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Vet Physiology > skeletal muscle physiology I > Flashcards

skeletal muscle physiology I Flashcards

1
Q

motorneuron=

A

neurons that innervates muscle fibers

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2
Q

motor unit=

A

single motorneuron and muscle fibers it innervates

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3
Q

small motor units=

A

fine activities

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4
Q

large motor units=

A

gross control

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5
Q

1st event at neuromuscular junction

A

AP propagated to presynaptic terminal, VOLTAGE-GATED CA2+ CHANNELS OPEN, Ca2+ permeability increases, Ca2+ flows in

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6
Q

2nd event at neuromuscular junction

A

CA2+ CAUSES RELEASE OF ACH stored in synaptic vesicles

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7
Q

3rd event at neuromuscular junction

A

Ach diffuses to post-synaptic membrane-called motor end plate

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8
Q

4th event at neuromuscular junction

A

ACH BINDS TO NICOTINE RECEPTORS, channels opens, Na+ moves in, K+ moves out

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9
Q

5th event at neuromuscular junction

A

motor end plate depolarizes from -90 mV to -50 mV- THIS IS THE END PLATE POTENTIAL (EPP)
- single vesicle of Ach produces miniature end plate potential (MEPP)

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10
Q

6th event at neuromuscular junction

A

depolarization spreads from motor end plate to muscle fiber cells

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11
Q

7th event at neuromuscular junction

A

EPP stops when Ach degraded by ACETYLCHOLINESTERASE (AchE)

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12
Q

botulinum toxin

A
  • produced by Clostridium botulinum
  • blocks release of Ach from presynaptic terminals
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13
Q

AChE inhibitors

A
  • prevent degradation of ACh in synaptic cleft
  • treat myasthenia gravis -> Ach receptors blocked by antibodies
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14
Q

physical characteristics of skeletal muscle

A

striated appearance, under voluntary control

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15
Q

skeletal muscle organization

A
  • muscle fiber (muscle cell or myocyte) contains MYOFIBRILS
  • groups of muscle fibers= FASCICULUS
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16
Q

muscle cells innervated by…

A

motorneurons

17
Q

events between AP in muscle fiber and contraction are called…

A

excitation-contraction coupling

18
Q

what are myofibrils?

A
  • basic unit of muscle cells
  • surrounded by sarcoplasmic reticulum
  • composed of actin, myosin, and titin -> thick and think filaments (myofilaments- repeat into sarcomeres)
19
Q

what is a sarcomere?

A
  • repeating thick and thin filaments along the myofibril
  • occur between adjacent Z lines (disks)
  • contractile unit
20
Q

Light band=

A

I band
- think filament= actin
- Z disks

21
Q

dark band=

A

A band
- thick filaments= myosin
- darkest region at end of A band= overlap -> overlap of actin think filaments with myosin thick filaments -> where force of contraction starts

22
Q

bare zone=

A

H zone
- center of sarcomere, no thin filaments

23
Q

M line=

A
  • dark-staining protein
  • links thick filaments
24
Q

thick filaments=

A
  • myosin: heavy chains and light chains
  • 1 pair of heavy chains: form tail
  • 2 pairs of light chains: form 2 globular heads -> have actin binding site & ATP binding site
25
Q

think filaments=

A
  • actin: 2 strands twisted
  • tropomyosin: runs along groove of twisted actin -> BLOCKS MYOSIN-BINDING SITE ON ACTIN
  • troponin: complex of troponin T, troponin I and troponin C at regular intervals along tropomyosin
26
Q

troponin T

A

attaches entire complex to tropomyosin

27
Q

troponin I

A

inhibits interaction of actin & myosin by covering binding site

28
Q

troponin C

A

Ca binding protein

29
Q

what do cytoskeletal proteins do

A

help align thick and thin filaments
- dystrophin
- titin
- nebulin

30
Q

dystrophin=

A

anchors myofibril scaffold to the cell membrane

31
Q

titin=

A

centers thick filaments in the sarcomere

32
Q

nebulin=

A

sets length of thin filaments

33
Q

muscle cell surrounded by…

A

sarcolemma

34
Q

sarcolemma has invaginations=

A

transverse (T) tubules
- extending into muscle cells -> carry depolarization from motor end plate to cell interior -> contact SR

35
Q

myofibrils surrounded by…

A

sarcoplasmic reticulum -> regulating Ca in cytosol

36
Q

sarcoplasmic reticulum

A
  • stores Ca2+ using the SERCA pump (Ca2+ ATPase)
  • Ca2+ bound to CALSEQUESTRIN in SR
  • Ca2+ release channel= RYANODINE RECEPTOR
37
Q
A

Vet Physiology (5 decks)

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