Anatomy & Physiology 10 Muscle Tissue Essay Quiz


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Anatomy & Physiology 10 Muscle Tissue Essay
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Sample Questions from the Anatomy & Physiology 10 Muscle Tissue Essay Quiz Flashcards

Question: How would muscle contractions be affected if skeletal muscle fibers did not have T-tubules?


Without T-tubules, action potential conduction into the interior of the cell would happen much more slowly, causing delays between neural stimulation and muscle contraction, resulting in slower, weaker contractions.

Question: The release of calcium ions initiates muscle contractions. Watch this video ( to learn more about the role of calcium. (a) What are "T-tubules" and what is their role? (b) Please also describe how actin-binding sites are made available for cross-bridging with myosin heads during contraction.


(a) The T-tubules are inward extensions of the sarcolemma that trigger the release of Ca++ from SR during an Action Potential. (b) Ca++ binds to tropomyosin, and this slides the tropomyosin rods away from the binding sites.

Question: What causes the striated appearance of skeletal muscle tissue?


Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell cause the entire cell to appear striated.

Question: Every skeletal muscle fiber is supplied by a motor neuron at the NMJ. Watch this video ( to learn more about what happens at the neuromuscular junction. (a) What is the definition of a motor unit? (b) What is the structural and functional difference between a large motor unit and a small motor unit? Can you give an example of each? (c) Why is the neurotransmitter acetylcholine degraded after binding to its receptor?


(a) It is the number of skeletal muscle fibers supplied by a single motor neuron. (b) A large motor unit has one neuron supplying many skeletal muscle fibers for gross movements, like the Temporalis muscle, where 1000 fibers are supplied by one neuron. A small motor has one neuron supplying few skeletal muscle fibers for very fine movements, like the extraocular eye muscles, where six fibers are supplied by one neuron. (c) To avoid prolongation of muscle contraction.

Question: What are the five primary functions of skeletal muscle?


Produce movement of the skeleton, maintain posture and body position, support soft tissues, encircle openings of the digestive, urinary, and other tracts, and maintain body temperature.

Question: What would happen to skeletal muscle if the epimysium were destroyed?


Muscles would lose their integrity during powerful movements, resulting in muscle damage.

Question: Watch this video ( to learn more about macro- and microstructures of skeletal muscles. (a) What are the names of the "junction points" between sarcomeres? (b) What are the names of the "subunits" within the myofibrils that run the length of skeletal muscle fibers? (c) What is the "double strand of pearls" described in the video? (d) What gives a skeletal muscle fiber its striated appearance?


(a) Z-lines. (b) Sarcomeres. (c) This is the arrangement of the actin and myosin filaments in a sarcomere. (d) The alternating strands of actin and myosin filaments.

Question: What are the opposite roles of voltage-gated sodium channels and voltage-gated potassium channels?


The opening of voltage-gated sodium channels, followed by the influx of Na+, transmits an Action Potential after the membrane has sufficiently depolarized. The delayed opening of potassium channels allows K+ to exit the cell, to repolarize the membrane.

Question: Describe how tendons facilitate body movement.


When a muscle contracts, the force of movement is transmitted through the tendon, which pulls on the bone to produce skeletal movement.

Question: Why is elasticity an important quality of muscle tissue?


It allows muscle to return to its original length during relaxation after contraction.

Question: How would muscle contractions be affected if ATP was completely depleted in a muscle fiber?


Without ATP, the myosin heads cannot detach from the actin-binding sites. All of the "stuck" cross-bridges result in muscle stiffness. In a live person, this can cause a condition like "writer's cramps." In a recently dead person, it results in rigor mortis.

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This course does NOT provide the education or experience needed for the diagnosing or treating any medical condition, all site contents are provided as general information only and should not be taken as medical advice.

Source:  OpenStax College. Anatomy & Physiology, OpenStax-CNX Web site., Jun 11, 2014
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