Chapter 9 - Muscle Tissue

FOR EXAM 3

Which of the following is not a recognized function of skeletal​ muscle?

controlled involuntarily

(6) Name the three types of muscle​ tissue, identify where they are​ found, and list their functions.​

Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle forms the heart and propels blood. Smooth muscle is found throughout the body and moves substances through hollow​ tubes, such as in the digestive tract and regulates the diameter of blood vessels.

The advantage of having many nuclei in a skeletal muscle fiber is the ability to

produce large amounts of the muscle proteins needed for muscle contraction.

At each end of the​ muscle, the collagen fibers of the​ epimysium, and each perimysium and​ endomysium, come together to form a

tendon.

What special terms are used to describe the plasma membrane and cytoplasm of a skeletal muscle​ fiber?

The _____ _____ is called the sarcolemma and the cytoplasm is called the sarcoplasm.

The repeating contractile unit of a skeletal muscle fiber is the

sarcomere.

Resting skeletal muscle​ fiber, where is the greatest concentration of Ca²​+?

terminal cisternae of the sarcoplasmic reticulum

Since each myofibril is attached at either end of the muscle​ fiber, when sarcomeres​ shorten, the muscle fiber

shortens.

Summarize the sliding filament theory.​

It is the process of sarcomere shortening caused by the sliding of thin and thick filaments past another.

Membrane potential is

the electrical gradient of a cell.

(5) Explain the function of​ sodium-potassium ion pumps.​

The​ sodium-potassium ion pump maintains the resting membrane potential of a cell by exporting three sodium ions out in exchange for two potassium ions entering the cell.

(3) Define depolarization​, and describe the events that follow it.​

Depolarization is the when the inside of the cell becomes positive due to sodium ions rushing in. After​ depolarization, repolarization occurs when potassium ions rush out of the cell causing the inside of the cell to become negative again.

Synaptic vesicles containing neurotransmitters are released by​ ________ when the action potential arrives.

exocytosis

(1) Describe the neuromuscular junction.​

The neuromuscular junction is where the axon terminals of a motor neuron interact with the skeletal muscle fiber midway along the​ fiber's length.

What causes calcium to be released from the sarcoplasmic​ reticulum?

Calcium is released when an action potential reaches the triad.

A single motor neuron together with all the muscle fibers it innervates is called​ a(n)

motor unit.

In which of the following would the motor units have the fewest muscle​ fibers?

muscles that control the eyes

(2) Describe the relationship between the number of fibers in a motor unit and the precision of body movements.​

The finer and more precise the​ movement, the fewer the number of muscle fibers in the motor unit.

The type of contraction in which the muscle fibers do not shorten is called

isometric.

In an isotonic​ contraction,

muscle tension exceeds the load and the muscle lifts the load.

(4) Compare concentric and eccentric contractions.​

Concentric contractions occur when the muscle tension exceeds the​ load, and the muscle shortens. Eccentric contractions occur when the muscle tension is less than the​ load, and the muscle elongates.

Creatine phosphate

acts as an energy reserve in muscle tissue.

Identify three sources of stored energy utilized by muscle fibers.​

​ATP, creatine​ phosphate, and glycogen

The type of muscle fiber that is most resistant to fatigue is the​ ________ fiber.

slow

​Large-diameter, densely packed​ myofibrils, large glycogen​ reserves, and few mitochondria are characteristics of

fast fibers.

Which of the following statements​ is/are not true regarding human​ muscles?

Fast fibers are high in myoglobin.

When comparing slow fibers to fast​ fibers, slow fibers

appear dark red.