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Biology 235 > Chapter 10: Muscle Tissue > Flashcards

Chapter 10: Muscle Tissue Flashcards

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1
Q

Motor Unit

A

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

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2
Q

Myogram

A

Record of a muscle contraction

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3
Q

Unfused (incomplete) Tetanus

A

When a skeletal muscle fiber is stimulated at a rate of 20 to 30 times per second, it can on partially relax between stimuli.

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4
Q

Fused (Complete) Tetanus

A

When a skeletal muscle fiber is stimulated at a high rate of 80 - 100 times per second, the muscle does not relax at all.

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5
Q

Motor Unit Recruitment

A

The process in which the number of active motor units increase.

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6
Q

Muscle Tone

A

A skeletal muscle exhibits a small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units.

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7
Q

Flaccid

A

A state of limpness in which muscle tone is lost.

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8
Q

Isotonic Contraction

A

Muscle contraction where the tension developed remains almost constant while the muscle changes length.

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9
Q

Concentric Isotonic Contraction

A

Tension generated is great enough to overcome resistance of the object to be moved, the muscle shortens and pulls on another structure such as a tendon.

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10
Q

Eccentric Isotonic Contraction

A

When the length of a muscle is increased during a contraction.

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11
Q

Isometric Contraction

A

The tension generated is not enough to exceed the resistance of the object to be moved and the muscle does not change its length.

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12
Q

Hypertrophy

A

Enlargement of exciting cells

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13
Q

Hyperplasia

A

An increase in the number of fibers

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14
Q

Pericytes

A

Stem cells found in association with blood capillaries and small veins.
New smooth muscles can arise from this cells.

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15
Q

Muscle Fibers

A

Most important component of skeletal muscle

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16
Q

Sacrolemma

A

Plasma membrane of muscle fiber. Muscle action potentials travel along the sarcolemma, ensures excitement.

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17
Q

Transverse (T) Tubules

A

Open to the outside the muscle fiber. Filled with interstitial fluid. Action potential travels through these.

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18
Q

Sarcoplasm

A

Within the sarcolemma. This is the cytoplasm of a muscle fiber.

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19
Q

Myoglobin

A

Red colored protein. Found only in muscle fibers. Binds in O2 molecules with interstitial fluid. Releases the O2 when its needed for ATP.

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20
Q

Myofibrils

A

Small contractile structures of skeletal muscles. Extend entire length of muscle fibers. Give muscle the striated appearance.

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21
Q

Sarcoplasmic Reticulum

A

Fluid filled membranous sac. Encircles each myofibrils. Stores Ca2+ when muscle are relaxed, releases Ca2+ through terminal cisterns when contracts.

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22
Q

Terminal Cisterns

A

Dilated end sacs of SR. Butt against the T Tubule from both sides. These cisterns releases Ca2+ when SR triggers muscle contractions.

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23
Q

Triad

A

Formed from 2 terminal cisterns and T tubule.

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24
Q

Thick Filament

A

Composed of protein myosin

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25
Q

Thin Filament

A

Composed of protein actin.

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26
Q

Sarcomeres

A

Basic functional unit of myofibrils. Compartments arranged from filaments inside the myofibril. Organized in bands and zones.

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27
Q

Tropomyosin

A

Regulatory Protein. Component of thin filament. When muscle is relaxed, covers myosin. This prevents myosin from binding with actin, thus preventing contraction.

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28
Q

Troponin

A

Regulatory Protein. Component of thin filament. Ca2+ changes shape when binds with troponin. This moves tropomyosin away from myosin. Muscle contractions begin to bind with actin.

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29
Q

Structural Proteins

A

Proteins that keep thick and thin filaments of myofibrils in proper alignment.

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30
Q

Titin

A

Structural protein. Connects Z disc to M line. Stabilizes thick filaments

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31
Q

A-actinin

A

Structural protein of z discs. Attaches to actin of thin filaments.

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32
Q

Myomesin

A

Structural proteins forms M line. Binds to thin filaments and connects to adjacent thick filaments.

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33
Q

Nebulin

A

Structural protein. Wraps around entire length of thin filaments.

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34
Q

Dystropnin

A

Link thin filaments of sarcomere to integral proteins to sarcolemma. Helps reinforce sarcolemma.

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35
Q

Myosin

A

Contractile Proteins. Makes up thick filaments.
Contains a tail and 2 heads. Binds to actin of thin filaments during a muscle contraction.

36
Q

Actin

A

Contractile proteins. Make up thin filaments. Contains myosin binding site where myosin bind during muscle contraction.

37
Q

Regulatory Protiens

A

Proteins that help switch muscle contractions on and off.

38
Q

Why Smooth Muscle Lack Straintions

A

Contain both thin/thick filaments and intermediate filaments. None of these are arranged in sarcomeres.

39
Q

Muscle Tissue

A

Skeletal
Cardiac
Smooth

40
Q

Skeletal Muscle

A

Move bones of skeleton
Striated; dark and light protein bands
Voluntary: control by neurons.

41
Q

Cardiac Muscle

A

Only found in the heart, forms heart wall.
Striated: dark and light bands of proteins.
Involuntary: alternating contractions and relaxations of heart is not continuously controlled. Autonomic.
Contains autorhythmicity.

42
Q

Autorhythmicity

A

Build in heart rhythm

43
Q

Smooth Muscle

A

Located in walls of hallow internal structures
Blood vessels, airways, organs in abdpelvic cavity. Also in skin attached to hair follicles.
Non striated: autorphythpmic
Involuntary: regulated by neurons of autonomic division

44
Q

Functions of Muscle Tissue

A
  1. Producing body movement: movement of whole body. Relies on function of skeletal muscles, bones and joints.
  2. Stabilizing body positions: skeletal muscle contractions stabilize joints and help maintain positions such as standing.
  3. Storing and moving substances within the body: Sphincters of smooth muscle prevent out flow of contents of hallow organs. Cardiac muscle pumps blood throughout body. Smooth muscle contraction/relaxation in blood vessels help adjust blood flow. Skeletal muscle promote flow of lymph and return of blood in veins.
  4. Generate heat: muscle tissue produces heat (thermogenesis). Heat produced is used to maintain body temp.
45
Q

Properties of Muscle Tissue

A
  1. Electrical Excitability: ability to respond to retain stimuli by producing electrical signals called muscle action potential.
  2. Contractility: ability to contract forcefully when stimulated by action potential.
  3. Extensibility: ability to stretch within limits without being damaged.
  4. Elasticity: Ability to return to its original shape after contraction or extension.
46
Q

Electrical Excitability

A

Both a property of muscle and nervous tissue
Ability to respond to certain stimuli by producing signals called muscle action potentials.
2 types:
1. Electrical: autorphytmic
2. Chemical: neurotransmitters released both by neurons or hormones in blood

47
Q

Contractility

A

Ability of muscular tissue to contract forcefully when stimulated by an action potential
Example: smashing food

48
Q

Extensibility

A

Ability of muscle tissue to stretch within limits without being damaged. CT within the tissue keeps it in range.
Smooth muscle is subject to the greatest amount of stretching.

49
Q

Elasticity

A

The ability of muscular tissue to return to its original length and shape after contraction.

50
Q

Muscle Fiber Ormyocytes

A

100-1000 cells that male up skeletal muscle cells
Fibers have elongated shapes

51
Q

Fascia

A

Dense sheet of irregular CT
Lines body walls and limbs
Supports and surrounds muscles and organs

52
Q

Connective Tissue Layer of Skeletal Muscles

A

Extend from the fascia to protect and strengthen skeletal muscles
1. Epimysium
2. Perimysium
3. Endomysium
All these layers of CT extend beyond muscle fibers to form rope like tendon that attaches a muscle to periosteum of bone.

53
Q

Epimysium

A

Dense Irregular CT
outer layer, encircles the entire muscle

54
Q

Perimysium

A

Dense irregular CT
Surrounds groups of 10-100 muscle fibers into bundles. These muscle bundles are known as fascicles.

55
Q

Fascicles

A

Bundles of fibers that are formed by the Perimysium
Give meat its grain

56
Q

Endomysium

A

Reticular fibers
Penetrates the interior of each fascicle
Separates individual muscle fibers from one another

57
Q

Somatic Motor Neurons

A

Nerves that stimulate skeletal muscles to contract.

58
Q

Capillaries In Tissue

A

Plentiful in muscular tissue, each muscle fiber is in close contact to capillaries

59
Q

Level of Organization of Skeletal Muscle

A
  1. Skeletal Muscle: made of fascicles that contain muscle fibers, blood vessels and nerves wrapped in Epimysium.
  2. Fascicle: Bundle of muscle fiber wrapped in Perimysium.
  3. Muscle Fiber (Cell): cell covered by Endomysium and sacrolemma. Contain nuclei and organelles. Striated appearance.
  4. Myofibril: thread like contractile element within sarcoplasm of muscle fibers composed of filaments
  5. Filaments (myofilaments): Contractile protein within myofibril. 2 types: thick filaments and thin filaments
60
Q

Thick Filaments

A

Composed of myosin

61
Q

Thin Filaments

A

Composed of actin

62
Q

Z Disc

A

Occurs at the boarder of a sarcomere. Narrow region of dense material that separate one sarcomere from the next.

63
Q

A Band

A

Dark middle part of sarcomere that extend the entire length of the thick filament. Includes the parts of thin filaments that overlap thick filaments.

64
Q

I Band

A

Lighter, dense area of sarcomere that contains remainder of thin filaments but no thick filaments. Z disc passes through center of each I Band.

65
Q

H Zone

A

Narrow region in center of each A Band that contain thick filaments but not thin filaments.

66
Q

M Line

A

Region in center of H Zone that contains proteins that hold back myosin tail.

67
Q

Muscle Metabolism

A

Muscle fibers produce ATP in 3 ways:
1. From creatine phosphate
2. Anaerobic glycolysis
3. Aerobic respiration

68
Q

Creatine Phosphate

A

Synthesize excess ATP produced when muscles are relaxed. This is energy rich molecule is found in muscle fiber.

69
Q

Anaerobic Glycolysis

A

Faster than aerobic but yields less ATP
Breakdown of glucose gives rise to lactic acid when O2 is absent or in low concentration.
Glycolysis occurs in the cytosol, produces a net gain of 2 ATP molecules and 2 lactic acids. Lactic acid diffuses out of muscle into blood stream.

Glycolysis also breaks down glucose molecules into 2 molecule of pyruvic acid.

70
Q

Aerobic Respiration

A

Slower than anaerobic but yields more ATP. Requires O2. Pyruvic acid formed by glycolysis enters mitochondria where a series of O2 requiring reactions occur.
These reactions are :Krebs cycles and electron transport. These reactions produce ATP, CO2, H2O and Heat.

71
Q

2 Sources of O2 for Muscles

A

1.O2 that diffuses into muscle fibers from blood
2. O2 released by myoglobin within muscle fibers.

72
Q

Muscle Fatigue

A

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

73
Q

Oxygen Debt

A

Refers to added O2, over and above the resting O2 consumption that is taken into the body after exercise.

74
Q

Payback or Restore in O2 Debt

A

The extra O2 must payback or restore metabolic conditions to resting levels by:
1. Convert lactic acid back into glycogen. Stored in liver
2. To resynthesizes creatine phosphate and ATP in muscle fibers
3. Replace the O2 removed from myoglobin.

75
Q

Red Muscle Fibers

A

Skeletal muscle fibers that have a high myoglobin content. Appear darker.

76
Q

White Muscle Fibers

A

Skeletal muscle fibers that have a low content of myoglobin. Appear lighter.

77
Q

Slow Oxidative Fibers

A

Appear dark red due to large amount of myoglobin.
Location: postural neck muscles
Recruitment: used first
Contains: Many mitochondria and capillaries
High: ATP by aerobic respiration, fatigue resistance
Low: glucose storage, creatine kinase
Slow: ATP by hydrolysis, contraction velocity
Function: Maintaining posture during endurance activities

78
Q

Fast Oxidative Glycolytic Fibers

A

Appear red/pink due to medium amount of myoglobin
Location: lower limb muscles
Recruitment: used second
Contains: Many mitochondria and capillaries
Intermediate: ATP by aerobic/anaerobic respiration, fatigue resistance, creatine kinase, glycogen stores
Fast: ATP hydrolysis, contraction velocity
Function: walking, sprinting

79
Q

Fast Glycolytic Fibers

A

Appear white/pale due to small amount of myoglobin
Location: extracellular muscles
Few: mitochondria, capillaries
Low: ATP by anaerobic glycolysis, fatigue resistance
Fast: ATP hydrolysis, contraction velocity
High: creatine kinase, glycogen stores
Function: rapid intense movement of short duration

80
Q

Intercalated Discs

A

Irregular transverse thickenings of sarcolemma
Unique to cardiac muscles.
Connect the ends of cardiac muscles to one another.

81
Q

Visceral (Single Unit) Muslce Tissue

A

More common type of smooth muscle
Found in skin, blood vessels and hallow organs: stomach, intestines, uterus, bladder

82
Q

Multi Unit Muscle Tissue

A

Second type of smooth muscle

Consists of individual fibers with its own motor neuron terminals

83
Q

Sarcoplasm of Smooth Muscle

A

Contains:
Thick/thin filaments
Intermediate filaments
Coveolae
No tubules

84
Q

Caveolae

A

Found in Smooth Muscle
Small pouch like invaginations of the PM
Contains extracellular Ca2+ used for muscle contraction

85
Q

Calmodulin

A

Smooth muscle regulatory protein enzyme
Regulates contractions and relaxations
Binds to Ca2+ in sarcoplasm, activates myosin
Works slowly

Biology 235 (29 decks)

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