Mastering A&P Chapter 9 - Muscle Tissue Quiz
13 Questions
103 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

The cross bridge cycle starts when ________.

Ca2+ from the sarcoplasmic reticulum binds to troponin

Place the steps that occur during a single cross bridge cycle in the correct order from left to right.

  • Activated myosin head binds to actin, forming a cross bridge. (correct)
  • ATP is hydrolyzed to ADP and Pi and the energy released re-cocks the myosin head. (correct)
  • ATP binds to the myosin head and detaches it from actin. (correct)
  • ADP is released and myosin slides the thin filament toward the center of the sarcomere. (correct)

What is myosin?

Myofilament with a knob-like head

What is actin?

<p>Myofilament stiffened and stabilized by tropomyosin</p> Signup and view all the answers

What is sarcoplasm?

<p>The cytoplasm of a skeletal muscle fiber</p> Signup and view all the answers

What is a fascicle?

<p>Bundle of skeletal muscle fibers enclosed by connective tissue called perimysium</p> Signup and view all the answers

What is the sarcolemma?

<p>Membrane of muscle cell</p> Signup and view all the answers

What blocks myosin-binding sites on actin?

<p>Tropomyosin</p> Signup and view all the answers

What are skeletal muscle fibers?

<p>Long, cylindrical cells</p> Signup and view all the answers

What is a sarcomere?

<p>Contractile unit</p> Signup and view all the answers

What are myofibrils?

<p>Made up of several sarcomeres</p> Signup and view all the answers

In the event that a muscle cell runs out of ATP, what step of the cross bridge cycle is most directly inhibited or terminated?

<p>Cross bridge detachment (A)</p> Signup and view all the answers

What best explains rigor mortis after death?

<p>Cross bridge detachment cannot occur. (C)</p> Signup and view all the answers

Flashcards

Cross Bridge Cycle Initiation

Starts when Ca2+ binds to troponin.

Role of Calcium

Elevated Ca2+ causes troponin to move tropomyosin away from actin's binding sites.

Cross Bridge Formation

Myosin heads bind to actin, forming a link between filaments.

Power Stroke

Sliding of thin filament toward the sarcomere's center.

Signup and view all the flashcards

Cross Bridge Detachment

ATP binding to myosin, causes myosin to detach from actin.

Signup and view all the flashcards

Myosin Head Re-cocking

Hydrolyzes ATP into ADP and Pi

Signup and view all the flashcards

Myosin

Myofilament with a knob-like head; essential for muscle contraction.

Signup and view all the flashcards

Actin

Myofilament stabilized by tropomyosin; forms thin filaments.

Signup and view all the flashcards

Sarcoplasm

Cytoplasm within skeletal muscle fibers.

Signup and view all the flashcards

Fascicle

Bundles of muscle fibers encased in perimysium.

Signup and view all the flashcards

Sarcolemma

Plasma membrane surrounding muscle cells.

Signup and view all the flashcards

Sarcomere

Fundamental contractile unit of striated muscle.

Signup and view all the flashcards

Tropomyosin

Blocks myosin-binding sites on actin when muscle is relaxed.

Signup and view all the flashcards

Study Notes

Cross Bridge Cycle Initiation

  • The cross bridge cycle begins when Ca2+ from the sarcoplasmic reticulum binds to troponin.
  • Elevated Ca2+ levels cause a conformational change in troponin, moving tropomyosin away from actin's myosin-binding sites.

Steps in the Cross Bridge Cycle

  • Myosin heads bind to actin, forming a cross bridge.
  • Release of ADP results in the "power stroke," sliding the thin filament towards the sarcomere's center.
  • ATP binds to myosin, prompting detachment from actin.
  • ATP is hydrolyzed into ADP and inorganic phosphate (Pi), re-cocking the myosin head.
  • The cycle continues as long as calcium ions and ATP are present, leading to muscle contraction.

Muscle Fiber Structure

  • Myosin: Myofilament characterized by a knob-like head, essential for muscle contraction.
  • Actin: Myofilament that is stabilized by tropomyosin, forming the structure of thin filaments.
  • Sarcoplasm: The cytoplasm within skeletal muscle fibers, containing necessary organelles and proteins.
  • Fascicle: Bundles of muscle fibers encased in connective tissue known as perimysium.
  • Sarcolemma: The plasma membrane surrounding muscle cells, crucial for maintaining ionic gradients.

Sarcomere and Myofilaments

  • Sarcomere: The fundamental contractile unit of striated muscle, comprising alternating thick (myosin) and thin (actin) filaments.
  • Myofibrils: Structures made of aligned sarcomeres that run the length of the muscle fiber, facilitating contraction.

Tropomyosin and Muscle Contraction

  • Tropomyosin blocks the myosin-binding sites on actin when muscle fibers are relaxed, preventing contraction.

Physiological Responses

  • Cross bridge detachment is significantly hindered when ATP levels drop, leading to muscle stiffness.
  • In rigor mortis, calcium leaks into the cytoplasm post-mortem, resulting in sustained contraction due to the absence of ATP for detachment.

Important Facts About Cross Bridge Cycling

  • Detachment requires ATP, thus lacking ATP halts the cycle and maintains cross bridges.
  • During cycling, only half of myosin heads detach at any time while calcium is available.
  • Myosin is in an energized state with ADP and Pi bound before the cross bridge cycle initiates.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Description

Test your knowledge on the cross bridge cycle and muscle physiology with this quiz based on Chapter 9 of Mastering Anatomy & Physiology. Understand key concepts including calcium ion dynamics and muscle contraction. Perfect for students seeking to reinforce their understanding of this essential topic.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser