Exam deck 6 Flashcards
What is the primary function of skeletal muscle?
Skeletal muscle is responsible for posture (static force) and movement (dynamic force).
Name the three types of muscle tissue
The three types of muscle tissue are skeletal, cardiac, and smooth muscle.
What is the molecular basis of muscle contraction?
The interaction of actin and myosin forms the molecular basis of muscle contraction.
Define the sarcomere.
A sarcomere is the region from one Z-line to the next Z-line, comprising a highly ordered filament arrangement for efficient interaction.
What are the main components of thick and thin filaments?
Thick filaments: Myosin polymers with ATPase and actin-binding sites.
Thin filaments: Actin helices with G-actin (myosin-binding sites) and tropomyosin guarding the binding sites.
What is the sliding filament theory?
It describes how tension is generated by the sliding of actin and myosin filaments during muscle contraction.
What powers the sliding of filaments in the cross-bridge cycle?
The cross-bridge cycle is powered by ATP hydrolysis by myosin heads.
What role does calcium play in muscle contraction?
Calcium binds to troponin, causing a conformational change that moves tropomyosin, exposing actin binding sites for myosin to attach.
Where does the calcium for muscle contraction come from?
Calcium is released from the sarcoplasmic reticulum in response to an action potential.
What are the two main muscle fiber types and their characteristics?
Fast, fatigable (glycolytic): Sparse mitochondria and myoglobin, quick energy use, fatigue quickly.
Slow, fatigue-resistant (oxidative): High mitochondria and myoglobin content, sustain activity longer without fatigue.
What are some proposed mechanisms of muscle fatigue?
Muscle fatigue can result from lactate and H⁺ accumulation, glycogen/ATP depletion, or a combination of both.
What percentage of body weight is composed of muscle?
Muscle makes up approximately 50% of body weight, with skeletal muscle accounting for about 40%.
What are the macroscopic components of skeletal muscle?
Skeletal muscle includes structures like fibers, fascicles, and connective tissues organized for force production and movement.
How are skeletal muscles organized for movement?
They work in antagonistic pairs, where one muscle reverses the action of the other.
Describe the structure of myosin heads in thick filaments.
Myosin heads resemble “golf clubs in a bag,” with each head containing an ATPase and an actin-binding site. The arrangement ensures directional movement.
