Muscular System

Week 7 Study Guide

Skeletal Muscle Structure and Organization

  1. Do muscles pull or push?

  2. Outline the different levels of organization of skeletal muscle, from largest to smallest unit of organization.

  3. What’s the smallest unit that is responsible for contraction within the muscle fiber? Name the individual components within this contractile unit that are responsible for producing a contraction.

The Neuromuscular Junction

  1. Draw a diagram of the interface of the neuromuscular junction. Include the following components: muscle fiber, sarcolemma, motor end plate (with axon terminal of motor neuron that regulates the muscle fiber), transverse tubules, sarcoplasmic reticulum, sarcoplasm, actin, and myosin.

  2. What is excitation-coupling and how is it involved in producing contractions?

  3. Draw a diagram and explain in words to illustrate the steps of excitation-coupled contraction.  Label and explain the function of the following parts: axon terminal of somatic motor neuron, ACh, neuromuscular junction, sarcolemma, nicotinic ACh receptor, action potential, T-tubule, voltage-gated Ca2+ channels on sarcolemma, DHP Receptor, Ryanodine Receptor Ca2+, troponin, tropomyosin, actin, myosin,

Excitation Coupling and the Sliding Filament Model

  1. Draw a diagram of the sliding filament model of contraction.

  2. What are the two roles of ATP in muscle contraction and the role of ATP during relaxation?

  3. What is the role of the Ca2+ ATPase pump and when is it important?

Physiology and Integration of Function

  1. Draw a timeline that details the preferred source of ATP during muscle contraction.

  2. Do all muscle contractions result in muscle shortening/movement of bone? Explain.

  3. Define a motor unit and recruitment. Based on these descriptions, how is the strength of a contraction regulated? Use the following terms in your explanation: twitch, summation, tetanus

  4. What three factors influence the strength of contraction?

    1. How does the thickness of the fiber affect strength of contraction?

    2. How does the initial length of the fiber at rest affect strength of contraction? 

  5. Similar to post synaptic potentials, muscle contractions can also be considered graded. Explain what this means and the mechanism that contributes to this phenomenon.

  6. Make a table to compare and contrast the characteristics three types of muscle fibers (i.e. slow-twitch, fast-twitch oxidative-glycolytic, fast-twitch glycolytic).

Three Types of Muscle

  1. Make a Venn diagram that compares the similarities and differences between the three types of muscles.