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anatomy and physiology 1 > Muscular System > Flashcards

Muscular System Flashcards

1
Q

special characteristics of muscle tissue

A

excitability (irritability/responsiveness)
contractility
extensibility
elasticity

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2
Q

function of skeletal muscles

A 
producing movement
maintain posture/body position
stabilize joints
generate heat
protect abdominal organs
link the body and the external environment  (manipulation)
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3
Q

function of cardiac muscles

A

pump blood

involuntary contractions of the heart

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4
Q

functions of smooth muscles

A

peristalsis-alternating contractions and relaxations that mix and squeeze substances thru the lumen of hollow organs
propulsion of substances

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5
Q

is each skeletal muscle an organ

A

yes
it is made up of several different tissues (skeletal muscle fibers, bv, nerve fibers, connective tissue) working together to perform a common function

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6
Q

endomysium

A

fine sheath of areolar connective tissue

reticular fibers that surround each muscle fiber

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7
Q

perimysium

A

fibrous connective tissue that surrounds groups of muscle fibers called fascicles

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8
Q

epimysium

A

overcoat of dense irregular connective tissue that surrounds the entire muscle

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9
Q

origin

A

the muscles attachment to the immovable/less moveable bone

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10
Q

insertion

A

the attachment of the muscle to the moveable bone

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11
Q

sarcolemma

A

plasma membrane of muscle

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12
Q

sarcoplasm

A

cytoplasm of muscle cells that usually contains large amounts of glycosomes and myoglobin

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13
Q

glycosomes

A

granules of stored glycogen that provide glucose during muscle cell activity

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14
Q

myoglobin

A

red pigment that stores and binds oxygen

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15
Q

what attaches muscles to bones

A

tendons

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16
Q

sarcoplasmic reticulum

A

elaborate smooth endoplasmic reticulum w interconnecting tubules surrounding each myofibril
functions in the regulation and storage of intracellular calcium levels

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17
Q

excitability

A

irritability/responsiveness

the ability to receive and respond to a stimuli- any change in the inside/outside envt

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18
Q

contractility

A

the ability to shorten forcibly when adequately stimulated

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19
Q

extensibility

A

the ability to extend or stretch even beyond resting length when relaxed

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20
Q

elasticity

A

ability of a muscle to recoil and resume its resting length after stretching

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21
Q

location of skeletal muscles

A

attached to bones/skin/other muscles

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22
Q

location of cardiac muscle

A

in the heart

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23
Q

location of smooth muscle

A

hollow visceral organs and blood vessels

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24
Q

structure of skeletal muscle

A

multinucleated
long
striated
cylindrical

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25
Q

structure of cardiac muscle

A 
uninucleated
short 
branching
striated
cylindrical
intercalated disks- gap junx
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26
Q

structure of smooth muscle

A

uninucleated
long
spindle like
gap junx

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27
Q

ctrl of skeletal muscle

A

voluntary

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28
Q

ctrl of cardiac muscle

A

involuntary

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29
Q

ctrl of smooth muscle

A

involuntary

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30
Q

reproduction of skeletal?

A

no

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31
Q

reproduction of cardiac?

A

minimal

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32
Q

reproduction of smooth?

A

yes

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33
Q

myofibrils

A 
rodlike contractile elements that make up most of the muscle volume (hundreds to thousands in a single fiber) 
has striations (perfectly aligned repeating series of dark A bands, and light I bands)
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34
Q

T-tubules

A

continuation of sarcolemma that protrudes deep into the cell forming an elongated tube that increases muscle fibers surface area, and conducts nerve impulses to the deepest regions of the muscle cell
allows every sarcomere to open voltage sensor proteins which release calcuim from adj SR terminal cisternae

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35
Q

triad

A

the relationship that occurs bt the paired SR terminal cisternae and T-tubule

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36
Q

T-tubule proteins act as

A

voltage sensors, so they can change shape when there is an electrical impulse to to open calcium ion channels on the SR

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37
Q

smallest contractile unit of Skeletal and cardiac muscles is

A

Sarcomere- located between two successive Z disks

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38
Q

z-disk

A

coin shaped sheet of proteins that anchors thin filament

39
Q

m-line

A

middle line that anchors the myosin

40
Q

A-band

A

dark
contains thick and thin filaments
actin+myosin

41
Q

I-band

A

light
only thin filaments
actin

42
Q

H-zone

A

only thick filaments

myosin

43
Q

3 filaments in a sarcomere

A

thick filament
thin filament
elastic filament

44
Q

thick filament

A

myosin

extends entire length of A band

45
Q

thin filament

A

actin, troponin, tropomyosin

extends across the I band and partially into the A band

46
Q

elastic filament

A

made of titin
extends from Z disk to M line and holds thick filaments in place
assists muscle cell to spring back after stretching

47
Q

sliding filament mechanism

A

proposes that changes in overall fiber length are directly associated with changes in overlap between the 2 sets of filaments
H-zone disappears as actin and myosin slide over eachother in contraction

48
Q

neuromuscular junx: AXON TERMINAL

A

the branched end of a neurons axon that contains synaptic vesicles w the neurotransmitter ACH

49
Q

neuromuscular junx: SYNAPTIC CLEFT

A

small space separating axonal terminals with the motor end plate of the muscle fiber

50
Q

neuromuscular junx: MOTOR END PLATE

A

specific part of the sarcolemma looking towards the axon terminal; contains ACH receptors

51
Q

first thing to happen at the neuromuscular junx

A

nerve impulse reaches the axon terminal and travels down the T-tubules

52
Q

second thing to happen at the neuromuscular junx

A

voltage gated calcium channels on the SR open and release calcium down the electrochemical gradient

53
Q

3rd thing to happen at the neuromuscular junx

A

calcium entry causes ACH (neurotransmitter) to be released via exocytosis and diffuse across the synaptic cleft

54
Q

4th thing to happen at neuromuscular junx

A

2 ACH bind to the ACH receptors on the NaK chemical gated channels at the motor end plate

55
Q

neurotransmitter

A

chemical that is released from a nerve cell which thereby transmits an impulse from a nerve cell to another nerve, muscle, organ, or tissue

56
Q

at the skeletal muscle fiber level ACH the neurotransmitter

A

allows the NaK gates to open and begin depolarization of the sarcolemma

57
Q

neurotransmitter used in skeletal muscle contraction

A

Acetylcholine

58
Q

termination of ACH caused by

A

acetylcholinesterase
an enzyme in the synaptic cleft that breaks down ACH into acetic acid and choline
prevents continued contraction

59
Q

resting potential

A

the potential difference (-70mv) across the membrane of a resting neuron/skeletal muscle
the outside (extracellular face) is positive
the inside face is negative

60
Q

resting potential is generated by

A

difference in concentration of Na, K, Cl, proteins, and anions

61
Q

sodium is the major

A

extracellular ion

62
Q

potassium is the major

A

intracellular ion

63
Q

depolarization

A

when Na+ enters the cell causing it to become more positive (or less negative)
change from -70mv until cell reaches -55mv threshold

64
Q

at -55mv

A

the Na+ voltage gated channels open and only sodium floods in until sarcolemma reaches +30mv

65
Q

at +30mv

A

an action potential is created
sodium gates close
potassium gates open to let K+ out
repolarization begins

66
Q

repolarization

A

Na+ voltage gated channels close
K+ voltage gated channels open and K+ diffuses out
electrical polarity -70mv becomes restored in the sarcolemma

67
Q

action potential is started when

A

depolarization brings sarcolemma to -55mv

Na+ voltage gated channels open only Na comes in

68
Q

action potential formed when

A

cell reaches +30mv

carried down T-tubules

69
Q

action potential causes the opening of

A

Ca++ voltage gated channels

the calcium binds to troponin

70
Q

the binding of calcium to troponin causes

A

troponin to move tropomyn exposing the myosin binding sites

71
Q

action potential is all or nothing because

A

either threshold is reached or not, no in between

72
Q

how is electrical imbalance restored

A

thru repolarization

73
Q

ionic imbalance is restored thru

A

the sodium potassium pump
3 Na+ out
2 K+ in

74
Q

absolute refractory period

A

part of the refractory period where the Na+ channel is resetting and another AP cannot be generated

75
Q

relative refractory period

A

part of the refractory period where as long as it is under -55mv a second action potential can be generated

76
Q

importance of calcium in muscle contraction

A

binds to troponin removing the tropomyosin blockage
cross bridge formation
working powerstroke-myosin head piviots and pulls actin filament towards m-line

77
Q

calcium is stored in the

A

sarcoplasmic reticulum

78
Q

when nervous system stimulation ceases calcium

A

is actively pumped back into the extracellular fluid for storage and later use

79
Q

importance of ATP in muscle contraction

A

attaches to myosin head
allows detaching of cross bridge
becomes hydrolzyed to ADP and Pi and cocks myosin head back to high energy state

80
Q

motor unit

A

motor neuron and all the muscle fibers it supplies (nerve/muscle functional unit)
has muscle fibers spread thru the muscle insulated by endomysium
so contraction of a single motor unit cause weak contraction of the whole muscle

81
Q

muscle twitch

A

the response of a musce to a single action potential of its motor neuron

82
Q

muscle tone

A

constant slightly contracted state of all muscles due to spinal reflexes that activate groups of motor units alternately in response to input from stretch receptors in muscles
keeps muscles healthy, firm, ready to respond

83
Q

twitch myogram: LATENT

A

1st few ms after stimulation from depolarization to calcium release 2ms

84
Q

twitch myogram: CONTRACT

A

cross bridges form
muscle shortens
10-100 ms

85
Q

twitch myogram: RELAX

A

calcium is reabsorbed
muscle tension goes to zero
10-100ms

86
Q

3 ways ATP can regenerate

A

interaction w creatine phosphate
aerobic respiration
lactic acid fermentation

87
Q

interaction of ADP w creatine phosphate

A

1atp per 1cp

unique high energy molc stored in muscles that supplies ATP in exercising until muscles metab adj itself to the demand

88
Q

aerobic resp

A

95%
32atp
glucose-pyruvic acid-krebs cycle-ETC
uses glucose 1st 30 min then fat for energy

89
Q

lactic acid fermentation

A

2 atp
glucose-pyruvate-lactic acid-blood-fuel-pyruvic acid
used in anaerobic resp when bulging muscles compress bv and impair 02 delivery

90
Q

pain causing discontinuation of exercise is

A

from lactic acid build up in liver

91
Q

only 40% of energy released in muscle activity is

A

useful as work

remaining 60% given off as heat

92
Q

differences of smooth muscle

A 
thin short spindle shaped fibers
connective tissue is only endomysium
less developed SR
no myofibrils/ T-tubules
actin and myosin present but not arranged in sarcomere
gap junctions
calcium binds to CALMODULIN which activates MYOSIN KINASE which phosphorylates myosin, activating myosin ATPases that provide energy for contraction
contractions/relaxations take longer
93
Q

similarities bt skeletal and smooth muscle

A

actin and myosin in sliding mechanism
CALCIUM IS FINAL TRIGGER
ATP IS ENERGY SOURCE

94
Q

differences of cardiac muscle

A

behaves as a functional synctium-intercalated disks
cells are mechanically, chemically, electrically connected
autorhythmic cells-self excitable and can initiate own depol
use Ca influx rather than Na to create AP
more mitochondria
ability to switch to whatever nutrient supply is readily available (fat drops on top)
20% Ca comes from ecf
danger of lack of o2 not nutrients
slower

anatomy and physiology 1 (8 decks)

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