Bio201 Exam 3 Study Guide Muscular System

1. List AND describe the functions of skeletal muscles.
Movement, Posture, supports soft tissue, guard entrances and exits, provides
heat? Maintains body temperature, storage of minerals.
2. List AND describe the characteristics of skeletal muscle.
Responsiveness (excitability)
a. to chemical signals, stretch and electrical changes across the plasma
membrane
Conductivity
b. local electrical change triggers a wave of excitation that travels along the
muscle fiber
Contractility -- shortens when stimulated
Extensibility -- capable of being stretched
Elasticity -- returns to its original resting length after being stretched
3. What are two other names for a muscle fiber?
Myofiber, myocyte
4. Describe the number and location of nuclei in a myofiber.
This cell is approx 100 m in diameter & a few cm long
These giant cells have many nuclei
5. Muscle cells are packed full of which type of protein filament?
Myofibrils, bundle of protein filaments
6. Make sure you understand the difference between a myofiber and a myofibril!
Myofiber- muscle fiber
Myofibril- filament that makes up the muscle cell
7. What is another name for the muscle cytoplasm?
Sarcoplasm (muscle cytoplasm) contains glycogen and mitochondria to provide
energy for contraction and myoglobin for binding oxygen
8. What is another name for the plasma membrane of a myofiber?
Sarcrolemma
9. Describe the location of the T tubules, sarcoplasmic reticulum, and terminal
cisternae. What is the function of each of these structures?
Sarcolemma has tunnel-like infoldings that penetrate the cell
Circles around myofibrils
Carry electric current to cell interior
Transmits signal to contract
10.What is a “triad” referring to?
Triad = 1 T-tubule and 2 terminal cisternae( dilated sacs)
11. Label the connective tissue wrappings of a skeletal muscle.