12 Questions
What is the basic unit of a muscle?
Muscle cell
Which type of muscle cells lack gap junctions between adjacent cells?
Skeletal muscle cells
What gives skeletal muscles their striated appearance?
Sarcomeres
Which connective tissue surrounds each individual muscle fiber?
Endomysium
What are the contractile proteins found in myofibrils?
Myosin and actin
What is the functional unit of a skeletal muscle?
Sarcomere
What is the role of acetylcholine released by motor neurons at the neuromuscular junction?
Depolarizes the muscle fiber membrane
What contributes to the strength of a muscle contraction?
Increasing the number of active motor units
Which ion channels are directly coupled to ACh receptors on the muscle membrane?
Cation-selective ion channels
What is acetylcholinesterase's role in muscle contraction?
Breaks down acetylcholine in the junctional cleft
Why can muscle contraction take longer than 100 ms?
Slow release of intracellular calcium from the sarcoplasmic reticulum
What characterizes small motor units?
Fine control of movement
Test your knowledge on the basic unit of muscle cells, myofibrils, actin, and myosin in frog skeletal muscle. Explore the regular structure and arrangement of contractile proteins in muscle fibers.
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