9. Muscle Tissue

A fascicle is a:

a. Muscle

b. Bundle of muscle fibers enclosed by a connective tissue sheath

c. Bundle of myofibrils

d. Group of myofilaments

Thick and thin myofilaments have different compositions. For each descriptive phrase, indicate whether the filament is, a. thick or b. thin. 

_____ (1) contains actin 

_____ (2) contains ATPases 

_____ (3) attaches to the Z disc 

_____ (4) contains myosin 

_____ (5) contains troponin 

_____ (6) does not lie in the I band

The function of the T tubules in muscle contraction is to:

a. Make and store glycogen

b. Release Ca²⁺ into the cell interior and then pick it up again

c. Transmit the action potential deep into the muscle cells

d. Form proteins

True or false: Most muscles contain a predominance of one skeletal muscle fiber type. Explain the reasoning behind your choice.

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.

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

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.

Michael had a nervous habit of chewing on the inner lining of his lip with his front teeth. The lip grew thicker and thicker from years of continual irritation. Michael's dentist noticed his greatly thickened lip, then told him to have it checked to see if the thickening was a tumor. A biopsy revealed hyperplasia, but no evidence of neoplasia. What do these terms mean? Did Michael have cancer of the mouth?

Why are the connective tissue wrappings of skeletal muscles important? Name these connective tissue coverings, beginning with the finest and ending with the coarsest.

a.

Why are the connective tissue wrappings of skeletal muscles important? Name these connective tissue coverings, beginning with the finest and ending with the coarsest.

b.

Compartment syndrome can result from all of the following except

(a) Compressing a nerve in the wrist

(b) Compartments swelling with blood due to an injury involving blood vessels

(c) Torn ligaments in a given compartment

(d) Pulled tendons in the muscles of a given compartment

(e) Torn muscles in a particular compartment

Which of the following statements about myofibrils is not correct?

(a) Each skeletal muscle fiber contains hundreds to thousands of myofibrils.

(b) Myofibrils contain repeating units called sarcomeres.

(c) Myofibrils extend the length of a skeletal muscle fiber.

(d) Filaments consist of bundles of myofibrils.

(e) Myofibrils are attached to the plasma membrane at both ends of a muscle fiber.

An action potential can travel quickly from one cardiac muscle cell to another because of the presence of

(a) Gap junctions

(b) Tight junctions

(c) Intercalated discs

(d) Both a and c

What three layers of connective tissue are part of each muscle? What functional role does each layer play?

How does cardiac muscle tissue contract without neural stimulation?