Chapter 10 Anatomy

What tissue types are present in each skeletal muscle?

Connective

Nervous

Muscle

Epithelial

The act of shivering is an example of skeletal muscle performing what function?

Heat production

Arrange the following structures from smallest to largest.

1.Myofilaments, 2.Myofibrils, 3. Muscle Fibers ,4. Muscle Fascicle

Muscles are considered organs because they are composed not only of muscle tissue, but also of ______, and nervous tissue

epithelial, connective

Match the muscle component with its description

Muscle:Multiple bundles housing many muscle fibers

Fascicle:A bundle of muscle fibers

Muscle fiber: Elongated, multinucleated, cylindrical cell

Myofibril: Long, cylindrical contractile element within muscle cell

Myofilament:Short contractile proteins of two types: thick and thin

Match each property of a muscle cell with its description.

Excitability:Cell is responsive to stimuli

Contractility:Stimulation of muscle cells generates tension within the cell.

Elasticity:Choice, A contracted muscle cell recoils to its resting length when the applied tension is removed.

Extensibility:A muscle cell is capable of extending in length in response to the contraction of opposing muscle cells.

Muscle fibers in a muscle on the anterior side of the arm may be as long as ______.

35cm

The external urethral sphincter is a circular muscle band that relaxes to allow urine to pass. This exemplifies what property of skeletal muscle tissue?

Regulation of elimination

The concentric layers of connective tissue in muscle provide ______, sites for distribution of blood vessels and nerves, and a means of ______ to the skeleton.

protection, attachment

Muscle fibers contain cylindrical structures called myofibrils, which are composed of ______.

myofilaments

Match each muscle unit with the connective tissue layer that surrounds it.

Muscle:Epimysium

Fascicle:Perimysium

Muscle cell:Endomysium

In a laboratory experiment, isolated muscle tissue can be stimulated to contract upon application of an electrical stimulus. What property of muscle tissue does this best describe?

Excitability

The innermost connective tissue layer of a muscle is ______.

endomysium

Order the connective tissue components of skeletal muscle tissue from deepest to most superficial.

1. Endomysium

2. Perimysium

3.Epimysium

In a transverse section, each skeletal muscle is composed of ______, which are bundles of muscle fibers.

fascicles

The perimysium of a muscle contains extensive arrays of blood vessels and nerves that supply muscle fascicles. These arrays are called ______.

neurovascular bundles

The shortening of muscle cells is called_____,a property that allows muscle cells to cause body movement.

Contraction

The epimysium of a muscle is composed of ______ connective tissue.

dense irregular

The endomysium is composed of what type of connective tissue?

Areolar

A cord-like structure that attaches a muscle to a bone is a?

tendon

When you bend your arm at the elbow, the biceps brachii muscle in the upper arm contracts and the bones of the forearm move. Where is the insertion site of the biceps brachii?

In the forearm

In a muscle, the perimysium surrounds ______ muscle cells.

fascicles of

The superior attachment of a muscle ______.

is a term used for muscles moving the axial skeleton

The epimysium of a muscle surrounds ______.

the entire skeletal muscle

Neurons that stimulate muscle contraction are called ______ neurons.

motor

Tendons attach muscle to bone but they can also attach muscle to ______.

another muscle

The plasma membrane of a skeletal muscle fiber is called the ______.

sarcolemma

The less mobile attachment of a muscle is called its ______.

origin

True or false: In muscles moving the appendicular skeleton, the distal attachment is less mobile than the proximal attachment.

False

Match the name of the component of a muscle fiber with its description.

Sarcolemma:Plasma membrane of a muscle fiber

Muscle fiber:A muscle cell

Sarcoplasm: Cytoplasm of a muscle fiber

Sarcoplasmic reticulum: Smooth endoplasmic reticulum in a muscle fiber

T-tubule:Narrow, tubular extensions of the sarcolemma into the sarcoplasm

Skeletal muscles are classified as voluntary muscles because they are controlled by the ______ nervous system and we can voluntarily move our skeletal muscles.

somatic

The sarcoplasmic reticulum stores ______ needed to initiate muscle contraction.

calcium

In a skeletal muscle cell, two terminal cisternae and the centrally placed T-tubule form a structure called a

triad

The sarcoplasm of a skeletal muscle fiber contains many ______ because of the muscle fiber's need for abundant energy.

mitochondria

Skeletal muscle fibers are ______.

multinucleate

Match the name of the muscle cell component with its function.

Myofibrils:Choice, Thick and thin filaments

Thick and thin filaments

Sarcolemma: Regulates entry and exit of materials

Sarcoplasm: Site of metabolic processes for normal muscle fiber activities

Sarcoplasmic reticulum: Stores calcium ions needed for muscle contraction

T-tubule:Transports a muscle impulse from the sarcolemma throughout the entire muscle fiber

If a skeletal muscle is injured, surrounding___cells may be stimulated to differentiate and assist in its repair and regeneration.

satellite or stem

The deep invaginations of the sarcolemma that extend into the sarcoplasm of skeletal muscle fibers as a network of narrow membranous tubules are called ______.

transverse tubules

Myofibrils consist of bundles of ______.

myofilaments

Parts of the sarcoplasmic reticulum that appear as blind sacs perpendicular to the fiber's length are called ______.

terminal cisternae

The cytoplasm of a skeletal muscle cell is referred to a ______.

sarcoplasm

During development, many groups of ________ fuse to form single skeletal muscle fibers

myoblasts

True or false: A single myofibril runs the length of the muscle fiber.

True

During development, groups of myoblasts fuse to form single muscle fibers. Cells that do not fuse are called ______.

satellite cells

A thick filament consists of ______ molecules.

myosin

The sarcoplasm of a skeletal muscle fiber contains hundreds to thousands of long, cylindrical structures termed ______.

myofibrils

Match the muscle fiber component with its function.

Myofibrils:Contain myofilaments that are responsible for muscle contraction

Thick filament:Bind to thin filaments and cause contraction

Thin filament:Bind to thick filaments and cause contraction

Actin: Binding site for myosin to shorten a sarcomere

Tropomyosin: Covers the active sites on actin when muscle cell is at rest

Thick filaments are about ______ the diameter of thin filaments.

two times

There are many successive groupings of ______ that run the entire length of a myofibril.

myofilaments

The myosin heads point ______ the edges of the filament and project outward toward the surrounding thin filaments.

toward

Each myosin strand has a free ______ head and an attached ______ tail.

globular, elongated

Match the component of a muscle cell with its description.

Myofibrils:Cylindrical bundles of myofilaments that are as long as the muscle fiber

Thick filament: Composed of myosin

Thin filament:Composed of actin, troponin, and tropomyosin

Actin: Double-stranded contractile protein

Tropomyosin:Double-stranded regulatory protein

Thin filaments are about ______ the diameter of thick filaments.

Half

The reservoirs and specific sites for calcium ion release to initiate muscle contraction are called ______.

terminal cisternae

True or false: Troponin attaches to tropomyosin to hold it in place over the surface of the actin

True

Thick filaments are assembled from bundles of the protein called

myosin

The functional contractile unit of a skeletal muscle fiber is known as a ______.

sarcomere

Each myosin protein molecule in a thick filament consists of ______ strands.

two

Match the structure with its description.

H-zone:Lighter region in the middle of an A band

M-line:Appears as a dark protein disc in center of H zone

Z-disc: Made of dark proteins called connectins

I-band: Light band containing thin filaments only

Thin filaments are about ______ nanometers in diameter.

5-6

Functionally, troponin provides a binding site for ______ ions.

calcium

A Z disc serves as an attachment site for ______ filament ends.

thin

Myofibrils contain multiple ______; thus, there are numerous ______ in each myofibril.

Z-discs, sarcomeres

When a muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction?

A-band

The ______ zone (or band) is a light, central region in the A band.

H

At maximal contraction of a muscle fiber, the thin filaments are pulled into this zone, and the ______ zone disappears.

H

The _____ line is a thin transverse protein meshwork structure in the center of the H zone of a relaxed muscle fiber.

M

The Z-disc is a thin transverse protein structure in the center of the ______ band.

I

The dark bands of skeletal muscle are called _____ bands and the light bands of skeletal muscle are called _____ bands.

A, I

The middle of the H zone contains the ______.

M line

The striated appearance in skeletal muscle cells is due to size and density differences between ______ and ______ filaments.

thick, thin

The H-band (or H-zone) is more lightly shaded because only____ilaments are present.

Thick

In a relaxed muscle fiber there are no thin filaments overlapping the thick filaments in the ______ zone.

H

The M-line serves as an attachment site for the ______ filaments and keeps them ______ during contraction and relaxation.

thick, aligned

When a skeletal muscle contracts, it exerts tension on its ______.

Attatchment Site

When viewed under a light microscope, the light bands, called ______ bands, contain only ______ filaments.

I, thin

As a result of muscle fiber contraction, the I bands ______ in length.

shorten

Under the light microscope, the dark bands, called ____ bands, contain the entire ______ filament.

A, thick

The ______ zone (or band) is a light, central region in the A band.

H

The___filament theory explains how muscle fibers shorten during contraction.

sliding

The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a ______.

neuromuscular junction

As a result of muscle fiber contraction the ______ lines or discs in one sarcomere move closer together.

Z

The attachment of ACh to a receptor on the motor end plate causes the receptor to open, allowing _____ ions to enter the muscle fiber.

sodium

The arrival of a nerve impulse at the synaptic knob of a motor neuron causes synaptic vesicles to release____into the synaptic cleft.

acetylcholine

After being generated, the muscle impulse continues to spread throughout the muscle fiber as long as ______ keeps the motor end plate receptors open.

acetylcholine

Each muscle fiber is controlled by a(n) ______ neuron.

motor

Match the structure with the label in the diagram.

A: ACh

B: ACh receptor

C:Calcium

D: Sarcoplasmic reticulum

What would be the effect of a drug that blocks release of ACh from the synaptic knob?

No sodium enters the muscle cell through ACh receptors.

Upon release from the synaptic knob, acetylcholine attaches to receptors on the _____.

motor end plate

T-tubules are located adjacent to _____, which are reservoirs storing the calcium ions required for muscle contraction.

terminal cisternae

What would be the effect(s) of a drug that blocks the activity of AChE?

The muscle cell would be continually stimulated.

ACh would remain in the synaptic cleft longer than normal.

Spread of a muscle impulse along the sarcolemma, then down the _____, causes calcium ions to leak out of the SR into the sarcoplasm of the muscle fiber.

transverse tubules

Once started, a muscle impulse will travel along the sarcolemma and into the muscle fiber via the ______.

T-tubules

______ distribute the muscle impulse throughout the inside of the muscle fiber.

T-tubules

To stop motor end plate stimulation, usually acetylcholine is quickly broken down and removed from the receptor by _____.

acetylcholinesterase

An action potential travels down the sarcolemma, through the t-tubules, to the ______.

terminal cisternae

As a result of ACh stimulation, calcium ions are released from the ______ of the sarcoplasmic reticulum.

terminal cisternae

What happens after acetycholine binds to receptors on the motor end plate?

A muscle impulse begins.

A single motor neuron typically controls ______ in a muscle.

numerous muscles fibers

Most muscles have ______ motor units, which means that several ______ neurons are needed to innervate an entire muscle.

many, motor