musch Flashcards
(109 cards)
1
Q
does skeletal muscle have cell to cell communication?
A
no
2
Q
is skeletal muscle neurogenic or myogenic?
A
neurogenic
3
Q
how do cardiac muscle cells communicate?
A
intercalated discs
4
Q
are cardiac cells neurogenic or myogenic?
A
myogenic
5
Q
how do smooth muscle cells communicate>
A
gap junctions
6
Q
are smooth muscle cells neurogenic or myogenic?
A
myogenic
7
Q
what is the plateau in cardiac muscle associated with?
A
- decrease perm to K+
2. increase perm to CA+
8
Q
in cardiac muscle, what is calcium release induced by?
A
calcium
9
Q
where are beta-1 receptors?
A
in the heart
10
Q
where are beta-2 receptors?
A
in the periphery
11
Q
what are two characteristics of EC coupling in smooth muscle?
A
- many steps
2. SLOW
12
Q
is there z line to z line contraction in smooth muscle?
A
no
13
Q
does shortening occur to a greater degree in smooth muscle or skeletal muscle?
A
smooth muscle
14
Q
is skeletal muscle electrically coupled?
A
no
15
Q
in what type of muscle is the duration of contraction controlled by the duration of the action potential?
A
cardiac muscle
16
Q
what are the two myosin ATPase isoforms?
A
- fast twitch fibers
2. slow twitch fibers
17
Q
fast twitch highly glycolytic fibers activity increases in what pH?
A
basic
18
Q
fast twitch highly oxidative highly glycolytic fibers activity increases in what pH?
A
basic
19
Q
slow twitch highly oxidative fibers activity increases at what pH?
A
acidic
20
Q
what types of fibers will stain for mitochondrial enzymes
A
FOG and SO
21
Q
what types of fibers will stain for oxidative enzymes
A
FOG and FG
22
Q
more muscle fiber units and myoglobin in what type of muscle?
A
type 1, SO
23
Q
which muscle fiber type has more glycogen stores
A
type 2
24
Q
which muscle fiber type has more triglyceride stores
A
type 1
25
which muscle fiber type has the most fatigue resistance?
type 1
26
which muscle fiber type has the lease fatigue resistance?
type 2b
27
which muscle fiber type has the most lactate dehydrogenase?
type 1, SO
28
which muscle fiber type has the a higher concentration of the enzymes involved in the Krebs cycle (i.e. succinate dehydrogenase and citrate synthase)?
type 1, SO; and type 2a, FOG
29
what are the series elastic elements of the muscles?
1. tendon
| 2. hinge region
30
what are the contractile elements of the muscle?
1. sarcomeres
31
what are the parallel elastic elements of the muscle?
1. sarcolemma
2. blood vessels and nerves
3. connective tissue
32
2 types of muscle contraction
1. isometric
| 2. isotonic
33
define isovolumic
contraction and shortening of contractile elements
34
in isometric contraction:
force of the great > force being produced by muscle
| (muscle shortens and weight does not move
35
in isotonic contraction:
force of the muscle > force of the weight
| muscle shortens and weight moves
36
active force is due to what?
due to contractile units
37
passive force is due to what?
1. sarcolemma
2. connective tissue
3. nerves and blood vessels
4. hinge region of myosin
38
total force production is dependent on what?
the cross-sectional area of the muscle
39
total force production is independent of what?
muscle fiber type
40
what is total tension in skeletal muscle the sum of?
active tension + passive tension
41
force development in muscle is uniquely dependent on
length of sarcomeres and entire muscle
42
to produce isotonic contraction: slope=
velocity of contraction
43
velocity =
distance/time
44
how can you change the velocity of contraction?
by changing the weight of the load
45
what is the maximal velocity of contraction dependent on?
cross-bridge cycling rate
46
what is isometric contraction dependent on?
the number of cross-bridges between actin and mysoin
47
the velocity of cross-bridge cycling rate is dependent on
1. type of myosin ATPase (fast or slow)
2. temperature effect on enzyme
3. intracellular pH - [H+] effect on enzyme
48
force is dependent on:
1. sarcomere length + number of cross-bridges
| 2. degree of activation->more Ca++ released-> more cross-bridges formed
49
what is temporal summation
frequency of firing of alpha- motor neurons
50
what is spatial summation
recruitment of different alpha motor neurons
51
what determines the speed of contraction
myosin ATP found on thick filament
52
what determines the speed of relaxation?
Ca++ being pumped back into the SR at a rate of Ca++/ATP
53
does relaxation of skeletal muscle require energy?
yes
54
the feet in the T-SR junction are thought to do what?
be the SR Ca++ release channel
55
is there ATP being used directly in Ca++ release in the feet region?
no
56
what does the Ca++ release from the SR do?
produces a conformational change in troponin that exposes the actin to the myosin head (NOT ENERGY DEPENDENT)
57
what is cocking?
the change of chemical to mechanical energy
58
when does cocking occur?
when ATP binds to myosin ATPase complex (hinge)
59
what is the power stroke?
the thin filament being pulled over the thick filament
60
what is the rate-limiting factor in muscle contraction?
powerstroke and detachment
61
overview of muscle contraction
1. attachment
2. cocking
3. powerstroke and detachment
62
what is the transfer of energy-state for muscle contraction?
electrical event -> chemical event - > mechanical event
63
what do myofibrils contain?
contractile units called sarcomeres
64
what is the contractile unit of the muscle?
sarcomere
65
what does each muscle cell contain?
myofibrils
66
what surrounds the individual fasiculi?
perimysium
67
what is a fasiculi?
individual bundles of muscle
68
what surrounds the entire muscle?
epimysium
69
what surrounds each muscle fiber?
endomysium
70
what coalesces with CT to become part of the tendon?
epimysium
71
what three things play a role in force production?
1. connective tissue
2. arteries and veins
3. nerves
72
what kind of receptors are associated with afferent nerve fibers?
1. mechanoreceptors (tension)
| 2. chemoreceptors (pain, metabolism)
73
what makes up the triad?
cisternae + T-tubule + cisternae
74
what is the cisternae associated with?
Ca++ release
75
what enzyme is responsible for Ca+ reuptake
calsequestrin
76
the functional Ca++ release channel
Ryanodine receptor
77
T-Tubule protein similar to VGCa++ channel
DHP receptor
78
the sarcomere is define from what to what?
z line to z line
79
What happens to the H zone during contraction?
gets smaller
80
what happens to the I zone during contraction?
gets smaller
81
what happens to the A zone during contraction?
does not change length
82
what makes up the A zone?
thick filaments
83
what happens in the hinge region?
active in coupling chemical to mechanical energy
84
myosin ATPase splits what?
ATP -> ADP + Pi
85
what are the two enzymes located in the M line?
1. creatine phosphokinase (CPK)
| 2. myokinase
86
creatine phospho kinase reaction
ADP + CrP -> ATP + Cr
87
myokinase reaction
ADP + ADP -> ATP + AMP
88
what is the length of actin thin filament?
1 um
89
what does tropomyosin do?
plays a regulatory role
90
Troponin I
inhibits active binding site
91
Troponin C
contains binding site for Ca++
92
Troponin T
binds to tropomyosin
93
what is the major protein in the Z line?
alpha- actinin
94
what does the Z line connect to?
the thin filaments
95
length from z line to z line
2.0-2.2 um
96
one myosin filament will interact with how many actin filaments?
6
97
titin
acts like an anchor and spring to keep the myosin filament in place
98
nebulin
molecular ruler in the assembly of actin
| -important in muscular hypertrophy
99
dystrophin
anchors the contractile proteins to the cellular membrane
100
alpha - actinin
located in the Z line and connects actin filaments together
101
all muscle fibers connected to the motor unit have what?
1. the same contractile properties
| 2. the same metabolic properties
102
eye muscle has what kind of motor control?
fine motor control
| *1 motor unit per fiber
103
quadriceps muscle has what kind of motor control?
gross motor control
| *1 motor unit per thousands of fibers
104
how wide is the synaptic cleft
~50 nm wide
105
chemoreceptors
[H+], K+, Pi
106
mechanoreceptors
muscle spindles and golgi tendon organs
107
muscle spindles run parallel to what?
extrafusal fibers
108
primary annulospinal ending
quick responders to changes in muscle length (dynamic)
109
secondary flower-spray
tonic input to muscle length (static)
