Problem 8.2a
The primary action of the biceps brachii muscle of the anterior arm is to flex the forearm at the elbow. However, when this muscle is inflamed, pain is felt in the shoulder. Explain this finding.
Problem 9.1a
Which type of muscle fascicle pattern has an appearance similar to a feather?
a. Fusiform
b. Triangular
c. Pennate
d. Parallel
Problem 10.10a
A muscle fiber relaxes when:
a. the concentration of Ca2+ in the cytosol returns to resting levels.
b. the supply of ATP is exhausted.
c. Ca2+ flood the cytosol.
d. acetylcholine is released from the axon terminal and the sarcolemma depolarizes.
Problem 10.1c
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
c. The plasma membrane of a muscle cell is called the sarcoplasmic reticulum.
Problem 10.1d
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
d. Muscle cells are contractile, conductive, distensible cells.
Problem 10.11a
Which of the following energy sources would provide the majority of the ATP for a person running a 26-mile marathon?
a. Stored ATP
b. Glycolytic catabolism
c. Oxidative catabolism
d. Creatine phosphate
Problem 10.12a
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
a. Muscle fibers generate more tension if the starting length of their sarcomeres is very short.
Problem 10.12b
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
b. Stimulation by a motor neuron before a muscle fiber has fully relaxed results in a condition called wave summation.
Problem 10.12c
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
c. Muscles that require a great deal of precise control will have large motor units.
Problem 10.12d
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
d. A muscle fiber changes length during isotonic concentric and isotonic eccentric contractions.
Problem 10.13a
Which of the following types of muscle fibers have low myosin ATPase activity and are classified as slow-twitch?
a. Type I fibers
b. Type IIa fibers
c. Type IIx fibers
d. Type III fibers
Problem 10.14a
Muscle tone is:
a. the result of voluntary shortening of the muscle.
b. the result of a small amount of involuntary activation of motor units by the nervous system.
c. abnormal—a person's muscles should be relaxed normally.
d. present only where there is damage to the nervous system.
Problem 10.15a
Fill in the blanks: Resistance-type activities will likely rely on_______energy sources, whereas endurance activities will probably rely on_____energy sources.
Problem 10.16a
Which of the following is not likely to result from endurance training alone?
a. Increase in oxidative enzymes in the muscle fiber
b. Increased numbers of mitochondria
c. Hypertrophy of the muscle fibers
d. Increase in blood supply to the muscle fibers
Problem 10.17a
Which of the following factors is/are responsible for muscular fatigue? (Circle all that apply.)
a. Accumulation of chemicals, including calcium and phosphate ions & increased blood flow to the muscle
b. Decreased availability of oxygen
c. Psychological and environmental factors
d. Depletion of key metabolic fuels, such as creatine phosphate
Problem 10.18a
What is thought to cause excess postexercise oxygen consumption?
Problem 10.19a
List some of the functions of smooth muscle tissue.
Problem 10.20a
Which of the following best describes single-unit smooth muscle tissue?
a. The fibers function individually.
b. It is found in organs that require precise control of contraction.
c. It contains gap junctions that couple the fibers electrically.
d. The amount of tension produced varies with the number of muscle cells recruited.
Problem 10.2a
How does a skeletal muscle fiber differ structurally from typical cells?
Problem 10.2a
Some athletes will consume only protein for several days before a competition, which reduces the amount of glycogen in both the muscle fibers and the liver. What effect would this have on their ability to perform activities that require short, powerful bursts of activity? How would it affect their ability to perform endurance activities?
Problem 10.21a
Mark the following statements as true for smooth muscle tissue, cardiac muscle tissue, and/or skeletal muscle tissue.
a. ____Actin attaches to dense bodies.
b. ____Cells are joined by intercalated discs.
c. ____The thick and thin filaments are arranged into sarcomeres.
d. ____The thick filaments contain myosin heads along their entire length.
e. ____The cells depolarize and contract as a unit.
f. ____ Ca2+ binding to troponin is the initiating event of contraction.
g. ____Ca2+ binding to calmodulin is the initiating event of contraction.
h. ____The sarcolemma has a distinct motor end plate.
Problem 10.3a
Ms. Sanchez was in a motorcycle accident in which she lost the use of her right upper limb muscles due to significant nerve damage. However, when an electrode is inserted into her muscles, they are able to contract. Explain specifically why nerve damage caused her to lose the use of her muscles. Why can they still respond to stimulation from an electrode?
Problem 10.4a
Match the following terms with the correct definition.
____Z-disc
____Sarcomere
____A band
____H zone
____I band
____M line
a. The dark band containing the entire length of the thick filament
b. The band of proteins in the middle of the H zone
c. The boundary between sarcomeres
d. The functional unit of contraction
e. The middle region of the A band containing only thick filaments
f. The light band containing only thin filaments
Problem 10.4a
Mr. Nasheed has cerebral palsy and suffers severe skeletal muscle spasms as a result of his condition. He is prescribed the drug dantrolene, which prevents the release of Ca2+ from the SR. Explain how this will treat his muscle spasms.
Problem 10.5a
What is the basic mechanism of contraction at the level of myofilaments?
Problem 10.5a
Jesse is a 2-year-old boy who presents with difficulty in walking and poor control of movements. When the doctor examines Jesse, she notices that when his muscles contract, they are very slow to relax and remain contracted well after the movement has been performed. She sends a sample of his tissue for genetic analysis, and the lab reports a genetic defect that causes the pumps in the SR to operate much more slowly than normal. How does a defect in DNA lead to a malfunctioning protein? How does this finding explain Jesse's symptoms? (Connects to Chapter 3)
Problem 10.6a
Paola is a 3-year-old girl with a disease that reduces the ability of her mitochondria to generate ATP. Explain the specific effects of this disease on the ability of Paola's muscles to function properly. What other tissues and organs are likely to be especially affected by her disease, and why? (Connects to Chapter 3)
Problem 10.8a
Order the following events of excitation and excitation-contraction coupling. Put 1 by the first event, 2 by the second, and so on.
____The motor end plate generates an end-plate potential.
____The action potential spreads along the T-tubules, SR Ca2+ channels are pulled open, and Ca2+ flood the cytosol.
____Acetylcholine binds to receptors on the motor end plate, and ligand-gated ion channels open.
____Ca2+ bind troponin, which allows tropomyosin to move away from the actin active site, initiating a contraction cycle.
____The action potential propagates through the sarcolemma and dives deeply into the cell along the T-tubules.
Problem 10.9a
Which of the following statements accurately describes the role of ATP in a muscle contraction?
a. ATP is directly responsible for the power stroke.
b. ATP moves troponin and tropomyosin away from actin.
c. ATP breaks the actin/myosin attachment and 'cocks' the myosin head.
d. ATP causes the myofilaments to shorten.
Ch. 10 Muscle Tissue and Physiology
Back