Podcast
Questions and Answers
What is responsible for the actual muscle contraction?
What is responsible for the actual muscle contraction?
- Ends of actin filaments
- Actin and myosin filaments (correct)
- Tendon fibers
- Myofibrils
Which part of the muscle fibers contains both myosin and actin filaments?
Which part of the muscle fibers contains both myosin and actin filaments?
- Myofibrils
- Tendon fibers
- I bands
- A bands (correct)
How many myofibrils does each muscle fiber typically contain?
How many myofibrils does each muscle fiber typically contain?
- Over 5000 myofibrils
- 10-20 myofibrils
- Several hundred to several thousand myofibrils (correct)
- 50-100 myofibrils
Which type of filaments are found in the light bands of myofibrils?
Which type of filaments are found in the light bands of myofibrils?
What causes the myofibrils to have alternate light and dark bands?
What causes the myofibrils to have alternate light and dark bands?
Which part of the muscle fibers is isotropic to polarized light?
Which part of the muscle fibers is isotropic to polarized light?
What happens to the ends of actin filaments in the contracted state according to the sliding filament mechanism of muscle contraction?
What happens to the ends of actin filaments in the contracted state according to the sliding filament mechanism of muscle contraction?
What is the primary cause of actin filaments sliding inward among the myosin filaments during muscle contraction?
What is the primary cause of actin filaments sliding inward among the myosin filaments during muscle contraction?
Where are the Z discs positioned in the contracted state according to the sliding filament mechanism of muscle contraction?
Where are the Z discs positioned in the contracted state according to the sliding filament mechanism of muscle contraction?
Why are the forces generated by cross-bridges from myosin filaments with actin filaments inactive under resting conditions?
Why are the forces generated by cross-bridges from myosin filaments with actin filaments inactive under resting conditions?
What factor determines whether the actin filaments begin to overlap one another in the relaxed state according to the sliding filament mechanism of muscle contraction?
What factor determines whether the actin filaments begin to overlap one another in the relaxed state according to the sliding filament mechanism of muscle contraction?
What is the initial trigger for contraction in muscle fibers?
What is the initial trigger for contraction in muscle fibers?
What is the major source of energy for the contractile process in muscle fibers?
What is the major source of energy for the contractile process in muscle fibers?
How many polypeptide chains make up a myosin molecule?
How many polypeptide chains make up a myosin molecule?
Which molecular characteristic describes the structure of myosin tails?
Which molecular characteristic describes the structure of myosin tails?
What occurs when myosin and actin filaments interact in muscle contraction?
What occurs when myosin and actin filaments interact in muscle contraction?
In the sliding filament model, what is the role of calcium ions in muscle contraction?
In the sliding filament model, what is the role of calcium ions in muscle contraction?
What part of the myosin molecule forms the body of the filament?
What part of the myosin molecule forms the body of the filament?
Which component of the myosin head is involved in controlling its function during muscle contraction?
Which component of the myosin head is involved in controlling its function during muscle contraction?
What is the approximate total length of each myosin filament?
What is the approximate total length of each myosin filament?
Which part of the myosin filament extends outward to the sides?
Which part of the myosin filament extends outward to the sides?
What is the role of the hinged heads in muscle contraction?
What is the role of the hinged heads in muscle contraction?
Why are there no cross-bridge heads in the center of the myosin filament for a distance of about 0.2 micrometers?
Why are there no cross-bridge heads in the center of the myosin filament for a distance of about 0.2 micrometers?
What is the function of cross-bridges in muscle contraction?
What is the function of cross-bridges in muscle contraction?
What is the role of titin molecules in muscle contraction?
What is the role of titin molecules in muscle contraction?
Where are the Z-discs located in relation to muscle contraction?
Where are the Z-discs located in relation to muscle contraction?
What is the primary function of the sarcomere in muscle physiology?
What is the primary function of the sarcomere in muscle physiology?
Why is titin described as a 'springy' molecule?
Why is titin described as a 'springy' molecule?
Which organelle supplies contracting myofibrils with energy in the form of adenosine triphosphate (ATP)?
Which organelle supplies contracting myofibrils with energy in the form of adenosine triphosphate (ATP)?
