Chapter 10: Muscle Tissue Flashcards
Contains epithelia, connective, and nervous tissue; composed of cells that optimize the universal cell property of contractility
Muscle tissue
the three types of muscle tissue
skeletal, cardiac, and smooth
contains bundles of very long, multinucleated cells with cross-striations; quick voluntary control
skeletal muscle
cross-striations and is composed of elongated, often branched cells bound to one another at structures called intercalated discs; rhythmic involuntary contractions
cardiac muscle
consists of collections of fusiform cells, which lack striations and have slow, involuntary contractions
smooth muscle
the cytoplasm of muscle cells
sarcoplasm
the smooth ER of muscle cells
sarcoplasmic reticulum
the muscle cell membrane and its external lamina
sarcolemma
During embryonic muscle development, mesenchymal _____ fuse, forming _____ with many nuclei. Then the further differentiate to form ____ muscle fibers
myoblasts; myotubes; striated
elongated nuclei are found peripherally just under the _______, a nuclear location unique to skeletal muscle fibers/cells
sarcolemma
a small population of reserve progenitor cells
muscle satellite cells
an external sheath of dense irregular connective tissue, surrounds entire muscle; carries large nerves, blood vessels, and lymphatics
epimysium
thin connective tissue layer that immediately surrounds each fascicle
perimysium
bundle of muscle fibers that make up a functional unit
fascicle
very thin layer of reticular fibers and scattered fibroblasts; surrounds the external lamina of individual muscle fibers
endomysium
___________ is an increase in the size of the cells, while _______ is an increase inn the number of cells
hypertrophy; hyperplasia
______ in these connective tissue layers of muscle serve to transmit the mechanical forces generated by the contracting muscle cells/fibers
collagens
______ CT layer becomes the tendon
epimysium
________ junctions which join the muscle to bone, skin, or another muscle
myotendinous
long cylindrical filament bundles; run parallel to the long axis of the fiber
myofibrils
the dark bands on the myofibrils; anisotropic or birefringent in polarized light
A bands
the light bands on the myofibrils; isotropic or doesn’t alter polarized light
I bands
each I band is bisected by a dark transverse line called ____
Z disc
the repetitive functional subunit of the contractile apparatus; extends from Z disc to Z disc
sacromere
each H band is bisected by a dark transverse line called ____
M line
narrow, less dense region of A band
H zone
Th A and I banding pattern in sarcomeres is due mainly to the regular arrangement of thick and thin ________
myofilaments
thick myofilaments are ________ and think myofilaments are _____
myosin; F-actin
large complex with two identical heavy chains and two pairs (4 in total) of light chains
myosin
the myosin heads bind both actins, forming transient crossbridges between the thick and thin filaments, and ATP, catalyzing energy release
actomyosin ATPase activity
thin, helical filaments that run between the thick filaments
actin
the thin filaments have two tightly associated regulatory proteins _____ and ______
tropomyosin and troponin
a long coil of two polypeptide chains located in the groove between the two twisted actin strands
tropomyosin
a complex of three subunits: TnT, TnC, and TnI; attach at specific sites regularly spaced along each tropomyosin molecule
troponin
subunit of troponin which attaches to tropomyosin
TnT
subunit of troponin which binds calcium
TnC
subunit of troponin which regulates the actin-myosin interaction
TnI
actin filaments are anchored perpendicularly on the Z disc by the actin-binding protein ____
α-actinin
accessory protein in I bands which support the thick myofilaments and connects them to the Z disc
titin
bisecting the H zone is the M line, containing a myosin-binding protein _____ that holds the thick filaments in place
myomesin
contain pumps and other proteins for calcium storage and surrounds the myofibrils
sarcoplasmic reticulum
calcium release from __________ of the sarcoplasmic reticulum
cisternae
trigger calcium release from SER and produce uniform contraction of all myofibrils, the sarcolemma has ___________
transverse or T-tubules
long fingerlike invaginations of the cell membrane penetrate deeply into the sarcoplasm and encircle each myofibril
T-tubules
adjacent to each T-tubule are expanded _____ ____ of SER
terminal cisternae
complex of a T-tubule with two cisternae; present in skeletal muscle
a triad
In a resting muscle, the myosin heads _____ bind actin because the binding sites are blocked by the _______-_______ complex on the F-actin filaments
cannot; troponin-tropomyosin
_____ ions bind troponin, causing a conformational change moving tropomyosin, exposing the ____-binding active sites
calcium; myosin
binding _____ causes myosin to pull thin the filaments farther into the __ band
actin; A band
energy for the myosin head pivot that pulls actin is provided by ______ of ATP bound to the myosin heads, after which myosin binds another ____ and detached from actin
hydrolysis; ATP
in the absence of ATP, the myosin head will stay permanently bound to the actin filament called
rigor mortis
enclose the small axon branches and cover their points of contact with the muscle cells
Schwann cells
the external ________ of the Schwann cell fuses with that of the ______
lamina; sarcolemma
a chemical synapse that connects a motor neuron to a muscle fiber
motor end plates (MEPs)
among the muscle fascicles are stretch detectors known as
muscle spindles
encapsulated by modified perimysium, containing intrafusal fibers
muscle spindle
few thin muscle fibers filled with nuclei
intrafusal fibers
smaller encapsulated structures that enclose sensory axons penetrating among the collagen bundles at the myotendinous junction
Golgi tendon organs
detect increases in tension; inhibit motor nerve activity if force becomes excessive
Golgi tendon organs
Different types of fibers can be identified on the basis of (1) their maximal rate of _________ (___ or __ fibers) and (2) their major pathway for ____ synthesis (_____ _____ or _____)
contraction; fast or slow; ATP; oxidative phosphorylation or glycolysis
Fast vs slow rate of fiber contraction are due largely to _____ isoforms with different maximal rates of ATP _______
myosin; hydrolysis
a globular sarcoplasmic protein similar to hemoglobin that contains iron atoms and allows for O2 storage
myoglobin
During embryonic development, mesenchyme cells around the primitive heart tube align into _____ arrays
chainlike
form complex junctions between interdigitating processes
cardiac muscle cells
each ______ muscle cell usually has only one nucleus and is centrally located
cardiac
transverse lines that cross the fibers at irregular intervals where the myocardial cells join
intercalated discs
_________ and fascia __________ junctions together provide strong intercellular adhesions (cells attach to other cells)
desmosomes and adherens
_____ junctions provide ionic continuity between the cardiac muscle cells; electrical synapses
gap
the major fuel of the heart
fatty acids/triglycerides
complex of a T-tubule with
a cisternae; present in cardiac muscle
a dyad
specialized for slow, steady contraction under the influence of autonomic nerves and various hormones
smooth muscle
this type of muscle is a major component of blood vessels and of digestive, respiratory, urinary, and reproductive tracts
smooth muscle
fibers of _____ muscle are elongated, tapering, and unstriated cells with single, central nucleus
smooth
each ____ muscle cell is enclosed by an external lamina and a network of type I and III collagen fibers comprising the endomysium
smooth
_____ muscle has rudimentary sarcoplasmic reticulum and no T-tubule system
smooth
in smooth muscle cells, bundles of thin and thick myofilaments _______ the sarcoplasm slanted
crisscross
thin filaments of smooth muscle lack _________ and have tropomyosin that doesn’t cover ____ sites
troponin; binding
In smooth muscle cells, _______a acts like troponin and myosin _____-chain _____ acts like tropomyosin
calmodulin; myosin light-chain kinase (MLCK)
contain α-actinin and are functionally like Z disc of striated and cardiac muscle
dense bodies
