9. Muscle Tissue

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?