Question Set 10

Place the organizational level of muscle tissue in order, beginning with the entire muscle and ending with the smallest component.

1. Muscle 2. Fascicle 3. Muscle Fiber 4. Myofibril 5. Myoofilament

Both thick and Thin

A band

1. Muscle Cell 2. Muscle Fascicile 3 Fascicle

Epimysium 2 Perimysium 3 Endomysium 1

Thin Filament

I band

Which is a characteristic of skeletal muscle from the selections below?

Multinucleated

Invaginations of the muscle cell membrane that extend deep into the cell are known as the

T-tubules.

Embryonic myoblasts fuse to form single muscle fibers during development; thus skeletal muscle cells are multinucleated.

True

The T-tubules and sarcoplasmic reticulum are unique to muscle fibers.

True

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

Z

A power stroke involves

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

If you were studying the neurotransmitter released from axon terminals at a neuromuscular junction, you would be studying?

acetylcholine.

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

actin

The action potential of a muscle fiber occurs

along the sarcolemma and down the T-tubules.

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

The ability of muscle cells to shorten is called _______, a property that allows muscle cells to cause body movement.

contractility

When a muscle relaxes,

crossbridges stop forming and muscle elasticity returns the muscle to rest length.

The axon of a motor neuron travels through the epimysium and perimysium, and enters the _________, where it delivers a nerve impulse to an individual ________.

endomysium; muscle fiber

The multiple nuclei in skeletal muscle cells are the result of the

fusion of myoblasts.

The neurons that stimulate muscle contraction are called _____ neurons.

motor

A skeletal muscle cell contains hundreds to thousands of _________, which are complex organelles; they are cylindrical in shape—about 2 micrometers in diameter and as long as the cell.

myofibrils

Myoglobin is a molecule within muscle cells that can bind

oxygen

If you were studying the functions of skeletal muscle, you would be studying all of the following except

production of blood cells.

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

sarcoplasmic reticulum.

Order of muscle contraction

1. A nerve impulse causes acetylcholine (ACh) release at a neuromuscular junction. 2.ACh binds receptors on the motor end plate, initiating a muscle impulse. 3. Calcium ions bind to troponin, causing tropomyosin to move and expose active sites. 4.Myosin heads attach to actin and form crossbridges. 5.A cyclic "attach, pivot, detach, return" event occurs. 6.Calcium ions are moved back into the sarcoplasmic reticulum by ATP-driven pumps 7. Myofilaments passively return to their original state.

Muscle Architecture size largest to smallest

1. Fascicle 2. Fibers 3. Myofibril 4. Sarcomere 5. Myofilament 6. F-actin 7. Tropomyosin 8. Tropnin 9. Ca+2

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

A

appropriate Thin filament

Actin binding sites for myo

1. _________is the step in which the muscle fiber develops tension and may shorten. 2. The myosin head must have a(n) ______ molecule bound to it to initiate the process. 3. The head extends to expose a(n) ________site on the thin filament. 4. The attachment of the myosin head and thin filament forms a -__________between the two filaments. 5. The _________stroke then pushes the myosin head forward, moving the thin filament across. 6. Once additional ATP binds, myosin will release the actin and hydrolyze another ATP in what is called the ___________stroke.

Contraction ADP active crossbridge power recovery

Which letter is associated with a zone (in a relaxed muscle) that is a little more lightly shaded because only thick filaments are present?

H

Thick Filament

H Band m line

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

I Band

One of the five important functions of skeletal muscle contraction is heat production.

True

A sarcomere is defined as the distance from one _____ to the next adjacent ____ . (The same answer fills in both spaces.)

Z disc

Which is a correct listing of the hierarchy of a skeletal muscle's components, beginning with the smallest? a: Myofibrils b: Muscle fiber c: Fascicled: Skeletal muscle

a, b, c, d

1.Relaxation begins when nerve signals quit stimulating the synaptic knob from releasing _____. 2. Acetylcholine dissociates from its _______ and no new molecules of acetylcholine are released. 3. Active transport pumps in the SR move ______ back into the cisternae. 4. _____ moves back into position blocking active sites, and no more contractions can occur. 5. Finally, the muscle fiber returns to its resting _______.

acetylcholine receptor calcium Tropomyosin length

Check all that are proteins of thin filaments.

actin tropinin tropomyosin

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

extensibility.

1.Excitation-contraction coupling refers to the events that link the action potentials on the sarcolemma to activation of the ________. 2. First, a wave of action potentials spread from the end plate in all directions, reaching the T-tubules and then the ______. 3. Action potentials then open voltage ion gates in the_________releasing calcium from the sarcoplasmic reticulum (SR) into the cytosol. 4. Calcium will bind to the ________of the thin filaments. 5. Other active sites are open for ____________heads to bind and continue the contraction.

myofilaments sarcoplasm. T-tubles Troponin myosin

Which protein makes up the thick filaments?

myosin

appropriate Thick Filaments

myosin myosin head

A single ________ molecule consists of two intertwined polypeptides forming a twisted filamentous tail and a double globular head. A ________ filament consists of 200 to 500 myosin molecules bundled together with the heads projecting outward in a helical array. A thin filament consists of two intertwined chains of G actin molecules, smaller filamentous _________ molecules, and troponin.

myosin thick tropomyosin

The contractile unit of a myofibril is called the

sarcomere.

For relaxation to occur,

sarcoplasm calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin.

The component of a muscle fiber that quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber is called the

transverse tubule (T-tubule).

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

troponin

In the hierarchy of skeletal muscle fiber components, the myofibril is made up of myofilaments.

true