Exam 3 Study Guide Flashcards
Part 2
What determines the power of a muscle?
The power of a muscle is determined by a number of factors, including:
Muscle size
Larger muscles have more muscle cells, which allows them to generate more power.
Muscle fiber type
There are two main types of muscle fibers: slow twitch and fast twitch. Slow twitch fibers are better for endurance activities, while fast twitch fibers are better for power activities.
Motor unit recruitment
This measures how many motor neurons are activated in a muscle, which determines the strength of the contraction.
Movement speed
The speed of movement affects how much power a muscle can generate. At a slower speed, a muscle needs to generate more power to perform the same task.
Type of muscle action
The type of muscle action involved, and the time available to develop force, can affect a muscle’s ability to generate power.
The power of a muscle can be calculated using the equation: Power = Work/Time = Force x Velocity
What propagates the action potential down the muscle fibers?
In muscle fibers, the propagation of an action potential is facilitated by the T-tubules, which are invaginations of the muscle cell membrane that allow the electrical signal to spread deep into the muscle fiber, triggering the release of calcium ions from the sarcoplasmic reticulum and initiating muscle contraction; essentially, the T-tubules conduct the action potential throughout the muscle fiber
What is the name of the plasma membrane of a muscle fiber?
The sarcolemma is the plasma membrane of the muscle cell and is surrounded by basement membrane and endomysial connective tissue.
Where are the acetylcholine receptors in the sarcolemma? What part?
Acetylcholine receptors are primarily located on the motor end plate of the sarcolemma, which is a specialized region on the muscle fiber where it interacts with the motor neuron at the neuromuscular junction; this area is characterized by numerous folds in the sarcolemma that increase the surface area for neurotransmitter binding.
Where does the energy for muscle contraction come from?
Muscles need energy to produce contractions. The energy is derived from adenosine triphosphate (ATP) present in muscles. Muscles tend to contain only limited quantities of ATP.
