Midterm #2 Flashcards
(387 cards)
1
Q
What two components of the body are considered the “anatomy of the CNS?”
A
Brain and spinal cord
2
Q
Brain and spinal cord are separated into ___ matter and ____ matter
A
gray, white
3
Q
Gray matter consists of _______ somas, _____, and ____
A
unmyelinated, dendrites, axons
4
Q
White matter consists mainly of _______ axons
A
myelinated
5
Q
The spinal cord contains major pathways for information flowing back and forth between the ____ and the ____, _____ and ____ of the body
A
brain, skin, joints, muscles
6
Q
The spinal cord is divided into ____ main regions: ?
A
4: cervical, thoracic, lumbar, sacral, AND coccygeal
7
Q
How many segments does the cervical region contain?
A
8
8
Q
How many segments does the thoracic region contain?
A
12
9
Q
How many segments does the lumbar region contain?
A
5
10
Q
How many segments does the sacral region contain?
A
5
11
Q
How many segments does the coccygeal region contain?
A
1
12
Q
Each segments gives rise to a ____ ___ of spinal nerves, and each nerve splits into ____
A
bilateral pair, roots
13
Q
The _____ root carries sensory (afferent) information to the CNS
A
dorsal
14
Q
The _____ root carries motor (efferent) information to muscles and glands
A
ventral
15
Q
Gray matter also consists of sensory and motor ____
A
nuclei
16
Q
_____ are clusters of cell bodies in the CNS
A
Nuclei
17
Q
_____ are clusters of cell bodies in the PNS
A
Ganglia
18
Q
White matter in the spinal cord consists of tracts of axons carrying information to and from the ____
A
brain
19
Q
What are ascending tracts?
A
Dorsal and external lateral, and carry sensory information to the brain
20
Q
What are descending tracts?
A
Ventral and interior lateral, and carry commands to motor neurons
21
Q
The spinal cord can act as the ______ ____ to initiate a response to a stimulus without receiving input from the _____
A
integrating center, brain
22
Q
The fact that the spinal cord can act as an integrating center without the brain is particularly important in ?
A
body movement
23
Q
What are the 6 major divisions of the brain?
A
- Cerebrum
- Cerebellum
- Diencephalon
- Midbrain
- Pons
- Medulla
24
Q
What major divisions of the brain are part of the brainstem?
A
Midbrain, pons, medulla
25
What are the 4 major regions of the brainstem?
Midbrain, pons, medulla, reticular formation
26
The brainstem contains 11/12 ___ nerves
cranial
27
What is the purpose of the cranial nerves?
To carry sensory and motor information for the head and neck
28
The brainstem is involved in 6 basic processes in the body, what are they?
1. Sleep and arousal
2. Muscle tone
3. Stretch reflexes
4. Coordination of breathing
5. Blood pressure regulation
6. Modulation of pain
29
In the medulla, the white matter contains all ascending _____ tracts and descending ______ tracts
somatosensory, corticospinal
30
Nuclei in the medulla control many involuntary functioning including the ? and the ?
cardiovascular center, medullary respiratory center
31
The medulla also contains the ____ center, the _____ center, and is responsible for _____, _____, and _____
vomiting, deglutition, coughing, sneezing, hiccuping
32
The Pons contains ____ and ____, and relays information between the ____ and _____, and assists the medulla in the ?
nuclei, tracts, cerebellum, cerebrum, coordination of breathing
33
The midbrain is also know as the ?
mesencephalon
34
The midbrain is the junction between the lower ___ and ____
brainstem, diencephalon
35
The primary function of the midbrain is controlling ?, it also relays _____ and _____ reflexes and contains the ?
eye movement, auditory, visual, substantia nigra
36
The reticular formation extends throughout the ____
brainstem
37
The Ret. Formation is important in 3 main functions: ?
1. Consciousness
2. Arousal
3. Attention and Alterness
38
The ret. formation also projets and filters sensory information to the ____
cortex
39
The RAS is inactivated during sleep, and damage can induce a ____
coma
40
The ____ is the second largest brain structure, and contains 2 cerebellar hemispheres
cerebellum
41
The cerebellum processes sensory information related to ____, and coordinates the ?
movement, execution of movement
42
The cerebellum sends feedback signals to ____ areas of the cerebral cortex via its connections to the ___ and ___
motor, thalamus, pons
43
The cerebellum is the main area of regulating ____ and ____
posture, balance
44
The diencephalon lies between the _____ and _____
brainstem, cerebrum
45
The diencephalon contains two primary structures, the _____ and the _____
thalamus, hypothalamus
46
The diencephalon also contains two endocrine structures, the ____ ____ and _____
pineal gland, pituitary
47
The thalamus is considered the ____ center
relay
48
The thalamus receives sensory information from the ____ tract, ___, ____ ___ and relays it to the relevant sensory areas in the ____
optic, ears, spinal cord, cortex
49
The thalamus also relays information from the cerebellum to ____ areas in the cortex
motor
50
What is the main function of the pineal gland?
Cyclically release melatonin involved in sleep/wake
51
The hypothalamus is considered the center for _____
homeostasis
52
The _____ influences autonomic and endocrine function
hypothalamus
53
What are the 4 main functions of the hypothalamus?
1. Helps maintain blood glucose concentrations
2. Maintains body temperature
3. Controls body osmolarity
4. Controls food intake
54
Pituitary is the ____ of the hypothalamus
output
55
Posterior pituitary is _____ tissue
neural
56
Anterior pituitary is _____ tissue
endocrine
57
What is neurohypophysis?
The posterior pituitary gland, stores and releases oxytocin and vasopressin produced in the hypothalamus
58
What are the two main organs/glands that are influenced by oxytocin?
mammary glands and the uterus
59
What is the main organ that is influenced by vasopressin?
kidneys
60
What is the hypothalamic–hypophysial portal system?
The conduit that connects the brain to the anterior pituitary. Controls growth, metabolism, and reproduction
61
The ____ is the largest and most distinctive part of the brain
cerebrum
62
Gray matter in the cerebrum includes the ____ _____, ____ ____, and the _____ ____
cerebral cortex, basal ganglia, limbic system
63
White matter in the cerebrum includes _____?
tracts
64
Cerebrum is the area of _____ processing
higher
65
The cerebrum is divided into __ hemispheres, further divided into __ lobes, and is connected by the _____ ______
2, 4, corpus callosum
66
The basal ganglia is __ nuclei collectively termed
3
67
What are the 3 nuclei in the basal ganglia?
Globus pallidus, putamen, caudate nucleus
68
What are the major roles of the basal ganglia?
Regulating the initiation and termination of movement. Receives input from cerebral cortex and provides output to motor portions of the cortex
69
What is the role of the limbic system?
Plays a primary role in a range of emotions, including pain, pleasure, docility, affection, and anger. Also learning and memory
70
What are the 3 major components of the limbic system?
Cingulate gyrus, amygdala, hippocampus
71
The _____ ____ is the outermost layer of the cerebrum and is the integrating center for the CNS
Cerebral cortex
72
The cerebral cortex is divided into 3 specializations: ?
1. Sensory areas (sensory input into perception)
2. Motor areas ( skeletal muscle movement)
3. Association areas (integrate info from sensory and motor and helps direct voluntary behaviors and deal with complex integrative functions)
73
Describe the Frontal lobe
Skeletal muscle movement
Primary motor cortex
Motor association area
74
Describe the Parietal lobe
Primary somatic sensory cortex
Sensory association area
75
Describe the Occipital lobe
Vision
Visual association area
Visual cortex
76
Describe the Temporal lobe
Hearing
Auditory cortex
Auditory association area
77
Which cortex is responsible for taste?
Gustatory
78
Which cortex is responsible for smell?
Olfactory
79
True or False: the cortex can undergo plasticity?
True
80
The distribution of functional areas in the two hemispheres is considered ?
not symmetrical
81
Sensory systems provide us with information about the environment both ____ and _____ our body
inside, outside
82
What are examples of special senses versus somatic senses?
Special: vision, taste, smell, hearing, equilibrium
Somatic: touch, pain, itch, temperature, proprioception
83
What is the general property of a sensory system?
A sensory neuron with a transducer (receptor), that converts a physical stimulus into an intracellular signal, usually through the opening or closing of gated channels
84
Describe Simple Receptors
Neurons with free nerve endings. They may have myelinated or unmyelinated axons. Pain, itch, and temperature are under this category
85
Describe Complex Neural Receptors
Nerve endings are enclosed in connective tissue capsules. Touch and proprioception are under this category
86
Describe Special Sense Receptors
Cells that release neurotransmitter onto sensory neurons. Special senses except olfactory are under this category
87
What is considered as under the category of Chemoreceptors?
Blood chemoreceptors, taste, and smell
88
What is considered as under the category of Mechanoreceptors?
Touch, proprioceptors, auditory (hair cells), and balance (cupula)
89
What is considered as under the category of Photoreceptors?
Vision (rods and cones)
90
What is considered as under the category of Thermoreceptors?
Thermal receptors
91
Physical stimuli are transduced into_____ _____ (graded potentials)
receptor potentials
92
Mechanically gated channels converts mechanical stimulus into ______ signals
electrical
93
What are receptive fields?
Sensory neurons are activated by stimuli that fall within a specific physical area
94
______ creates larger receptive fields, whereas small receptive fields are found in more _____ areas
Convergence, sensitive
95
Somatosensory neurons bring information to the ___
CNS
96
Visceral sensory information is integrated in the _____ and _____ ____
brainstem, spinal cord
97
Almost all special and somatic sensory information is routed through the ___
thalamus
98
Special senses have dedicated _______ regions, somatic senses are integrated in the _____ ______ cortex
cortical, primary somatosensory
99
CNS distinguishes 4 properties of a stimulus: ?
1. Modality
2. Location
3. Intensity
4. Duration
100
What is sound localization?
Depends on the timing in which sound reaches the auditory cortex from each ear
101
The location of the stimulus is coded according to ?
Which receptive fields are being activated
102
Most sensory stimuli for specific regions of the body are projected to ?
Particular areas of the somatosensory cortex
103
Lateral inhibition can _____ accuracy of localization
increase
104
Because action potential amplitude is constant, ____ cannot be determined by amplitude
intensity
105
Intensity is determined by ?
The number of receptors being activated (population coding) and the frequency of action potentials coming from receptors (frequency coding)
106
Duration of stimulus is determined by ?
How long action potentials are being activated
107
Order these following statements into the following order in terms of intensity and duration of stimulus:
1. Receptor potential is integrated at the trigger zone
2. Frequency of action potential is proportional to stimulus intensity. Duration of a series of action potentials is proportional to stimulus duration
3. Neurotransmitter release varies with the patters of action potentials arriving at the axon terminal
4. Receptor potential strength and duration vary with the stimulus
4, 1, 2, 3
108
Duration also depends on _____ ______
receptor adaptation
109
What are Tonic receptors?
Slowly adapting receptors that respond for the duration of a stimulus
110
What are Phasic receptors?
Rapidly adapt to a constant stimulus and turn off
111
Each receptor is most sensitive to a particular type of _____
stimulus
112
A stimulus above threshold initiates AP's in a sensory neuron that projects to the ___
CNS
113
Stimulus intensity and duration are coded in the ?
pattern of AP's reaching the CNS
114
Stimulus location and modality are coded according to ?
which receptors are activated or by the timing of receptor activation
115
Each sensory pathway projects to a specific region of the _____ _____ dedicated to a particular receptive field. The brain can then tell the ____ of each incoming signal
cerebral cortex, origin
116
The autonomic nervous system of the ______ control of _____ muscle, _____ muscle, many _____, and some _____ tissue
involuntary, smooth, cardiac, glands, adipose
117
The autonomic system is subdivided into 2 categories: ?
Sympathetic and parasympathetic
118
Which subdivision of the autonomic system is responsible for rest-and-digest, and which is responsible for fight-or-flight
Parasympathetic: rest-and-digest
Sympathetic: fight-or-flight
119
______ reflexes are important for homeostasis
Autonomic
120
The autonomic nervous system works closely with the ____ system and ______ system to maintain homeostasis
endocrine, behavioral
121
The _______, ____, and ______ initiate autonomic, endocrine, and behavioral responses
hypothalamus, pons, medulla
122
_______ control is a hallmark of the autonomic division
Antagonistic
123
Autonomic pathways consist of __ neurons that synapse in an autonomic ganglion
2
124
______ is common in autonomic pathways, __ preganglionic will synapse with __-__ postganglionic neuron
Divergence, 1, 8-9
125
Self contained neurons within ganglia can act as mini-______ ____
integrating centers
126
Sympathetic and parasympathetic branches originate in ____ regions
different
127
Pathways differ by _____ __ ______ in the CNS and the ______ __ _____
point of origin, location of ganglia
128
In the Sympathetic system, ganglia are mainly found in __ ganglion chains running alongside the ______ column
2, vertebral
129
In the Sympathetic system, preganglionic neurons originate in what region(s)?
Thoracic and lumbar
130
In the Sympathetic system, there are ____ preganglionic, and ____ post ganglionic neurons
short, long
131
In the Parasympathetic system, preganglionic neurons originate in the _____ and exit via _____ ___ or from the ____ ____ of the spinal cord
brainstem, cranial nerves, sacral region
132
In the Parasympathetic system, the ganglia are mainly located on or near their ____ ____
target organs
133
In the Parasympathetic system, there are ____ preganglionic, and ____ post ganglionic neurons
long, short
134
In the Parasympathetic system, the cranial nerve __ (____) contains 75% of all parasympathetic neurons
X, vagus
135
The sympathetic pathways use ______ and _____
acetylcholine, norepinephrine
136
The parasympathetic pathways use ____
acetylcholine
137
Nicotinic is ____, but Adrenergic and Muscarinic are _______, while some sympathetic neurons are _____ (ACh)
ionotropic, metabotropic, cholinergic
138
True or False: all autonomic neurons are adrenergic and cholinergic?
False
139
The adrenal medulla secretes _______
catecholamines
140
The adrenal medulla is a specialized _______ structure associated with the ______ nervous system
neuroendocrine, sympathetic
141
The adrenal medulla is often described as a modified sympathetic ganglion, and contains _______ cells which are modified postganglionic neurons
chromaffin
142
Receptors are not clustered under _____, neurotransmitter diffuses to _______
varicosities, receptors
143
Autonomic neurotransmitters are synthesized in the _____
axon
144
The primary neurotransmitters, acetylcholine and norepinephrine can be synthesized in the ______
varicosities
145
Neurotransmitter release is _____ to other types of neurons
similar
146
Order these statements properly according to norepinephrine release:
1. NE is removed from the synapse
2. Action potential arrives at the varicosity
3. NE is metabolized by monoamine oxidase
4. Receptor activation ceases when NE diffuses away from the synapse
5. Ca2+ entry triggers exocytosis of synaptic vesicles
6. NE can be taken back into synaptic vesicles for re-release
7. NE binds to adrenergic receptor on target
8. Depolarization opens voltage-gated Ca2+ channels
2, 8, 5, 7, 4, 1, 6, 3
147
What is ACh synthesized from?
Choline and acetyl CoA
148
Order these statements properly according to ACh synthesis:
1. In the synaptic cleft, ACh is rapidly broken down by the enzyme acetylcholinesterase
2. Recycled choline is used to make more ACh
3. Acetylcholine (ACh) is made from choline and acetyl CoA
4. Choline is transported back into the axon terminal by the cotransport with Na+
3, 1, 4, 2
149
Sympathetic adrenergic receptors are all __-_____ ____ receptors (metabotropic receptors)
g-protein coupled
150
There are two main categories of sympathetic adrenergic receptors: ?
Alpha, the most common
Beta, with multiple subtypes
151
Parasympathetic cholinergic (ACh) receptors in target tissues are __-_____ coupled receptors: ______ receptors
g-protein, muscarinic
152
There are __ subtypes of muscarinic receptors
5
153
Where is M1 receptor found in, and the effect of the second messenger?
Found in: stomach, salivary glands
Effect of second messenger: activates phospholipase C
154
Where is M2 receptor found in, and the effect of the second messenger?
Found in: heart
Effect of second messenger: decreases cAMP, inhibits voltage gated calcium channels, activates K+ channels
155
Where is M3 receptor found in, and the effect of the second messenger?
Found in: smooth muscle of some organs, airways, glands
Effect of second messenger: activates phospholipase C
156
What is the primary function of all muscle is to ?
Generate force and/or movement in response to a physiological stimulus
157
In all muscle types, the generation of force depends on the ?
conversion of chemical energy (ATP)
158
Skeletal muscles are primarily ____ by somatic motor neurons
voluntary
159
Skeletal muscles are _____ and ______
striated, multinucleated
160
Cardiac muscles are primarily ____ by spontaneous ___ activity
involuntary, electrical
161
______ muscle can be altered by autonomic NS, or hormones
Cardiac
162
Cardiac muscles are _____ and ______
striated, uninucleated
163
Smooth muscle is primarily ____ by autonomic control, spontaneous, hormones, paracrines, or autocrines
involuntary
164
Smooth muscle provides mechanical control of ?
Digestive tract, urinary tract, reproductive tract, blood vessels, airways
165
Skeletal muscle is usually attached to ____ by ____
bones, tendons
166
What is the origin of skeletal muscle?
Closest to the trunk or to more stationary bone
167
What is the insertion of skeletal muscle?
More distal or more mobile attachment
168
What are the antagonistic muscle groups in skeletal muscle?
Flexor-extensor pairs
169
What is a flexor?
Brings bones together
170
What is an extensor?
Moves bones away
171
Skeletal muscle takes up about __% of the total body weight and __-__% of daily energy expenditure
40, 15-60
172
What is the muscle terminology equivalent of a "muscle cell?"
Muscle fiber
173
What is the muscle terminology equivalent of a "cell membrane?"
sarcolemma
174
What is the muscle terminology equivalent of a "cytoplasm?"
sarcoplasm
175
What is the muscle terminology equivalent of a "modified endoplasmic reticulum?"
sarcoplasmic reticulum
176
What is a muscle fasicle?
bundle of fibers
177
Single muscle fibers often extend the ____ length of a muscle
entire
178
Striations correspond to ordered arrays of ?
thick and thin filaments within the myofibrils
179
What is F-Actin?
Backbone of thin filaments, double stranded alpha helical polymer of G-actin molecules. Contains binding site for thick filaments (myosin)
180
What is tropomyosin?
2 identical alpha helices that coil around each other and sit in the two grooves formed by actin strands, regulates the binding of myosin to actin
181
_____ ____ is a heterotrimer
Troponin complex
182
The troponin complex consists of:
[1] troponin __ (TnT): binds to a single molecule of tropomyosin
[2] troponin __ (TnC): Ca2+ binding site
[3] troponin __ (TnI): under resting conditions is bound to actin inhibiting contraction
T, C, I
183
The troponin complex is situated every __ actin molecules
7
184
Thick filaments consist of a _____ of myosin molecules
bundle
185
Each heavy chain contains __ light chains
2
186
Thick filaments consists of __ intertwined heavy chains
2
187
Myosin head contains a region for binding ____ as well as a site for binding and hydrolyzing ___
actin, ATP
188
Regulatory light chain regulates ?
ATPase activity of myosin
189
Essential light chain stabilizes the ?
myosin head
190
What is Titin?
A very large protein extending from M line to Z line, appears to be involved in stabilization of thick filaments and the elastic recoil behavior of muscle
191
What is Nebulin?
A large protein that interacts with the thin filaments, believed to regulate the length of thin filaments and contribute to the structural integrity of myofibrils
192
What is the Z disk?
Zigzag protein structure that is the attachment site for the thin filaments
193
What are I bands?
Lightest band of sarcomere, region occupied only by thin filaments
194
What are A bands?
Darkest band of sarcomere, encompasses entire length of the thick filaments, including very dark area where thin and thick filaments overlap
195
What is the H zone?
Central region of A band, consists only of thick filaments
196
What is the M line?
Proteins form the attachment site for thick filaments, equivalent to z disk for thin filaments
197
The I band has ____ only
actin
198
The H zone has _____ only
myosin
199
The M line is where ___ is linked with accessory proteins
myosin
200
The A band is where ___ and ____ overlap
actin, myosin
201
Glucose is stored as glycogen in the _____
sarcoplasm
202
The force generated by a contracting skeletal muscle is referred to as ?
muscle tension
203
What is the sliding filament model in muscle contraction?
The sarcomere shortened during contraction. As contraction takes place, actin and myosin do not change length, but instead slide past one another
204
What is a neuromuscular junction?
Point of synaptic contact between somatic motor neuron and individual muscle fibre
205
What is excitation-contraction coupling?
An action potential initiated in the skeletal muscle fibre results in an increase in intracellular Ca2+
206
What are the brain regions involved in voluntary movements?
Primary motor cortex, corticospinal tract, upper motor neuron, alpha motor neuron
207
What are the 5 components of the primary motor cortex?
Basal ganglia, premotor cortex, thalamus, cerebellum, midbrain
208
What is the corticospinal tract?
Descending tract (ventral and interior lateral white matter)
209
What is an upper motor neuron?
Brain to brainstem or spinal cord
210
What is an alpha motor neuron?
Spinal cord (or brainstem) to muscle
211
What is a motor unit?
A single motor neuron and all the muscle fibers it innervates
212
Alpha-motor neurons are ___, ______ axons
large, myelinated
213
Each axon branches and innervates ?
several muscle fibres
214
The number of muscle fibres/motor unit varies. ____ for delicate and precise work, ____ for powerful, less precise contractions
<10, >100s
215
What is superoxide dismutase?
Enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide
216
What is ALS?
A neurodegenerative motor neuron disease. Upper and/or lower motor neurons degenerate leading to muscle atrophy and weakness from disuse
217
What are the 3 components of a neuromuscular junction?
1. Presynaptic motor neuron filled with synaptic vesicles
2. The synaptic cleft
3. The postsynaptic membrane of the skeletal muscle fibre
218
Somatic motor neuron branches at its _____ end
distal
219
The neuromuscular junction consists of 3 structures: ?
1. Axon terminals
2. Motor end plates on the muscle membrane
3. Schwann cell sheaths
220
What is a motor end plate?
The region of sarcolemma at the neuromuscular junction
221
What is the purpose of junctional folds?
Increase surface area on sarcolemma
222
Motor neuron vesicles contain _____, muscle sarcolemma contains ?
acetylcholine, nicotinic acetylcholine receptors
223
What is the extracellular matrix?
meshwork of proteins and proteoglycans
224
Nicotinic Acetylcholine receptors are members of cys-loop receptor family of ligand gated ion channels; classified as a _______ ____ _____
Monovalent cation channel
225
The opening of ACh receptor requires __ acetylcholine molecules
2
226
Na+ entry through nACh generate an _______ ___-____ _____ that spreads to adjacent voltage Na+ channels on the sarcolemma and initiates an action potential
excitatory end-plate potential
227
Once APs stop firing in the alpha motor neuron acetylcholine in the synaptic cleft must be removed, what are the 2 options?
1. Diffused away
2. Broken down to acetate and choline by the enzyme acetylcholinesterase
228
Choline is transported back into the motor neuron and combined with acetyl CoA by the enzyme ? to make acetylcholine
choline acetyltransferase
229
What does autoimmune mean?
body produced antibodies that bind to ACh receptors
230
What is Myasthenia gravis?
Means severe weakness of muscle, and is a disorder of neuromuscular transmission
231
Action potentials propagate from the sarcolemma to the interior of muscle fibres along the ?
Transverse tubule network
232
Sarcolemma penetrates into the muscle fibre in the form of __-____ and wrap around each ______ in specific regions
T-tubules, myofibril
233
The ultimate intracellular signal that triggers contraction in all muscle types is a rise in ?
intracellular calcium [Ca2+]i
234
Depending on the muscle type, Ca2+ can enter the sarcoplasm from the extracellular space via ?
Voltage gated Ca2+ channels or can be released into the sarcoplasm
235
T-tubules penetrate the muscle fibre and surround the myofibrils at 2 points in each sarcomere: ?
At the A band and I band junctions
236
Along its length the tubules are associated with 2 cisternae to form a "?"
triad
237
What is a DHP receptor?
L-type Ca2+ channel, it is voltage sensitive
238
What is a RyR?
Ryanodine receptor, it is a Ca2+ release channel on SR
239
Besides mechanically, ryanodine receptors can also be activated by ____?
Ca2+
240
An increase in [Ca2+]i triggers contraction by removing the inhibition of ?
cross bridge cycling
241
Ca2+ binds low affinity sites on troponin C which induces a conformational change in the ?, which causes the troponin complex and the tropomyosin to move, revealing the ?
troponin complex, myosin binding site on the actin
242
Order these statements in the proper order:
1. Myosin hydrolyzes ATP. Energy from ATP rotates the myosin head to the cocked position. Myosin binds weakly to actin
2. Myosin releases ADP at the end of the powerstroke
3. ATP binds to myosin. Myosin releases actin
4. Power stroke begins when Pi is released
3, 1, 4, 2
243
The release of Pi strengthens the bond between ___ and ___
actin, myosin
244
What is a power stroke?
A conformational change in which the myosin head returns to its un-cocked state and while doing so pulls the actin filament generating force and motion
245
The termination of contraction requires the removal of ?
Ca2+
246
Once the AP has subsided, Ca2+ must be removed so that the myosin binding site on actin can be converted by _______
tropomyosin
247
Ca2+ can be removed to the extracellular space by the ? or by the ?
Na-Ca exchanger, Ca2+ pump which uses ATP
248
_______ and _____ maximize Ca2+ uptake by the SR
Calsequestrin, calreticulin
249
Order these statements according to Ca2+ reuptake into the SR:
1. Ca2+ is bound in the SR by calreticulin and calsequestrin
2. Na-Ca exchanger and Ca2+ pump in the plasma membrane both extrude Ca2+ from the cell
3. Ca2+ pump sequesters Ca2+ within the SR
2, 3, 1
250
Elastic recoil of titin and other connective tissues causes sarcomeres to ?
return to initial resting position
251
What is rigor mortis?
Development of rigid muscle several hours after death, Ca2+ leaks into the sarcoplasm ad binds troponin
252
Why does ATP production stop and cause rigor mortis?
Ca2+ cannot be removed (SERCA pump needs ATP), ATP needed to release myosin head from actin, and so it remains in latched cross bridge formation until muscles begin to deteriorate
253
Ca2+ reuptake into the SR is mediated by?
the sarcoplasmic and endoplasmic reticulum Ca2+-ATPase (SERCA)-type Ca2+ pump
254
In terms of the timing of E-C coupling, there is a ? between motor neuron AP and muscle fibre AP, and there is a ? between muscle fibre AP and contraction time when Ca2+ is being released and binding troponin
slight delay, delay
255
Muscles need a steady supply of ___ to function
ATP
256
What are all 3 instances in muscles where ATP is required?
1. Myosin ATPase (contraction)
2. Ca2+ ATPase: SERCA (relaxation)
3. Na+K+ ATPase ( after AP in muscle fibre)
257
What are the 2 main sources of ATP for muscles?
1. Free intracellular ATP
2. ATP formed from phosphocreatine
258
One glucose molecule can then be broken down to pyruvate by glycolysis resulting in the production of __ ATP molecules
2
259
Glycolysis takes place in the _____ of muscle
sarcoplasm
260
What is muscle fatigue?
A decrease in muscle tension as a result of previous contractile activity that is reversible with rest
261
What is Central fatigue?
The feeling of tiredness and a desire to cease activity, it preceded physiological cell fatigue
262
Low __ from acid production during ____ _____ may influence the sensation of fatigue perceived by the brain
pH, ATP hydrolysis
263
What is peripheral fatigue?
Failed excitation-contraction coupling at the T-tubule, and an accumulation of phosphate, acid and ADP
264
What are the possible problems that causes peripheral fatigue?
1. Problems with excitation-contraction coupling
2. At the T-tubule, with repeated AP firing, K+ builds up in the T-tubules changing the threshold
3. Within the muscle fibres, buildup of inorganic phosphate
265
What are the different accumulation theories in terms of muscle fatigue?
Troponin C leads to decreased Ca2+ sensitivity
Myosin head leads to the release of Pi and ADP
Sarcoplasmic reticulum leads to reduced Ca2+ reuptake and release
266
What are the two classification of skeletal muscle?
Maximal velocity of shortening (fast or slow)
The primary pathway they use to form ATP (oxidative or glycolytic)
267
The velocity of shortening is dependent on ? and differs with ?
ability to hydrolyze ATP, different isoforms of myosin heavy chain
268
Slow fibres contain _____ with _____ ATPase activity and is considered Type __
myosin, slower, I
269
Fast fibres contain _____ with _____ ATPase activity and is considered Type __
myosin, faster, II
270
Fibres containing a large amount of mitochondria have a high capacity for ____ metabolism, and are classified as ____ fibres
aerobic, oxidative
271
Fibres containing a small amount of mitochondria but have a large store of glycogen, are classified as ____ fibres
glycolytic
272
There are 3 types of skeletal muscle fibres: ?
Type I: slow-oxidative fibre
Type IIA: fast-oxidative- glycolytic fibre
Type IIX: fast-glycolytic fibre
273
What are the determinants of force on a muscle cell?
Fibre diameter, fatigability, initial resting length, frequency of activation
274
What are the determinants of force on an entire muscle?
Number of muscle cells activated
275
Muscle length influences tension development by determining ?
the degree of overlap between actin and myosin filaments
276
The amount of tension developed is ? to the number of cross bridges formed
directly proportional
277
The force developed by a muscle fibre is increased by the summation of ?
multiple twitches
278
A single action potential in a single muscle fibre results in ?
an individual muscle twitch
279
Does a single twitch represent the maximal force that a muscle fibre can develop?
No
280
If a subsequent action potential occurs before the muscle fibre is allowed to relax, a more forceful contraction occurs due to ?
summation of single twitches
281
How is summation possible?
A single AP does not cause release of the entire Ca2+ store from the SR. A second AP causes a second wave of Ca2+ that may keep additional troponin complexes activated allowing for more cross bridges to be formed so Ca2+ remains elevated for a longer period of time
282
What is tetanus?
A maintained contractile response to repeated stimuli
283
What is unfused tetanus?
Reached steady state of contraction but stimuli are far enough apart that the muscle fibre slightly relaxes between stimuli
284
What is fused tetanus?
The stimulation rate is fast enough that the fibre does not relax, instead it reaches maximum tension and remains there
285
One way to increase tension developed by a single muscle fibre is to increase ?
the rate at which action potentials occur in the fibre
286
In a whole skeletal muscle force may be increased by the recruitment of additional ?
motor units
287
What is a motor neuron pool?
The group of all motor neurons innervating a single muscle
288
What is the size principle?
As the stimulus onto the motor neuron pool increases, additional larger motor neurons are recruited
289
In a large-diameter motor neuron, Rm is ___ and conduction velocity is ___
low, high
290
In a small-diameter motor neuron, Rm is ___ and conduction velocity is ___
high, low
291
All muscle fibres within one motor unit are ? type
the same
292
Smaller motor neurons innervate ____ muscle fibres and constitute _____ motor units
smaller, smaller
293
In a whole skeletal muscle force may be increased by summing contractions of ______ ____
multiple fibres
294
Small motor neurons tend to innervate the ____ number of (_____ diameter) muscle fibres (slow-oxidative) constituting ____ motor units
least, small, small
295
Intermediate size motor neurons tend to innervate an ____ number of (_____ diameter) muscle fibres (fast-oxidative-glycolytic) establishing ____ sized motor units
intermediate, medium, intermediate
296
Large motor neurons tend to innervate a ____ number of (_____ diameter) muscle fibres (fast-glycolytic) making up ____ motor units
large, large,large
297
What is asynchronous recruitment?
During submaximal contraction the CNS modulates firing rates of upper motor neurons to allow different motor units to maintain contraction in order to prevent fatigue
298
What is tension?
The force tending to pull the attachment points of a muscle toward one another
299
What is isotonic contraction?
The muscle contracts, shortens, and creates enough force to move a load
300
What is isometric contraction
The muscle contracts but does not shorten. The force created cannot move a load
301
What is concentric contraction?
Where the muscle shortens while generating force
302
What is eccentric contraction?
Muscle lengthens while generating force and acts to decelerate the joint at the end of a movement
303
How do the sarcomeres shorten during isometric contraction without the muscle changing length?
Elastic elements in tendons, elastic and connective tissue in and around muscle fibres
304
What is the proper order of these statements: ?
1. Isometric contraction: muscle has not shortened
2. Muscle at rest
3. Isotonic contraction: the entire muscle shortens
2, 1, 3
305
How has skeletal muscle increased ATP synthesizing capacity?
Increase in mitochondria size and number, increased capillary density, increase in glycolytic enzymes
306
There is a ______ remodeling of muscle mass
constant
307
Changing rates of contractile ____ _____ and ____, regulated by pathways that are influenced by mechanical stress, physical activity, availability of nutrients, growth factors and age
protein synthesis, degradation
308
To increase muscle mass, _____ ____> _____ ____
protein synthesis, protein degradation
309
There are 2 proposed mechanisms by which muscle mass may be increased: ?
1. Hypertrophy (increased diameter)
2. Hyperplasia (increased number)
310
What are myosatellite cells?
Involved in muscle repair and may form new fibres
311
Satellite cells migrate to the damaged region and, depending on the severity of the injury, ____ to the existing muscle fibre to cause regeneration
fuse
312
When skeletal muscle is subjected to an overload stimulus, it causes perturbations in muscle fibres and the related extracellular matrix. This sets off a chain of myogenic events that ultimately leads to: ?
Increase in size of sarcomeres and number of myosin and actin
Increased number of sarcomeres within a muscle length, increased myofibrils
Increased sarcoplasmic storage (glycogen)
313
Several studies show a greater rate of myofiber hypertrophy for Type __ fibers in comparison to Type __ and is genetically predetermined
II, I
314
What is skeletal muscle atrophy?
Protein degradation > protein synthesis, and can occur due to disuse
315
What is cachexia?
Weakness and/or wasting due to chronic disease
316
Cardiac muscle is made up of _____ ____ (myocardial muscle cells) which are ______, branched cells and usually contain a ____ ____
cardiac myocytes, shorter, single nucleus
317
Cardiac muscle is interconnected by _____ _____: ______ link mechanically, and ___ ______ link them electrically
intercalated disks, desmosomes, gap junctions
318
Like skeletal muscle, cardiac muscle is ____ and has ____ containing a similar array of ____ and ___ filaments
striated, sarcomeres, thick, thin
319
Cardiac muscle has less abundant but larger __-_____ in comparison to skeletal muscle
T-tubules
320
Cardiac muscle has ___ amounts of sarcoplasmic reticulum and requires the entry of ?
smaller, extracellular Ca2+
321
Approximately 1% of myocardial cells are specialized non-contracting _____ cells (pacemakers) that generate action potentials spontaneously. This depolarization begins in the _____ ___ (main pacemaker of the heart). They are ____ and contain ___ contractile fibres
autorhythmic, sinoatrial node, smaller, few
322
Autorhythmic have an ____ resting membrane potential of -60mV, they never truly rest
unstable
323
HCN channels open from ___ to nearly ___ and allow a net influx of Na+, causing the cell to become depolarized
-60, -40
324
HCN channels close and __-___ Ca2+ channels open, allowing Ca2+ to flow in, further depolarizing the cell to reach threshold
T-type
325
Once reaching threshold __-___ Ca2+ open allowing an influx of Ca2+, causing the depolarizing spike of the action potential
L-type
326
HCN channels are only in ________ cells
autorhythmic
327
Order these statements in regards to APs in contractile myocardial cells:
1. Once the adjacent cell reached threshold voltage gated Na+ open causing the Na+ spike of action potential
2. There is a brief repolarization from fast K+ channels before the Ca2+ influx through the L-type Ca2+ channels occurs and the fast K+ channels close leading to a sustained depolarization
3. Ions that entered from an AP are transferred to adjacent cells through gap junctions leading to depolarization of the adjacent cell
4. The positive voltage change of the AP slowly opens L-type Ca2+ channels
5. Once the Ca2+ channels close, slow K+ channels repolarize the cell
3, 1, 4, 2, 5
328
Long action potential duration prevents ?
summation of contraction
329
In cardiac muscle L-type Ca2+ channels (DHP receptors) are not _____ coupled to _______ receptors therefore Ca2+ entry is necessary for contraction
mechanically, ryanodine
330
Although removal of Ca2+ to extracellular space is slightly more important in cardiac muscle, ? is still the primary mechanism
reuptake into the SR
331
In cardiac muscle the SERCA pump is regulated by ?
phospholamban
332
When phosphorylated: Ca2+-pump inhibition is removed, enhancing ? and ________
relaxation rates, contractility
333
Rate and amount of Ca2+ uptake is increased, causing ? and a ____ store of Ca2+ for subsequent contractions
quicker relaxation, larger
334
Frequency summation in individual fibres and multiple fibre recruitment are used for regulating force generation in ______ muscle
skeletal
335
In cardiac muscle an increase in intracellular Ca2+ in the cardiac myocytes enhances ______ ______
contractile force
336
Cardiac muscle is capable of _____ single twitch contractions
graded
337
If cytosolic Ca2+ is low some actin remains covered by
_______
tropomyosin
338
Cardiac muscle generates a greater force when slightly ______
stretched
339
The heart has neuronal input that modifies _______/_______
conduction, contraction
340
The heart is innervated by the ______ nervous
system
autonomic
341
The ______ increases heart rate/conduction and contractility (autorhythmic and contractile); The ________ decreases heart rate/conduction (autorhythmic)
sympathetic, parasympathetic
342
Order these statements in order of the Sympathetic modulation of Contraction:
1. Phosphorylation of SERCA increases the speed of Ca2+ re-uptake which increases Ca2+ storage
2. Increases rate of myosin ATPase
3. Phosphorylation of ryanodine receptors enhances sensitivity to Ca2+, increasing release of Ca2+ from the sarcoplasmic reticulum
4. Phosphorylation of Ca2+ channels increases calcium conductance during action potentials
4, 3, 2, 1
343
Skeletal length tension relationship explained by degree of overlap between ?
thick and thin filaments
344
A slightly stretched sarcomere increases the Ca2+ sensitivity of the ______. A stretched sarcomere has a ______ diameter which may reduce the distance that Ca2+ needs to diffuse increasing ______ of cross-bridge cycling
myofilaments, decreased, probability
345
A slightly stretched sarcomere puts additional ____ on stress-activated Ca2+ channels, increasing Ca2+ entry from ______ space and increasing Ca2+ induced Ca2+ release
tension, extracellular
346
Heart rate is under _____ control
tonic
347
Why is heart hate considered under tonic control?
Autorhythmic cells can be modulated by sympathetic and parasympathetic neurons
348
With no autonomic stimulation, autorhythmic cells of the SA node have an intrinsic firing rate of ?
~90 action potentials per minute
349
At resting heart rate of ? parasympathetic is
dominant
70-72 BPM
350
Parasympathetic neurons containing ACh mainly innervate the ? influencing autorhythmic myocardial cells, decreasing the frequency of action potentials (aka decreasing ____ ___).
SA and AV node, heart rate
351
ACh acts on _____ ____ cholinergic receptors opening K+ channels and closing T-type Ca2+ channels and HCN channels
muscarinic (M2)
352
Since the pacemaker activity does not usually reside within the AV node, these mechanisms act at the AV node to decrease ______ ____
conduction velocity
353
In HCN channels there is a ____ rate of depolarization. Slower depolarization requires more _____ to reach threshold
decreased, time
354
In K+ (GIRK) channels there is a ____ shift in maximum diastolic potential. Starting from a more negative value, ___ requires more time to reach threshold.
negative, Vm
355
In T-type Ca2+ channels there is a _____ shift in the threshold. Reaching a more positive threshold requires more ____
positive, time
356
_____ _____ receptors can be activated by NE released from sympathetic neurons or epinephrine from the adrenal medulla
Beta1 adrenergic
357
Increased Na+ conductance through HCN channels and Ca2+ through T-type channels causes: ?
Cells reach threshold more rapidly
Decreased level of repolarization
358
______ muscle must operate over a range of lengths
Smooth
359
______ muscle layers may run in several directions
Smooth
360
______ muscle contract and relax much more slowly
Smooth
361
______ muscle uses less energy to generate and maintain force
Smooth
362
______ muscle can sustain contraction without fatigue
Smooth
363
______ muscle contraction initiated electrically or chemically
Smooth
364
______ muscle controlled by autonomic nervous system
Smooth
365
______ muscle's Ca2+ from extracellular space and/or SR
Smooth
366
______ muscle Ca2+ initiates cascade eventually turning on myosin ATPase
Smooth
367
______ muscle is spindle-shaped, uninucleate cells
Smooth
368
______ muscle is troponin & T-tubules absent
Smooth
369
intermediate filaments (non-contractile) and dense bodies
(similar to z-lines) form extensive cytoskeletal structure in _____ musle
smooth
370
In ______ muscle, thin filaments are anchored to the cell membrane or dense bodies.
smooth
371
Smooth muscle myosin has _____ heads all along its length
hinged
372
Smooth muscle has functional variability, and its categorized by: ?
1. Location
2. Contraction pattern
3. Communication with neighboring cells
373
In humans smooth muscle can be divided into 6 major
groups: ?
1. Vascular: blood vessel walls
2. Gastrointestinal: walls of digestive tract and associated organs
3. Urinary: wall of bladder and ureters
4. Respiratory: airway passages
5. Reproductive: uterus in females and other reproductive structures in males and females
6. Ocular: iris and ciliary body
374
Contraction pattern in smooth muscle can be divided into 4 patterns: ?
1. A phasic smooth muscle that is usually relaxed
2. A phasic smooth muscle that cycles between contraction and relaxation
3. A tonic smooth muscle that is usually contracted
4. A tonic smooth muscle whose contraction is varied as needed
375
Communication with neighboring cells is divided into 2 categories: ?
1. Unitary (single unit) smooth muscle: contains jab junctions similar to cardiac muscle cell. Allows coordinated contraction, and is often referred to as visceral smooth muscle
2. Multiunit smooth muscle: not electrically coupled. Electrical isolation of cells allows for finer motor control
376
Smooth muscle may contract in response to _______ _____ or ________ ______
synaptic transmission, electrical coupling
377
Smooth muscle can be innervated by multiple neurons, capable of releasing different ______
neurotransmitters
378
Receptor subtype differences in muscle (α-adrenergic: ? vs β-adrenergic: _____ _____)
Gi vessel constriction, airway dilation
379
Circulating hormones, stretch and local factors, including paracrine signals, acidity, oxygen and carbon dioxide concentration, and osmolarity, can also alter smooth muscle _____
tension
380
Action potentials can be initiated by _____, ______, or ______ stimulation
neural, hormonal, mechanical
381
Slow wave potentials fire _____ _____ when they reach threshold, but pacemaker potentials always ______ to threshold
action potentials, depolarize
382
Smooth muscle cells produce a wide range of membrane potentials (Vm) and in some smooth muscle Vm oscillations can lead to tonic contractions in the absence of ?
action potentials
383
Action potentials usually do not occur in _____ smooth
muscle.
multiunit
384
Autonomic neurons create a local depolarization that spreads _______ (graded fashion) throughout the muscle fibre triggering ?
electrotonically, Ca2+ entry
385
Autonomic AP initiation (spikes or plateaus) and Spontaneous AP (slow wave, pacemaker) are for _____ _____; but, graded potentials are for ________
single units, multi units
386
Contraction due to electrical signaling is known as _________ coupling
electromechanical
387
Both extracellular entry and intracellular release of Ca2+ activate contraction and cytosolic [Ca2+]i is increased by three different mechanisms:
1. Ca2+ entry through voltage gated channels or ligand gated ion channels
2. Ca2+ release from the SR (Ca2+-induced Ca2+ release from RyR, IP3 Ca2+ release from IP3R)
3. Ca2+ entry through voltage-independent channels (store operated Ca2+ channels, stretch activated channels)
