The muscular system

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1

Three Types of muscle:

  1. Cardiac - striated - involuntary
  2. Smooth - nonstraited - involuntary
  3. Skeletal - striated - voluntary
2

Describe skeletal muscle:

  • Attached to the body's skeleton
  • Cigar-shaped, multinucleate cells
  • some muscle fibers are nearly 1 foot long
  • striated (stripes)
  • voluntary
  • contract rapidly, tires easily
3

Name the connective tissues that wrap the skeletal muscle from outer to inner:

  1. epimysium - outer connective tissue
  2. perimysium - wraps the fascicle
  3. endomysium - located between the fibers
4

Describe smooth muscle:

  • No striations
  • INVOLUNTARY
  • found in the walls of hollow visceral organs, ie. stomach, bladder
  • spindle-shpaed
  • Two layers - Circular and Longitudinally
  • contracts slow and steady.
5

Describe Cardiac Muscle:

  • only found in the heart
  • striated
  • INVOLUNTARY
  • figure 8 shaped bundles
  • intercalated discs
6

What is the functions of skeletal muscle?

  • produces movement
  • maintains posture and body position
  • stabilizes joints
  • generates heat
  • protects organs
7

What is the functions of smooth muscle?

  • regulates the passage of substances (food, blood, digestive system dumping)
  • activates the arrector pili (goosebumps which are located in every single hair follicle)
8

Sarcolemma

The plasma membrane of the muscle fiber

9

Sarcoplasmic reticulum (SR)

Specialized endoplasmic reticulum of muscle cells

10

Sarcoplasm

The nonfibrillar cytoplasm of a muscle fiber

11

Myofibril

Rodlike bundle of contractile filaments (myofilaments) found in muscle fibers (cells)

12

Myofilament

Filament that constitutes myofibrils.

consists of two types: actin and myosin

13

Myocardium

Layer of the heart wall composed of cardiac muscle

14

Segment of a muscle fiber

Look in notes and be able to label the parts

15

The two prominent proteins in the myofibril

1. Thin ACTIN filament

2. Thick MYOSIN filament

16

Define Thin ACTIN filament:

A contractile protein of muscle

17

Define thick MYOSIN filament

One of the principal contractile proteins found in muscle

18

One single sarcomere is always found between what?

Z disc to Z disc within the H zone

19

Myofibril or fibril

A complex organelle composed of bundles of myofilament.....

see pictures and labels in power point

20

Where is the sarcolemma located?

directly under the epimysium

21

Myosin tails

arranged to point towards the center of the sarcomere.

22

Myosin heads

arranged to point to the sides of the myofilament band

23

The function of the myocin head:

It attaches to actin and pulls across , ATP is activated to contraction then they release after contraction....returning to relaxed state.

24

What encases each individual myofibril?

Sarcoplasmic reticulum

25

Stimulation and contraction steps:

  1. Excitability
  2. contractility
  3. extensibility
  4. elasticity
26

Contraction excitability

Ability to receive and respond to a stimulus (receives signal and responds)

27

Contraction contractility:

Ability to shorten (forcibly) when adequately stimulated...ie flex of arm, write with a pencil.

28

Contraction extensibility:

Ability of muscles to be stretched

29

Contraction elasticity

Ability to recoil and resume resting after being stretched.

30

Antagonistic muscle

  1. muscle that reverses, or opposed, the action of another muscle
  2. Hormone that opposes the action of another hormone
31

How many nerves come off the brain?

12

32

Nerves never cross from

one side of the body to the other

33

Motor neuron cell body is located ________________

inside the spinal cord

34

synaptic cleft

Gap between the nerve and muscle

35

muscle contractions are caused by

lack of calcium

36

muscle cramps are caused by

lack of K+ Potasium

37

The nerve does not physically touch the muscle due to the ________________________

synaptic cleft

38

The seven steps to action potential

  1. Action potential activates
  2. Acetylcholine physically attaches to calcium channels causing them to open into the axon terminal
  3. Acetylcholine is released and exits the cell
  4. Acetylcholine goes across cleft - cation channels
  5. Channels open and calcium ions enter
  6. Potassium ions exit
  7. Action potential happens at maximum potential capacity

PLEASE VERIFY THESE SEVEN STEPS BY WATCHING THE VIDEO SHOWN IN CLASS.......DON'T RELY ON MY INTERPRETATION

39

______________________physically attaches to an opening in a channel and without this the channel will NOT open

Acetylcholine

40

Involved in action potential

Acetylcholine

Calcium

K+

Na

41

Nerve impulses are also known as

action potentials

42

Define a whole muscle response known as a twitch

Single muscle response in which muscle contracts and then fully relaxes

43

Define a whole muscle response known as a tetanus

Sustained muscle contraction caused by repeated stimulation (such as lock jaw - no relaxation)

44

Define a whole muscle response known as tonus

Normal, continuous state of partial muscle contraction (breathing)

45

Muscle fatigue due to 02 deficit:

  • Unable to contract even though it is still being stimulated.
  • True muscle fatigue
46

Define true muscle fatigue

When the muscle quits entirely, rarely occurs, more common in marathon runners

47

Oxygen deficit

Occurs during prolonged muscle activity

Must be paid back (example would be rapid and deep breathing)

48

Isotonic contractions

  • Same TONE
  • Myofilaments are sliding normally
  • Examples: bending the knee, rotating the arms, smiling
49

Isometric contractions

  • Same MEASUREMENT
  • Myofilaments are spinning their wheels not going anywhere
  • Example - trying to lift a 400 lb dresser alone, pushing a car while the break is on
50

Effect of aerobic exercise on muscles

  • endurance
  • stronger more flexible muscles
  • greater resistance to fatigue
  • Examples: jogging, biking, zumba
51

Effect of resistance exercise on muscles.

  • Isometric
  • forcing muscles to contract and forcefully pushed as far to the limit as possible.
  • requires little time and little equipment
  • your body is the equipment
  • Example: Body building
52

Muscle terms

  • origin
  • insertion
  • prime mover
  • synergist
  • antagonist
53

__________________attaches to the more stationary bone wereas ___________________refers to the more moveable bone.

Origin

Insertion

54

Most movement is accomplished trhough the cooperation of groups of muscles. However, one ______________ or _________________ is generally responsible for most of the movement

chief muscle

prime mover

55

Synergist muscle

A muscle that helps the prime mover

56

Antagonists

Help return the body parts moved by synergists and prime movers back to their original positions

57

When flexing your forearm and then extending the forearm the following work together

The biceps brachii contracts to flex the forearm. To extend the forearm, the triceps contract while the biceps brachii relaxes.

58

Prime movers

Muscle mainly responsible for a given movement

59

Antagonists

muscles that oppose or reverse a movement

muscle that opposes action of prime mover

60

Synergists

Help prime movers by producing the same movement or by reducing undesirable movement.

61

Fixators

  • specialized synergists
  • hold bones still or stabilize the orgin of a prime mover so all the tension can be used to move the insertion bone.
62

Arrangement of a circular fascicle:

Concentric rings - ex....eyes and mouth

63

Arrangement of a Convergent fascicle

Converge toward a single insertion tendon

ex....pectoralis major

64

Arrangement of a Parallel fascicle

Run parallel to the long axis of the muscle

ex....sartorius, fusiform ex biceps

65

Arrangement of a Pennate fascicle

Attach obliquely to a central tendon

Unipennate - extensor digitorum longus

Bipennate - rectus femoris

Multipennate - deltoid

66

Requirements for muscle contraction

ATP molecules and calcium ions

67

Insertion

where muscle attaches to bone that moves on contraction

68

Flexion

movement that makes joint angle smaller

69

tricep

muscle in posterior upper arm that is antagonist in flexion of lower arm

70

motion is voluntary in this muscle

skeletal

71

pectoral "pecs"

chest muscles

72

extension

movement that makes joint angle larger

73

tendons

connective tissue that attaches muscle to bone

74

motor unit

combination of motor neuron and muscle fiber

75

myosin

protein making up thinck filaments of sarcomere

76

threshold stimulus

minimum stimulus needed to cause muscle fiber to contract

77

biceps

anterior upper arm muscle

78

functions of the muscular system

movement, posture, heat production

79

sliding filament model

describes/explains muscle contraction

80

isometric contraction

muscle tenses and produces no movement

81

origin

where muscle attaches to stationary bone

82

supination

palms forward

83

appears striated

skeletal muscle

84

fiber

muscle cells

85

bicep

muscle in anterior upper arm that is prime mover in flexion of lower arm

86

bursae

fluid filled sac between tendon and bone

87

latissimus dorsi "lats"

back muscle

88

triceps

posterior upper arm muscle

89

fatigue

caused by repeated muscle contraction without rest

90

smooth muscles

found in walls of digestive tract/blood vessels

91

sarcomere

basic unit of muscle

92

motor neuron

specialized nerve cell that stimulates a muscle fiber

93

body

main part of the muscle

94

deltoid "delts"

shoulder muscle

95

synergist

muscle that helps prime mover

96

prime mover

muscle mainly responsible for a given movement

97

prime mover must do this to produce motion

contract

98

tendon sheath

fluid filled tube enclosing some tendons

99

lactic acid

build up in muscles during rapid exercise

100

neuromuscular junction

point of contact between motor neuron and muscle fiber

101

actin

protein making up thin filaments of sarcomere

102

motion is involuntary in this muscle

cardiac muscle, smooth muscle

103

isotonic contraction

muscle shortens and produces movement

104

antagonist must do this to allow motion

relax

105

contains intercalcated disks

cardiac muscle

106

The "tug of war" refers to pairs of muscles working in opposition...

antagonists

107

lactic acid is often produces with this kind of exercise

anaerobic