Exercise 12 - Skeletal Muscle Structure.
Area of sarcolemma across from synaptic end bulbs of axon terminal; contains neurotransmitter receptors. - Correct
Answer Motor end plate.
Center point of attachment for thick filaments. - Correct Answer M line.
Connective tissue covering surrounding individual muscle fibers. - Correct Answer Endomysium.
Connective tissue covering surrounding the muscle. - Correct Answer Epimysium.
Connective tissue surrounding a fascicle. - Correct Answer Perimysium.
Divides into synaptic end bulbs at neuromuscular junction. - Correct Answer Axon terminal.
Do the lengths of the thin or thick filaments change when a muscle contracts? Explain. - Correct Answer No. Filament
length does not change, but there is greater overlap of thin and thick filaments when the muscle fiber contracts
(shortens).
Does the A band length change when a muscle contracts? Explain. - Correct Answer No. By definition, the A band is
the length of the thick filaments; since the filament length does not change, the A band length does not change.
Does the H zone length change when a muscle contracts? Explain. - Correct Answer Yes. The H zone is the portion
of the thick filaments that does not overlap with thin filaments. As thin filaments are pulled over thick filaments, this
zone becomes smaller and eventually disappears when muscle is fully contracted.
Does the I band length change when a muscle contracts? Explain. - Correct Answer Yes. The I band contains the
portion of the thin filaments that does not overlap with thick filaments. When a muscle fiber contracts, thin filaments
are pulled over the thick filaments, so there is more overlap of thin and thick filaments and a shorter I band.
Finger-like invaginations of plasma membrane; extend into interior of fiber and surround myofibrils. - Correct Answer
T-tubules.
Found in synaptic end bulbs of axon terminal; contains neurotransmitter molecules. - Correct Answer Synaptic
vesicles.
Length decreases when sarcomere shortens. - Correct Answer I bands and H zone.
Length does not change when sarcomere shortens. - Correct Answer Thick and thin filaments.
Name the following nestled, cylindrical structures in order from largest (1) to smallest (5):
Myofibril.
Fascicle.
Filaments.
Muscle fiber.
Muscle. - Correct Answer 1. Muscle.
2. Fascicle.
3. Muscle fiber.
4. Myofibril.
5. Filaments.
Parts of axon terminal that form neuromuscular junction. - Correct Answer Synaptic end bulbs.
Plasma membrane of skeletal muscle fiber. - Correct Answer Sarcolemma.
Point of attachment for thin filaments. - Correct Answer Z disc.
Area of sarcolemma across from synaptic end bulbs of axon terminal; contains neurotransmitter receptors. - Correct
Answer Motor end plate.
Center point of attachment for thick filaments. - Correct Answer M line.
Connective tissue covering surrounding individual muscle fibers. - Correct Answer Endomysium.
Connective tissue covering surrounding the muscle. - Correct Answer Epimysium.
Connective tissue surrounding a fascicle. - Correct Answer Perimysium.
Divides into synaptic end bulbs at neuromuscular junction. - Correct Answer Axon terminal.
Do the lengths of the thin or thick filaments change when a muscle contracts? Explain. - Correct Answer No. Filament
length does not change, but there is greater overlap of thin and thick filaments when the muscle fiber contracts
(shortens).
Does the A band length change when a muscle contracts? Explain. - Correct Answer No. By definition, the A band is
the length of the thick filaments; since the filament length does not change, the A band length does not change.
Does the H zone length change when a muscle contracts? Explain. - Correct Answer Yes. The H zone is the portion
of the thick filaments that does not overlap with thin filaments. As thin filaments are pulled over thick filaments, this
zone becomes smaller and eventually disappears when muscle is fully contracted.
Does the I band length change when a muscle contracts? Explain. - Correct Answer Yes. The I band contains the
portion of the thin filaments that does not overlap with thick filaments. When a muscle fiber contracts, thin filaments
are pulled over the thick filaments, so there is more overlap of thin and thick filaments and a shorter I band.
Finger-like invaginations of plasma membrane; extend into interior of fiber and surround myofibrils. - Correct Answer
T-tubules.
Found in synaptic end bulbs of axon terminal; contains neurotransmitter molecules. - Correct Answer Synaptic
vesicles.
Length decreases when sarcomere shortens. - Correct Answer I bands and H zone.
Length does not change when sarcomere shortens. - Correct Answer Thick and thin filaments.
Name the following nestled, cylindrical structures in order from largest (1) to smallest (5):
Myofibril.
Fascicle.
Filaments.
Muscle fiber.
Muscle. - Correct Answer 1. Muscle.
2. Fascicle.
3. Muscle fiber.
4. Myofibril.
5. Filaments.
Parts of axon terminal that form neuromuscular junction. - Correct Answer Synaptic end bulbs.
Plasma membrane of skeletal muscle fiber. - Correct Answer Sarcolemma.
Point of attachment for thin filaments. - Correct Answer Z disc.
