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physiology > test 3 ch 12 > Flashcards

test 3 ch 12 Flashcards

1
Q

what are the functions of muscle?

A

body movement, posture, protection and support, elimination of waste, heat production

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2
Q

the anatomy of the skeletal muscle

A

> deep fascia
epimysium
perimysium surrounds fascicles
fascicles contain muscle fibers
endomysium surrounds muscle fibers (aka muscle cell)
muscle fibers contains myofibrils
myofibrils contain bundles of myofilaments
myofilaments
actin (thin)
myosin (thick)

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3
Q

increase the angle at a joint

A

extensor

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4
Q

decreases the angle at a joint

A

flexor

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5
Q

moves limb away from midline of the body

A

abductor

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6
Q

moves limb towards the midline of the body

A

adductor

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7
Q

moves insertion upward

A

levator

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8
Q

moves insertion downward

A

depressor

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9
Q

rotates a bone along its axis

A

rotator

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10
Q

constricts an opening

A

sphincter

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11
Q

excitable plasma membrane of the muscle cell that propagates the AP

A

sarcolemma

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12
Q

an invagination of the sarcolemma that travels across the muscle cell and propagates the AP.; makes up part of the triad

A

T-tubule (transverse tubule)

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13
Q

storage facility for Ca++ and makes up the terminal cisternae of the triad

A

sarcoplasmic reticulum

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14
Q

what are two myofilaments?

A

actine and myosin

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15
Q

myofilament that is double stranded and is wrapped by tropomyosin and troponin (“gatekeeper”) complex, has active binding sites for the other myofilament

A

actin

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16
Q

myofilament that is double headed and acts ATPase and forms crossbridges with the other myofilament, has two binding sites (one for other myofilament and the other for ATP)

A

myosin

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17
Q

contains myofilaments that are arranged in sarcomeres

A

myofibrils

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18
Q

ends of sarcomere

A

Z discs

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19
Q

runs the entire length of thick filament and contains thin filament as well

A

A band

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20
Q

middle of sarcomere; serves as attachment site for thick filaments

A

M line

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21
Q

what are all parts of a sarcomere?

A

z discs (ends), a band (entire length of filament), i band, m line (middle), titin

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22
Q

single motor neuron and the muscle fibers it innervates

A

motor unit

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23
Q

the location where the synaptic knob of a neuron synapses with a muscle cell

A

neuromuscular junction (NMJ)

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24
Q

neurotransmitter released at NMJ; responsible for muscle contraction

A

ACh

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25
enzyme in NMJ that breaks apart ACh
acetylcholinesterase
26
what is the resting membrane potential of a skeletal muscle cell?
-70mV to -90mV
27
what is the threshold for muscle cell?
-65mV to -70mV
28
describe the events at the neuromuscular junction (NMJ)
a. action potential reaches synaptic knob b. Ca++ voltage gates open and Ca++ flows into the knob c. Ca++ stimulates the vesicles filled with ACh to meld with membrane and release ACh into the cleft d. ACh diffuses across the cleft and binds to ACh receptors at motor end plate e. chemical-gated Na+ channels open and Na+ rushes in causing depolarization, if threshold is reached then AP is produced and propagated along the sarcolemma and down the tubules
29
describe the events of the excitation-contraction coupling (sliding filament)
a. action potential triggers Ca++ voltage gates in the SR to open, allowing Ca++ into the sarcoplasm b. Ca++ binds to troponin causing the tropomyosin complex to move and expose the myosin binding site found on actin c. myosin head attaches to actin to form a “crossbridge” d. power stroke occurs when ADP+P are released from the head e. new ATP binds to myosin head allowing it to detach f. ATP splits to ADP+P releasing energy that allows the myosin head to re-cock and reattach to new actin molecule g. cycle repeats as long as there are action potentials, Ca++, and ATP
30
what is rigor mortis?
the stiffening of the body that begins a couple hours after death and lasts for about two days
31
what is the physiology behind rigor mortis as it relates to the sliding filament theory?
rigor mortis occurs because the actin doesn't detach which is caused by the ATP lacking in dead cells and without ATP the active transport pumps needed to move Ca++ from the cytoplasm into the sarcoplasmic reticulum; as a result Ca++ remains attached to troponin so that tropomyosin cannot inhibit cross-bridge formation, after a while the myosin heads cannot release from actin because they cannot bind to a new ATP
32
at rest, where does skeletal muscle obtain most of its energy?
from aerobic metabolism of fatty acids
33
describe the phosphagen system
ATP → ADP + P - phosphocreatine + ADP → ATP + creatine (phosphocreatine can only supply energy in skeletal muscle) - 10 to 15 seconds of energy during maximum exertion - formed in the Cytosol; not dependent on oxygen
34
2 ATP and pyruvate - 50 to 60 seconds of energy during maximum exertion - Glucose - Formed in the Cytosol
glycolysis
35
34 ATP for every glucose - a lot more ATP from fatty acids - 5 to 6 minutes of energy during maximum exertion (may be greater dependent on contributing nutrients) - Oxygen + (Glucose, pyruvate, fatty acids, amino acids) - Formed in the Mitochondrion
aerobic cellular respiration
36
contraction _____ is related to the size of a muscle
power
37
contraction _____ is related to the slow or fast myosin ATPase variant
speed
38
provide ATP through aerobic cellular respiration
oxidative fibers
39
fibers of small diameter, contain slow myosin ATPase, contractions are slower and less powerful, long duration with fatigue, large amounts of myoglobin
slow oxidative fibers (type I fibers)
40
least numerous of skeletal muscle fibers, contain fast myosin ATPase, produce fast, powerful contractions, slightly less capillary support causes less nutrient and oxygen availability leading to medium duration of activity
fast oxidative/glycolytic fibers
41
provide ATP through anaerobic cellular resipiration
glycolytic fibers
42
fibers the have extensive capillary work, large numbers of mitochondria, large supply of myoglobin, and considered fatigue resistant
characteristics of oxidative fibers
43
trunk and lower limb muscles, maintains posture or running a marathon, medium duration, moderate activity like walking or biking
all examples of oxidative fibers
44
fibers that have fewer mitochondria, small amounts of myoglobin, appear white, large glycogen reserves, tire easily (fatigable) and short duration of sustained activity
characteristics of glycolytic fibers
45
most prevalent skeletal muscle fiber type, largest diameter, contain fast myosin ATPase, provide power and speed, short duration, minimal myoglobin and mitochondria
fast glycolytic fibers
46
upper/lower limn muscles, short duration, intense activity such as sprinting or weightlifting
examples of glycolytic fibers
47
latent period, contraction period, or relaxation period of a muscle
muscle twitch
48
change in the number of motor units activated to maintain work, more muscle tension is directly related to more motor units activated
recruitment
49
summation of contractile forces due to muscle stimulation occurring before complete relaxation of muscle fiber, calcium accumulates in sarcoplasm
wave summation (temporal summation/treppe)
50
past wave summation, muscle fiber is stimulated ~ 25-35 stimuli per second, allows even less relaxation
incomplete tetanus
51
~40-60 stimuli per second, no relaxation allowed, can lead to fatigue
complete tetanus
52
generated by involuntary somatic innervation
muscle tone
53
tension is produced but muscle length does not chane
isometric contraction
54
contraction with muscle shortening
isotonic (concentration) contraction
55
contraction with muscle lengthening
eccentric contraction
56
weak contraction
shortened
57
minimal contraction
stretched
58
maximal contraction
resting
59
increase in muscle fiber size
hypertrophy
60
decrease in muscle fiber size
atrophy
61
increase in muscle fiber numbers
hyperplasia
62
replace muscle tissue with fibrotic or scar tissue
fibrosis
63
basic monosynaptic stretch reflex (knee-jerk reflex) process
1. Stretch on a muscle stretches spindle fibers. 2. This activates sensory neuron. 3. Sensory neuron activates alpha motor neuron. 4. Motor neuron stimulates extrafusal muscle fiber to contract. 5. Stretch on spindle is reduced.
64
describe effects of aging
* Loss of muscle mass – initial onset mid 30’s but progressively worse after 50’s * Smaller muscle fiber diameter * Decreased muscle fiber number * Reduced density of blood capillaries * Decreased fine motor control * Decreased muscle strength and endurance * Decreased ability to repair * Decreased muscle elasticity – tissue replaced by adipose or fibrous connective tissue
65
describe cardiac muscle tissue
* Branched, striated muscle fibers * Intercalated discs – provide quick communication * 1 or 2 nuclei, involuntary innervation * Many mitochondria, aerobic cellular respiration * Can contract without neural stimulation; pacemaker cells initiate action potentials
66
describe smooth muscle tissue
* Retains mitotic ability * Found in the cardiovascular, respiratory, digestive, urinary, and female reproductive systems * Spindle shaped cells, have actin and myosin but no striations * Involuntary innervation, single nuclei * Ca++ binds to calmodulin in the sarcoplasm; most Ca++ comes from extracellular fluid * Prolonged duration of contraction

physiology (14 decks)

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