Ch. 10 Muscle tissue

Invaginations of the muscle cell membrane that extend deep into the cell and allow impulses/action potentials to penetrate the inner cell are known as the

T-tubules.

The neurons that stimulate muscle contraction are called_________ neurons.

motor

Which of the following structures has the active sites to which the heads of the thick filaments will bind?

Actin

A motor unit within the powerful quadriceps muscle would

generally contain several hundred fibers.

Which is a correct listing of the hierarchy of a skeletal muscle’s components, beginning with the smallest?

1. Myofibrils

2. Muscle fiber

3. Fascicle

4. Skeletal muscle

a, b, c, d

The membranous network that wraps around myofibrils and holds relatively high concentrations of calcium is known as the

sarcoplasmic reticulum.

During skeletal muscle contraction, more force is created when more motor units are activated.

true

The embryonic-like cells that remain in adult skeletal muscle tissue are known as satellite cells.

true

Which is the neurotransmitter that causes the release of calcium ions from reservoirs within the muscle cell and thereby initiates the steps of contraction?

Acetylcholine

A sarcomere is defined as the distance from one_________ to the next adjacent_________ . (The same answer fills in both spaces.)

Z disc

The structure responsible for attaching muscle to bone is a

tendon

Which is not a protein found in thin filaments?

Myosin

When a muscle is isometrically contracted, its length _________. 

does not change

Consider the difference between lifting a light pad of paper versus a heavy textbook. The primary way the level of force of muscle contraction is controlled is by

recruiting a different number of motor units.

A power stroke involves

a myosin head pulling a thin filament toward the center of the sarcomere.

Which is the correct order of the connective tissue layers of a skeletal muscle, beginning with the most superficial?

a: Endomysium
b: Epimysium
c: Perimysium

b, c, a

To initiate a smooth muscle cell contraction, calcium enters the cell and binds to

calmodulin, which then binds to and activates myosin light-chain kinase.

The characteristic of muscle that allows it to be passively stretched is

extensibility

What is the letter associated with the dark bands in a sarcomere?

A

The myofibril is made up of sarcomeres.

true

The action potential of a muscle fiber occurs

along the sarcolemma and down the T-tubules.

Which protein makes up the thick filaments?

Myosin

A motor unit consists of

 a single motor neuron and the multiple muscle fibers it controls.

The narrow space that separates the motor neuron and the skeletal muscle fiber in a neuromuscular junction is called the

synaptic cleft.

The spring-like property that returns muscle to its original length after a contraction ends is

elasticity

Which letter is associated with the light band and contains thin filaments only?

I

Muscles that are used for precisely controlled movements generally contain large motor units.

false

During skeletal muscle fiber contraction, the I bands and H zones narrow.

true

Smooth muscle tissue is found in the organs of the digestive tract, the walls of blood vessels, and the iris.

true

In general, a skeletal muscle is composed of
a: connective tissue sheaths
b: nerves
c: arteries
d: veins
e: muscle fibers

a, b, c, d, e.

Which are possible functions of skeletal muscles?

a: Maintenance of posture.
b: Both highly coordinated and localized simple movements.
c: Temperature regulation.
d: Support of certain body organs.
e: Regulation of the movement of material through certain body tracts.

a, b, c, d, e

The type of muscle fibers that are striated, form Y-shaped branches, and are joined by intercalated discs are

cardiac

The calcium ions involved in skeletal muscle contraction bind to a(n)_________ subunit.

troponin

The movements of smooth muscle can be voluntary controlled.

false

Which letter is associated with the line that is a thin protein structure that serves as an attachment site for thin filament ends?

Z

The property of muscle tissue that allows an impulse to travel down the entire length of the cell membrane is

conductivity.