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.

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?

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?

What is thought to cause excess postexercise oxygen consumption?

List some of the functions of smooth muscle tissue.

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.

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?

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?