HUMAN PHYSIOLOGY-ACCESS >CUSTOM<
15th Edition
ISBN: 9781260584189
Author: Fox
Publisher: MCG CUSTOM
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 12, Problem 21RA
Explain why the myosin heads don't bind to the actin when the muscle is at rest. Then, provide a step-by-step explanation of how depolarization of the muscle fiber plasma membrane by ACh leads to the binding of the myosin heads to actin. (That is, explain excitation-contraction coupling.)
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Describe the contraction of a muscle fiber, starting with what events take place at the neuromuscular junction, explaining how depolarization along the length of the sarcolemma occurs, the role of calcium (where it is released, what it binds to, etc.), and the events that occur after calcium binds to troponin. Draw a few simple, labelled diagrams of a neuromuscular junction and sarcomere and outline the steps of excitation-contraction coupling, including power stroke, recovery stroke, formation of cross bridges, role of ATP, etc.
As mentioned in class, one additional major use of ATP in skeletal muscle (besides
powering the myosin heads) is the recycling of calcium ions back into the sarcoplasmic
reticulum after depolarization. The resting concentration of Ca++ in the muscle cell
cytoplasm is about 50-100 nM, and the spike concentration after depolarization is about
10-20 μΜ.
a) Consider a single sarcomere. What is the number of free calcium ions within the
sarcomere at rest? What is the number of free calcium ions after depolarization?
b) The major ion pump responsible for calcium ion recycling is SERCA (sarco/endoplasmic
reticulum calcium ATPase). SERCA uses one molecule of ATP to pump two calcium ions,
and the resting level can be restored in about 10-20 ms. How many molecules of ATP are
used in a single sarcomere for pumping calcium in a single "twitch"?
c) Assume that a single "twitch" is sufficient to drive one sarcomere from its fully extended
length (about 2.5 µm) to its fully contracted length (about 1…
Briefly describe why contraction of the muscle cell is called “sliding filament theory” (what is sliding?) and what do we mean by “excitation-contraction coupling?” (What is being excited, and what is coupled?)
Chapter 12 Solutions
HUMAN PHYSIOLOGY-ACCESS >CUSTOM<
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...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- What is the function of the sarcoplasmic reticulum in muscle cell contraction?arrow_forwardIn 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.arrow_forwardExplain why (a) calcium ions and (b) ACh are vital for muscle contraction.arrow_forward
- For the following five events, which is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber? 1. Tropomyosin shifts, exposing the myosin-binding sites on actin. 2. Calcium is released from the sarcoplasmic reticulum and binds to the troponin complex. 3. An action potential is propagated down the transverse tubules. 4. Cycles of myosin cross-bridge formation and breakdown cause the thin filaments to slide toward the center of the sarcomere. 5. An action potential in a motor neuron causes the axon to release acetylcholine, which triggers an action potential in a muscle fiber. 1 → 2 → 3 → 4 → 5 3 → 2 → 4 → 1 → 5 2 → 1 → 3 → 5 → 4 5 → 3 → 2 → 1 → 4 4 → 3 → 1 → 2 → 5arrow_forwardSkeletal muscle cells undergo contractions based on a molecular mechanism involving: 1)the sliding of actin and myosin filaments past each other without any change in filament length 2) the shortening of actin filaments following direct interaction with myosin 3) dynamic instability of microtubules 4)nonearrow_forwardGive an account of the excitation-contraction coupling (Figure 3) in skeletal muscle fibers. Highlight the role of dihydropyridine receptors and ryanodine receptors and the fate of A detailed description of the cross bridge cycle is not calcium ions after contraction. necessary. -Axon teminal of (=) somatic motor neuron ACh Muscle fiber potential Pion ++ Action potential- Na Motor end plate- T-tubule Sarcoptasmic reticulum lellll Ca2+ DHP receptor Tropomyosin Troponin z disk Actin M line Myosin head Myosin thick filamentarrow_forward
- Explain how optimal skeletal muscle force (high muscle tension) can be achieved during a high intensity exercise. (Mention and explain how wave summation, motor recruitment summation, muscle length, and type of muscle fibers activated can affect muscle force).arrow_forwardOne of the primary characteristics of all muscle tissue is contractility, the ability to shorten (contract) and lengthen (relax). You've identified the various components of a myofibril above. Now, use the table below to indicate what occurs to each band, line, or zone when the muscle contracts vs. relaxes. What occurs to this region / structure during contraction/relaxation? Region / Structure A-Band H-Band I-Band M-Line Z-Line Zone of Overlap Sarcomere No change Shortens Lengthens Muscle Contraction Muscle Relaxationarrow_forwardDiscuss the sequence of events between a Motor Neuron Action Potential and Skeletal Muscle Fiber Contraction?arrow_forward
- Hill's equation gives a relation between muscle contraction rates νν and muscle tension TT (T+α)(ν+β)=(T0+α)β(T+α)(ν+β)=(T0+α)β for positive parameters αα and ββ and resting tension T0T0. Rewrite the equation so that the contraction rate is a function of tension.arrow_forwardPut these events that occur in skeletal muscle in the correct chronological sequence: 1. Opening of mechanically-gated ryanodine receptors (RyR) on the sarcoplasmic reticulum 2. Ca²+ binding to troponin to initiate contraction 3. Activation of voltage-gated dihydropyridine (DHP) receptor in the T-tubule 4. Na+ influx through ligand-gated ion channels on the motor end plate 4, 3, 2, 1 2, 1, 4, 3 3, 1, 2, 4 4, 3, 1, 2 3, 1, 4, 2arrow_forwardDescribe the basic sequence of events that occurs at the neuromuscular junction and in the muscle cell during excitation and excitation-contraction coupling.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Human Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning
Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning
Human Biology (MindTap Course List)
Biology
ISBN:9781305112100
Author:Cecie Starr, Beverly McMillan
Publisher:Cengage Learning
Human Physiology: From Cells to Systems (MindTap ...
Biology
ISBN:9781285866932
Author:Lauralee Sherwood
Publisher:Cengage Learning
GCSE PE - ANTAGONISTIC MUSCLE ACTION - Anatomy and Physiology (Skeletal and Muscular System - 1.5); Author: igpe_complete;https://www.youtube.com/watch?v=6hm_9jQRoO4;License: Standard Youtube License