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69 Cards in this Set

  • Front
  • Back
EVENTS
1.AP conduction in motor neuron=
depolarizes terminal
EVENTS
2. ACh released at NMJ=
crosses cleft
EVENTS
3. ACh binds to ACh gated ion channes=
increase Na G
4. Na influx-depolarizes muscle=
produces EPP
5. EPP-->AP (muscle) conducted all over muscle surface depolarizing?
entire muscle membrane including T tubules, SR depolarizes as well
T tubules are
extensions of the sarcolemma located near the Z disc, which increase the surface area of the muscle membrane
Z disc runs parallel to the
T tubule
6. Depolarization of SR now releases?
Ca++ onto myofibrils
7. Ca++ triggers
filament interaction, sliding of actin and myosin
8. filaments overlap
shortening muscle
9. Ca++ pumped into?
SR (sequestered) ends contraction
B. SLIDING FILAMENT MECHANISM
is what the entire mechanism is called
SFM
1. Relaxed
barely overlapping
2. Contracted
overlapped with Z discs close together
C. MYOSIN COMPLEX
1. Globular
protein heads
Myosin complex
2. cross bridges?
flexible hinges where they join into myosin
Myosin complex
3. at the head?
molecule of ATPase enzyme
D. ACTIN COMPLEX (3 COMPONENTS)
1. F-actin
is a double stranded protein molecule, the ends attach to the Z disc
AC
2. Tropomyosin
is a protein that wraps around F actin
Tropomyosin blocks
the active sites if the muscle is relaxed.
Tropomyosin has ? molecules (active sites) for myosin interaction
ADP
AC
3. Troponin
system that helps to bind tropomyosin to actin, 3 subunits
Subunits of troponin
1. Troponin I
has affinity for actin
SOT
2 Troponin t
affinity for tropomyosin
SOT
3. troponin c
affinity for calcium
E. TROPONIN-TROPOMYOSIN COMPLEX (T-TM)
1. inhibits actin myosin binding sites by?
blocking active sites
T-TM
2. ? inhibits the T-TM inhibition
calcium
T-TM cont.
2. Ca binds to Troponin C this ?
pulls tropomyosin into groove
unblocks actin filaments
unblocks active sites
T-TM
3. Interaction and movement is called
power stroke
T-TM
3.cont.
a. ? binds to actin and pulls inward
myosin head
T-TM
3. POWER STROKE cont.
b. ? provides energy for power stroke
cleavage of ATP (on myosin head)
3.cont.
c. new ATP allows release of
actin and myosin
3. cont.
d. binding and release occurs in a racket motion indep of one another why?
more efficient and shortening is much faster
F. SARCOMERE LENGTH & TENSION
1. max tension develops at max level of overlap between?
actin & myosin filaments
SLT
2. Tension ? @ the point where?
Z discs run into myosin bands
SLT
3. No tension develops if?
actin and myosin filaments are too far apart
G. LOAD VS VELOCITY
1. Velocity is maximal if ?
muscle contracts with no load
L VS V
2. Velocity decreases with
increasing load
EXCITIATION/CONTRT. COUPLING
A. MUSCLE ACTION POT.
1.AP in muscle is of ? duration than in nerves, it is also ? than in nerves
longer duration/ slower
MAP
2. ? resting potentials
similar -70 to -90
MAP
3. Ap travels deep into the fiber by the
transverse tubule system
B. T-TUBULES
1. extensions of ? into the heart of the cells to the opposite side
sarcolemma
TT
2. Tiny tubules purpose
brings AP
TT
3. AP depolarizes ?, what is next to them?
t tubules, sarcoplasmic reticulum
C. SARCOPL. RETICUL (SR)
1. ? is released when depolarized
Calcium
SR
a. greatest conc of Ca in Sr is
at terminal cisternal at end of SR
SR
b. t tubule depolarization triggers SR to release?
Ca that is dumped into the cytoplasm
SR
c. Ca released into the cytoplasm binds to ?
troponin c & pulls tropomyosin off actins active site.
SR
C. cont
Ca released into the cytoplasm allows
what interaction
actin myosin interaction (disengages troponin tropomyosin inhibitor)
SR
C. cont
Ca released unblocks ? sites
active sites (were blocked by tropomyosin) & contraction occurs
SR cont
2. SR is filled with what pump
Ca
SR cont
2. a. ? pump in the walls of SR
ATPase
SR cont
2. b. pumps constantly to ?
requester Ca into SR
MOTOR UNIT OUTPUT=
one motor neuron axon and all indivdual muscle fibers it innervates
MUO
A. WHOLE MUSCLE CONTRACTION=
MANY MOTOR UNITS
A. WHOLE MUSCLE CONTR.
1. isometric=
muscle contracting w/out shortening (means same length)
WMC
2. isotonic=
muscle contractions without changing tension, fixed load (same tension)
MUO
B. Summation
multiple fiber summation=
recruitment of additional motor units
Summation
-size principle
stronger signal will recruit larger motor units
Summation
2. Freq. summation
an increase rate of contraction
Summation
3. tetanization=
last as long as ? present
represents max freq summation
Ca.
C. FATIGUE
1. follows rate of ?
muscle glycogen depletion=metabolic fatigue (no fuel)
FATIGUE
2. neuromuscular fatigue=
(in tx fatigue) loss/depletion of ACh
Fatigue
3. interruption of blood flow lose
O2
D. HYPERTROPHY
1.Fiber hypertrophy
increase in size due to max force exertion
HYPERTROPHY
is the result of ?
increased # of myofibrils, with a build up of glycolytic enzymes in cells
E. ATROPHY
1. If muscle unused=
rate of decay of contractile protein eceeds rate of replacement
ATROPHY
2. Denervation=
no signals, atrophy begins immed. upon denervation
Denervation can develop contracture=
fibrous tissue replaces muscle tissue
fibrous tissue shortens permanently with time.