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DAT Biology > Muscular System > Flashcards

Muscular System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

functions

A
  1. body movement
  2. stabilization of body position
  3. substance movement throughout body (pumping force in veins/lymp)
  4. generating heat
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2
Q

muscle types

A

smooth, cardiac, and skeletal muscle

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3
Q

smooth muscle

A
  • present in organs, airways, blood vesseks
  • involuntary
  • 1 nucleus per cell
  • not striated
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4
Q

cardiac muscle

A
  • present in heart
  • involuntary
  • 1 nucleus per cell
  • striated (contains sarcomere)
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5
Q

skeletal muscle

A
  • present around bone
  • voluntary
  • many nuclei per cell
  • striated (contain sarcomere)
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6
Q

skeletal anatomy

A

muscle > muscle fascicles > muscle fibers (muscle cells) > myofibrils (contractile protein)

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7
Q

sarcolemma

skeletal M. anatomy

A

cell membrane

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8
Q

sarcoplasm

skeletal M. anatomy

A

cytoplasm of m. cells

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9
Q

protective sheaths

skeletal M. anatomy

A
  • epimysium (covers muscle)
  • perimysium (covers muscle fasicles)
  • endomysium (covers muscle fibers)
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10
Q

sarcomere

A

functional unit inside myofibrils, contains thin (actin) and thick myosin filaments that cause contractions

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11
Q

actin

A
  • thin
  • Z line/ I band
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12
Q

myosin

A
  • thick
  • A band/ H zone
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13
Q

sarcoplasmic reticulum (ER)

A

surrounds many sarcomeres arranged in fibers
* releases stored calcium into sarcoplasm when muscle cell is depolarized

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14
Q

sarcolemma

A

wraps SR, sarcomeres, to form muscle
* contains T tubule –> makes AP faster

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15
Q

Z line

A
  • ends of sarcomere
  • thin actin filaments branch from Z line to middle of sarcomere
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16
Q

M line

A
  • midpoints
  • thick myosin filaments branch from M lines towards Z lines
17
Q

I band

A

only actin filaments

18
Q

A band

A
  • actin and myosin overlap
  • does NOT change size during contraction
19
Q

H zone

A

only myosin present

20
Q

muscle contraction stimulation

A
  1. AP reaches motor end plate
  2. Ach is released at neuromuscular junction
  3. Ach bind to ligand-gated Na+ receptors –> Na+ enters cell = graded potential created
  4. graded potential trigger voltage gated Na+ channels to open
    * can produce AP on muscles IF stimulus is large enough
    * AP travels to T-tubules and causes Ca++ release
21
Q

cross bridge cycling

A
  1. initially actin/myosin unbound because tropomyosin blocks binding site on actin
  2. neuron sends signal to muscle at neuromuscular synapse, releasing ACh
  3. ACh causes AP in muscle cells which spread out quickly via T-tubules
  4. due to AP, SR releases many Ca++ ions into muscle cell
  5. Ca++ causes troponin to move tropomyosin, allowing myosin to bind to actin
    * myosin is attached to ADP + Pi in higher energy “cocked” position
22
Q

cross bridge cycling (6-9 steps)

A
  1. release of ADP + Pi causes power stroke where myosin moves along actin
  2. ATP binds causing release of actin from myosin
  3. ATP is hydrolyzed to ADP + Pi causing myosin to become “cocked” again
23
Q

when does rigor mortis occurs?

A

when there is not more ATP to release myosin

24
Q

motor unit

A

all the muscle fibers innervated by a single neuron

25
Q

small motor unit

A

few muscle fibers for precise movement

26
Q

large motor units

A

many muscle fibers used in powerful movements

27
Q

type 1 (slow twitch)

type of fiber

A
  • high myoglobin so looks red
  • slow to fatigue but slow contraction velocity–> slow oxidative (oxidative phosphorylation)
  • mitochondria are in higher numbers
28
Q

type 2 (fast twitch)

type of fiber

A
  • low myoglobin so looks white
  • fast to fatigue, but fast contraction velocity
  • muscle cells don’t divide, just grow more/thicker/longer sarcomeres
  • type ll a: fast oxidative glycolytic fibers
  • type ll b: fast glycolytic fibers
29
Q

twitch contractions

A
  • contraction of a m. fiber through motor unti stimulation @ same size and duration
  • all or non principle: depolarization will cause all m. fibers to twitch if above threshold but will not cause any twitching if the depolarization is below threshold
30
Q

latent

twitch contraction phase

A

AP spreads over sarcolema and T-tubules, signaling SR to release Ca++

31
Q

contraction

twitch contraction phase

A

cross bridges form as Ca++ binds to troponin
* muscle tension increases

32
Q

relaxation

twitch contraction phase

A

Ca++ is pumped back into SR
* muscle tension decreases

33
Q

twitches can add up to create?

A

summation = larger overall contraction

34
Q

wave summation

A
  • depolarizing motor unit during relaxation (can cause tetanus)
  • resulting depolarization is larger but can eventually cause fatigue
35
Q

motor unit summation

A

AP to different motor units at different times
* small (most excitable), larger (least excitable)

36
Q

tetanus

A

stimulated frequently meaning no relaxation period
* sustained until muscle fibers are fatigued

37
Q

muscle tone

A

caused by weak, involuntary twitches

38
Q

skeletal muscle types

A

agonists, antagonists, synergists

DAT Biology (20 decks)

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