Chapter 10 (Mastering A&P)

At what stimulus frequency was maximal tetanic tension developed?

146 stimuli/sec

What are two mechanism(s) to end neural transmission at the neuromuscular junction?

ACh diffuses away from the synaptic cleft. ACh is broken down into acetic acid and choline by the enzyme acetylcholinesterase (AChE).

Tamara's muscle weakness and fatigue becomes progressively worse over the course of the day. This is a hallmark sign of myasthenia gravis, an autoimmune disorder that affects the ability of a motor neuron to communicate with a muscle fiber. What synaptic events must happen first for excitation to occur?

Acetylcholine is released from the axon terminal and diffuses across the synapse to bind to a receptor in the surface of the motor end plate.

The injection that dramatically improved Tamara's symptoms was Tensilon, an acetylcholinesterase inhibitor. What is acetylcholinesterase, and why was this injection effective in relieving Tamara's symptoms?

Acetylcholinesterase is the enzyme that clears acetylcholine from the synapse. Inhibiting this enzyme will enable acetylcholine to be available for a longer period to bind to receptors.

For a weight to be lifted, which of the following must occur?

An isotonic muscle contraction with a force greater than the load.

The cross bridge cycle starts when ________?

Ca2+ from the sarcoplasmic reticulum binds to troponin

What occurs during the latent period of muscle contraction?

Calcium is released from the sarcoplasmic reticulum.

What is the type of chemical reaction used to rebuild ADP into ATP?

Dehydration synthesis

Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?

Glycolysis

Myasthenia gravis is an autoimmune disorder that results in the production of antibodies that either block or cause the destruction of the ACh receptor. Why do you think that Tamara's symptoms become worse as the day progresses?

In the morning, the neuronal reserves of acetylcholine are larger, allowing for sufficient neurotransmitter release and resulting in effective muscle signaling. As the day progresses and the stores of acetylcholine become depleted, muscle function becomes progressively worse.

Which of the following produced an increase in stimulus intensity?

Increasing voltage applied

Which of the following processes produces 36 ATP?

Krebs cycle and oxidative phosphorylation

Which of the following occurs during the latent period of isotonic concentric contraction?

Muscle tension is produced, and the weight will not move.

Which of the following occurs during isotonic concentric contraction?

The length of the muscle decreases with contraction.

As the stimulus voltage was increased in this activity, which of the following occurred?

The muscle force generated increased.

What best describes describes the relaxation phase?

The sarcomeres are increasing in length, and the force generated decreases.

Which of the following describes the relationship between stimulus frequency and muscle tension?

When stimulus frequency increases, muscle tension increases to a maximum value.

Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?

White fast twitch fibers

Which of the following would result in fused or unfused tetanus compared to a single muscle twitch?

increasing the stimulus frequency

Which of the following can trigger a muscle twitch?

release of acetylcholine or electrical stimulation

The speed of muscle contraction is called the ______

shortening velocity

To transition from unfused tetanus to fused tetanus, ______

stimulus frequency increased