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anatomy > muscle terms > Flashcards

muscle terms Flashcards

1
Q

what does motor mean

A

term used in the nervous system to describe a neuron that controls a muscle

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2
Q

epimysium

A

out layer membrane that covers the whole muscle

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3
Q

perimysium

A

covering for the fascicles (10-100 muscle fibers that are in bundles) of the muscle fiber

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4
Q

fascicle

A

bundle of muscle fibers

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5
Q

endomysium

A

is inside each fascicle and separates each individual muscle fiber

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6
Q

sarcolemma

A

plasma membrane of muscle cell

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7
Q

tranverse (t) tubules

A

infoldings inside the sarcolemma that circle around myofibrils, and action potential travels along it to spread throughout the muscle

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8
Q

sarcoplasm

A

cytoplasm in the muscle fiber containing glycogen and myoglobin

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9
Q

myofibrils

A

bundle of filaments wrapped in sarcoplasmic reticulum, inside the sarcoplasm. is the striated contractile organelle

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10
Q

sarcoplasmic reticulum

A

membranes that wrap around the myofibrils –> net pattern

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11
Q

terminal cisternae

A

sac like structures in the sarcoplasm reticulum that stores and releases calcium

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12
Q

what are the 2 types of myofilaments

A

actin (thin filaments) and myosin (dark filaments)

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13
Q

sarcomere

A

“compartments” that contain myofilaments and that is responsible for contracting

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14
Q

A band

A

spans the entire dark bands (thick filaments) area –> includes overlap

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15
Q

I band

A

area with only thin filaments (light bands)

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16
Q

H zone

A

area in the center of each band that has thick but no thin (no overlap)

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17
Q

Z line/discs

A

separate one sarcomere from the other and holds the actin in place

18
Q

M line

A

in middle where myosin is held in place

19
Q

what are the 3 proteins in myofibrils

A

contractile (generates force during contraction), regulatory (switch the contraction process off and on), structural (keep thick and thin in their proper alignment)

20
Q

describe what one myosin molecule looks like

A

2 golf clubs twisted together
head is the golf club, the tail is the handles that point towards the M line

21
Q

what do the myosin heads contain

A

2 binding sites (actin and atp)
atp site hydrolyzes the atop to generate energy for muscle contraction

22
Q

describe actin molecule

A

form helix shape with myosin binding sites for myosin heads and contain regulatory proteins

23
Q

what are the 2 regulatory on actin

A

tropomyosin: cover the myosin binding sites
troponin: hold tropomyosin in place and binds calcium and changes shape

24
Q

what are the 2 functions of atp

A

activates myosin head and detaches flexed myosin head from actin

25
Q

axon terminal

A

end bulb filled w vesicles containing neurotransmitters

26
Q

synaptic cleft

A

space between axon terminal and motor end plate

27
Q

motor end plate

A

has receptors for NT and binds them

28
Q

neurotransmitters

A

chemical released from vesicles into synaptic cleft that bind to receptors in the motor end plate that create an electrical signal in the muscle

29
Q

describe what happens during contraction

A
  1. myosin heads have atp binding site that works as an enzyme to hydrolyze atp into adp + p to store energy during contraction cycle + calcium is released into cytoplasm and binds to troponin-tropomyosin and causes them to shift to expose myosin binding sites
  2. energized myosin head attaches to myosin binding site and releases hydrolyzed phosphate group (cross bridge is formed)
  3. myosin head flexes and creates 45 deg angle. as it changes, it pulls the actin towards the center of the sarcomere and does a power stroke (comes from stored energy in myosin head) + adp +p falls off
  4. myosin head detaches from actin only when another atp binds to it and atp reactivated head and returns it to 90 deg angle
30
Q

what is rigor mortis

A

when cross bridges don’t disconnect due to lack of atp (3hrs after death)

31
Q

describe what happens at a synapse

A
  1. act pot arrives at the synaptic end bulb
  2. the depolarizing phase of the impulse opens the voltage Ca2+ gates that are in the membrane of the syn. end bulb –> Ca2+ flows in
  3. Ca2+ in the cytoplasm triggers the fusion of the vesivle membrane with the cell membrane –> causing release of NT into the synaptic cleft
  4. Nt binds to Nt receptors in the post syn. motor end plate and opens ion gated channels and depolarization creates an act pot in the post syn. muscle
32
Q

isotonic vs isometric contractions

A

isotonic: creates tensions and changes the length causing movement
isometric: creates tensions with no change in length (hold)

33
Q

muscle twitch

A

a single stimulus-contraction-relaxtion cycle in muscle fiber

34
Q

wave summation

A

when many successive stimuli arrive before relaxation -> muscle tension is increased to a maximum (larger than in treppe)

35
Q

complete vs incomplete tetany

A

incomplete: quivering of muscle
complete: smooth continuous contraction with no relaxation (rapid delivery of stimuli)

36
Q

treppe

A

when a second stimulus occurs after relaxation and continuously causes an increase in muscle response to a maximum

37
Q

recruitment

A

increase in muscle tension due to an increase in the motor units activated

38
Q

motor unit

A

group of muscle fibers controlled by a single motor unit

39
Q

muscle tone

A

tension in relaxed muscle

40
Q

stimulus contraction relaxation cycle

A
41
Q

what factors affect the force of a contraction

A

motor units and recruitment –> the number of muscle fibers activated and the frequency of neural stimulation to the muscle

42
Q

what does the muscle look like at rest (before contraction)

A

myosin heads are activated (in up right position)
atp is hydrolyzed to adp + p
app + p is attached
actin active sites are covered by tryponin and actin + myosin is slightly overlapped
calcium is in cisternae

anatomy (12 decks)

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