MCAT Biology : Muscles and Myocytes
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Example Questions
Example Question #2 : Other Muscle Concepts
Which of the following muscles is an antagonist for the biceps brachii?
Brachioradialis
Biceps femoris
Triceps brachii
Brachialis
Triceps 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.
Example Question #81 : Muscles And Myocytes
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 temporalis is the origin of the masseter.
The temporalis is the insertion of the masseter.
The temporalis is the antagonist of the masseter.
The temporalis is the synergist of the masseter.
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.
Example Question #81 : Muscles And Myocytes
During muscle contraction, which parts of a sarcomere change in length?
The H zone and actin
The A band and H zone
The H zone and I band
The I band and A band
The H zone and myosin
The H zone and I band
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.
Example Question #82 : Muscles And Myocytes
Which type of muscle has both striations and multiple nuclei?
Skeletal muscle
Cardiac muscle
Both skeletal muscle and smooth muscle
Both skeletal muscle and cardiac muscle
Smooth muscle
Skeletal muscle
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.
Example Question #81 : Muscles And Myocytes
Which of the following answer options is not a function of the sarcolemma?
Creates an ion potential across the muscle surface
Controls the tonic state of myocytes
Allows attachment sites for communication hormones
Controls the iron levels of cardiac tissue
Creates T-tubules from invaginations along the membrane
Controls the iron levels of cardiac tissue
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.
Example Question #81 : Muscles And Myocytes
Which is not a function of muscle tissue?
Peristalsis
Motion
Leverage
Locomotion
Thermoregulation
Leverage
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.
Example Question #287 : Biology
What type of muscle cell is quadrangular, and features intercalated disks and multiple nuclei?
Smooth muscle
Cardiac muscle
None of the other answers
Thick muscle
Skeletal muscle
None of the other answers
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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