Review Questions Flashcards
What are the four major characteristics of muscle tissue?
Contractility, excitability, extensibility, and elasticity.
What are the three types of muscle tissue?
Skeletal muscle, cardiac muscle, and smooth muscle.
In terms of their nuclei, skeletal muscle fibers are different from smooth and cardiac muscle in what two ways?
Skeletal muscle is multinucleated and the nuclei are at the edge of the cell instead of near the center.
When a muscle contracts what happens to the z disks?
The distance between them decreases because the contraction pulls them together.
When a muscle contracts what happens to the A band.
The length of the A band which is the myosin myofilament stays the same.
When a muscle contracts what happens to the I band
The length of the I band decreases and and the amount of overlap between the actin and myosin myofilaments increase.
What happens to the H zone when a muscle contracts.
The H zone decreases since the actin myofilaments are pulled closer together.
What happens to the length of the myosin myofilaments when a muscle contracts.
It stays the same.
What happens to the length of the actin myofilament when a muscle contracts.
It stays the same
The concentration of Ca2+ in the sarcoplasmic reticulum is decreasing. Is the muscle starting to contract or has it finished contracting?
It is starting to contract because calcium ions are heading into the sarcomere.
The myosin heads of a sarcomere have just received a boost of energy. Is the power stroke or the return stroke about to happen.
The return stroke since the ATP breaks the connection before splitting into ADP and P.
A myosin head has an ADP attached to it, but not an individual phosphate. Which is going to happen next: the return stroke or the power stroke?
Power stroke
If you could look at several muscle fibers in action, how could you determine which fibers are a part of the same motor unit?
All of the fibers in the motor unit will contract identically at the same time.
What is the function of acetylcholinesterase? If it were not present what would happen to a muscle fiber.
A-chase inactivates ACh after ACh has stimulated the postsynaptic membrane. If the enzyme were not present, the muscle fiber could not relax once it started contracting.
There are two major roles the ATP plays in a muscle contraction and relaxation. The first involves the sarcoplasmic reticulum, well the second involves the meiosin head what are the two roles
ATP provides the sarcoplasmic reticulum with energy for the active transport of calcium ions into the sarcoplasmic reticulum. ATP attaches to the myosin heads making them release the active sites and giving energy for the return stroke.
