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BIOL 235 - Section 1 > Chapter 10 - Muscular Tissue > Flashcards

Chapter 10 - Muscular Tissue Flashcards

1
Q

Four main functions of muscle tissue

A

Producing body movements, stabilizing body positions, storing and moving substances within the body, generating heat

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2
Q

Shivering

A

Involuntary contractions that increase rate of heat production (contraction=heat)

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3
Q

Four properties of muscle tissue that contribute to homeostasis

A

Electrical excitability (action potentials respond to stimuli)
Contractility
Elasticity
Extensibility (stretch)

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4
Q

Fascia

A

dense sheet or broad band of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs of the body.
Fascia allows free movement of muscles; carries nerves, blood vessels, and lymphatic vessels; and fills spaces between muscles.

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5
Q

Epimysium

A

is the outer layer, encircling the entire muscle. It consists of dense irregular connective tissue.

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6
Q

Perimysium

A

is also a layer of dense irregular connective tissue, but it surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles called fascicles

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7
Q

Fascicles

A

The grainy look of meat, bundles of muscle fibers.

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8
Q

Endomysium

A

penetrates the interior of each fascicle and separates individual muscle fibers from one another. The endomysium is mostly reticular fibers.

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9
Q

Aponeurosis

A

When the connective tissue elements extend as a broad, flat sheet,

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10
Q

Nerve and blood supply

A

Generally, an artery and one or two veins accompany each nerve that penetrates a skeletal muscle.

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11
Q

Somatic motor neuron

A

neurons that stimulate skeletal muscle to contract threadlike axon that extends from the brain or spinal cord to a group of skeletal muscle fibers

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12
Q

Sarcolemma

A

plasma membrane of a muscle cell

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13
Q

Transverse tubules

A

Thousands of tiny invaginations of the sarcolemma, tunnel in from the surface toward the center of each muscle fiber.

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14
Q

Sarcoplasm

A

cytoplasm of a muscle fiber.

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15
Q

Myoglobin

A

This protein, found only in muscle, binds oxygen molecules that diffuse into muscle fibers from interstitial fluid. and releases when mitochondria need it

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16
Q

Myofibrils

A

Look like little threads, contractile organelles of skeletal muscle.

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17
Q

Sarcoplasmic reticulum

A

Fluid-filled system of membranous sacs

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18
Q

Terminal cisterns

A

Dilated end sacs of the sarcoplasmic reticulum butt against t tubule from both sides.

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19
Q

Triad

A

A transverse tubule and the two terminal cisterns

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20
Q

Muscular hypertrophy

A

muscle growth that occurs after birth occurs by enlargement of existing muscle fibers

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21
Q

Fibrosis

A

the number of new skeletal muscle fibers that can be formed by satellite cells is not enough to compensate for significant skeletal muscle damage or degeneration, the muscular tissue undergoes fibrosis, the replacement of muscle fibers by fibrous scar tissue.

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22
Q

Muscular atrophy

A

decrease in size of individual muscle fibers as a result of progressive loss of myofibrils.

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23
Q

Thin filament

A

are 8 nm in diameter and 1–2 􏱌m long* and composed mostly of the protein actin,

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24
Q

Thick filament

A

16 nm in diameter and 1–2 􏱌m long and composed mostly of the protein myosin

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25
Q

Sarcomere

A

basic functional units of a myofibril

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26
Q

Z disc

A

plate-shaped regions of dense protein material called Z discs separate one sarcomere from the next.

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27
Q

Myosin

A

motor protein in all three types of muscle tissue. like two twisty golf clubs

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28
Q

Titin

A

connects a Z disc to the M line of the sarcomere, thereby helping stabilize the position of the thick filament. Accounts for most elasticity and extensibility of myofibrils

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29
Q

Sliding filament mechanism

A

skeletal muscle shortens during contraction because the thick and thin filaments slide past one another.

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30
Q

Contraction cycle, four steps

A

ATP hydrolysis, Attachment of myosin to actin to form cross-bridges,
Power stroke,
Detachment of myosin from actin

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31
Q

Excitation contraction coupling

A

Increase in calcium concentration starts muscle contraction, decrease stops it. When a muscle fiber is relaxed, the concentration of calcium in the sarcoplasm is very low, but there is a large amount of calcium stored inside the SR.
Muscle action potential propagagtes along sarcolemma into T tubles, calcium channels open, flooding, combines/moves tropomyosin away from myosin binding sites on actin. Myosin binds.

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32
Q

Ca2+ release channels

A

Open in the SR with muscle action potential

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33
Q

Ca2+ active transport pump

A

Use ATP to move calcium from sarcoplasm into SR.

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34
Q

length tension relationship

A

Forcefulness of muscle contraction depends on the length of the sarcomeres within a muscle before contraction begins.

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35
Q

Neuromuscular junction

A

Where muscle action potentials arise, the synapse between a somatic motor neuron and a skeletal muscle fiber

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36
Q

Somatic motor neuron

A

the neurons that stimulate skeletal muscle fibers to contract. has a threadlike axon that extends from the brain or spinal cord to a group of skeletal muscle fibers.

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37
Q

Synapse

A

Region where communication occurs between two neurons, or between a neuron and a target cell.

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38
Q

Synaptic cleft

A

A small gap separating two cells.

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39
Q

Neurotransmitter

A

a chemical messenger between two cells

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40
Q

Axon terminal

A

End of the motor neuron

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41
Q

Synaptic end bulb

A

end divides into a cluster of SEB, the neural part of the NMJ.

42
Q

Synpatic vesicle

A

Suspended in the cytosol within each SEB are hundreds of these membrane enclosed sacs.

43
Q

ACh

A

Inside each synaptic vesicle are thousands of molecules of acetylcholine, the neurotransmitter

44
Q

Motor end plate

A

The region of the sarcolemma opposite the synaptic end bulbs, is the muscle fiber part of the NMJ.

45
Q

ACh receptor

A

30-40mil, integral transmembrane proteins to which ACh specifically binds.

46
Q

Junctional folds

A

Deep grooves in the motor end plate that provide a large surface area for ACh.

47
Q

Muscle action potential - steps

A

1) Release- ACh is released from synaptic vesicle
2) Activation-ACh binds to ACh receptor
3) Production -Muscle action potential is produced
4) Termination-ACh is broken down

48
Q

AChE

A

Enzyme which breaks down ACh

49
Q

Production of ATP in muscle fibers

A

A large amount of ATP is required to power the contraction cycle, to pump calcium into the sarcoplasmic reticulum, and for other metabolic reactions. However the ATP present inside muscle fibers is only enough for a few seconds. Thus, must make more through 1)creatine phosphate, 2) anaerobic glycolysis or 3) aerobic respiration

50
Q

Creatine phosphate

A

When relaxed produce excess ATP. Excess synthesizes creatine phosphate.
The enzyme creatine kinase catalyzes the transfer of 1 phosphate group from ATP to creatine, or from creatine to ADP which generates ATP. (first source, lasts 15seconds)

51
Q

Anaerobic glycolysis

A

Glucose is catabolized to generate ATP. Blood to contracting muscle fibers via facilitated diffusion. Also produced through breakdown of glycogen in muscle fibers. Produces 2 molecules of ATP, (w/o oxygen, 2 minutes)

52
Q

Aerobic respiration

A

Pyruvic acid formed by glycolysis enters mitochondria (krebs, electron transport chain), producing ATP, CO2, H2O, heat. 30to32 molecules ATP, several minutes to an hour. Relies on oxygen.

53
Q

Muscle fatigue

A

The inability of a muscle to maintain force of contraction after prolonged activity.

54
Q

Central fatigue

A

Feelings of tiredness before muscle fatigue, caused by changes in central nervous system.

55
Q

Oxygen debt

A

Added oxygen, over and above the resting consumption that is taken into the body after exercise. (1) to convert lactic acid back into glycogen stores in the liver, (2) to resynthesize creatine phosphate and ATP in muscle fibers, and (3) to replace the oxygen removed from myoglobin.

56
Q

Recovery oxygen uptake

A

metabolic changes that occur during exercise can account for only some of the extra oxygen used after exercise.
elevated temp increases reactions, using more ATP, and tissue repair occurring.

57
Q

Control of muscle tension

A

The total force or tension that a single muscle fiber can produce depends mainly on the rate at which nerve impulses arrive at the neuromuscular junction, as well as amount of stretch before contraction, nutrient and oxygen availability. The total tension a whole muscle can produce depends on the number of muscle fibers that are contracting in unison.

58
Q

Motor unit

A

consists of a somatic motor neuron plus all of the skeletal muscle fibers it stimulates

59
Q

Twitch contraction

A

the brief contraction of all muscle fibers in a motor unit in response to a single action potential in its motor neuron.

60
Q

Latent period

A

a brief delay between application of the stimulus and beginning of contraction. 2 msec. the muscle action potential sweeps over the sarcolemma and calcium ions are released from the sarcoplasmic reticulum.

61
Q

Contraction period

A

10-100msec. Calcium binds to troponin, myosin-binding sites on actin are exposed and cross-bridges form. Peak tension develops in the muscle fiber.

62
Q

Relaxation period

A

10-100msec. Calcium is actively transported back into the sarcoplasmic reticulum, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases.

63
Q

Refractory period

A

When a muscle fiber receives enough stimulation to contract, it temporarily loses its excitability and cannot respond for a time. 5msec for skeletal muscle, 300msec for cardiac muscles.

64
Q

Frequency of stimulation

A

Number of nerve pulses arriving at neuromuscular junction per second.

65
Q

Wave summation

A

stimuli arriving at different times cause larger contractions

66
Q

Unfused (incomplete) tetanus

A

sustained but wavering contraction

67
Q

Fused (complete) tetanus

A

Sustained contraction, no twitches. When a skeletal muscle fiber is stimulated at a higher rate of 80 to 100 times per second, it does not relax at all.

68
Q

Motor unit recruitment

A

number of active motor units increases. Contraction doesn’t occur in unison to delay fatigue. Weakest recruited first.

69
Q

Muscle tone

A

small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units. established by neurons in the brain and spinal cord that excite the muscle’s motor neurons.

70
Q

Flaccidity

A

Limpness, loss of muscle tone due to motor neurons serving a skeletal muscle being damaged or cut.

71
Q

Isotonic contraction

A

Tension remains constant while muscle changes length.

72
Q

Concentric isotonic contraction

A

tension great enough to overcome resistance, muscle shortens and pulls to produce movement (picking up a book from a table)

73
Q

Eccentric isotonic contraction

A

Length of muscle increases during a contraction, muscle lengthens while contracting (placing a book on a table). Causes more damage.

74
Q

Isometric contraction

A

Tension generated not enough to exceed resistance, muscle does not change length. (holding something steady, maintaining posture) expends energy without movement.

75
Q

Slow oxidative fiber

A

dark red, large amounts of myoglobin and capillaries. many large mitochondria, generate ATP by aerobic respiration. 100to200msec. Resistant to fatigue.

76
Q

Fast oxidative glycolytic fiber

A

Largest. Large amount of myoglobin and capillaries, dark red. high intracellular glycogen level generate ATP by anaerobic glycolysis. Fast, less than 100msec but brief.

77
Q

Fast glycolytic fiber

A

Low myoglobin, few capillaries, few mitochondria, appear white. large amounts of glycogen generate ATP through glycoysis. strongly and quickly, fatigue quickly.

78
Q

Distribution and recruitment of different types of fiber

A

Depends on action of muscle, person’s exercise, and genetics.
SO- postural muscles (neck)
FOG - lower limb muscles
FG - upper limb muscles

79
Q

Cardiac muscle tissue

A

principal tissue in the heart wall. sheets of connective tissue that contain blood vessels, nerves, and the conduction system of the heart. has an endomysium and perimysium, but lacks an epimysium.

80
Q

Intercalated disc

A

microscopic structures are irregular transverse thickenings of the sarcolemma that connect the ends of cardiac muscle fibers to one another.

81
Q

Desmosomes

A

hold the fibers together

82
Q

Gap junctions

A

which allow muscle action potentials to spread from one cardiac muscle fiber to another

83
Q

Smooth muscle tissue

A

.

84
Q

Visceral (single unit) smooth muscle tissue

A

found in the skin and in tubular arrangements that form part of the walls of small arteries and veins and of hollow organs such as the stomach, intestines, uterus, and urinary bladder. Autorhythmic. neighboring fibers, which then contract in unison, as a single unit.

85
Q

Multiunit smooth muscle tissue

A

Individuals fibers with their own motor neuron terminals and few gap junctions. Stimulation of one vis- ceral muscle fiber causes contraction of many adjacent fibers, but stimulation of one multiunit fiber causes contraction of that fiber only.
walls of large arteries, airways to the lungs, in the arrector pili muscles that attach to hair follicles, in the muscles of the iris that adjust pupil diameter, and in the ciliary body that adjusts focus of the lens in the eye.

86
Q

Microscopic anatomy of smooth muscle

A

A single relaxed smooth muscle fiber is 30–200 um long. It is thickest in the middle and tapers at each end

87
Q

Caveolae

A

Small pouch like invaginations for the plasma membrane, contain extracellular calcium used for muscle contraction.

88
Q

Dense bodies

A

Attach to thin filaments or bundles of intermediate filaments(similar to z discs), which pull on dense body’s attachment to sarcolemma, causing a length-wise shortening of the muscle fiber.

89
Q

Calmodulin

A

A regulatory protein, which binds to calcium in cytosol (regulates contraction/relaxation of smooth muscle cells). After binding to calcium, activates myosin light chain kinase, which uses ATP to add a phosphate group to a portion of the myosin head which then binds to actin so contraction can occur.

90
Q

Smooth muscle tone

A

A state of continued partial contraction because calcium ions enter/exit smooth muscle fibers slowly

91
Q

Stress relaxation response

A

Can change length but still contract. To action potentials, stretching, hormones, changes in pH, oxygen, co2, temp or ion levels.
When smooth muscle fibers are stretched, they initially contract, developing increased tension. Within a minute or so, the tension decreases.

92
Q

Hypertrophy

A

enlargement of existing cells

93
Q

Hyperplasia

A

increase in the number of fibers

94
Q

Myasthenia gravis

A

an autoimmune disease that causes chronic, progressive damage of the neuromuscular junction. The immune system inappropriately produces antibodies that bind to and block some ACh receptors, thereby decreasing the number of functional ACh receptors at the motor end plates of skeletal muscles

95
Q

Muscular dystrophy

A

group of inherited muscle-destroying diseases that cause progressive degeneration of skeletal muscle fibers.

96
Q

Spasm

A

sudden involuntary contraction of a single muscle in a large group of muscles

97
Q

Cramp

A

painful spasmodic contraction, may be caused by inadequate blood flow, overuse, dehydration, injury, low electrolytes.

98
Q

Tic

A

spasmodic twitching made involuntarily by muscles that are ordinarily under voluntary control.

99
Q

Tremor

A

rhythmic, involuntary, purposeless contraction that produces a quivering or shaking movement.

100
Q

Fasciculation

A

involuntary, brief twitch of an entire motor unit that is visible under the skin; it occurs irregularly and is not associated with movement of the affected muscle.

101
Q

Fibrillation

A

spontaneous contraction of a single muscle fiber that is not visible under the skin but can be recorded by electromyography. May signal destruction of motor neurons.

BIOL 235 - Section 1 (9 decks)

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