Pathophys Block 3 Flashcards
1
Q
Skeletal Muscle Structure
A
Muscle –> Fasciculus –> Muscle fibers –> fiber -> myofibril
2
Q
Cell membrane of muscle
A
Sarcolemma
3
Q
Stem cells for muscle growth
A
satellite cells
4
Q
What is a myofiber made up of?
A
many myofibrils (parallel)
5
Q
Myofibers are ___nucleated
A
multi
6
Q
Each nuclei of myofibers maintains a certain area of local control within the cell, called___
A
Myonuclear domain
7
Q
Satellite (stem cells) are ____ until activated
A
quiescent
8
Q
neuronal circuits for walking & reflexes are contained within the ____
A
spinal cord
9
Q
Basis of muscle hypertrophy
A
Satellite cells
10
Q
Higher brain center activate and command ___
A
neuronal circuits (walking, maintaining equilibrium)
11
Q
Motor neurons are located in the ___ portion of the spinal cord
A
anterior
12
Q
Motor neurons are ___ than other neurons
A
bigger (50-100%)
13
Q
Sensory fibers enter cord and are transmitted to higher centers, or ____
A
synapse locally to elicit motor reflexes
14
Q
Somatic motor neuron types
A
Alpha (various), Beta & Gamma (muscle spindles)
15
Q
Targets of special visceral motor neurons
A
mostly facial
16
Q
Targets of general visceral motor neurons
A
mostly cardiac and smooth muscle
17
Q
Where the alpha motor neuron innervates fiber (other fibers in motor unit)
A
neuromuscular junctions
18
Q
Network of tubules that conduct signal within the muscle fiber
A
Sarcoplasmic reticulum
19
Q
What powers activity of the muscle fibers
A
mitochondria
20
Q
What does the number of mitochondria in the muscle fiber depend on
A
fiber type and training status
21
Q
thick filament
A
myosin
22
Q
thin filament
A
actin
23
Q
attached to Z line
A
actin
24
Q
Which motor neurons original in the spinal cord
A
lower
25
lower motor neurons (spinal cord) directly or indirectly do what?
innervate effector targets
26
What motor neurons originate in the motor cortex (precentral gyrus)
upper
27
What fibers make up the bulk of muscle?
Extrafusal
28
What fibers provide the force for muscle contraction?
Extrafusal fibers
29
What are extrafusal fibers stimulated by?
alpha motor neurons
30
Intrafusal fibers are encapsulated in sheaths to form ____
muscle spindles
31
Gamma motor neuron stimulation excites what fibers
intrafusal fibers (in muscle spindle)
32
Where are upper MNs located
motor cortex (prefrontal)
33
Where are lower MNs located
brainstem and SC
34
What are symptoms in upper MN lesions
spasticity
35
What are symptoms in lower MN lesions
paralsis
36
NT for upper MNs
glutamate
37
NT for lower MN
ach
38
where do upper MN target
within the CNS
39
what fibers provide pathways for multi-segmental reflexes
propriospinal fibers
40
Muscular Dystrophy sx
Weakness (esp. pelvic girdle muscles), marked lordosis, enlarged calves
41
Muscular Dystrophy genetics
X-linked (more common in men)
42
What are propriospinal fibers important for
proprioception (sensing of relative position of body parts and strength of effort used in movement)
43
Most signals from brain terminate on ____
interneurons
44
Characteristics of interneurons
small and highly excitable; compromise neuronal circuitry for motor reflexes
45
where do you have secondary clefts
motor end plate
46
Muscarinic receptor location
smooth and cardiac muscle
47
Nicotinic receptor location
skeletal muscle
48
Nicotinic receptors are ____ channels
ligand-gated ion
49
Muscarinic receptors are ____ channels
2nd messenger signaling
50
In MG, immune system attacks receptors at____
NMJ
51
Ach binding sites are blocked by ____
curare, various toxins
52
Where is the muscle spindle located
muscle belly
53
The muscle spindle senses ___
muscle length & (rate of change in length)
54
Where is the golgi tendon organ located
tendon
55
The golgi tendon organ senses
tendon tension (and rate of change)
56
What ion reestablishes membrane potential in AP
K+ (out)
57
What is the muscle AP mainly driven by
influx of Na+
58
What are voltage gated Na+ channels responsible for
rapid influx of sodium ions during the AP potential of nerve cells
59
What channels can we change to change AP
K+ (Na+ not as much variation)
60
difference in fiber types and fiber contractions are based on ____
what sodium channels are present and what potassium channels are present (mainly K)
61
signals from muscle sensory receptors are mainly for ____ muscle control
intrinsic (subconscious)
62
Muscle spindles detect both static and dynamic changes in ____
muscle length
63
Na/K pump
3 Na out, 2 K in
64
What can cause inhibition of Na/L pump and cause cell to swell and burst
ouabain
65
What carries the nervous impulses inside the cell
Transverse tubules
66
Where are Ca ion released from
sarcoplasmic reticulum
67
What effect does tropomyosin have
allow myosin heads to attach to actin filaments
68
Larger muscles with coarse movements have ___ muscle spindles
few
69
What pump collects Ca after AP to get ready to go again
SERCA
70
Basic walking reflexes reside in ___
spinal cord
71
Pressure on the bottom of the feet causes ____
extensor reflex (more complex)
72
Inflammation of peritoneum can cause __
abdominal muscle spasm
73
Pain signals can cause ___
reflex activation and spasm of local muscles
74
ATP causes what in terms of muscle contraction
reseting cross bridge
75
contraction and relaxation time series response to a single stimulus
twitch
76
size is relative to ____ in a twitch
intensity of stimulus
77
fully summated response -fused into maximal curve
tetanus
78
Twitch responses add to each other when multiple stimuli do not allow full relaxation
summation
79
faster you use muscle affects its
strength
80
less frequency, _____ force
less
81
at long lengths, ____ ability to develop force
low
82
faster you go, ____ force
less
83
what can muscle cramps be due to
cold, ischemia, over-activity
84
reflex contraction ____ painful stimulus and causes _____ muscle contraction
increases; more
85
crossed extensor reflex stimulus
pain
86
crossed extensor reflex response
ipsilateral flexion; contralateral extension
87
painful stimulus causes limb to withdraw from stimulus
flexor withdrawal reflexes
88
crossed extensor reflex
painful stimulus elicits an extensor reflex in opposite limb
89
crossed extensor reflex afferent fibers
II, III, IV
90
crossed extensor reflex number of synapses
polysynaptic reflex arc
91
what do muscle spindles and GTOs transmitted to higher centers informing the brain of
changes in muscle tension and length
92
golgi tendon organ response
relaxation of muscle
93
golgi tendon organ stimulus
muscle contraction (tension)
94
golgi tendon organ afferent fibers
Type IB
95
GTO number of synapses
disynatpic reflex arc
96
what is the function of the GTO
equalize force among muscle fibers
97
GTO signal muscle force where?
throughout the entire physiological range
98
what does coactivation of alpha and gamma motor neurons cause
prevents spindle from being unloaded during contraction
99
what is the stretch reflex response
contraction of muscle
100
what is the stretch reflex stimulus
muscle stretch
101
what is the stretch reflex # of synapses
monosynaptic reflex arc
102
what is the stretch reflex afferent fibers type
Type Ia
103
what does the static response respond to
degree of stretch
104
what does the dynamic response respond to
rate of change of length
105
intrafusal fibers are innervated by____
gamma MNs
106
nuclear bag intrafusal fibers are innervated by____
Type Ia sensory afferent
107
nuclear chain intrafusal fibers are innervated by____
Type II sensory afferents
108
nuclear bag intrafusal fibers
dynamic
109
nuclear chain intrafusal fibers
static
110
What is muscle aging a result of
Decreased muscle fibers, muscle fiber number, and muscle length
111
What is increased in aging muscle
number of fiber with central nuclei & ragged red fibers
112
ragged red fibers show what
breakdown of mitochondria
113
Muscle function in aging
Decreased relative strength, Decreased power (decreased Vmax myosin)
114
What is greater, the decrease in strength or power in aging muscles?
power
115
Muscle power is important to what?
ADLs, fall risk, etc.
116
Motoneuron changes in aging
decreased number of motor neurons, decreased diameter of motor neurons, increased size but decreased complexity of motor endplate
117
Aging - axons and NMJs
increased size but decreased complexity of motor end plate
118
Aging - motor unit changes
decreased MU firing rate and increased MU size
119
What muscles are impacted more by aging
lower body; distal
120
Mechanisms of muscle action
Primary vs secondary; changes in physical activity; denervation/reinervation process' oxidative/nitrosative stress/ DNA damage
121
Human disuse models
Spinal cord injury, immobilization, unloading, detraining
122
What are disuse effects on fiber types dependent on
Types of disuse (spinal cord injury, causes type 1 fiber atrophy with slow-to-fast fiber type shift); specific muscles
123
What are disuse effects on muscle function
performance (strength, size, endurance), muscle quality (?)
124
What type of atrophy do you get with spinal cord injury
type 1 fiber atrophy with slow-to-fast fiber type shift
125
What type of atrophy do you get with cancer
type 2 fibers with fast-to-slow fiber type shift
126
specificity
the adaptation of the body or change in physical fitness is specific to the type of training undertaken
127
Hypertrophy vs Atrophy balance
balance between protein synthesis and protein breakdown (towards breakdown)
128
Hypertrophy
select fibers get larger, nuclei are added to normalize myonuclear domain size
129
Hyperplasia
Increase in number of muscle fibers
130
Blood markers of muscle
CK, Myoglobin (radioimmunoassay), Lactate dehydrogenase, Troponin
131
Problem of blood markers
Variability (only used semi-quantitatively)
132
Indirect Damage Markers - Muscles
Force loss, soreness, muscle problems in blood, inflammation, neuromuscular changes
133
Direct Damage Markers - Muscles
confocal/light microscopy, electron microscopy, IHC
134
Muscle Damage: Biceps Model
Maximal eccentric actions of the elbow flexors
135
Repeated Bout Effect Mechanism
Neural adaptation, Tissue-level adaptation, Sarcomere-level adaptation, Systemic adaptation
136
Neural Adaptation
RBE effect present w/ electrically stimulated contractions
137
Tissue-level adaptation
Altered passive stiffness/ECM
138
Sarcomere-level adapation
"popped" sarcomeres
139
Systemic adaptation
altered inflammatory response
140
Fatty acid oxidation ____ with obesity
Decreases
141
Most muscles (in humas) have _____ fiber type compositions
mixed
142
Muscles fibers vary by their favored source of fuel - ______
glycolytic (CHO) vs. oxidative
143
What effects are additive with exercise
insulin
144
Shorter exercise fuel source
carbs
145
Skeletal Muscle glucose uptake's basal activity is is largely regulated via _____
GLUT1
146
Skeletal Muscle glucose uptake's contraction (activity) is regulated by what?
insulin signals translocation of GLUT4 glucose receptors to surface
147
Hyperglycemia
High blood glucose after a meal
148
Hypoglycemia
Low blood glucose after fasting
149
Reactive hypoglycemia occurs when
crashing after a meal
high glucose --> insulin --> too much glucose cleared from blood --> low blood glucose
150
Pancreas secretes _____ to bring blood glucose back down to normal
insulin
151
Pancreas secretes _____ to bring blood glucose back down to normal
glucagon
152
Insulin secreted by ______
beta cells (pancreas)
153
Insulin does what?
Stimulates glucose transporters to help take glucose from the blood across the cell membrane
154
Which hormones control blood glucose levels:
Insulin, Glucagon, Epinephrine, NE, Cortisol
155
Where is blood glucose stored
muscle and liver (converted to glycogen)
156
What could happen to blood glucose?
stored muscle/liver (glycogen), converted to fat, excreted, used immediately for energy (muscle and brain cells)
157
Three key enzymes that regulate glycolysis
Hexokinase, Phosphofructokinase, Pyruvate kinase
158
What is Hexokinase inhibited by
glucose-6-phosphate
159
What is Phosphofructokinase inhibited by
iATP, citrate, and H+
160
What is pyruvate kinase inhibited by
ATP
161
What is pyruvate kinase activated by
fructose-1,6-bisphophate
162
What are the net products of glycolysis
2 ATP, 2 pyruvate, 2 NADH
163
What are your glucose sources
Muscle glycogen, blood glucose, liver glycogen
164
What are the net products from one glucose in the lactic acid system (anaerobic metabolism)
2 ATP
165
What are the net products from one glucose in the oxygen system (aerobic metabolism)
32 ATP
166
how are proteins as an energy source
Not a good first choice (15%) - must break down into AA then transform into acetyl CoA
167
How are lipids as an energy source
Only use oxidative metabolism, main form of storage and exchange is triglycerides
168
Explain fat breakdown for energy
must free FA from backbone, beta oxidation cuts FA into 2C pieces (acetyl CoA) to be used in Krebs cycle
169
The longer the fatty acid, ____
the greater the ATP return
170
Describe CHO breakdown for energy
can be broken down without o2 using glycolysis- break 6C glucose --> 2 3C pyruvate (2 ATP net gain) further process pyruvate using O2
171
What is unique about CHO as an energy source
only nutrient that can create energy via both anaerobic and aerobic processes
172
Where is glucose for CHO breakdown stored
in muscle as muscle glycogen
173
What is CHO's storage form
Glycogen
174
What is fat's storage form
Triglycerides
175
What is protein's storage form
Tissue
176
What are dietary sources of creatine metabolism
Meat and fish
177
What is PCr
Phosphocreatine - a spatial and temporal buffer
178
What can PCr do
can rapidly replenish ATP from ADP + PCr --> ATP + Cr
179
Autogenic inhibition reflec
a sudden relaxation of muscle at very high muscle tension (protects against muscle tears)
180
What does increased muscle tension cause in GTO
compress nerve endings, opening stretch sensitive ion channels
181
What are GTO formed by branches of
Type Ib afferent fibers
182
GTO organs only affect _____
individual muscle (adjacent muscles are not affected)
183
What does coactivation of alpha and gamma motor neurons prevent
prevents spindle from being unloaded during contraction, hence proper damping function of spindle is maintained
184
what is the strecth reflex response
contraction of muscle
185
What does sudden stretch of the muscle excite
muscle spindle
186
afferent impulses to the spinal cord excite ____ to result in contraction of the muscle
a-motor neuron
187
what happens at the same time in the stretch reflex
synergistic muscles are activated, antagonistic muscles are inhbited
188
What the afferents in the static response
Type Ia
189
What are the afferents in the dynamic response
Type Ia and Type II
190
Integrin extracellular binding activity is regulated from where?
inside the cell
191
What does integrin binding to the ECM do
indues signals that are transmitted into the cell
192
List the steps in Neurotransmission
AP, Opening of voltage-gated CA channels/influx of Ca into presynaptic terminal, release of ach to cleft, ach binds with nicotinic receptors on postsynaptic membrane (ach-receptor complex), Na inyo post-synaptic cell, Endplate potential (change in MP of myofiber),generate muscle AP, muscle contraction
193
What is the action of Fast K+ channels in striated muscle
terminates AP
194
What is the action of Inward K+ channels in straited muscle
stabilizes membrane potential; increases K+ entry in fatigue
195
What is the action of ATP sensitive K+ channels in straited muscle
stabilizes membrane potential; increases K+ entry in fatigue
196
What is the action of Na+ activated K+ channels in straited muscle
stabilizes membrane potential; increases K+ entry in fatigue
197
What is the action of ATP sensitive K+ channels in straited muscle
stabilizes membrane potential; reduces Ca+ entry
198
WHat is the gating mechanism for ATP sensitive K+ channels in straited muscle
decreased ATP and ph
199
What is the Na/K pump activated by?
increase in cell volume
200
How does sodium-potassium pump play a role in osmotic balance
Na (3) out of cell and K (2) into cell
201
What does binding of the DHP receptor to the ryanodine receptor in muscle cells do
releases CA ions from the SR (active troponin to release from tropomyosin)
202
What does tropomyosin do when it troponin has been released from it
shift position, allowing myosin heads to attach to the actin filament
203
Where is the location of Troponin C
Actin filaments
204
What is the function and location of Calsequestrin
Sequesters Ca2+ within SR
205
What is the function and location of parvalbumin
cytoplasm, accelerates relaxation
206
What is the function and location of calmodulin
cytoplasm, modulates protein kinase (and other enzymes)
207
The motor cortex is divided into ____ subareas
3 (primary, premotor, supplemental)
208
what is the function of the primary motor cortex
fine motor movement elicited by stimulation
209
what is the function of the premotor area
movement of muscle groups to perform a specific task
210
what is the function of the supplemental motor area
functions in concert with premotor area to provide attitudinal, fixation, or positional movement of the body
211
what does the supplemental motor area provide the background for
fine motor control of the arms and hands by premotor and primary motor cortex
212
what does stimulation of the supplemental motor area elicit
attitudinal, fixation, or positional movement for the body
213
what does damage to Broca's area cause
decreased speech capability
214
what does damage to the hand skills area cause
motor apraxia (the inability to perform fine hand movements)
215
what is the direct pathway to transmit cortical motor signals
corticospinal tract
216
what type of movements is the corticospinal tract for
discrete detailed movements
217
where does the indirect pathway signal to for the transmission of cortical motor signals
signals to basal ganglia, cerebellum, and brainstem nuclei
218
describe the fibers in the cotricospinal tract
majority of fibers cross to the opposite side in the medulla and descend in the lateral corticospinal tracts
219
what cells give rise to large fibers with fast transmission rates in the corticospinal tract
Giant pyramidal cells (Betz cells)
220
what do cortiospinal neurons synapse with
interneurons anterior motor neurons and a few sensory relay neurons in cord gray matter
221
what do MOST corticospinal neurons synapse with
interneurons
222
some corticospinal and rubrospinal neurons synapse directly with ______ (esp. in the cervical enlargement)
alpha motor neurons
223
corticospinal neurons that synapse directly with alpha motor neurons in the spinal cord (esp. within the cervical enlargement) innervate what muscles?
hand and fingers
224
what are incoming sensory pathways to the motor cortex
subcortical fibers from somatic sensory areas (opposite hemispheres - pass through the corpus callosum), somatic sensory fibers from the thalamus, ventrolateral and ventroanterior nuceli of thalamus, fiebrs from the intralaminar nuclei of the thalamus (some may be pain)
225
excitation of what is needed to cause muscle contraction
50-100 giant pyramidal cells
226
where does sensory feedback important for motor control (fine tune muscle movement) come from
muscle spindle, tactile receptors, and proprioceptors
227
what causes auto-correction in terms of feedback for motor control
length mismatch
228
what would a lesion to the primary motor cortex cause
loss of voluntary control of discrete movement of distal segments of the limbs
229
what would a lesion to the basal ganglia cause
muscle spasticity from loss of inhibitory input from accessory areas of the cortex that inhibit excitatory brainstem motor nuclei
230
what does stimulation of the red nucleus cause
relatively fine motor movement (but not as discrete as primary motor cortex)
231
what is the accessory route for transmission of discrete signals from the motor cortex
red nucleus
232
what is the red nucleus and the rubrospinal tract
substantial input from the primary motor cortex
233
brainstem is an extension of the _____
spinal cord
234
what is the function of the brainstem in motor function
performs motor and sensory functions for the face and head (cranial nerves)
235
what type of centers does the brainstem have for motor control
stereotypic movement and equilibrium centers
236
what is within the utricle and saccule in the vestibular apparatus
sensory organs for detecting the orientation of the head with respect to gravity (macula)
237
what is the vestibular apparatus
system of bony tubes and chambers in the temporal bone
238
what does the vestibular apparatus contain
semicircular ducts, utricle, saccule
239
how is information from the hair cells in the inner ear transmitted to the brain
vestibular nerve
240
when the body is accelerated forward, the hair cells of the maculae bend _____
backwards (falling backward feeling; reflex causes body to lean foward)
241
what is the cerebellum responsible for
coordinating muscle activity and sequencing motor activities
242
what does the cerebellum do to make corrective changes
compares actual motor movements with intended movements (monitors and makes corrective adjustments in activities initiated by other parts of the brain)
243
what is the vermis (located in the center) of the cerebellum control
controls axial movements of the neck, shoulders, and hips
244
what is the intermediate zone of the cerebellum controlling
motion of distal portions of upper and lower limbs (esp. hands and feet)
245
what does the lateral zone of the cerebellum contol
sequencing movements of the muscle (important for timing and coordination of the movement)
246
What are the efferent pathways from the cerebellum
fastigoreticular tract and cerebellothalamocortical tract
247
what does the fastigoreticular tract do
controls equilibrium
248
what does the cerebellothalamocortical tract do
coordinates agonist and anatagonist muscle contractions
249
what are the afferent pathways to the cerebellum
dorsal and ventral spinocerebellar tracts
250
where does the dorsal spinocerebellar tract transmit information from
muscles spindle but also from GTO, tactile, and joint receptors
251
where does the ventral spinocerebellar tract transmit information from
signals from anterior horn and interneurons
252
what information does the ventral spinocerebellar tract transmit
information on which signals have arrived at the cord
253
what information does the dorsal spinocerebellar tract transmit
apprises the brain of momentary status of muscle contraction, muscle tension, and limb position and forces acting on the body surface
254
what is the neuronal organization of the cerebellar cortex
molecular, purkinje, granular cell layers
255
where does the output from the cerebellum come from
comes from a deep nuclear cell layer located below the layers of cortex
256
what are the four functional sections of the basal ganglia
striatum (caudate and putamen), globus pallidus, substaintia nigra, subthalamus
257
what is the motor function of the basal ganglia
control complex patterns of motor activity (help to match learned patterns - throwing balls, wiritng)
258
athetosis
spontaneous writing movements of the hand, arm, neck, and face
259
chorea
flicking movements of the hands, face, and shoulders
260
Parkinson disease
rigidity, tremor, akinesa (loss of dopamingeric input from substantia nigra to the caudate and putemen)
261
what would a lesion to the globus pallidus cause
athetosis
262
what would a lesion to the substantia nigra cause
Parkinsons disease
263
what would a lesion to the putamen cause
chorea
264
what would a lesion to the caudate nucleus and putament cause
Huntingtons chorea
265
what would a lesion to the subthalamus cause
hemiballismus
266
hemiballismus
sudden flailing movements of the entire limb
267
Huntington chorea
los of GABA containing neurons to globus pallidus and substantia nigra
268
how does the brain stem level of motor control maintain equilibrium
adjusting axial tone
269
what role does the cortical level play in integrating motor control
issues commands to set into motions the patterns available in the spinal cord and controls intensity and modifies the timing
270
what role does the cerebellum play in integrating motor control
adjust cord motor activity, equilibrium, and planning of motor activity
271
How does the deep nuclear cell activity work in motion
at beginning of motion there is excitatory signals sent into motor pathway by deep nuclear cell to enhance movement, followed by inhibitory signals milliseconds later (provides dampaning function to stop movement from overshooting mark)
272
what is the function of purkinje cells
correct motor errors (listen to feedback tracts)
273
what does climbing fiber input in purkinje cells do
adjusts the sensitivity of purkinje cells to stimulation of parallel fibers (changes long-term sensitivity to mossy fiber input)
