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A&P Module 3 > Muscular system part 1 > Flashcards

Muscular system part 1 Flashcards

1
Q

How many muscles are there in the human body

A

600

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2
Q

what is the essential function of muscle

A

contraction or shortening

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3
Q

muscular contractions provide

A

body movement, propel body fluids and food, generate heartbeat, and distribute heat

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4
Q

What are the 3 types of muscle tissue that humans have

A
  • Skeletal muscle
  • cardiac muscle
  • smooth muscle
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5
Q

Skeletal and smooth muscle cells are both

A

elongated; hence their cells are called muscle fibers

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6
Q

what are the functions of skeletal muscles

A
  • support the body and maintains posture
  • make bones and other body parts move
  • help maintain a constant body temperature
  • contractions assists in blood and lymphatic circulation
  • help protect bones and internal organs and stabilize joints
  • form sphincters to regulate the passage of substances
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7
Q

what are sphincters

A

specialized donut-shaped muscles that help to pinch shut openings

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8
Q

what are the properties of the skeletal muscles

A
  • excitability
  • contractility
  • extensibility
  • elasticity
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9
Q

What is Endomysium

A

a thin layer of areolar connective tissue that surrounds each individual muscle fiber (muscle cell)

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10
Q

What are muscle fibers grouped into bundles called

A

fascicles

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11
Q

what is perimysium

A

a sheath of connective tissue that covers the dascicles

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12
Q

what is epimysium

A

the connective tissue layer that closely surrounds the bulk of the entire skeletal muscle

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13
Q

collagen fibers of the epimysium continue as a strong

A

tendon that attaches the muscle to a bone that they will move

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14
Q

what is aponeurosis

A

connective tissue forms broad fibrous sheets that attach muscles indirectly to bones, cartilages, or connective tissue coverings

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15
Q

what is a skeletal muscle fiber

A

a single cells that contracts in response to stimulation and relaxes when the stimulation ends

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16
Q

what is the plasma membrane called in the skeletal muscle

A

sarcolemma

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17
Q

what is the cytoplasm called in the skeletal muscle

A

sarcoplasm

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18
Q

what is the smooth endoplasmic reticulum called in the skeletal muscle

A

sarcoplasmic reticulum

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19
Q

what is the storage site for calcium (Ca++)

A

sarcoplasmic reticulum

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20
Q

Nuclei are pushed aside by

A

the long ribbon-like organelles known as myofibrils

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21
Q

what does the sarcoplasmic reticulum do

A

encases hundreds or even thousands myofibrils which are bundles of myofilaments

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22
Q

the sarcoplasm contains

A
  • mitochondria between myofibrils
  • glycogen that provides stored energy for muscle contraction
  • myoglobin that binds oxygen until it is needed for muscle contraction
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23
Q

Alternating Light (I) and Dark (A) bands along the length of the myofibrils give the muscle cell its

A

striated appearance

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24
Q

Each myofibril is composed of

A

numerous sarcomeres

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25
Q

Each sarcomere extends between two dark, vertical lines called

A

Z lines

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26
Q

The light (I) band has a midline interruption (darker area) called

A

Z discs

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27
Q

The dark (A) band has a lighter central area called the

A

H zone

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28
Q

The M Line is the

A

center of the H zone that contains tiny protein rods that hold the adjacent thick filaments together

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29
Q

a sarcomere contains two types of proteins called

A

myofilaments

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30
Q

Thick and dark (A band) are filaments composed of

A

a single protein called myosin

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31
Q

Thin and light (I band) are filaments composed of

A

3 proteins
- actin
- troponin
- tropomyosin

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32
Q

The thick filaments are located in the ___ while the thin filaments are located in the __

A
  • center
  • ends
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33
Q

When a sarcomere shortens

A

the actin filaments slide past the myosin filaments and approach one another, forming hundreds of cross-bridges

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34
Q

These cross-bridges then move like the oars of a boat to

A

pull the thin filaments toward the center of the sarcomere

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35
Q

this movement is called the

A

sliding filament theory of muscle contraction

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36
Q

The sliding filament theory of muscle contraction brings the

A

Z lines closer together and increases the zone of overlap between thin and thick filaments

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37
Q

The myosin filaments contain the

A

ATPase enzyme which breaks down ATP and release energy needed for muscle contraction

38
Q

Troponin and tropomyosin are inhibitory proteins that prevent the

A

sliding of the actin and myosin filaments when the muscle fiber is relaxed

39
Q

The nerve impulses for voluntary movement come from the

A

motor areas of the brain

40
Q

the motor areas of the brain generate

A

motor impulses

41
Q

what do the motor impulses travel along

A

motor nerves

42
Q

after motor nerves

A

motor neurons in the spinal chord

43
Q

motor neurons carry the impulses to the

A

muscles and cause them to contract

44
Q

what is a motor unit

A

a single motor neuron and all the skeletal muscle cells it stimulates constitute a motor unit

45
Q

each motor neuron has a long extension called an

A

axon

46
Q

An axon reaches the muscle and branches into a number of

A

axon terminals

47
Q

the axon terminals form

A

junctions with the sarcolemma of a different muscle cell

48
Q

The junctions that contain vesicles filled with a chemical are called

A

Neuromuscular junctions

49
Q

What is the chemical in the vesicles called

A

nuerotransmitter

50
Q

What is the specific neurotransmitter that stimulates skeletal muscle cells

A

Acetylcholine

51
Q

What is the point where the axon terminal of a motor neuron contacts the sarcolemma of a muscle cell

A

neuromuscular junction

52
Q

The axon terminal contains presynaptic vesicles containing a chemical called

A

neurotransmitter acetylcholine

53
Q

the sarcolemma of the muscle fibers contain

A

receptor sites for acetylcholine

54
Q

At the synapse the synaptic cleft is

A

the tiny space between the axon terminal and the sarcolemma

55
Q

events at the neuromuscular junctions

A
  1. motor impulse
  2. calcium channels open
  3. calcium stimulates the release of acetylcholine
  4. sarcolemma becomes more permeable to sodium ions
  5. generates a current called action potential
  6. a single nerve impulse produces only one contraction
56
Q

what happens in event 1

A

contraction begins when a motor impulse arrives at the axon terminal

57
Q

what happens in event 2

A

calcium channels open and the calcium enters the axon terminal

58
Q

what happens in event 3

A

calcium stimulates the release of acetylcholine from presynaptic vesicles. Acetylcholine crosses the synaptic cleft and binds to receptors in the sarcolemma of the muscle fiber

59
Q

what happens in event 4 (depolarization)

A

if enough acetylcholine is released, the sarcolemma becomes more permeable to sodium ions that rush into the muscle cells and diffuse potassium ions
- the imbalance gives the cell excessive positive sodium ions

60
Q

what happens in event 5

A

action potential if generated and travels over the sarcolemma conducting electrical impulse resulting in the contraction of the muscle

61
Q

when acetylcholine is broken down by acetylcholinesterase in event 5 what occurs

A

repolarization

62
Q

what happens in event 6

A

a single nerve impulse produces only one contraction. Until one Is over the next one cannot start

63
Q

depolarization is followed by repolarization which involves

A

the outflow of potassium ions that will restore positive charge to the outside of the sarcolemma

64
Q

AcetylCholinesterase enzyme in the sarcolemma

A

inactivates acetylcholine and in the absence of further impulses, the muscle fiber will relax and return to its original length

65
Q

Graded responses are produced in 2 ways

A
  1. by changing frequency
  2. by changing the number of muscle cells being stimulated
66
Q

what is an example of changing the frequency of muscle stimulation

A

muscle twitches, Tetanus

67
Q

what is an example of changing the number of muscle cells being stimulated at a time

A

stronger muscle contraction

68
Q

ATP is the

A

primary source of energy and is not stored in large amounts in muscle fibers

69
Q

Secondary sources of energy are

A

Creatin PO4 and Glycgoen

70
Q

Creatine PO4

A

an energy-transferring molecule; the energy released by the break down of creatine is used to synthesize more ATP

71
Q

Glycogen

A

the most abundant source of ATP
when energy is needed for sustained contractions it is first broken down to glucose and then ATP

72
Q

aerobic metabolism

A

oxygen is present

73
Q

anaerobic metabolism

A

oxygen is not present

74
Q

muscles have 2 sources of oxygen

A
  1. hemoglobin
  2. myoglobin
75
Q

Hemoglobin

A

circulating blood brings a continuous supply of oxygen carried by the protein hemoglobin present in the red blood cells

76
Q

myoglobin

A

muscle fibers carry a protein called myoglobin which stores some oxygen

77
Q

what are the 3 pathways for ATP generation

A
  1. aerobic respiration
  2. anaerobic glycolysis
  3. direct phosphorylation
78
Q

aerobic respiration (Kreb’s cycle)

A
  • occurs in mitochondria
  • very efficient yields 32 ATP
  • slow
  • requires lots of oxygen during strenuous activty
79
Q

Anaerobic glycolysis

A
  • occurs in the cytoplasm
  • glucose breaks down to pyruvic acid and produces 2 ATP molecules
  • pyruvic acid is converted to lactic acid
  • 2 1/2 times faster
80
Q

lactic acid accumulation produces severe

A

muscle fatigue and soreness

81
Q

direct phosphorylation

A
  • it can regenerate ATP by transferring its phosphate to ADP
  • generates ATP very rapidly but it supplies only for 8 seconds
82
Q

creatine phosphate is rebuilt when a muscle is

A

resting by transferring a phosphate group from ATP to creatine

83
Q

what is oxygen debt (deficit)

A

in spite of the increase in respiratory rate, muscle fibers literally run out of oxygen

84
Q

the intermediate lactic acid produced in an anaerobic process

A

lowers the pH of the intracellular fluid within the muscle cell which contributes to muscle fatigue

85
Q

muscle tone is a steady or

A

constant state of partial contraction in a resting muscle

86
Q

hypertrophy

A

muscle increases in size due to exercise

87
Q

atrophy

A

muscle decreases in size

88
Q

what are the types of muscle contractions

A
  1. isotonic contractions
  2. isometric contractions
89
Q

isotonic contraction

A
  • muscle contracts and brings movement
  • tone or tension remains the same
  • examples include jogging, swimming, weight lifting etc
90
Q

isometric contractions

A
  • involves contraction without movement
  • tension in muscles increases
  • examples include pushing against the wall with bent elbows, both hands pushing equally

A&P Module 3 (7 decks)

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