Muscles (General, Skeletal, Smooth) Flashcards
Generated from Lectures 13-17
Skeletal muscle fibers can be up to __________ cm long.
30
A muscle cell from a biceps contains approximately __________ sarcomeres.
100,000
The protein __________ connects F-actin to the dystroglycan complex.
Dystrophin
__________ is a protein greater than 1 µm in length found in skeletal muscle.
Titin
The thick filaments of skeletal muscle are __________ nm in diameter.
16
The __________ complex is a heterotrimer consisting of three different proteins.
Troponin
The troponin subunit TnT binds to __________.
Tropomyosin
The troponin subunit TnC has two pairs of __________ binding sites.
Ca2+
When intracellular ATP is depleted, skeletal muscles enter a state of __________.
Rigor (death!!!!)
__________ muscle is not under voluntary control.
Smooth
Skeletal muscle receives excitatory neuronal input via __________ motor neurons.
Somatic
The __________ is a specialized region of the skeletal muscle fiber membrane where a motor neuron terminates.
Motor end plate
Curare is a plant alkaloid that inhibits the __________ receptor
Nicotinic acetylcholine
__________ is an autoimmune disease in which antibodies block acetylcholine receptors at the neuromuscular junction.
Myasthenia gravis
The __________ receptor in the T-tubule triggers Ca2+ release from the sarcoplasmic reticulum.
Dihydropyridine
The dihydropyridine receptor physically interacts with the __________ receptor to release Ca2+ from the sarcoplasmic reticulum.
Ryanodine
RyR1 is the primary ryanodine receptor isoform expressed in __________ muscle.
skeletal
Diltiazem and amlodipine are examples of dihydropyridine receptor __________.
antagonists
Ryanodine is a _______ alkaloid that can act as a ryanodine receptor agonist or antagonist depending on the concentration.
plant
Caffeine activates ryanodine receptors by potentiating their sensitivity to __________.
Ca2+
Malignant hyperthermia is a rare, life-threatening condition often caused by mutations in the __________ receptor gene.
Ryanodine
.
__________ is a muscle relaxant that prevents Ca2+ release from the sarcoplasmic reticulum and is used to treat malignant hyperthermia.
Dantroline
Tacrolimus is an __________ drug that binds to FKBP12, a protein that regulates ryanodine receptor activity.
immunosuppressant
SERCA stands for sarco/endoplasmic reticulum Ca2+ -__________.
ATPase
__________ is a regulatory protein that inhibits SERCA activity.
Phospholamban
Increased β-adrenergic stimulation __________ the association between SERCA and phospholamban.
reduces
The protein __________ connects actin filaments to the Z-line
α-actinin
In an __________ contraction, muscle length remains constant while force increases
isometric
In an __________ contraction, muscle shortens while force remains constant.
isotonic
__________ contraction is analogous to isovolumetric contraction in the heart.
Isometric
__________ contraction is analogous to ventricular ejection in the heart.
Isotonic
A muscle __________ is a single contraction-relaxation cycle in response to a single action potential.
twitch
The __________ of shortening is the speed at which a muscle changes length during contraction
velocity
The maximum velocity of shortening occurs at the __________ load.
smallest
The maximum force a muscle can generate occurs at the __________ load.
greatest
__________ occurs when a muscle fiber is stimulated at a high frequency and does not relax completely between stimuli.
Tetanus
__________ muscles oppose the action of agonist muscles
Antagonist
Bones act as __________ in the lever systems of the body
levers
Joints act as __________ in the lever systems of the body.
fulcrums
A __________ lever system amplifies velocity.
third-class
The force developed by a single muscle cell increases with increasing __________ of stimulation.
frequency
The force developed by a whole muscle can be increased by recruiting more __________.
motor units
__________ muscle fibers have the fastest contractile speeds.
Fast/Type II
__________ muscle fibers utilize oxidative phosphorylation to produce ATP.
Slow/Type I
__________ muscle fibers have the largest diameter
Type IIb
The __________ isoform determines a muscle fiber’s type.
Myosin heavy chain (MHC)
Skeletal muscle can produce ATP through three main pathways: direct phosphorylation, __________ glycolysis, and __________ cellular respiration.
anaerobic, aerobic
__________ is a molecule stored in muscle that can rapidly regenerate ATP from ADP.
Creatine phosphate
Creatine supplementation can modestly improve performance in __________ , __________ exercise lasting less than 30 seconds.
intensive, repetitive
Caffeine can __________ the ergogenic benefit of creatine.
counteract
__________ is the primary energy source for muscle contraction.
ATP
During short-duration exercise, ATP stored in muscles is used __________.
first
After about 10 seconds of exercise, ATP is formed from __________ and ADP.
creatine phosphate
Anaerobic glycolysis becomes the primary source of ATP production after about __________ seconds of exercise.
30-40
The anaerobic threshold is the point at which muscle metabolism shifts from __________ to __________ pathways for ATP production.
aerobic, anaerobic
During prolonged-duration exercise, ATP is generated by the breakdown of nutrient energy fuels through the __________ pathway.
aerobic
__________ is a byproduct of anaerobic glycolysis.
Lactic acid
Lactic acid can be used as fuel by the liver, __________, and __________.
kidneys, heart
The liver can convert lactic acid back into __________ or glucose.
pyruvic acid
Amateur runners often experience “hitting the wall” around kilometer 30-35 due to the depletion of __________ stores.
glycogen
__________ is the largest glycogen storage organ in the body.
Muscle
A single bout of exercise can improve whole-body __________ sensitivity for up to 48 hours.
insulin
The aerobic pathway for ATP production utilizes __________, pyruvic acid, free fatty acids, and amino acids as fuel sources.
glucose
Aerobic respiration produces approximately __________ ATP molecules per glucose molecule.
32
Approximately __________% of the energy released during muscle activity is given off as heat.
60
__________ is the body’s response to cold temperatures, involving rapid muscle contractions to generate heat.
Shivering
Malignant hyperthermia occurs due to mutations in the __________ receptor, leading to uncontrolled muscle contraction and heat production.
Ryanodine
Muscle __________ is the physiological inability to contract despite continued stimulation.
fatigue
Muscle fatigue is not primarily caused by the __________ of ATP.
depletion
Factors contributing to muscle fatigue include lactic acid buildup, __________ command fatigue, and failure of excitation-contraction coupling.
central
During recovery from exercise, __________ reserves are replenished, lactic acid is converted to pyruvic acid, glycogen stores are replaced, and ATP and creatine phosphate reserves are replenished.
oxygen
Excess __________ consumption is required after exercise to return the muscle to its resting state.
oxygen
Muscle __________ are sudden, involuntary contractions that can be painful.
cramps
Factors that can contribute to muscle cramps include dehydration, low blood levels of calcium, magnesium, or __________, and certain medications.
potassium
__________ exercise involves muscle shortening while contracting.
Concentric
__________ exercise is the most efficient way to induce muscle hypertrophy.
Isometric
__________ exercise occurs when a muscle attempts to contract while being passively stretched
Eccentric
Delayed onset muscle soreness (DOMS) and muscular injury typically result from __________ exercise.
Eccentric
During prolonged exertion, muscles produce H+ and __________, leading to acidification.
lactate
The sensation of muscle fatigue is actually a function of the __________.
brain
Muscle pain during exercise is primarily due to __________ accumulation.
harmful metabolite (H+, lactate, ATP(?))
__________ is a plant compound that activates TRPV1 receptors, which are involved in sensing lactate and muscle pain.
Capsaicin
The first phase of DOMS is thought to be caused by __________ of the muscle.
microtrauma
The second phase of DOMS involves __________ and __________ infiltration to remove damaged muscle tissue.
macrophages, neutrophils
__________ produced by macrophages contribute to the soreness experienced during DOMS.
Prostaglandin E2
DOMS typically disappears after a few __________ .
days
Muscle hypertrophy is the __________ in the size of muscle fibers.
increase
Muscle __________ is the decrease in the size of muscle fibers.
atrophy
__________ atrophy occurs when a muscle is not used, such as when immobilized in a cast.
Disuse
__________ atrophy occurs due to nerve damage, leading to loss of muscle function.
Denervation
Smooth muscle contraction is __________ (faster/slower) than skeletal muscle contraction.
slower
Smooth muscle cells lack __________ , which is present in skeletal muscle and regulates contraction.
troponin
In smooth muscle, Ca2+ activates __________ that eventually phosphorylate myosin heads, leading to cross-bridge formation.
kinases
__________ smooth muscle exhibits continuous, low-level contraction.
Tonic
__________ smooth muscle is only active for discrete periods of time.
Rhythmic/phasic
__________ smooth muscle cells act independently, while __________ smooth muscle cells function as a single unit.
Multi-unit, single-unit
Dense bodies in smooth muscle contain __________ that anchor intermediate filaments.
α-actinin
__________ is the major inhibitory neurotransmitter causing relaxation of smooth muscle in the gastrointestinal tract.
Nitric oxide
What is the name of the calcium-binding protein that, when bound to calcium, can bind to and activate myosin light chain kinase in smooth muscle?
Calmodulin
Why is calmodulin important in smooth muscle?
This complex is important because once myosin light chain kinase is activated, it can phosphorylate myosin light chains, allowing myosin to interact with actin and initiate contraction
What enzyme is responsible for dephosphorylating myosin light chains in smooth muscle, leading to relaxation?
Myosin light chain phosphatase
Name the most potent constrictor and the most common vasodilator involved in the local humoral control of smooth muscles.
The most potent constrictor is endothelin, and the most common vasodilator is adenosine
After the motor neuron action potential in skeletal muscle contraction, ______ enters voltage-gated channels and acetylcholine is released into the synapse.
Ca2+
VX nerve gas is a/an ________ inhibitor.
acetylcholinesterase
After acetylcholine binds to the motor end plate in skeletal muscle, ______ enters the muscle through channels.
sodium
What is the latent period in muscle contraction?
The amount of time it takes to generate force in a muscle after an action potential; it is not instantaneous.
EMG stands for __________ and is used to measure and observe _________.
Electromyography; individual motor unit action potentials
T-tubules full name is _______-tubules and they are found on top of the _________ in all striated muscle (cardiac and skeletal, not smooth).
transverse-tubules, sarcolemma
After an action potential in skeletal muscle, the connection between the dihydropyridine receptors and the ryanodine receptors is altered; this allows for the _________ receptors to release calcium into the _________.
ryanodine, cytosol
Ryanodine receptors are located on the _________ in skeletal muscle.
sarcoplasmic reticulum cisterna
Dihydropyridine receptors are located on the ________ in skeletal muscle.
sarcolemma (inside the t-tubule)
Dihydropyridine receptors in skeletal muscle are ________-gated.
voltage
True or False: there are multiple isoforms of ryanodine receptors.
True
RyR1 receptors are primarily expressed in _______ muscle.
skeletal
In skeletal muscle, ryanodine receptors are ______-sensitive.
voltage
In cardiac muscle (and neurons), ryanodine receptors are ______-sensitive.
calcium
True or False: in skeletal muscle, there is physical coupling of dihydropyridine receptors and ryanodine receptors.
True
RyR2 is primarily expressed in the _________.
myocardium
[Skeletal] Once calcium leaves the SR via ryanodine and dihydropyridine coupling, it activates _______ to cause muscle contraction.
troponin C
The reason why caffeine can make some people “twitchy” is because it can cause _______ receptors to become more sensitive, leading to more muscle contraction.
ryanodine
What receptor gene is defective in most cases of malignant hyperthermia?
Ryanodine receptor gene (RYR1)
The activity of RyR can be up-regulated by ______ phosphorylation
upon the activation of β-adrenergic receptor on the plasma membrane
PKA
The rate at which _________ moves calcium across the SR
membrane can be controlled by the regulatory
protein phospholamban.
SERCA
Increased β-adrenergic stimulation
__________ the association between SERCA and PLB
by the phosphorylation of PLB by PKA.
reduces
[skeletal] When PLB
is associated with SERCA, the rate of calcium
movement is ________; upon dissociation of PLB,
calcium movement _________.
reduced, increases
In stressed skeletal muscle, hyperphosphorylation of RyR1 leads to calcium leak in the _______ and less calcium available for release during contraction.
sarcoreticulum
__________ is a calcium-dependent,
non-lysosomal cysteine protease.
Calpain
A muscle fiber develops its greatest tension when there is optimal overlap between thick and ____ filaments.
thin
True or False: velocity doubles when there are multiple sarcomeres in series.
True
True or False: force doubles when there are multiple sarcomeres in series.
False, no change; doubles when multiple are in parallel
Name the three ways that muscle fibers can form ATP
- creatine phosphate
- glycolysis
- oxidative phosphorylation
_________ (type of macromolecule) enhance muscle creatine uptake.
Carbohydrates
Creatine is used (therapeutically) in ________ and _______.
chronic heart failure, mitochondrial disorders
True or False: creatine shows significant benefits on endurance aerobic exercise.
False!
Creatine in combination with caffeine and ephedra may cause _________.
stroke
During a long term event like a marathon, most ATP is produced _________ (aerobically/anaerobically)
aerobically
The anaerobic threshold is _________.
the point at which muscle metabolism converts to anaerobic
Direct phosphorylation makes _____ ATP, requires ________ (oxygen/no oxygen), and the duration of energy provided is ______ seconds.
1 ATP per creatine phosphate, no oxygen to make ATP (yes to make CP), 15 sec
Direct phosphorylation is the coupled reaction of _______ and ________ to make ATP.
creatine phosphate (CP) and ADP
The energy source for the anaerobic pathway is ________.
glucose
The anaerobic pathway produces _______ ATP per glucose, requires _______ (oxygen/no oxygen), and the duration of the energy provided lasts ______ seconds.
2 ATP per glucose, no oxygen, 30-40ish seconds
The anaerobic pathway (also known as glycolysis) makes _______ and ________.
ATP, lactic acid
Lactic acid is converted back to ______ or ______ by the ______.
glucose or pyruvate, liver
Lactic acid is used as fuel by what three organs?
liver, kidneys, heart
In anaerobic glycolysis, lactic acid accumulation can result in _________, which may slow down the reaction.
lowering the pH
“Hitting the wall” is a loss of _______ stores.
glycogen
A single bout of exercise improves whole-body insulin sensitivity for up to _____ hours.
48
The aerobic pathway uses oxygen to create ______ ATP per glucose, and the duration of energy produced lasts _______.
32, hours
What percent of energy released in muscle activity is useful as work?
~40%
The remaining energy not used as work generated in muscle activity is _________.
given off as heat, ~60%
Malignant hyperthermia results is __________.
muscle rigidity, acidosis, very high body temperatures
Type I muscle fibers have ______ (high/low) myosin-ATPase activity, and high ______ (glycolytic/oxidative) capacity.
low, oxidative
Type IIa muscle fibers have ______ (high/low) myosin-ATPase activity, and high ______ (glycolytic/oxidative) capacity.
high, oxidative
Type IIb muscle fibers have ______ (high/low) myosin-ATPase activity, and high ______ (glycolytic/oxidative) capacity.
high, glycolytic
What is muscle fatigue?
Physiological inability for muscles to contract despite continued stimulation
Muscle fatigue occurs when ___________ imbalances interfere with E-C coupling, and/or prolonged exercise damages the _______ and interferes with calcium regulation and release.
ionic imbalances (K+, Ca2+, inorganic phosphate), SR
In order to fix oxygen debt after exercise, what occurs?
High heart rate and breathing rate continue after exercise stops, elevated blood flow
How do you prevent skeletal muscle cramps?
Hydration, fitness, and an adequate diet
Delayed onset muscle soreness and muscular injury
usually results from extensive __________ exercise.
eccentric
Some of the pH receptors in afferent neurons that help to signal that muscle damage may be occurring (muscle fatigue) are ________.
ASIC (acid sensing ion current) receptors, Transient Receptor Potential Channel (TRPV1), Purinergic (P2X) receptors
ASIC receptors sense ______ when muscle damage occurs.
H+ (low pH)
TRPV1 receptors sense ________ when muscle damage occurs.
lactate (lactic acid)
Purinergic (P2X) receptors sense ______.
ATP
A sensation of fatigue occurs when the pH is _____, the concentration of ATP is _______nM, and the concentration of lactate is _______mM.
7.3, 400nM ATP, 1mM lactate
A sensation of pain occurs when the pH is _____, the concentration of ATP is _______nM, and the concentration of lactate is _______mM.
7.2, 500nM ATP, 10mM lactate
Soreness in the second phase of DOMS is thought to be due to _________.
inflammatory bradykinin
Muscles that aren’t used will atrophy, represented in the phrase “____________”.
use it or lose it
_______ represent the largest mass of cells within our body.
Muscle cells
______________ lipids increase with increase adipose tissue, leading to insulin-signaling disruption and impaired glucose uptake.
Intramyocellular lipids (IMCL)
Type I fibers have _____ (many/few) mitochondria, ______ (many/few) capillaries, ______ (high/low) myoglobin content, and have a _______ rate of fatigue.
many, many, high (red), slow
Type IIa fibers have _____ (many/few) mitochondria, ______ (many/few) capillaries, ______ (high/low) myoglobin content, and have a _______ rate of fatigue.
many, many, high (red), intermediate
Type IIb fibers have _____ (many/few) mitochondria, ______ (many/few) capillaries, ______ (high/low) myoglobin content, and have a _______ rate of fatigue.
few, few, low (white), fast
Red or white muscle is determined by _______ content.
myoglobin; high myoglobin = red, low myoglobin = white
Type I fibers are also known as __________.
slow-oxidative
Type IIa fibers are also known as _______.
fast-oxidative-glycolytic
Type IIb fibers are also known as _______.
fast-glycolytic
Skeletal muscle maintains a more _______ resting membrane potential than neurons.
negative
In skeletal muscle, the t-tubule membranes contain a ______ channel that helps contribute to Vm.
chloride (ClC-1)
True or False: smooth muscle has sarcomeres.
False, only cardiac and skeletal have sarcomeres
The regulatory proteins for contraction in skeletal muscle are ______________.
troponin and tropomyosin
The regulatory proteins for contraction in smooth muscle are ______________.
calmodulin and myosin light chain kinase
The regulatory proteins for contraction in cardiac muscle are ______________.
troponin and tropomyosin
The M line in a sarcomere is ___________.
the region in the center of the H zone that contains proteins that hold thick filaments together at the center of the sarcomere.
The Z discs in a sarcomere are ___________.
narrow, plate-shaped regions of dense material that separate one sarcomere to the next.
The A band in a sarcomere is ___________.
the dark, middle part of the sarcomere that extends the entire length of the thick filaments, and includes those parts of the thin filaments that overlap thick filaments.
The I band in a sarcomere is ___________.
the lighter, less dense area of the sarcomere that contains remainder of thin filaments but no thick filaments. A Z disc passes through center of each I band.
The H zone in a sarcomere is ___________.
the narrow region at the center of each A band that contains thick filaments but no thin filaments.
One tropomyocin has _____ actin monomers.
7
Muscle is relaxed when there is _______ (low/high) cytosolic calcium.
low
Muscle is activated when there is _____ (low/high) cytosolic calcium.
high
In the troponin complex, TnI binds to _______ and inhibits contraction.
actin
In the troponin complex, TnC binds to ________.
calcium
In the troponin complex, TnT binds to _________.
tropomyosin
_________ is a structural protein that forms the M line of a sarcomere; it binds to titin and connects adjacent _____ filaments.
Myomesin, thick
________ is a structural protein that wraps around the entire length of each _____ filament. It helps anchor _____ filaments to Z discs.
Nebulin, thin
________ is a structural protein that helps to transmit tension generated by sarcomeres to tendons.
Dystrophin
Smooth muscle thin actin filaments lack ______.
troponin
Smooth muscle Ca2+ activates ________ that will eventually induce conformational changes of the myosin heads in order to form cross bridges
kinases
True or False: Smooth muscle cell overall contraction squeezes the cell from every direction
True
Contraction is much ________ (faster/slower) in smooth muscle relative to striated muscle
slower
Single-unit smooth muscle have _________ gap junctions than multi-unit smooth muscle.
more
Multi-unit smooth muscle is ______ (location), while single-unit smooth muscle is found in the _______ (location).
vascular, GI tract
Filaments in smooth muscle are organized in _______.
slightly
diagonal chains
In smooth muscle, _______ attach intermediate filaments (vimentin & desmin) which serve as anchors from which the thin filaments can exert force
dense bodies
True or False: In smooth muscle, actin myosin overlap persists in stretched state, meaning that there is no loss of cross bridge potential.
True
True or False: In smooth muscle, resting length is above optimal length
False, resting length is below optimal length
The most potent intrinsic constrictor in smooth muscle is ________.
peptide endothelin
The most common intrinsic vasodilator in smooth muscle is ________.
adenosine
True or False: There is no specialized connection between the nerve fiber and the smooth muscle cell, unlike in skeletal muscle
True
True or False: Smooth muscle can be made to contract by hormones and paracrine agents
True
Smooth muscle myosin needs to be _________ to bind actin
phosphorylated
In smooth muscle, myosin phosphorylation by _______ allows actin-myosin interaction
Myosin Light Chain Kinase (MLCK)
In smooth muscle, phosphorylation of myosin light chain by protein kinase C _______ (inhibits/activates) actin-myosin interaction.
inhibits
True or False: In smooth muscle, MLCK & PKC phosphorylation sites on myosin light chain are different
True
In the absence of Ca2+ , caldesmon binds ______.
actin, analogous to troponin in skeletal muscle (remember, smooth muscle doesn’t have troponin!)
In smooth muscle, calcium ______ (promotes/inhibits) contraction.
promotes
True or False: Smooth muscle cell response can be a graded response.
True
True or False: In smooth muscle, there cannot be contraction without a change in resting membrane potential.
False, no change in Vm is needed (example: IP3 calcium release, kinase activity)
In skeletal muscle, the resting membrane potential is around _____.
-90mV
In skeletal muscle, the Vm is greater (-90mV) because of an increased ________ gradient, an increased ________ gradient, and a greater resting _______ permeability.
sodium, chlorine, chlorine
The sarcoplasmic reticulum contains ________, a calcium-binding protein.
calsequestrin
Of the two pairs of calcium-binding sites in TnC, one high-affinity and always ___________, while the other is low-affinity and calcium binding results in _________.
bound under physiological conditions (to calcium or magnesium); results in a conformational change
A myofibril cross-section has ______ arrangement; this means that ____ thick filaments surround a thin filament and ______ thin filaments surround a thick filament.
3-6 arrangement; 3; 6
What is compartment syndrome?
Fluid/pressure build up in
a muscle compartment
What type of disorder is fibromyalgia?
A non-articular rheumatic disorder
Contraction regulation in smooth muscle can be controlled by many things, name some.
ACh and NE; hormones; local chemical changes; stretching
True or False: Skeletal muscle has no junctions between fibers.
True
_________ is a movement disorder in which involuntary sustained or intermittent muscle contractions cause twisting and repetitive movements, abnormal postures, or both.
Dystonia
_________ is an ongoing random-appearing sequence of one or more discrete involuntary movements or movement fragments.
Chorea
True or False: Skeletal muscle doesn’t hyperpolarize.
True (tetanus wouldn’t be possible if it did)
Name the five stages of the Muscle Contraction Cycle (Power-Stroke)
Attached State; Released State; Cocked State; Cross-Bridge State; Power-Stroke State
In the Muscle Contraction Cycle, ADP is released from the myosin head between the ________ State and the _________ State.
Power-Stroke, Attached
In the Muscle Contraction Cycle, what occurs to change from the Attached State to the Released State?
ATP binds to the myosin head, causing dissociation of the actin-myosin complex
In the Muscle Contraction Cycle, what occurs to change from the Released State to the Cocked State?
ATP is hydrolyzed, causing the myosin heads to return to their resting conformation
In the Muscle Contraction Cycle, what occurs to change from the Cocked State to the Cross-Bridge State?
An increase in calcium causes a cross-bridge to form, and the myosin head binds to a new site on actin
In the Muscle Contraction Cycle, what occurs to change from the Cross-Bridge State to the Power-Stroke State?
Inorganic phosphate is released. The myosin heads change conformation, resulting in the power stroke. The filaments slide past each other
In the Muscle Contraction Cycle, what occurs to change from the Power-Stroke State to the Attached State?
ADP is released
The sources of calcium in both cardiac and smooth muscle are the SL and the SR; however, it is only the _____ in skeletal muscle.
SR
In skeletal muscle, cytosolic calcium can be removed via _____ which pumps out calcium, and ______ which exchanges sodium and calcium.
PMCA, NCX
_________ is used to re-sequester calcium into the SR.
SERCA
In the SR, calcium is bound by ________ and _________.
calreticulin, calsequestrin
PMCA stands for __________.
Plasma Membrane Ca2+ ATPase
SERCA stands for __________.
Sarco/Endoplasmic Reticulum Ca2+ -ATPase
SERCA is normally inhibited by ______, with which it is closely associated.
phospholamban (PLB)
In the NCX, ______ sodium are exchanged for 1 calcium.
3
In smooth muscle, thromboxane and TXA receptor binding releases ______.
Rho
In smooth muscle, Rho binds to Rho kinase and activates it. Rho kinase inactivates ________.
MLCP (myosin light chain phosphatase)
________ is a calcium binding protein that tonically inhibits the ATPase activity of myosin in smooth muscle.
Calponin
In the smooth muscle, the absence of calcium causes _______ to bind actin.
caldesmon
In smooth muscle, calcium release from the SR can occur due to calcium-induced calcium release or ___________.
IP3 activation of SR calcium channels
In smooth muscle, calcium enters the cytoplasm via channels located in _______.
caveoli
The two types of action potentials in smooth muscle are __________ and ___________.
Pacemaker potentials, Oscillation potentials
In smooth muscle, acetylcholine release causes ________.
contraction via muscarinic receptors
In smooth muscle, epinephrine/norepinephrine release causes ________.
a variable response, depends on what receptor (alpha, beta adrenergic)
In smooth muscle, nitric oxide release causes ________.
the production of cGMP, which relaxes smooth muscle
In general in smooth muscle, the parasympathetic nervous system ______ (raises/lowers to cause depolarization/hyperpolarization) Vm while the sympathetic nervous system ________ (raises/lowers Vm to causes depolarization/hyperpolarization).
Para raises to cause depolarization, sympa lowers to cause hyperpolarization (usually)
What are varicosities in smooth muscle?
Swellings in nerve fibers that release neurotransmitter when it passes “close” to the smooth muscle cells
What is myogenic autoregulation in smooth muscle?
It’s a type of intrinsic control where stretching of the smooth muscle cells induces spontaneous depolarization and contraction.
What are some examples of humoral control compounds in smooth muscle?
angiotensin II, ADH (vasopressin), epinephrine, ANP (atrial natriuretic peptide)
In smooth muscle, sympathetic activation of α adrenergic receptors primarily causes _________, while β adrenergic receptors causes __________.
contraction, relaxation
