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HISTOLOGY > MUSCLE > Flashcards

MUSCLE Flashcards

1
Q

MUSCLE CELL CALSSIFICATION

A

Striated (muscle cells with a banded appearance) or nonstriated (not banded) * Muscle cells can have a single nucleus or be multinucleate * Muscle cells can be controlled voluntarily (consciously) or involuntarily (automatically)

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2
Q

SKELETAL MUSCLE

A

Striated, “voluntary”, and multinucleated * Cells can be very long * Contracts rapidly but tires easily * Is extremely adaptable and can exert forces ranging from a fraction of an ounce to over 70 pounds * Satellite cells: Like a muscle “stem cell,” can divide to become new skeletal muscle cells (adult skeletal muscle cells do not divide).

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3
Q

CARDIAC

A

Occurs only in the heart * Is striated, not voluntary, uni- or bi- nucleate * Contracts at a fairly steady rate set by the heart’s pacemaker cells * Cells are called cardiac myocytes * Form branching networks connected at intercalated disks * Neural controls allow the heart to respond to changes in bodily needs Limited capacity for repair

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4
Q

SMOOTH MUSCLE

A

Nonstriated, involuntary, and have a single nucleus * Smooth muscle cells are small and tapered * can divide and regenerate * Found in walls of hollow organs and blood vessels * Contract alone or under nervous system control * Smooth muscle helps maintain blood pressure, and squeezes or propels substances (i.e., food, feces) through organs

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5
Q

FUNCTIONAL CHARACTERISTICS OF MUSCLE TISSUE

A

ExCoExEl
Excitability, or irritability – the ability to receive and respond to stimuli * Contractility – the ability to shorten forcibly * Extensibility – the ability to be stretched or extended * Elasticity – the ability to recoil and resume the original resting length

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6
Q

functions of skeletal muscle

A

roduce skeletal movement * Maintain body posture * Support soft tissues * Stabilize joints * Guard body openings * Generate heat

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7
Q

n overcoat of dense regular and irregular connective tissue that surrounds the entire muscle; Separates muscle from surrounding tissues

A

epimysium

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8
Q

fibrous connective tissue that surrounds groups of muscle fibers called fascicles; Contains blood vessel and nerve supply to fascicles

A

perimysium

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9
Q

– fine sheath of connective tissue composed of collagen and reticular fibers surrounding each muscle cell/fiber; Contains capillaries and nerve fibers contacting muscle cells; Contains satellite cells (stem cells) that repair damage

A

Endomysium

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10
Q

surrounds muscle (which are bundles of fascicles) *

A

epimyseum

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11
Q

surrounds fascicles

A

perimyssium

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12
Q

which are bundles are fibers/cells

A

fascicle

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13
Q

surrounds muscle fibers (which are filled with myofibrils)

A

ENDOMYSIUM

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14
Q

long cylinders of sarcomeres

A

MYOFIBRIL

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15
Q

contract to shorten muscles. (Made up of myofilaments)

A

Sarcomeres

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16
Q

2 TYPE OF MUSCLE ATTACHMENT

A

DIRECT AND INDIRECT

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17
Q

epimysium of the muscle is fused to the periosteum of a bone

A

DIRECT MUSCLE ATTACHMENT

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18
Q

onnective tissue wrappings (endomysium, perimysium, and epimysium) come together at ends of muscles and extend beyond it as a tendon (bundle) or aponeurosis (sheet)

A

INDIRECT MUSCLE ATTACHMENT

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19
Q

INNERVATION AND VASCULARIZATION

A

Nerves * Skeletal muscles are voluntary muscles, controlled by nerves of the somatic nervous system * Muscles have extensive vascular systems: * supply large amounts of oxygen and nutrients * carry away wastes

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20
Q

Formation of Skeletal Muscle Fibers

A
  • Skeletal muscle cells are called fibers * Myoblasts join to form muscle fibers
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21
Q

SKKELETAL MUSCLE FIBERS

A

Are very long cylindrical cell with hundreds of nuclei just beneath the sarcolemma * Each cell is a syncytium produced by fusion of embryonic mesodermal cells (myoblasts) * Fibers are 10 to 100 m in diameter, and up to hundreds of centimeters long

22
Q

re densely packed, rod-like contractile elements * Make up most of the muscle cell volume * Made up sarcomeres, which are themselves bundles of protein filaments (myofilaments)

A

MYOFIBRIL

23
Q

The smallest contractile unit of a muscle * The region of a myofibril between two successive Z discs * Composed of myofilaments made up of contractile proteins * The repeating pattern of myofibrils notice the presence of a repeating portion known as a sarcomere

A

SARCOMERE

24
Q

Myofibrils and sarcomeres consist of thick and thin myofilaments * These filaments are responsible for the striations of muscle, which are alternating dark and light bands * Myofilaments are responsible for muscle contraction * Thin filaments: * made of the protein actin * Thick filaments: * made of the protein myosin

A

MYOFILAMENT

25
Q

The contractile units of muscle * Structural units of myofibrils (that is, myofibrils are made up of many sarcomeres postioned end to end) * Form visible striated patterns within myofibrils: * alternating dark, thick filaments(A bands) and light, thin filaments(I bands)

A

SARCOMERE

26
Q

the center of the A band

A

M LINE

27
Q

MIDLINE OF SARCOMERE

A

M LINE

28
Q

the centers of the I band

A

Z LINE/DISC

29
Q

at 2 ends of sarcomere

A

Z LINE

30
Q

coin-shaped sheet of proteins (connectins) that anchors the thin filaments and connects myofibrils to one another

A

Z LINE

31
Q

The densest, darkest area on a light micrograph * Where thick and thin filaments overlap

A

ZONE OF OVERLAP

32
Q

The area around the M line * Has only thick filaments but no thin filaments

A

H ZONE

33
Q
  • Strands of protein that reach from tips of thick filaments to the Z line * Stabilize the filaments
A

titin

34
Q

re extensions of the sarcolemma that join with the SR at specialized regions

A

transverse tubules

35
Q

The cell membrane of a muscle cell * Surrounds the sarcoplasm (cytoplasm of muscle fiber) * Muscle contractions are started by a change in transmembrane potential (electrical charge on either side of the membrane)

A

sarcolemma

36
Q

A rapid, transitory reversal of the transmembrane potential that propagates quickly along the length of an electrically excitable cell. * Huh? Basically, a portion of a cell goes from negative to positive charge very quickly and this spreads from one part of the cell to the next to the next and so on.

A

action potential

37
Q

are continuous with the sarcolemma and have the same properties * They conduct action potentialsto the deepest regions of the muscle * These impulses signal for the release of Ca2+ from adjacent terminal cisternae * Allow entire muscle fiber to contract simultaneously

A

transverse tubules

38
Q
  • Transverse tubules encircle the sarcomere near zones of overlap (why?) * Ca2+ released by SR causes thin and thick filaments to interact
A

zone of overlap andt tubules

39
Q

n elaborate membranous structure that runs longitudinally, surrounding each myofibril * Similar in structure to smooth endoplasmic reticulum * Helps transmit action potential to myofibril * Forms chambers (terminal cisternae) attached to T tubules that release calcium during muscle contraction

A

sarcoplasmic reticulum

40
Q

Concentrate Ca2+ inside (via ion pumps) * When stimulated by an action potential, they release Ca2+ into sarcomeres to begin muscle contraction

A

terminal cisternae

41
Q

Structure formed by 1 T tubule and 2 terminal cisternae (thickenings of the SR) * T tubules and SR provide tightly linked signals for muscle contraction * T tubule proteins act as voltage sensors * SR has receptors that regulate Ca2+ release from the terminal cisternae

A

a triad

42
Q

caused by interactions of thick and thin filaments * Structures of protein molecules detemine interactions

A

muscle contraction

43
Q

Thin filaments are chiefly composed of the protein actin held together bynebulin * The subunits contain the active sites to which myosin heads attach during contraction * Tropomyosin strands block active sites * Troponin holds tropomyosin and actin together (at rest)

A

Myofilaments: Thin Filaments

44
Q

Longitudinal section within one sarcomere

A

filaent

45
Q

binds tropomyosin to actin

A

troponin

46
Q

3 suvbsunit of troponin

A

consists of three subunits * TnI: binds to actin * TnT: bonds to tropomyosin * TnC: binds calcium * controlled by Ca2+, kind of like the “lock” and Ca2+ is the “key”

47
Q

2+ binds to receptor on troponin molecule * Troponin–tropomyosin complex changes shape, moves troponin out of the way * Exposes the active site of each actin molecule (bead)

A

initiating contraction

48
Q

During contraction, myosin heads: * interact with actin filaments, forming cross-bridges * pivot, producing motion It is the pivoting of myosin heads that causes muscle contraction and therefore all movements

A

myosin action

49
Q

sliding filament model of contraction

A

hin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree * In the relaxed state, thin and thick filaments overlap only slightly * Upon stimulation, myosin heads bind to actin and sliding begins * Myosin heads pull the actin thin filaments closer together, sliding them in between the thick filaments * As this event occurs throughout the sarcomeres, the muscle shortens * Z lines move closer together * width of A band stays the same * width of the I band and the H zone both shrink

50
Q
A

HISTOLOGY (4 decks)

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