Muscle Physiology Quiz

Study Notes

The sliding filament model of contraction involves actin and myosin sliding past each other but not shortening.

Tropomyosin is a long, fibrous protein that winds around the actin polymer, blocking all the myosin-binding sites.
Myoglobin is a protein that holds a reserve supply of oxygen in muscle cells.
Troponin is a regulatory protein that moves tropomyosin aside and exposes myosin binding sites when Ca+ is released during muscle contraction.

The sarcoplasmic reticulum is an elaborate network of membranes in skeletal muscle cells that functions in calcium storage.
Sarcoplasm is the cytoplasm of a striated muscle fiber.
The neuromuscular junction is the point of contact between a motor neuron and a skeletal muscle cell.
A fascicle is a bundle of skeletal muscle cells.
Muscle fibers are grouped into fascicles, which form skeletal muscles.

Glycogen is a complex carbohydrate consisting of stored glucose molecules in skeletal muscles; breaks down to release glucose when it is needed for energy.
Muscle types can be classified as:
- Cardiac: forms most of the heart, exhibits autorhythmicity, and has a striped appearance.
- Skeletal: has a striped appearance, voluntary, and forms the walls of hollow internal structures.
- Smooth: involuntary, forms the walls of hollow internal structures.

The contractile unit of muscle is the sarcomere.
The ability of an electrical impulse to stimulate a muscle cell to contract is called excitability.
The ability of muscle cells to shorten and generate a pulling force is called contractility.
The ability of muscle cells to recoil after being stretched is called elasticity.
The ability of muscle cells to be stretched back to its original length by contraction of an opposing muscle is called extensibility.
Cross bridges are the connections of a myosin head group to an actin filament during muscle contraction.