Concept explainers
(a)
To determine: The comparison between the skeletal and smooth muscle contraction with respect to signal for crossbridge activation
Introduction: The skeletal muscles perform the function of attaching bones with the skin. The skeletal muscles perform voluntary muscular movements. The smooth muscles are present along the walls of the internal organs. They are involved in performing the involuntary muscular movements.
(b)
To compare: The skeletal and smooth muscle contraction on the basis of the source(s) of calcium required for Ca2+ signal.
Introduction: Calcium plays an important role in facilitating contraction by reacting with regulatory proteins. The absence of calcium prevents the interaction of actin and filament. The smooth muscles contain the same contractile elements as smooth muscles. They both contain actin and myosin that interact through the crossbridge.
(c)
To determine: The comparison between the skeletal and smooth muscle contraction on the basis of signal that releases Ca2+ from the sarcoplasmic reticulum.
Introduction: The Ca2+ plays an important role in initiating contraction of the muscles. The sarcoplasmic reticulum provides a source of Ca2+ for both the skeletal muscles and the smooth muscles. In addition, extracellular fluid also provides the source of Ca2+ for smooth muscles.
Want to see the full answer?
Check out a sample textbook solutionChapter 12 Solutions
HUMAN PHYSIOLOGY: AN INTEG ACCESS C
- What is the function of the sarcoplasmic reticulum in muscle cell contraction?arrow_forwardExplain why (a) calcium ions and (b) ACh are vital for muscle contraction.arrow_forwardSkeletal muscle fibres are very metabolically active and are adapted to create a lot of ATP from aerobic cellular respiration. Additionally, cells require other things to stay alive. Explain how the following three organ systems contribute to allowing a muscle cell to carry out its roles: a) Respiratory system b) Cardiovascular system c) Gastrointestinal system asap please.arrow_forward
- 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.arrow_forward(a) Describe the structure of a sarcomere and indicate the relationship of the sarcomere to myofilaments. (b) Explain the sliding filament model of contraction using appropriately labeled diagrams of a relaxed and a contracted sarcomere.arrow_forwardSummation in a single muscle fibre means that Select one: a. the fibre increases the frequency of contraction b. the fibre stays contracted longer c. the fibre increases the force of the contraction and stays contracted longer d. the fibre increases the force of the contraction e. the fibre increases both the force and frequency of contractionarrow_forward
- 1) Paula is a scientist who is developing a drug called Fremtol that will be used to treat muscle spasms. This drug acts on specific skeletal muscles to (1) block the release of Ca2+ ions from the sarcoplasmic reticulum, (2) inhibit the pivoting ability of the myosin heads of the thick filaments, and (3) block the production of ATP by the mitochondria in skeletal muscles. By using this drug, contraction of certain skeletal muscle fibers is reduced, which keeps those muscles from producing spasms. In the above scenario, Fremtol’s effect of blocking the pivoting ability of the myosin heads of the thick filaments would have which of the following consequences? a. decreased release of acetylcholine at the neuromuscular junction b. inhibition of the power stroke c. reduced production of myoglobin d. All of the above e. None of the above 2) Paula is a scientist who is developing a drug called Fremtol that will be used to treat muscle spasms. This drug acts on specific skeletal muscles to…arrow_forwardFor 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_forwardWhich of the following step(s) about the excitation of skeletal muscle is/are incorrect? 1. Acetylcholine is released and binds to motor end plate receptors 2. An action potential is created and moves down T-tubules 3. Calcium is released from the sarcoplasmic reticulum 4. Calcium ions bind to tropomyosin to shift troponin off the binding sites for cross-bridging 5. Myosin forms cross-bridges and binds with actin to pull it towards middle of sarcomerearrow_forward
- Put 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_forwardStriated and smooth muscle activation differ because: a.) striated muscle activation is due to structural changes in the actin thin filament while smooth muscle activation requires structural changes in the myosin thick filament b.) striated muscle excitation is voltage dependent and smooth muscle is not c.) striated muscle activation requires calcium but smooth muscle does not d.) troponin C binds calcium in striated muscle while tropomyosin binds calcium in smooth muscle e.) A & Darrow_forward2) Paula is a scientist who is developing a drug called Fremtol that will be used to treat muscle spasms. This drug acts on specific skeletal muscles to (1) block the release of Ca2+ ions from the sarcoplasmic reticulum, (2) inhibit the pivoting ability of the myosin heads of the thick filaments, and (3) block the production of ATP by the mitochondria in skeletal muscles. By using this drug, contraction of certain skeletal muscle fibers is reduced, which keeps those muscles from producing spasms. In the above scenario, Fremtol’s effect of blocking the release of Ca2+ ions from the sarcoplasmic reticulum would most directly prevent which the following? a. activation of tropomyosin b. activation of troponin c. activation of actin d. All of the above e. None of the abovearrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage LearningHuman Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning