Chapter 10: Muscle Tissue Flashcards by nono bennafield

Contains epithelia, connective, and nervous tissue; composed of cells that optimize the universal cell property of contractility

Muscle tissue

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the three types of muscle tissue

skeletal, cardiac, and smooth

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contains bundles of very long, multinucleated cells with cross-striations; quick voluntary control

skeletal muscle

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cross-striations and is composed of elongated, often branched cells bound to one another at structures called intercalated discs; rhythmic involuntary contractions

cardiac muscle

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consists of collections of fusiform cells, which lack striations and have slow, involuntary contractions

smooth muscle

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the cytoplasm of muscle cells

sarcoplasm

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the smooth ER of muscle cells

sarcoplasmic reticulum

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the muscle cell membrane and its external lamina

sarcolemma

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During embryonic muscle development, mesenchymal _____ fuse, forming _____ with many nuclei. Then the further differentiate to form ____ muscle fibers

myoblasts; myotubes; striated

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elongated nuclei are found peripherally just under the _______, a nuclear location unique to skeletal muscle fibers/cells

sarcolemma

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a small population of reserve progenitor cells

muscle satellite cells

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an external sheath of dense irregular connective tissue, surrounds entire muscle; carries large nerves, blood vessels, and lymphatics

epimysium

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thin connective tissue layer that immediately surrounds each fascicle

perimysium

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bundle of muscle fibers that make up a functional unit

fascicle

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very thin layer of reticular fibers and scattered fibroblasts; surrounds the external lamina of individual muscle fibers

endomysium

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___________ is an increase in the size of the cells, while _______ is an increase inn the number of cells

hypertrophy; hyperplasia

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______ in these connective tissue layers of muscle serve to transmit the mechanical forces generated by the contracting muscle cells/fibers

collagens

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______ CT layer becomes the tendon

epimysium

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________ junctions which join the muscle to bone, skin, or another muscle

myotendinous

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long cylindrical filament bundles; run parallel to the long axis of the fiber

myofibrils

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the dark bands on the myofibrils; anisotropic or birefringent in polarized light

A bands

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the light bands on the myofibrils; isotropic or doesn’t alter polarized light

I bands

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each I band is bisected by a dark transverse line called ____

Z disc

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the repetitive functional subunit of the contractile apparatus; extends from Z disc to Z disc

sacromere

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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