PhysiologyLesson 2 of 9 in the course Muscle Tissue

Skeletal Muscle: Organization, Neuromuscular Signaling, and Contraction

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Skeletal muscles are best known for producing movement, but they also stabilize the body, protect organs, control openings, and generate heat. This lesson introduces these functions and explains how connective tissue organizes a skeletal muscle and transfers force.

Skeletal muscles contract to produce movement, such as walking or lifting an object. They also control or slow movement. For example, muscles can resist gravity and make small, continuous adjustments that keep the body upright and balanced.

All flashcards

How are the three connective tissue layers of skeletal muscle organized?
Epimysium surrounds the whole muscle, perimysium surrounds fascicles, and endomysium surrounds individual muscle fibers.
What is an aponeurosis?
A broad, tendon-like sheet of connective tissue that can receive force from a muscle.
What is a motor unit?
One motor neuron and all the muscle fibers it innervates.
How does calcium enable skeletal muscle contraction?
Calcium shifts regulatory proteins associated with thin filaments, exposing actin-binding sites for myosin.
What functions do skeletal muscles perform besides producing movement?
They help maintain posture and joint stability, support and protect organs, control some openings, and generate heat.

Quiz questions

  1. At the neuromuscular junction, what happens when acetylcholine binds to receptors on the motor end-plate?Answer: Receptor channels open, allowing positive ions to enter and depolarize the membrane.
  2. In skeletal muscle, what structure is called a triad?Answer: A T-tubule flanked by sarcoplasmic reticulum membranes on both sides.
  3. What is the primary role of acetylcholinesterase at the neuromuscular junction?Answer: It breaks down acetylcholine in the synaptic cleft.
  4. Which protein forms the thick filaments in skeletal muscle sarcomeres?Answer: Myosin.
  5. What do myosin heads do after calcium exposes actin's binding sites?Answer: They attach to actin and pull it toward the sarcomere center.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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