Anatomy of a Sarcomere
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Questions and Answers

What is the main component of each thin filament?

  • Troponin
  • G-actin (correct)
  • Tropomyosin
  • Myomesin

In the A-band of the sarcomere, what maintains the arrangement of myosin filaments?

  • Myomesin (correct)
  • Actin
  • Tropomyosin
  • Troponin

What protein anchors the plus end of actin filaments at the Z-line in the sarcomere?

  • Myomesin
  • Troponin
  • Tropomyosin
  • Titin (correct)

Which area of the A-band contains only myosin filaments without overlapping with actin filaments?

<p>H-zone (A)</p> Signup and view all the answers

What represents the functional unit of the myofibril where myosin and actin filaments interact during muscle contraction?

<p>Sarcomere (C)</p> Signup and view all the answers

Where do two sets of actin filaments originate from in each sarcomere?

<p>Z-lines (C)</p> Signup and view all the answers

What is the composition of myofibrils in cardiac muscle fibers?

<p>Thick myosin filaments and three types of thin myofilaments (C)</p> Signup and view all the answers

What is the function of the lateral portions of intercalated disks in cardiac muscle fibers?

<p>Rapid flow of ions between adjacent myocytes (B)</p> Signup and view all the answers

What is the primary function of the Transverse (T) tubule in muscle contraction?

<p>Allowing propagation of electrical changes into the sarcoplasm (C)</p> Signup and view all the answers

Which components make up the predominant composition of thin myofilaments in cardiac muscle fibers?

<p>Actin and tropomyosin (B)</p> Signup and view all the answers

What is the structural organization of myofibrils in cardiac muscle fibers?

<p>A-bands aligned on the same level, with I-bands containing thin myofilaments (C)</p> Signup and view all the answers

Which structure is responsible for the release of stored Ca ions from the sarcoplasmic reticulum during muscle contraction?

<p>Sarcoplasmic reticulum (D)</p> Signup and view all the answers

What is the role of fasciae adherentes in intercalated disks in cardiac muscle fibers?

<p>Provide physical attachment and mechanical stability (C)</p> Signup and view all the answers

What percentage of intra cellular Calcium ions enter the sarcoplasm from the extracellular fluid through the T-tubules?

<p>25% (B)</p> Signup and view all the answers

Which filament type is present in both A & I bands of myofibrils in cardiac muscle fibers?

<p>Both thick myosin and thin myofilaments (A)</p> Signup and view all the answers

Which component is responsible for shortening of sarcomeres during muscle contraction?

<p>Thick myosin filaments (D)</p> Signup and view all the answers

What is an essential function of the dilated terminal of the sarcoplasmic reticulum?

<p>Facilitating Influx of Ca ions from the extracellular fluid (D)</p> Signup and view all the answers

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