How are motor neurons involved in muscle contractions? Select all that apply. The release of calcium ions into muscle fiber causes a shift in the proteins of thick filaments, allowing myosin to bind to actin. The release of calcium ions into muscle fiber causes a shift in the thin filaments, allowing myosin to bind to actin. A signal from the motor neuron leads to the release of calcium ions from the muscle fiber's sarcoplasmic reticulum. Muscle fibers respond to signals from motor neurons whose axon endings lie far from the muscle fiber.

How are motor neurons involved in muscle contractions? Select all that apply. The release of calcium ions into muscle fiber causes a shift in the proteins of thick filaments, allowing myosin to bind to actin. The release of calcium ions into muscle fiber causes a shift in the thin filaments, allowing myosin to bind to actin. A signal from the motor neuron leads to the release of calcium ions from the muscle fiber's sarcoplasmic reticulum. Muscle fibers respond to signals from motor neurons whose axon endings lie far from the muscle fiber.

Human Biology (MindTap Course List)

11th Edition

ISBN:9781305112100

Author:Cecie Starr, Beverly McMillan

Publisher:Cecie Starr, Beverly McMillan

Chapter6: The Muscular System

Section: Chapter Questions

Problem 10SQ

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Figure 38.37 Which of the following statements about muscle contraction is true? The power stroke occurs when ATP is hydrolyzed to ADP and phosphate. The power stroke occurs when ADP and phosphate dissociate from the myosin head. The power stroke occurs when ADP and phosphate dissociate from the actin active site. The power stroke occurs when Ca2+ binds the calcium head.
The _____ is the basic unit of muscle contraction. a. myofibril b. sarcomere c. muscle fiber d. myosin filament
How do actin and myosin interact in a sarcomere to bring about muscle contraction? What roles do ATP and calcium play?
In the diagram below, label the fine structure of a muscle, down to one of its myofibrils. Identify the basic unit of contraction in a myofibril.
Skeletal muscle is described as striated. What are the lighter, thinner stripes noted under the microscope? Group of answer choices troponin actin myosin dystrophin Rather than innervating individual muscle fibers, motor neurons often innervate two or more muscle fibers. The motor neuron and the muscle fibers it innervates are together called a: Group of answer choices motor unit myofibril muscle fascicle motor fascia Fast glycolytic muscle fibers allow for relatively quick ATP energy production by splitting glucose (but eventually leads to fatigue), a process described as: Group of answer choices fermentation aerobic pathway anaerobic pathway ATP reserve use
The sliding filament model depicts how myosin motors attached to actin lead to muscle contraction. This process proceeds in a precise series of events. Indicate which of the following shows the correct order of steps in the sliding filament model. Group of answer choices Myosin binds ATP; myosin tightly binds actin; power stroke; myosin releases actin Myosin binds GTP; myosin releases actin; power stroke; myosin tightly binds actin Actin binds ATP; power stroke; myosin tightly binds actin; actin releases ADP Actin binds ADP; myosin releases actin; power stroke; actin releases ADP
In a skeletal muscle if calcium levels in the cytosol increase, as calcium is released from the sarcoplasmic reticulum (SR,) how would this affect the position of the actin and myosin filaments? Group of answer choices Calcium released from the SR binds to calmodulin. Calmodulin activates myosin light chain kinase, causing cross bridge formation. Calcium released from the SR binds to troponin, moving tropomyosin and allowing for cross bridge formation. Calcium released from the SR binds to troponin, moving tropomyosin and inhibiting cross bridge formation. Calcium released from the SR binds to troponin, causing actin to detach from myosin. pick one answer
Why is ATP required for skeletal muscle contraction? Choose all that apply. Release myosin and actin and reset the myosin head ATP causes rigor mortis Attaching ATP to the myosin head initiates the power stroke Pump calcium ions back into the sarcoplasmic reticulum via active transport ATP is not required for skeletal muscle contraction
For the skeletal muscle, hydrolyzation of ATP: Group of answer choices At the myosin head gives rise to the generation of power stroke. At the actin G-molecule gives rise to the generation of power stroke. At the myosin head give rise to the rotation of myosin head to the "cocked back" position. At the actin G-molecule give rise to the rotation of myosin head to the "cocked back" position.
We control muscle force using motor unit recruitment. When we recruit more motor units, what is happening at the organ/cell/molecular level? more myofibrils within a muscle cell are activated more muscle cells are excited the rate of crossbridge cycling is increased the number of myosin heads bound to actin within a muscle cell is increased more Ca++ is released into the cyoplasm of the muscle cell
In the process of muscle contraction, which of the following steps requires hydrolysis of ATP to complete? movement of myosin head, pulling the thin filament binding of myosin head to active site on actin resetting of the myosin head back to its ready position letting go of myosin head from the active site on actin sliding of tropomyosin causing exposure of actin
Myosin filaments iterdigitate with actin filaments in order to bring about muscle contraction. Provide below the 5 steps that are required for Myosin to move along actin.