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Example Questions
Example Question #291 : Mcat Biological Sciences
Which of the following statements is false concerning smooth muscle?
It dilates arteries upon contraction
It is stimulated by the sympathetic nervous system
It contains thick and thin filaments
It is involuntarily controlled
It dilates arteries upon contraction
Smooth muscle is involuntarily controlled, and is used to regulate the autonomic functions in the body. When stimulated by the sympathetic nervous system, contracting smooth muscle cells will shrink the diameter of arterioles and arteries, causing vasoconstriction.
Example Question #292 : Mcat Biological Sciences
A student is looking at a muscle biopsy under the microscope, and is having trouble identifying the type of muscle present. He notes that the muscle is striated and mononucleated. Which type of muscle is he observing?
Cardiac muscle or smooth muscle
Skeletal muscle or cardiac muscle
Smooth muscle
Cardiac muscle
Skeletal muscle
Cardiac muscle
Both cardiac and skeletal muscle is striated, however, cardiac muscle is mononucleated, whereas skeletal muscle in multinucleated. Smooth muscle is not striated. The student is observing muscle that is both striated and mononucleated, meaning it must be cardiac muscle.
Smooth muscle: mononucleated with no striations
Skeletal muscle: multinucleated with striations
Cardiac muscle: mononucleated with striations
Example Question #293 : Mcat Biological Sciences
Which of the following muscle types can influence how blood is moved through the body?
Skeletal muscle
Smooth muscle
Smooth, cardiac, and skeletal muscle
Smooth and cardiac muscle
Cardiac muscle
Smooth, cardiac, and skeletal muscle
All muscle types play some role in helping to move blood through the body. The heart actively pumps blood through the circulatory system. Smooth muscle in the arteries and arterioles works to constrict or dilate various shunts and pathways to direct blood flow. Skeletal muscle contractions alter the shape of the muscle, pushing blood in various directions to affect its flow.
You can test this principle by making a tight fist with one hand; when you release the fist, look at the color of your palm compared to your hand that remained open. The hand that made a fist pushed blood away from the surface due to the change in shape, causing your palm to look white.
Example Question #11 : Types Of Muscle Cells
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?
White fibers have less myoglobin than red fibers
Red fibers have more mitochondria than white fibers
White fibers fatigue more quickly than red fibers
White fibers utilize aerobic respiration more than red fibers
White fibers utilize aerobic respiration more than red fibers
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.
Example Question #294 : Mcat Biological Sciences
Red muscle fibers would be expected to __________.
contain many mitochondria and tire easily
contain many mitochondria and be impervious to fatigue
contain few mitochondria and tire easily
contain few mitochondria and be impervious to fatigue
contain many mitochondria and be impervious to fatigue
The two main types of muscle fibers are red and white fibers. Also known as slow twitch and fast twitch fibers, respectively, red fibers are used for high endurance activities, such as long distance running, while white fibers are used for quick movements, such as jumping. We expect red fibers to have more mitochondria and myoglobin, as these are essential to extended aerobic respiration and fatigue prevention.
Example Question #295 : Mcat Biological Sciences
Compared to type II muscle cells, type I muscle cells contain more:
I. Mitochondria
II. Calcium ions
III. Myoglobin
I and III
I and II
II only
I only
I and III
Type I muscle cells, or red muscle cells, use aerobic respiration, whereas type II muscle cells, or white muscle cells, use anaerobic respiration. Aerobic respiration requires oxygen; therefore, myoglobin must be present to carry oxygen within type I muscle cells. Aerobic respiration occurs in mitochondria. This means that type I cells must have more mitochondria and myoglobin to facilitate aerobic respiration.
Calcium ions from the sarcoplasmic reticulum are essential for muscle contraction, and are found in equal amounts in both cell types.
Example Question #71 : Muscles And Myocytes
ATP used by red muscle cells is produced in the __________ and the ATP used by white muscle cells is produced in the __________.
cytoplasm . . . mitochondria
mitochondria . . . mitochondria
mitochondria . . . cytoplasm
cytoplasm . . . cytoplasm
mitochondria . . . cytoplasm
Recall that red muscle cells primarily use aerobic respiration and white muscle cells primarily use anaerobic respiration to produce ATP. Aerobic respiration, which involves the Krebs cycle and oxidative phosphorylation, occurs in the mitochondria. On the other hand, anaerobic respiration (glycolysis) occurs in the cytoplasm.
Type I muscle fibers, or red muscle, will use the mitochondria from ATP production and contain large amounts of myoglobin to help supply oxygen for these aerobic processes. In contrast, type II muscle fibers, or white muscle, will use glycolysis and lactic acid fermentation in the cytoplasm and contain very little myogloblin.
Example Question #72 : Muscles And Myocytes
A physician is examining the leg muscles of a marathon runner. What might the physician conclude upon this examination?
The runner's legs have larger type II muscle fibers
The runner's legs have larger type I muscle fibers
The runner's legs have a larger number of type II muscle fibers
The runner's legs have a larger number of type I muscle fibers
The runner's legs have larger type I muscle fibers
To answer this question you must know that running for long periods of time, such as running a marathon, requires aerobic respiration and sustained muscle contraction over a longer period of time. Type I muscle cells are most suited for these exercises because they utilize aerobic respiration and are slow to fatigue. In contrast, type II muscle fibers can function on anaerobic respiration and fatigue very quickly.
Muscle cells do not undergo mitosis, and therefore cannot increase in number due to training. Instead, the size of the muscle fibers will grow. In a marathon runner, we would expect there to be very large type II muscle fibers in the muscles of the legs.
Example Question #12 : Types Of Muscle Cells
Which of the following types of muscle is under voluntary motor control?
None of these
Smooth muscle
Cardiac muscle
Skeletal muscle
Skeletal muscle
Skeletal muscle is under voluntary control, and are innervated by the somatic nervous system. Skeletal muscle is responsible for skeletal movement, such as swinging the arms or lifting the legs.
Cardiac and smooth muscle are under the control of the autonomic nervous system. Cardiac muscle contracts the heart autonomously, without additional neuronal input.
Example Question #74 : Muscles And Myocytes
Activation of the parasympathetic nervous system would most likely correspond with increased activity in which type of muscle tissue?
Cardiac muscle
Visceral smooth muscle
Vascular smooth muscle
Skeletal muscle
Visceral smooth muscle
The parasympathetic nervous system is more simply characterized as the “rest and digest” system, as it is activated during times of rest and helps in the digestion of food. Visceral smooth muscle tissue is mostly involved in digestion, and helps move food through the gastrointestinal tract.
In contrast, vascular smooth muscle is incorporated into the vascular tissues and plays a key role in vasoconstriction. Vasoconstriction helps increase blood pressure, increasing cardiac output during times of stress. Cardiac muscle is more active when the heart beats more rapidly, which would not occur while a person is at rest. Increased activity in vascular smooth muscle, cardiac muscle, and skeletal muscle occurs at times when the sympathetic nervous system ("fight or flight") is activated.
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