muscle physiology (ch 9) Flashcards
(154 cards)
1
Q
characteristics of muscle tissue
A
excitable
contractile
elastic
2
Q
types of muscle
A
smooth
cardiac
skeletal
3
Q
where is smooth muscle found
A
mostly hollow internal organs
4
Q
where is cardiac muscle found
A
heart
5
Q
where is skeletal muscle found
A
mainly attached to bones
6
Q
parts of skeletal muscle
A
belly
attachments (origin and insertion)
7
Q
belly
A
thickest part of the muscle
8
Q
origin
A
more proximal/less movable end of the muscle
9
Q
insertion
A
more distal/more movable end of the muscle
10
Q
myo means…
A
muscle
11
Q
connective tissue consists of…
A
collagen
12
Q
endomysium
A
found around each muscle cell (fiber)
13
Q
perimysium
A
found around each fascicle (grouping)
14
Q
epimysium
A
found around an entire muscle
15
Q
internal tension
A
tension within cells
16
Q
external tension
A
tension to bones to move a load
17
Q
functions of skeletal muscle
A
movement
tone (tension)
heat
18
Q
why does tone need to be maintained in skeletal muscle
A
posture, supporting joints
19
Q
how is/how much heat is created by skeletal muscle
A
over 80% of body heat is created through muscle metabolism
20
Q
sarco means…
A
muscle
21
Q
sarcolemma
A
muscle cell membrane
22
Q
T tubules
A
pits that go deep off the membrane
23
Q
sarcoplasm
A
muscular cytoplasm
24
Q
myofibrils
A
cylindrical subunits of contractile protein
25
terminal cisternae
"end containers" of wide sarcoplasmic reticulum near the T tubule
26
glycogen
starch (chains of glucose)
27
myoglobin function
transferring O2
28
how many mitochondria are in the sarcoplasm
many
29
where are the nuclei found in skeletal muscle
at/near the sarcolemma
30
anatomy of a muscle cell
sarcolemma
sarcoplasm
glycogen
myoglobin
mitochondria
many nuclei
31
myofilaments are...
proteins
32
titin is...
elastic protein myosin connections to the z-disc
33
thick myofilaments consist of...
myosin
34
thin myofilaments consist of...
actin
tropomyosin
troponin
35
actin characteristics
g-globular
f-filamentous
36
tropomyosin characteristics
rod-shaped
37
troponin characteristics
3 polypeptides
I binds to actin
T binds to tropomyosin
C binds to Ca++
38
myosin is shaped like...
golf clubs
39
A bands are dark because of...
thick myosin filaments
40
the H zone is...
an area of no overlap, the center is pale because there are no thin filaments
41
I bands are pale because...
there are no thick myosin filaments
42
the Z disc is...
where thin filaments are connected to each other mid I-band
43
sarcomeres are...
the distance between adjacent z-discs
44
contractions cause...
I bands to become smaller
H zones to disappear
A bands to stay the same
sarcomeres to shorten
45
alpha motor neuron function
stimulating muscle fibers/cells
46
a motor unit is...
one alpha neuron and all the muscle fibers that it innervates
47
fine control involves...
many small motor units
48
gross control involves...
relatively few, large motor units
49
fine control muscle
extra-ocular eye muscle
50
gross control muscle
gluteus maximus
51
neuromuscular junctions are...
a type of synapse (clasp/join)
52
synaptic knobs are...
widened neuron endings
53
acetylcholine (ACh) is found in ____ and serves as a ____
membrane vesicles, neurotransmitter
54
synaptic clefts are
spaces/separations
55
acetylcholinesterase (AChE) is...
an enzyme that breaks apart acetylcholine
56
motor end plates are found...
on muscle membranes (sarcolemmas)
57
function of junctional folds
to increase surface area
58
ACh receptors are...
ACh-gated ion channels (similar to that of sodium and potassium)
59
resting membrane potential of muscle
-90 mV
60
resting membrane potential of neurons
-70 mV
61
why is resting membrane potential at the charges they are
Na+ and K+ ATP pump, Na+ and K+ gradient
62
action potential is...
charge that moves
63
action potential process
change occurs in membrane charge
gets recreated along the membrane
spreads and acts as a signal along it
64
muscle stimulation by a neuron is comparable to...
a wave
65
steps of muscle stimulation by a neuron
AP from neuron reaches synaptic knob, opens voltage-gated calcium channels in neuron knob, Ca++ diffuses into the neuron, inducing exocytosis of ACh, which diffuses to ACh receptors on the sarcolemma, which allow Na+ to come in, then K+ to come out, resulting in the muscle cell creating an AP that moves along the sarcolemma
66
how does muscle stimulation from a neuron stop
by getting rid of ACh via enzyme AChE
67
steps of excitation-contraction coupling
AP propagated along sarcolemma and down T tubules, opening voltage-gated Ca++ channels in the SR, leading Ca++ to diffuse out, binding to troponin and moving tropomyosin to exposed binding sites, myosin then binds to actin, the heads bend and release ADP and P, ATP attaches to myosin to release a crossbridge, the head recocks, and process repeats
68
when does excitation-contraction coupling stop
when APs no longer release Ca++ around the myofilaments and ATP is no longer available
69
rigor mortis is...
the rigidity of death
70
why does rigor mortis occur
a lack of ATP causes Ca++ pumps to stop working, increasing Ca++ around actin and myosin, with no way to release
71
effect of nerve gas
inhibits AChE, meaning ACh stays at the neuromuscular junction and the muscle stays contracted
72
why is nerve gas deadly
it causes muscles to stay contracted, but the diaphragm needs to relax so you can breathe
73
contraction of a whole muscle means...
each cell will contract to its maximum when stimulated
74
a myogram displays
time vs tension
75
a muscle twitch is...
a rapid jerk response to a single stimulus
76
a stimulus is...
above threshold
77
latent period
muscle APs cause Ca++ to release from the SR and expose binding site crossbridges
78
contraction
actin and myosin interact, leading to shortening
79
relaxation
no muscle APs lead to a decrease in Ca++, covering of binding sites, and release of ATP
80
wave summation occurs when...
stimulus frequency is changed (increased)
81
tetanus
a sustained contraction
82
fused/complete tetanus is...
a smooth/held contraction
83
why do muscles not relax during tetanus
Ca++ is being maintained around the myofilament
84
recruitment is also known as...
multiple motor unit summation
85
recruitment occurs by...
changing stimulus intensity
86
what is the size principle
small motor units are recruited first, large motor units are recruited last
87
what is the maximal stimulus
the smallest stimulus needed to get all motor units functioning/contracting
88
force out of a muscle depends on...
number of motor units recruited
size of muscle fibers
frequency of stimulus
length-tension relationship
89
size of muscle fibers determines...
overall muscle size
90
what is the optimal length of a muscle
slightly longer than resting length
will produce the best interaction of actin and myosin
91
isometric contraction
"same measurement"
contraction with no length change of a muscle
92
isotonic contraction
"same tone/tension"
contraction with a length change
93
types of isotonic contractions
concentric and eccentric
94
concentric isotonic contractions
when muscle shortens while it has tension
95
eccentric isotonic contractions
when muscle lengthens while maintaining tension
96
metabolism is ____ and ____
anabolism and catabolism (build-up and breakdown of various molecules
97
ATP stores provide ____ energy
a little bit of
98
the creatine kinase system provides ____ energy
6 seconds worth of energy
99
the myokinase system provides ____ energy
10 seconds worth of energy
100
creatine kinase system summary
creatine phosphate + ADP --> ATP + creatine
101
myokinase system summary
ADP + ADP --> AMP + ATP
102
glycolysis is...
anaerobic fermentation
103
glycolysis summary
glucose --> 2 3-carbon pyruvates + energy ferment into lactate
104
glycolysis can be described as...
inefficient but quick
105
glycolysis provides ____ energy
30-40 seconds worth of energy
106
aerobic activity summary
2 pyruvates + O2 --> CO2 + H2O + energy
107
aerobic activity can be described as...
efficient but slow
108
how much more energy does aerobic activity yield compared to glycolysis
15x more
109
fatigue is...
a decline in muscle force after sustained use
110
command fatigue
person gives up
111
physiological fatigue
muscle is stimulated to its maximum, still force then declines
112
short term reason for fatigue
decrease in membrane excitability
K+ fills T tubules
phosphates build up in muscle
113
long term reason for fatigue
SR damage decreases control of Ca++
114
what is oxygen used for post-exercise
replenishing O2
oxidizing lactic acid back to pyruvate in the liver
replenishing ATP and creatine-phosphate stores in muscle
dealing with higher post-exercise metabolism
115
cause for muscle soreness during exercise
increase in acids in the muscle (lactic, phosphate, carbonate) leads to pain
116
cause for muscle soreness after exercise
microtrauma to proteins leads to repair/increase in them, and an increase in muscle strength
117
more proteins means...
a muscle cell gets bigger
118
advantages of resistance exercise
increase in actin, myosin, and collagen
hypertrophy (much growth, cells and muscle enlarge)
119
advantages of endurance exercise
increase in mitochondria in muscle, myoglobin, and capillaries
increase in cardiovascular/respiratory efficiency
120
what is the best type of exercise and why
cross-training, it involves both resistance and endurance exercise
121
being a couch potato results in...
a loss of up to 5% of overall strength in one day
122
various muscle fiber types ____
predominate in various muscles, but all motor units in a muscle will be the same
123
aerobic fiber(s)
slow oxidative fiber, fast oxidative fiber
124
anaerobic fiber(s)
fast glycolytic fiber
125
appearance of slow oxidative fiber
red, small
126
appearance of fast oxidative fiber
pink, medium
127
appearance of fast glycolytic fiber
white, large
128
characteristics of slow oxidative fiber
high fatigue resistance
slow ATP use (slow twitch)
high myoglobin
low glycogen
129
characteristics of fast oxidative fiber
medium to high fatigue resistance
medium ATP use (relatively quick)
medium-high myoglobin
intermediate glycogen
130
characteristics of fast glycolytic fiber
fatigable (poor endurance)
quick ATP use (fast twitch)
low myoglobin
high glycogen
131
where is smooth muscle found
mostly in the walls of hollow internal organs
132
anatomy of a smooth muscle cell
intermediate-filament skeleton gives it shape
actin and myosin present at dense bodies
no T tubules, troponin, myofibrils, or sarcomeres
133
smooth and skeletal muscle similarites
stimuli to cells lead to changes in membrane potential
increase of Ca++ inside the cell leads to actin and myosin interaction
actin and myosin interaction causes muscle fiber contraction
134
what can stimulate a smooth muscle cell
any change in charge (positive or negative), does not always have to be an AP
135
varieties of stimuli to smooth muscle cells
multiunit and single unit
136
multiunit stimuli
neuron that interacts with each cell
137
single unit stimuli
no neuron stimulation to each cell, instead there are many gap junctions
138
in a pacemaker cell can...
spontaneously depolarize
139
excitatory signals lead to...
contraction
140
inhibitory signals lead to...
relaxation
141
types of smooth muscle cell stimuli
temperature, hormones, stretch, pH, pCO2, pO2
142
amount of SR in a smooth muscle cell
relatively little
143
most Ca++ in smooth muscle cell comes from
the outside (extracellular fluid) via diffusion
144
how does Ca++ induce actin and myosin interaction in smooth muscle
it binds to calmodulin, activating myosin light-chain kinase enzymes
kinase adds phosphate to myosin heads
145
actin to myosin ratio in smooth vs skeletal muscle
more in smooth muscle (13:1 vs 2:1)
146
the further a myosin head can go...
the more contraction there is
147
contraction characteristics in smooth muscle
slow
slow ATP-ase
148
twitch times of smooth vs skeletal muscle
skeleton = 0.1 sec
smooth = 1-3 sec
149
in regards to fatigue, smooth muscle is ____
fatigue resistant
150
why is smooth muscle fatigue resistant
it is constantly contracting, and uses ATP slowly
151
shortening/stretch of smooth vs skeletal muscle
greater in smooth muscle
skeletal: 30% shorter, 30% longer than at rest
smooth: 50% shorter, 100% longer than at rest
152
smooth muscle undergoes...
hyperplasia or mitosis
153
stretch/relaxation response in smooth muscles
stretching increases tension, then relaxation follows
154
even when stretched, a smooth muscle...
still contracts well
