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
