Human Physiology
15th Edition
ISBN: 9781259864629
Author: Fox, Stuart Ira
Publisher: Mcgraw-hill Education,
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Question
Chapter 12, Problem 25RA
Summary Introduction
To review:
The following:
The muscle fibers of a motor unit belong to the same type.
The smaller motor units with slow-twitch fibers are more frequently used than the large motor units with fast-twitch fibers.
Introduction:
Somatic motor neuron branches out their axons that interact with the skeletal muscles to release acetylcholine, which are neurochemicals that depolarize the muscle membrane. The axon is branched out and innervates a number of muscle fibers, which are together called a motor unit. Neurons that innervate less number of fibers are called small motor units, and the neurons that innervate large number of muscle fibers are called large motor units.
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Slow twitch muscle fibers are
characterized by all of the following
EXCEPT:
O a) used in endurance type of
activities
O b) contract rapidly and forcefully
Oc) resistant to fatigue
O d) have a direct relationship to the
oxidative energy system
Why does repeated stimulation of the muscle (at maximum stimulus) before it has completely recovered from the previous contraction lead to increasing force of contractions?
Which of the following is not true when comparing slow twitch red and fast twitch white muscle fibers?
Question 2 options:
a)
Red contain more mitochondria than white
b)
Red contain more myoglobin than white
c)
Red contracts more slowly than white
d)
Red contain more glycogen stores than white
Chapter 12 Solutions
Human Physiology
Ch. 12 - Describe the actions of muscles when they...Ch. 12 - Describe the different levels of muscle structure,...Ch. 12 - Define the terms motor unit and innervation ratio...Ch. 12 - Using the concept of recruitment, explain how...Ch. 12 - With reference to the sliding filament theory,...Ch. 12 - Prob. 3bCPCh. 12 - Describe a cycle of cross-bridge activity during...Ch. 12 - Prob. 4bCPCh. 12 - Use a flowchart to show the sequence of events...Ch. 12 - Prob. 5bCP
Ch. 12 - Explain how graded contractions and smooth,...Ch. 12 - Prob. 6bCPCh. 12 - Prob. 7aCPCh. 12 - Describe the relationship between the resting...Ch. 12 - Prob. 8CPCh. 12 - Prob. 9CPCh. 12 - Explain the different causes of muscle fatigue...Ch. 12 - Prob. 11CPCh. 12 - Prob. 12aCPCh. 12 - Describe all of the events that occur from the...Ch. 12 - Prob. 13CPCh. 12 - Explain the significance of reciprocal innervation...Ch. 12 - Describe the functions of gamma motor neurons and...Ch. 12 - Explain how cardiac muscle differs from skeletal...Ch. 12 - Contrast the structure of a smooth muscle cell...Ch. 12 - Distinguish between single-unit and multiunit...Ch. 12 - Describe the events by which depolarization of a...Ch. 12 - Prob. 1RACh. 12 - Prob. 2RACh. 12 - Prob. 3RACh. 12 - Prob. 4RACh. 12 - Prob. 5RACh. 12 - Prob. 6RACh. 12 - Prob. 7RACh. 12 - Electrical excitation of a muscle fiber most...Ch. 12 - The energy for muscle contraction is most directly...Ch. 12 - Prob. 10RACh. 12 - Prob. 11RACh. 12 - Prob. 12RACh. 12 - Which of these types of muscle cells are not...Ch. 12 - Prob. 14RACh. 12 - In an isotonic muscle contraction,...Ch. 12 - Prob. 16RACh. 12 - Prob. 17RACh. 12 - Prob. 18RACh. 12 - Using the concept of motor units, explain how...Ch. 12 - Prob. 20RACh. 12 - Explain why the myosin heads don't bind to the...Ch. 12 - Using the sliding filament theory of contraction,...Ch. 12 - Prob. 23RACh. 12 - Prob. 24RACh. 12 - Prob. 25RACh. 12 - What changes occur in muscle metabolism as the...Ch. 12 - Prob. 27RACh. 12 - Compare cardiac muscle, single-unit smooth muscle,...Ch. 12 - Your friend eats huge helpings or pasta for two...Ch. 12 - Prob. 30RACh. 12 - Prob. 31RACh. 12 - How is electrical excitation of a skeletal muscle...Ch. 12 - Prob. 33RACh. 12 - Prob. 34RACh. 12 - Prob. 35RACh. 12 - Prob. 36RACh. 12 - Refer to figure 12.22 to answer the following...Ch. 12 - Refer to figure 12.22 to answer the following...Ch. 12 - Prob. 39RACh. 12 - Refer to figure 12.22 to answer the following...
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- How does a muscle fiber incur an oxygen debt?arrow_forwardHow do actin and myosin interact in a sarcomere to bring about muscle contraction? What roles do ATP and calcium play?arrow_forwardwhy does a rapid series of muscle twitches yield a stronger overall contraction than a single twitch?arrow_forward
- A) Assuming that each individual muscle fiber generates the same amount of tension, which of the following skeletal muscles will produce the greatest amount of overall tension when fully stimulated? Muscle Total Number of Muscle Fibers in Muscle A 150 B 1000 C 600 Group of answer choices Muscle A Muscle B Muscle C B)The following list of events take place during a muscle contraction. Place the events in chronological order as they relate to a muscle contraction. Calcium is released from the sarcoplasmic reticulum. Myosin heads bind to actin. An action potential arrives at the axon terminal of a motor neuron. Calcium binds to troponin, displacing tropomyosin and exposing myosin head binding sites on actin. Myosin heads undergo power stroke and actin slides over myosin towards M line of sarcomere. Acetylcholine is released at the neuromuscular junction.arrow_forwardWhat is the general distribution of skeletal muscle fiber types in various body regions (trunk, upper limb, lower limb), and how is fiber type related to function of that body region?arrow_forwardWhich type of contraction develops more muscle tension: isotonic or isometric?arrow_forward
- Describe what is meant by muscle fiber "cross-bridges". What occurs to enable movement of the cross-bridges?arrow_forwardWhich of the following would be recruited in a muscle stimulation when contractile strength increases? A) Many small motor units with the ability to stimulate other motor units B) Motor units with the longest muscle fibers C) Motor units with larger, less excitable neurons D) Large motor units with small, highly excitable endurancearrow_forwarda) Describe how the isolated muscle behaved as it was stretched progressively. b) What effect does stretching the muscle have on contraction strength? Is this effect linear? c) What stretch resulted in the highest contraction force? What happens to the muscle at the highest stretch levels?arrow_forward
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