Human Anatomy (8th Edition) - Standalone book
8th Edition
ISBN: 9780321883322
Author: Frederic H. Martini, Robert B. Tallitsch
Publisher: PEARSON
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Chapter 9, Problem 3RC
Summary Introduction
Introduction:
A motor unit denotes the single motor neuron. All the muscle fibers present in the muscles are controlled by the motor neuron. The reduction in the size of the motor unit results in the finer control of the movement.
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The greater the number of _________ involved in a motor unit, the ________ the degree of fine muscle control.
Question 9 options:
a)
muscle fibers............less
b)
ligand gated channels………….less
c)
layers of epimysium.........less
d)
muscle fibers............greater
All the motor neurons that control skeletal muscles are, (a) multipolar neurons. (b) myelinated bipolar neurons. (c) unipolar, unmyelinated sensory neurons. (d) proprioceptors.
What would happen without input from gamma motor neurons?
A) Information about velocity would continue, but information about length would no longer be possible.
B) The spindles would be unable to provide feedback as the muscle contracted.
C) Neither the intrafusal nor extrafusal fibers would contract.
D) The extrafusal fibers would not contract, but the intrafusal fibers would continue to contract.
Chapter 9 Solutions
Human Anatomy (8th Edition) - Standalone book
Ch. 9 - 1. Active sites on actin become available for...Ch. 9 - Prob. 3RFTCh. 9 - Prob. 4RFTCh. 9 - 4. Another name for a muscle that is a prime mover...Ch. 9 - Prob. 1RFTCh. 9 - Prob. 6RFTCh. 9 - 7. The theory that explains muscle contraction is...Ch. 9 - Prob. 8RFTCh. 9 - Label the illustrations to the right as...Ch. 9 - Prob. 1RC
Ch. 9 - 2. The ability to recover from injuries in older...Ch. 9 - Prob. 3RCCh. 9 - Prob. 4RCCh. 9 - Prob. 5RCCh. 9 - A motor unit from a skeletal muscle contains 1500...Ch. 9 - 7. What is the role of the zone of overlap in...Ch. 9 - Several anatomy students take up weight lifting...Ch. 9 - Prob. 2CT
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- What is a motor unit? Why does a rapid series of muscle twitches yield a stronger overall contraction than a single twitch?arrow_forwardTo demonstrate muscle fatigue, a student held an 8 lb dumbbell in her hand and abducted her arm parallel to the floor. After 45 seconds, she has having difficulty holding that position so she rotated her hand 90 degrees. This allowed her to hold the dumbbell in position for an additional 20 seconds. Which of the following is the best explanation for this? A. Different motor units were contracting while others were relaxing. B. Muscles began to contract isotonically rather than isometrically. C. The load was reduced. D. The resistance to contraction was reduced. E. The change in position provided a greater range of motion at the shoulder.arrow_forwardWhen a cardica muscle is isolated and placed in a solution of sodium chloride, potassium chloride, and sodium bicarbonate, will muscle contraction occur if:a. muscle is stimulated directly by depolarizing the membrane? (provide a short explanation)b. muscle is stimulated by stimulating the nerve to the muscle? (provide a short explanation)arrow_forward
- 3) List and define the organizational structure of skeletal muscle beginning with the sacrcomere up ABC to a whole muscle. 4) Explain the differences between the zones and bands of a sarcomere. 5) List and explain the differences between contractile and non-contractile proteins. 6) What are the agonists, synergists, and antagonists to go from sitting to standing from a chair. 7) Provide an every day example of each of the 3 types of muscle actions. Name the muscle involved as well as the movement. 8) Why do we store energy as ATP and resynthesize it, instead of just storing all we need. 9) What are the differences between resting, steady state, and maximal metabolic rate? 10) Why would someone measure arm circumference? How would that be helpful? 11) MRI results in a grayscale of 0 (black) to 256 (white) for each pixel of tissue. How do we tell the difference between different types of tissue in the cross section of a limb (arm or leg, e.g. what's the difference between muscle and fat,…arrow_forwardWhich 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 whitearrow_forwardidentify the incorrect statement about skeletal muscle (A) the epimysium, perimysium, and endomysium form the tendon of the muscle (B) when putting down a weight (extending the elbow) the biceps brachii muscle is doing a concentric isotonic contraction (C) when doing a knee flexion, the hamstrings muscle group is the agonist (D) holding a plank is an example of an isometric contractionarrow_forward
- 4) You set up an experiment using an isolated mouse muscle-nerve preparation.a. Draw the force traces (used to measure the force of contraction using a force transducer) you wouldexpect to get if you stimulated the nerve at 3 different lengths: 1) slack, 2) the normal length of the musclein the body, and 3) stretched past a length the muscle could ever experience in a mouse. If the force tracesare different explain why. (Hint: refer back to the length-tension relationship)b. Draw the nerve signals you would record from a Group Ia muscle spindle afferent at each of those 3lengths. If the 3 conditions are different explain why. (Hint: refer back to the function of the musclespindlearrow_forward*When dynamic y-motor neurons are activated at the same time as a-motor neurons to muscle, [A] prompt inhibition of discharge in spindle la afferents takes place. [B] clonus is likely to occur. [C] the muscle will not contract. [D] the number of impulses in spindle la afferents is smaller than when a discharge alone is increased. [E] the number of impulses in spindle la afferents is greater than when a discharge alone is increased.arrow_forwardSeveral of the events that occur between the time a physician strikes apatient’s patellar tendon with a rubber hammer and the time the quadriceps femoris contracts (knee-jerk reflex) are listed below:(1) increased frequency of action potentials in sensory neurons(2) stretch of the muscle spindles(3) increased frequency of action potentials in the alpha motor neurons(4) stretch of the quadriceps femoris(5) contraction of the quadriceps femorisWhich of the following most closely describes the sequence ofevents as they normally occur?a. 4,1,2,3,5 c. 1,4,3,2,5 e. 4,2,3,1,5b. 4,1,3,2,5 d. 4,2,1,3,5arrow_forward
- Why does a motor unit of the eye have few musclefibers compared to a motor unit of the leg?arrow_forwardEvery skeletal muscle fiber is supplied by a motorneuron at the NMJ. Watch this video(http://openstaxcollege.org/l/skelmuscfiber) to learnmore about what happens at the neuromuscular junction. (a) What is the definition of a motor unit? (b) What is thestructural and functional difference between a large motorunit and a small motor unit? Can you give an exampleof each? (c) Why is the neurotransmitter acetylcholinedegraded after binding to its receptor?arrow_forwardContraction elicited by a single brief stimulus is called (a) a twitch, (b) wave summation, (c) multiple motor unit summation, (d) fused tetanus.arrow_forward
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