Test 5 Chap. 10 &11 Flashcards
What is a muscle fiber?
A muscle fiber is a single muscle cell specialized for contraction.
Define sarcomere.
The functional contractile unit of a muscle, composed of myofilaments.
What are myofibrils?
Cylindrical structures containing actin and myosin filaments, responsible for contraction.
What are actin and myosin?
Proteins involved in muscle contraction; actin forms thin filaments, myosin forms thick filaments.
What is the sarcoplasmic reticulum (SR)?
Stores calcium ions required for contraction.
What is sarcoplasm?
Cytoplasm of a muscle fiber, containing ATP and other organelles.
What defines the boundaries of a sarcomere?
Z-line.
What is the M-line?
Center of the sarcomere, where myosin filaments attach.
What does the I-band contain?
Contains only thin filaments, appears light under a microscope.
What is found in the A-band?
Contains overlapping thick and thin filaments, appears dark.
What is the H-zone?
Region within the A-band containing only thick filaments.
What is a neuromuscular junction?
Site where a neuron stimulates a muscle cell.
What is the motor end plate?
Region on the muscle cell receiving the signal.
What neurotransmitter is released to trigger muscle contraction?
Acetylcholine (ACh).
Fill in the blank: The sliding filament model describes how _______ slide past myosin filaments.
actin
What happens during muscle relaxation?
ACh is broken down by acetylcholinesterase, calcium is reabsorbed into the SR, and myosin releases actin.
What are fast-twitch fibers?
Contract quickly, fatigue rapidly, rely on anaerobic metabolism.
What are slow-twitch fibers?
Contract slowly, fatigue-resistant, rich in myoglobin and mitochondria.
What characterizes intermediate fibers?
Combination of fast and slow-twitch characteristics.
What does glycolysis produce?
2 ATP per glucose.
What type of respiration occurs in the mitochondria?
Aerobic respiration.
What is produced as a byproduct of anaerobic respiration?
Lactic acid.
What is the role of myoglobin in muscles?
Stores oxygen in muscle cells for aerobic respiration.
What is flexion?
Bending a joint.
What is extension?
Straightening a joint.
What do agonist muscles do?
Primary muscle causing movement.
What is the role of antagonist muscles?
Opposes the agonist.
What are synergist muscles?
Assist the agonist.
What is the diaphragm’s function?
Primary breathing muscle.
Which muscles elevate the jaw during mastication?
Masseter and Temporalis.
Name the rotator cuff muscles.
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
What is the function of the quadriceps?
Knee extension.
What do the hamstrings do?
Knee flexion.
What is myasthenia gravis?
Autoimmune disorder causing muscle weakness due to ACh receptor degradation.
What causes muscle fatigue?
ATP depletion and lactic acid accumulation.
What is a hernia?
Protrusion of an organ through muscle tissue.
What is tendonitis?
Inflammation of a tendon due to overuse.
What criteria are used for naming muscles?
- Location
- Shape
- Size
- Direction of Fibers
- Number of Origins
- Action
What is the difference between synarthrosis and diarthrosis joints?
Synarthrosis are immovable joints; diarthrosis are freely movable joints.
What type of joint is a ball-and-socket joint?
Allows multi-directional movement.
What type of movement does a hinge joint allow?
Flexion and extension.
What is the function of the trapezius muscle?
Role in shoulder movement and stabilization.
True or False: Fast-twitch fibers are more fatigue-resistant than slow-twitch fibers.
False.
What is the role of extrinsic muscles?
Control movement from outside a specific region.
What movements are involved in inversion and eversion?
Inversion turns the sole inward; eversion turns it outward.
