9. Muscle Tissue

A main function of muscle is to convert chemical energy to mechanical energy. Which property of muscles relates most directly to this function?

You are looking through a microscope at muscle tissue and you do not see any striations. What type or types of muscle could you be looking at?

What type of muscle tissue is shown in the slide below?

Which type of muscle cell is typically the largest?

Which type of muscle fascicle pattern has an appearance similar to a feather?

a. Fusiform

b. Triangular

c. Pennate

d. Parallel

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.

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.

How does a skeletal muscle fiber differ structurally from typical cells?

Thick filaments are composed of the protein

a. myosin.

b. actin.

c. troponin.

d. tropomyosin.

e.Choices b, c, and d are correct.

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

Fill in the blanks: Resistance-type activities will likely rely on_______energy sources, whereas endurance activities will probably rely on_____energy sources.

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

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

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.

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.

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.

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.

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? (Connects to Chapter 3)

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​)