BIOLOGY 124 - Sample Essay Questions for Exam #3
Name the 3 types of muscle.
Compare differences in cell structure, location, function and activation
Skeletal Muscle- Cylindrical, longest, striations (alternating light/dark bands), Attach to and
cover the bony skeleton (one exception: extraocular muscles), Moves bones of skeleton, Rapid
contractions, tires easily, adaptable force ranging from a fraction of an ounce to many pounds,
Cardiac Muscle-Striations, intercalated discs, gap junctions, Heart, Steady rate of contraction to
pump blood continuously, Involuntary, Internal pacemaker + other controls to alter rate
Smooth Muscle- Spindle-shaped, no striations, gap junctions, Walls of organs (stomach, bladder,
respiratory passages, blood vessels, etc.), Maintain internal environment (moves substances
through internal body channels), Slow sustained contractions, Involuntary
What is the purpose of glycogen and myoglobin in skeletal muscle cells?
*Glycogen – stored for energy production
Glycogen -> glucose + ATP
*Myoglobin- binds oxygen
Why does skeletal muscle have such a high blood and nerve supply?
Must be stimulated before contraction
High metabolic need
*ATP required for contraction + relaxation
*Nutrients, oxygen, waste + heat removal
Draw and label a sarcomere.
What structures are included in “triad?”
T-tubules + 2 terminal cisterns of SR
*Located at A/I band junction
*Zipped together via integral proteins (interaction during neural stimulation)
Describe the function of the troponin-tropomyosin complex.
Regulation of Contraction
Describe the role of calcium in muscle contraction.
(Explain where it is stored, what causes its release,
what happens after it is released, and how does it get put back into storage).
Calcium binds to troponin
Troponin undergoes a conformational change
Tropomyosin moves away from actin’s binding sites