BackMark the following statements as true or false. If a statement is false, correct it to make a true statement.
Stimulation by a motor neuron before a muscle fiber has fully relaxed results in a condition called wave summation.
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
A muscle fiber changes length during isotonic concentric and isotonic eccentric contractions.
Tell where each of the three types of muscle tissue would be found in the body. What is meant by the statement, 'Smooth muscles are involuntary in action'?
Linda's father suffers an apparent heart attack and is rushed to the emergency room of the local hospital. The doctor on call tells her that he has ordered some blood work and that he will be able to tell if her father actually had a heart attack by looking at the blood levels of CK and cardiac troponin. Why would knowing the level of CK and cardiac troponin help to indicate if a person suffered a heart attack?
Describe the events that occur from the time calcium ions enter the axon terminal at the neuromuscular junction until muscle cell contraction occurs.
After ACh attaches to its receptors at the neuromuscular junction, what is the next step?
a. Sodium channels open
b. Calcium binds to regulatory proteins on the thin filaments
c. Cross bridges attach
d. ATP is hydrolyzed
Chemical A binds and blocks acetylcholine receptors of muscle cells. Chemical B floods the cytoplasm of muscle cells with calcium ions. Which chemical would make the best muscle relaxant, and why?
What structural feature of a skeletal muscle fiber propagates action potentials into the interior of the cell?
What forms of energy reserves do resting skeletal muscle fibers contain?
Areas of the body where you would not expect to find slow fibers include the
(a) Back and calf muscles
(b) Eye and hand
(c) Chest and abdomen
(d) All of these
For each portion of a myogram tracing a twitch in a stimulated calf muscle fiber, describe the events that occur within the muscle fiber.
Characteristics of isometric contractions include all but:
a. Shortening
b. Increased muscle tension throughout the contraction phase
c. Absence of shortening
d. Used in resistance training
When a suicide victim was found, the coroner was unable to remove the drug vial clutched in his hand. Explain the reasons for this. If the victim had been discovered three days later, would the coroner have had the same difficulty? Explain.
Define neuromuscular junction, motor unit, tetanus, graded response, aerobic respiration, anaerobic glycolysis, muscle fatigue, and neurotransmitter.
When Eric returned from jogging, he was breathing heavily and sweating profusely, and he complained that his legs ached and felt weak. On the basis of what you have learned about muscle energy metabolism, respond to the following questions:
a. Why is Eric breathing heavily?