BIO 446L Exam 2 Practice Questions and Correct Answers
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Course
BIO 446
Institution
BIO 446
Skeletal Muscle Development 1. Come from mesenchymal cells to form myoblasts 2. Myoblasts fuse to form the the myotuble 3. Myotuble differentiates to form muscle fibers -Remaining myoblasts form satellite cells- allow for limited regeneration
Skeletal Muscle -striated -multinucleated -peripherally...
BIO 446L Exam 2 Practice Questions and
Correct Answers
Skeletal Muscle Development ✅1. Come from mesenchymal cells to form myoblasts
2. Myoblasts fuse to form the the myotuble
3. Myotuble differentiates to form muscle fibers
-Remaining myoblasts form satellite cells- allow for limited regeneration
Skeletal Muscle ✅-striated
-multinucleated
-peripherally located nuclei
-limited regeneration
-neuromotor units-single axons and all connecting nerve fibers
Endomysium ✅Thin delicate layer of reticular fibers and fibroblasts
Surrounds and supports each muscle cell
Perimysium ✅-Connective tissue that surrounds bundles of muscles cells= fasicles
-contain large blood vessels
Epimysium ✅Surrounds entire muscle
Organization of skeletal muscles ✅Made of
1. Myosin-thick filament
2. Actin- thin filament
Sarcomere ✅-Produce banding pattern in skeletal muscle
-Functional unit of muscle
-the segment of myofibrils between 2 z-lines
-contains myosin filament
How contraction happens ✅Actin attaches to Z-line and on the other side there's actin
which is a continuation of the sarcomere. When the muscle contacts the Z-line moves
toward A- band and actin overlaps the mysoin which causes the muscle to contract.
T-tuble ✅T-tubule and cisternae allow for signal to transmit to muscle
-invaginations of plasma membrane allow for uniform contraction
-triad= t-tubule and 2 terminal cisternae
Communication between neurons and muscles ✅-neurons communicate via synapse-
interellular junction between a neron and another cell
Classifed by type of junction
, -axodendritic- between axon and dendrite of another cell
-axosomatic- between axon and cell body of another cell
Inhibitory vs excitatory synapse ✅Inhibitory- makes post synaptic channel more
difficult to open
excitatory- causes post synaptic channel to open
M.A. of myasthenia gravis acetylcholine esterase ✅Autoimmune disorder that causes
repectors of acetyl choline to be blocked
-causes muscle weakness
Mechanism of contraction ✅1. Nerve impulse triggers release of AcH from synaptic
knob to synaptic cleft. AcH binds to receptors in MEP intiation an impulse in
sarcolemma
2. Ca2+ ions released from terminal cisternae to sarcoplasm
3. Ca2+ binds to tropomyosin on actin to expose active site where myosin binds to form
a cross bridge
4. Myosin head pivots moving filament toward sarcomere center. ATP binds and returns
it to the original position. Muscles shorten because of sliding of thick and then fialments
5. When impulse stops so does flow of Ca2+ ions and return to relaxed position.
Motor Unit ✅single axon and all the the fibers it innervates
Type I ✅slow red oxidative fibers
-slow twitch fatigue resistant
-need lots of blood
-last a long time
Type II a ✅Fast-intermediate oxidative glycolytic fibers
-fast twitch fatigue resistant
-uses glycogen for energy
Type II b ✅-white glycolytic fibers
-fast-twitch fatigue prone
Cardiac Muscle ✅-Post mitotic (don't divide)
-Formed by intercalcated discs which attach cells together and allow for communication
b/t cells via gap junctions
-No satellite cells
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