Skeletal Muscle Tissue 9.1 & 9.2

_ ____________ form passageways through the muscle fiber, like a network of tunnels through a mountain.

T tubules

__________ tubules, or _ tubules, are narrow tubes that are continuous with the sarcolemma and extend into the sarcoplasm at right angles to the cell surface.

Transverse T

_ _______ mark the boundary between adjacent sarcomeres.

Z lines

Z lines consist of proteins called ______, which interconnect thin filaments of adjacent sarcomeres.

actins

an ____________ provides attachment over a broad area that may involve more than one bone.

aponeurosis

Beacause each myofibril has a _______ appearance and the cell is jam-packed with myofibrils laying side by side, the entire muscle fiber appears to have bands, or ____________

banded striations

The membrane of the SR contains ion pumps that pump _________ ions from the sarcoplasm and into the SR. In the SR, some of the _________ ions remain free in solution; the rest become reversibly bound to storage proteins

calcium calcium

In addition to possesing ________ and _________ fibers, the perimysium contains blood vessels and ________ that maintain blood flow and innervate the muscle fibers.

collagen elastin nerves

There are numerous ___________, or powerhouses, scattered among the myofibrils.

mitochondria

A ________ _____________ begins when stored calcium ions are released into the sarcoplasm through gated calcium channels.

muscle contraction

A _______ _________ is a bundle of muscle fibers.

muscle fascicle

_______ _______ develop through the fusion of embryonic mesodermal cells, or myoblasts.

muscle fibers

Over time, most __________ fuse together to form larger, multinucleate cells.

myoblasts

during development, groups of embryonic cells called ___________ fuse, forming multinucleate cells which later develop into distinctive skeletal muscle fibers

myoblasts

A __________ is a cylindrical structure 1-2 micrometers in diameter and as long as the entire cell.

myofibril

Wherever a transverse tubule encircles a ___________, the tubule is tightly bound to the membranes of the sarcoplasmic reticulum

myofibril

The sarcoplasm of a single skeletal muscle fiber may contain hundreds to thousands of ____________.

myofibrils

After an injury, _________ cells may enlarge, divide, and fuse with damaged muscle fibers , thereby assisting in the repair of the tissue

myosatellite

____________ cells are stem cells that function in the repair of damaged muscle tissue.

myosatellite

The change in the transmembrane potential is triggered by a ______ _____ at one location on the sarcolemma and then swiftly propagated across the ________ of the muscle fiber

nerve cell surface

Each skeletal fiber contains hundred of ________ just internal to the plasma membraane

nuclei

Each ________ in a skeletal muscle fiber represents the contribution of a single myoblast.

nucleus

Muscle fascicles are separated from one another by the fibers of the ____________

perimysium

The _________ is a fibrous layer that divides the skeletal muscle into a series of compartments.

perimysium

The ___________ separates the sarcoplasm from the surrounding interstitial fluid.

sarcolemma

The plasma membrane of skeletal muscle fibers is called the __________

sarcolemma

Inside each sarcoplasm, T tubules encircle each ___________ at the zones of overlap.

sarcomere

Myofilaments have repeating functional units called __________.

sarcomeres

The cytoplasm surrounding the myofibrils is callled the ___________

sarcoplasm

The ___________ ____________, similar to the smooth endoplasmic reticulum of other cells, forms a tubular network around each individual myofibril.

sarcoplasmic reticulum

Although the membranes of the triad are tightly bound together, their fluid contents are _________ and distinct

separate

Changes in the transmembrane potential of the sarcolemma travel along the _ ________ into the cell interior.

t tubules

A ________ attaches the muscle to a specific point on a bone.

tendon

At either ends of a skeletal muscle, collagen fibers of the connective tissue layers merge to form either a bundle known as a ______, or a broad sheet called an ____________.

tendon aponeurosis

On either side of a T tubule, the tubules of the SR enlarge, fuse, and form expanded chambers called __________ __________

terminal cisternae

________ filaments are composed mainly of myosin.

thick

The H band contains _______ filaments, but no _____ filaments.

thick thin

the most abundant myofilaments are _____ filaments, composed primarily of ______.

thin actin

I bands contain _____ filaments, but no ________ filaments

thin thick

A sudden change in the ____________ ___________ is the first step that leads to a muscle contraction.

transmembrane potential

The differences in the distribution of positive and negative charges on either side of the sarcolemma is called the ______________ __________.

transmembrane potential

The combination of a pair of terminal cisternae plus a transverse tubule is known as a _______.

triad

In the _____ of __________, thin filaments are interspersed among the thick filaments.

zone overlap

The _ ______ connects the central portion of each thick filament.

M line

The _ _____ is the dense region of the sarcomere that contains thick filaments.

A Band

In a resting sarcomere, the _ _____ is a lighter region on either side of the M line.

H band

Each _ ______ extends from the A band of one sarcomere to the A band of the next.

I band

Myofibrils consist of bundles of protein filaments called _____________.

Myofilaments

The epimysium is connected to the _____ _______ and separates the _________ from surrounding tissues and organs

deep fascia muscle

multinucleate cells begin to ___________ into skeletal muscle fibers as they enlarge and begin producing the proteins involved in muscle _________

differentiate contraction

Individual muscle fibers are sheathed in a delicate _________ that contains capillaries, myosatellite cells, and the axons of the neurons that control the muscle fibers.

endomysium

Within a fascicle, the connective tissue of the ____________ surrounds the individual muscle fibers and loosely interconnects adjacent muscle fibers

endomysium

Some myoblasts do no fuse with developing muscle fibers, instead these unfused cells remain in the __________ of adult skeletal muscle tissue as ___________ cells

endomysium myosatellite

the genes in the nuclei of the skeletal muscle fiber control the production of __________ and structural proteins required for normal muscle contraction.

enzymes

The __________ is a dense layer of collagen fibers that surrounds the entire muscle

epimysium

A skeletal muscle contains muscle ______, the ___________ ________ that harness the forces of contraction, the blood vessels that nourish the muscle fibers, and the _______ that control the contractions.

fibers connective tissues nerves