac muscle are generally mononucleate, meaning that each cell has only on nucleus. In contrast, skeletal muscle cells contain multiple nuclei.
The correct answer is that skeletal muscle is striated and contains multiple nuclei per cell.
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Which of the following answer options is not a function of the sarcolemma?
Which of the following answer options is not a function of the sarcolemma?
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The sarcolemma is the specialized cell membrane of a myocyte, or muscle cell. It performs all of the functions of a non-specialized plasmolemma, and forms T-tubules, which are important for muscle contraction.
The sarcolemma is the specialized cell membrane of a myocyte, or muscle cell. It performs all of the functions of a non-specialized plasmolemma, and forms T-tubules, which are important for muscle contraction.
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What type of muscle cell is quadrangular, and features intercalated disks and multiple nuclei?
What type of muscle cell is quadrangular, and features intercalated disks and multiple nuclei?
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None of the answer options satisfy all of the criteria given in the question. Cardiac muscle cells have intercalated discs, but are mononucleate.
None of the answer options satisfy all of the criteria given in the question. Cardiac muscle cells have intercalated discs, but are mononucleate.
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An individual with long cancer is advised to undergo radiation therapy. The radiation therapy destroys all of his bone marrow. Which of the following will be deficient in this individual?
An individual with long cancer is advised to undergo radiation therapy. The radiation therapy destroys all of his bone marrow. Which of the following will be deficient in this individual?
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The primary function of red bone marrow is to make red blood cells in the process known as erythropoiesis. If all bone marrow is destroyed, then an individual will lose the ability to make red blood cells.
Myogenesis is performed by muscle fibers and satellite cells. Osteogenesis is performed by osteoblasts. Neurogenesis primarily occurs during early development and is performed by neural stem cells.
The primary function of red bone marrow is to make red blood cells in the process known as erythropoiesis. If all bone marrow is destroyed, then an individual will lose the ability to make red blood cells.
Myogenesis is performed by muscle fibers and satellite cells. Osteogenesis is performed by osteoblasts. Neurogenesis primarily occurs during early development and is performed by neural stem cells.
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Hematopoietic stem cells are the cells that are targeted in bone marrow transplants. These stem cells are found in the red marrow of the bone. Which part of a long bone would be targeted in order to extract hematopoietic stem cells for a transplant?
Hematopoietic stem cells are the cells that are targeted in bone marrow transplants. These stem cells are found in the red marrow of the bone. Which part of a long bone would be targeted in order to extract hematopoietic stem cells for a transplant?
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Red bone marrow is filled with hematopoietic stem cells. Red bone marrow is found in the heads, or epiphyses, of long bones. Yellow marrow fills the medullary cavity and consists mostly of fats. The diaphysis contains the medullary cavity and therefore contains no red marrow. The periosteum has no marrow in it at all.
Red bone marrow is filled with hematopoietic stem cells. Red bone marrow is found in the heads, or epiphyses, of long bones. Yellow marrow fills the medullary cavity and consists mostly of fats. The diaphysis contains the medullary cavity and therefore contains no red marrow. The periosteum has no marrow in it at all.
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Hypoxia would result in which of the following?
Hypoxia would result in which of the following?
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Since red bone marrow is a site of red blood cell and platelet production, hypoxia (low oxygen) would result in an increase in red marrow and therefore RBC concentration. Yellow bone marrow (typcially adipocyte-filled) can be converted into red bone marrow under conditions of low oxygen or blood loss.
Since red bone marrow is a site of red blood cell and platelet production, hypoxia (low oxygen) would result in an increase in red marrow and therefore RBC concentration. Yellow bone marrow (typcially adipocyte-filled) can be converted into red bone marrow under conditions of low oxygen or blood loss.
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What is the main function of red bone marrow?
What is the main function of red bone marrow?
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Red bone marrow is primarily located in flat bones (such as the sternum and pelvis) and in the epiphyses of long bones. It is responsible for producing red blood cells, a process known as erythropoiesis. At birth, all bones of the human skeleton carry out erythropoesis, but many bones stop this function as the newborn ages.
It is important to note that yellow bone marrow is found in the medullary cavity within the diaphyses of long bones and assists in fat storage.
Red bone marrow is primarily located in flat bones (such as the sternum and pelvis) and in the epiphyses of long bones. It is responsible for producing red blood cells, a process known as erythropoiesis. At birth, all bones of the human skeleton carry out erythropoesis, but many bones stop this function as the newborn ages.
It is important to note that yellow bone marrow is found in the medullary cavity within the diaphyses of long bones and assists in fat storage.
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Which muscle tissue type has the most nuclei per fiber?
Which muscle tissue type has the most nuclei per fiber?
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Skeletal muscle tissue has the most nuclei out of the different types. Cardiac has one or two nuclei per fiber, and smooth muscle cells only have one. This is because of the high metabolic demands of these cells. There is a constant need for protein production and repairs to maintain muscle tissue, processes which originate in the nucleus. It makes sense that skeletal muscle, which is most active and has the highest energy demands, has the greatest number of nuclei.
Skeletal muscle tissue has the most nuclei out of the different types. Cardiac has one or two nuclei per fiber, and smooth muscle cells only have one. This is because of the high metabolic demands of these cells. There is a constant need for protein production and repairs to maintain muscle tissue, processes which originate in the nucleus. It makes sense that skeletal muscle, which is most active and has the highest energy demands, has the greatest number of nuclei.
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There are 3 types of muscle: skeletal, smooth, and cardiac.
Which of these muscle types can humans control voluntarily?
There are 3 types of muscle: skeletal, smooth, and cardiac.
Which of these muscle types can humans control voluntarily?
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Skeletal muscle is the only type of muscle that can be controlled voluntarily. Skeletal muscle is the muscle type used to control the movement of our bones (and therefore our bodies). An exception to this rule is that smooth muscle can be controlled by some individuals, but to a extremely limited capacity.
Skeletal muscle is the only type of muscle that can be controlled voluntarily. Skeletal muscle is the muscle type used to control the movement of our bones (and therefore our bodies). An exception to this rule is that smooth muscle can be controlled by some individuals, but to a extremely limited capacity.
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Which answer correctly mactches an organ or structure with the type of muscle found there?
Which answer correctly mactches an organ or structure with the type of muscle found there?
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Smooth muscle is found is the bladder, intestines, blood vessels, and a lot of other places that have involuntary motion. Skeletal muscle connects bones and muscles and allows us to move things voluntarily. Cardiac muscle is found in one place—the heart; therefore, the only correct match is the bladder to smooth muscle.
Smooth muscle is found is the bladder, intestines, blood vessels, and a lot of other places that have involuntary motion. Skeletal muscle connects bones and muscles and allows us to move things voluntarily. Cardiac muscle is found in one place—the heart; therefore, the only correct match is the bladder to smooth muscle.
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How many different types of muscle tissue are there in the human body?
How many different types of muscle tissue are there in the human body?
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There are three classifications of muscle tissue: skeletal, cardiac, and smooth. A major distinction between these groups is that only skeletal muscle can be voluntarily controlled. Smooth muscle (such as that around blood vessels) and cardiac muscle (in the heart) are not consciously controlled. Each muscle type is unique to its specific function.
There are three classifications of muscle tissue: skeletal, cardiac, and smooth. A major distinction between these groups is that only skeletal muscle can be voluntarily controlled. Smooth muscle (such as that around blood vessels) and cardiac muscle (in the heart) are not consciously controlled. Each muscle type is unique to its specific function.
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Which muscle tissue type allows for voluntary control?
Which muscle tissue type allows for voluntary control?
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Skeletal muscle is the only tissue type that allows for voluntary control; cardiac and smooth do not. Unlike the muscles in your arm, you cannot simply will the other muscle types to work. Think about it: you cannot stop your heart from pumping simply by trying to.
Skeletal muscle is the only tissue type that allows for voluntary control; cardiac and smooth do not. Unlike the muscles in your arm, you cannot simply will the other muscle types to work. Think about it: you cannot stop your heart from pumping simply by trying to.
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Striations are alternating light and dark bands seen in muscle cells under a microscope. What type of muscle tissue does not have striations?
Striations are alternating light and dark bands seen in muscle cells under a microscope. What type of muscle tissue does not have striations?
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Smooth muscle is the only muscle type that does not have striations. Striated muscle cells can contract rapidly, but cannot sustain this activity for long. Smooth muscle, however, uses slow contractions and is resistant to fatigue from repetitive work.
Smooth muscle is the only muscle type that does not have striations. Striated muscle cells can contract rapidly, but cannot sustain this activity for long. Smooth muscle, however, uses slow contractions and is resistant to fatigue from repetitive work.
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Skeletal muscle fibers are made up of white and red fibers. White fibers are considered fast-twitch and red fibers are considered slow-twitch.
Which of these statements INCORRECTLY describes a difference between white and red fibers?
Skeletal muscle fibers are made up of white and red fibers. White fibers are considered fast-twitch and red fibers are considered slow-twitch.
Which of these statements INCORRECTLY describes a difference between white and red fibers?
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White fibers have less myoglobin than red fibers. White fibers have less mitochondria than red fibers. White fibers fatigue more quickly than red fibers.
White fibers primarily use anaerobic respiration (red primarily uses aerobic). Remember that red fibers are active over long periods of sustained stress, while white fibers are more explosive. Red fibers require oxygen from respiration and myoglobin to maintain activity.
White fibers have less myoglobin than red fibers. White fibers have less mitochondria than red fibers. White fibers fatigue more quickly than red fibers.
White fibers primarily use anaerobic respiration (red primarily uses aerobic). Remember that red fibers are active over long periods of sustained stress, while white fibers are more explosive. Red fibers require oxygen from respiration and myoglobin to maintain activity.
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