Notes in ✧ Muscle and Contraction

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Published	01/14/2024	The calcium channels that open during the plateau phase (myocardial action potential) are {{c1::L}}-type channels
Published	01/14/2024	The {{c1::sarcomere}} is the contractile unit of the myocardial cell
Published	01/14/2024	What part of a myocardial cell is responsible for carrying action potentials into the cell interior?{{c1::T tubules}}
Published	01/14/2024	What part of a myocardial cell is the site of storage and release of Ca2+ for excitation-contraction coupling?{{c1::Sarcoplasmic Reticulum (SR)}}
Published	01/14/2024	During the plateau of a myocardial action potential, Ca2+ enters the cell through {{c1::dihydropyridine}} receptors (L-type Ca2+ channels)
Published	01/14/2024	Entry of Ca2+ into the myocardial cell during the myocardial action potential triggers further release of Ca2+ through {{c1::ryanodine}} receptors (Ca…
Published	01/14/2024	In the myocardial cell, high intracellular Ca2+ binds to {{c1::troponin C}}, causing {{c2::tropomyosin}} to move out of the way, which allows actin an…
Published	01/14/2024	The magnitude of the tension that develops during myocardial excitation-contraction coupling is proportional to levels of intracellular {{c1::Ca2+}}
Published	01/14/2024	Relaxation of a myocardial cell occurs when:- Ca2+ is reaccumulated in the sarcoplasmic reticulum by the action of {{c1::Ca2+ ATPase (SERCA)}}- Ca2+ …
Published	01/14/2024	{{c1::Gap junctions}} are low-resistance paths between cardiac cells that allow for rapid electrical spread of action potentials
Published	01/14/2024	Contractility, or {{c1::inotropism}}, is the intrinsic ability of myocardial cells to develop force at a given muscle length
Published	01/14/2024	A positive inotropic effect {{c1::increases}} heart contractility
Published	01/14/2024	A negative inotropic effect {{c1::decreases}} heart contractility
Published	01/14/2024	Cardiac contractility correlates directly with intracellular {{c1::Ca2+}} concentration
Published	01/14/2024	Sympathetic stimulation increases myocardial contractility via {{c1::β1}} receptors
Published	01/14/2024	Sympathetic stimulation increases the activity of {{c2::Ca2+ ATPase aka SERCA}} via phosphorylation/inhibition of {{c1::phospholamban}}
Published	01/14/2024	Parasympathetic stimulation decreases {{c3::atrial}} contractility via {{c1::M2}} receptors
Published	01/14/2024	What effect does increased heart rate have on cardiac contractility?{{c1::Increased contractility (to an extent)}}
Published	01/14/2024	What effect does decreased heart rate have on cardiac contractility?{{c1::Decreased contractility}}
Published	01/14/2024	Cardiac contractility increases with {{c1::increased::increased or decreased}} catecholamines
Published	01/14/2024	Cardiac contractility increases with {{c1::increased}} intracellular Ca2+
Published	01/14/2024	Cardiac contractility increases with {{c1::decreased}} extracellular Na+
Published	01/14/2024	What is the effect of cardiac glycosides on contractility? {{c1::Increased contractility}}
Published	01/14/2024	Cardiac glycosides exert their actions via direct inhibition of the {{c1::Na+-K+ ATPase}} pump
Published	01/14/2024	What effect do cardiac glycosides have on intracellular Na+ concentration?{{c1::Increased}}
Published	01/14/2024	Increased intracellular [Na+] in cardiac myocytes causes decreased activity of the {{c1::Ca2+-Na+}} exchanger
Published	01/14/2024	Decreased activity of the Ca2+-Na+ exchanger (e.g. due to cardiac glycosides) causes {{c1::increased}} intracellular Ca2+ concentration
Published	01/14/2024	The velocity of shortening of cardiac muscle is maximal when afterload is {{c1::zero}}
Published	01/14/2024	The velocity of shortening of cardiac muscle {{c1::decreases}} as afterload increases
Published	01/14/2024	{{c1::Stroke volume}} is defined as the volume of blood ejected by one ventricular contraction
Published	01/14/2024	{{c1::Ejection fraction}} is defined as the fraction of the end-diastolic volume that is ejected in each stroke volume
Published	01/14/2024	The equation {{c1::SV = EDV - ESV}} may be used to calculate stroke volume
Published	01/14/2024	The equation {{c1::ejection fraction = SV/EDV}} may be used to calculate ejection fraction
Published	01/14/2024	Cardiac {{c2::contractility}} can be estimated by the left ventricular {{c1::ejection fraction}}
Published	01/14/2024	Ejection fraction is normally > {{c1::55}}%
Published	01/14/2024	What equation is used to calculate cardiac output given a patients stroke volume and heart rate?{{c1::CO = SV x HR}}
Published	01/14/2024	The Frank-Starling relationship states that the force of {{c1::contraction}} is proportional to the {{c2::end-diastolic length}} of the cardiac muscle…
Published	01/14/2024	What is the effect of increased venous return on end-diastolic volume (EDV)?{{c1::Increased EDV}}
Published	01/14/2024	Increases in contractility cause the Starling curve to shift {{c1::upward}}
Published	01/14/2024	Decreases in contractility (e.g. heart failure) cause the Starling curve to shift {{c1::downward}}
Published	01/14/2024	Exercise causes the Starling curve to shift {{c1::upward}}
Published	01/14/2024	{{c1::Isovolumetric contraction}} is the first phase of a cardiac cycle and represents the period between mitral valve closing and aortic valve openin…
Published	01/14/2024	{{c1::Ventricular (systolic) ejection}} is the second phase of a cardiac cycle and represents the period between aortic valve opening and closing
Published	01/14/2024	{{c1::Isovolumetric relaxation}} is the third phase of a cardiac cycle and represents the period between aortic valve closing and mitral valve opening…
Published	01/14/2024	{{c1::Rapid ventricular filling}} is the fourth phase of a cardiac cycle and represents the period just after mitral valve opening
Published	01/14/2024	{{c1::Reduced filling}} is the fifth phase of a cardiac cycle and represents the period just before mitral valve closing
Published	01/14/2024	The {{c2::width}} of a pressure-volume loop is the {{c1::stroke volume}}
Published	01/14/2024	Preload is approximated by ventricular {{c1::end-diastolic volume (EDV)}}
Published	01/14/2024	What effect does increased venous return have on preload?{{c1::Increased preload}}
Published	01/14/2024	Afterload is approximated by {{c1::mean arterial pressure}}
Published	01/14/2024	What effect does increased aortic pressure have on afterload?{{c1::Increased afterload}}
Published	01/14/2024	Increased {{c2::preload}} results in a(n) {{c1::increased}} width on a pressure-volume loop curve
Published	01/14/2024	Increased {{c2::afterload}} results in a(n) {{c1::decreased}} width and {{c1::increased}} height on a pressure-volume loop curve
Published	01/14/2024	Increased {{c2::contractility}} results in a(n) {{c1::increased}} width and {{c1::increased}} height on a pressure-volume loop curve
Published	01/14/2024	What effect does increased preload have on stroke volume? {{c1::Increased SV}}
Published	01/14/2024	What effect does increased afterload have on stroke volume? {{c1::Decreased SV}}
Published	01/14/2024	What effect does increased afterload have on end-systolic volume? {{c1::Increased ESV}}
Published	01/14/2024	What effect does increased contractility have on end-systolic volume? {{c1::Decreased ESV}}
Published	01/14/2024	What effect does increased contractility have on stroke volume? {{c1::Increased SV}}
Published	01/14/2024	What effect does increased preload have on ejection fraction? {{c1::Increased EF}}
Published	01/14/2024	Which phase of the cardiac cycle is the period of highest O2 consumption? {{c1::Isovolumetric contraction}}
Published	01/14/2024	According to the law of Laplace, cardiac wall stress = {{c1::P*r / 2H}}
Published	01/14/2024	Cardiac O2 consumption is directly related to the amount of {{c1::tension}} developed by the ventricles
Published	01/14/2024	What is the effect of increased afterload (increased aortic pressure) on cardiac O2 consumption? {{c1::Increased O2 consumption}}
Published	01/14/2024	What is the effect of increased ventricular diameter on cardiac O2 consumption? {{c1::Increased O2 consumption}}
Published	01/14/2024	What is the effect of increased contractility on cardiac O2 consumption? {{c1::Increased O2 consumption}}
Published	01/14/2024	What is the effect of increased heart rate on cardiac O2 consumption? {{c1::Increased O2 consumption}}
Published	01/14/2024	The reasons there is concentric left ventricular hypertrophy in response to systemic hypertension is that {{c1::increased}} wall thickness {{c1::decre…
Published	01/14/2024	The left ventricle compensates for increased afterload by {{c1::thickening (hypertrophy)}} in order to decrease wall tension
Published	01/14/2024	What effect does increased aortic pressure (afterload) have on cardiac wall stress?{{c1::Increased wall stress}}
Published	01/14/2024	According to the Fick principle: {{c2::Cardiac Output (CO)}} = {{c1::O2 consumption / (arterial O2 content - venous O2 content)}}
Published	01/14/2024	The resistance of a vessel may be calculated using Poiseuille's equation, which states R = {{c1::8ηl/πr4}}
Published	01/14/2024	The likelihood of turbulent flow may be calculated using Reynolds' number, which states NR = {{c1::ρdv/η}}
Published	01/14/2024	How does increased efferent sympathetic firing (e.g. baroreceptor reflex) affect contractility?{{c1::Increased contractility}}
Published	01/14/2024	What is the effect of β1-blockade on contractility (and SV)? {{c1::Decreased contractility}}
Published	01/14/2024	Class IV antiarrhythmics (non-dihydropyridine CCBs) are specific for the L-type calcium channel receptors in the {{c1::heart::overall location in the …
Published	01/14/2024	What drug class do diltiazem and verapamil belong to?{{c1::Class IV antiarrhythmics (non-dihydropyridine Ca2+ channel blockers)}}
Published	01/14/2024	Class IV antiarrhythmics (non-dihydropyridine CCBs) {{c1::decrease}} conduction velocity through the AV node
Published	01/14/2024	Cardiac glycosides (e.g. digoxin) exert their effects via inhibition of the {{c1::Na+-K+ ATPase}} pump
Published	01/14/2024	{{c2::Non-dihydropyridine}} CCBs primarily block L-type calcium channels in {{c1::cardiac}} muscle
Published	01/14/2024	Dihydropyridine CCBs have a(n) {{c1::-dipine}} suffix
Published	01/14/2024	Verapamil and diltiazem are both examples of {{c1::non-dihydropyridine}} Ca2+ channel blockers
Published	01/14/2024	{{c2::Non-dihydropyridine}} CCBs {{c1::decrease}} cardiac contractility and cardiac output
Published	01/14/2024	Inhibition of the SA node by non-dihydropyridine CCBs can cause {{c1::bradycardia}}
Published	01/14/2024	Which Ca2+ channel blockers have the most potent effects on vascular smooth muscle?{{c1::Amlodipine, Nifedipine::2}}
Published	01/14/2024	Which Ca2+ channel blocker has the most potent effects on cardiac muscle?{{c1::Verapamil}}
Published	01/14/2024	Activation of {{c2::β1}} adrenergic receptors on the cardiac myocytes causes {{c1::increased}} cardiac contractility
Published	01/14/2024	Unlike phenylephrine, norepinephrine causes increased {{c1::cardiac contractility}} due to β1 activation which results in increased pulse pressur…
Published	01/14/2024	The motor component of skeletal muscle reflexes is mediated by {{c1::lower::upper or lower}} motoneurons
Published	01/14/2024	The inverse muscle stretch reflex uses {{c1::Golgi tendon}} organs to monitor muscle {{c2::tension}}
Published	01/14/2024	In the inverse muscle stretch reflex, increased tension increases afferent impulses via {{c1::Ib}} nerve fibers
Published	01/14/2024	In the inverse muscle stretch reflex, some Ib afferent fibers inhibit {{c1::agonist::agonist or antagonist}} muscles causing muscle relaxation
Published	01/14/2024	{{c1::Malignant hyperthermia}} is a skeletal muscle hypersensitivity to volatile anesthetics
Published	01/14/2024	In addition to inhaled anesthetics, malignant hyperthermia may also be caused by {{c1::succinylcholine}} (muscle relaxant)
Published	01/14/2024	Malignant hyperthermia is usually related to a defect in {{c1::ryanodine}} receptors, which causes {{c2::increased}} Ca2+ release from the SR
Published	01/14/2024	Excessive heat production in malignant hyperthermia induces fever and {{c1::muscle damage (e.g. rhabdomyolysis)}}
Published	01/14/2024	Malignant hyperthermia is treated by {{c1::dantrolene}}, which is a(n) {{c2::ryanodine}} receptor antagonist that prevents release of Ca2+ from t…
Published	01/14/2024	Dantrolene is a muscle relaxant that is used to treat {{c1::malignant hyperthermia}} and {{c2::neuroleptic malignant syndrome}}
Published	01/14/2024	Complications of succinylcholine include {{c2::hyper}}-calcemia, {{c2::hyper}}-kalemia, and {{c1::malignant hyperthermia}}
Published	01/14/2024	{{c1::T-tubules}} are extensions of plasma membrane found in {{c2::striated}} muscle
Published	01/14/2024	T-tubules allow for {{c1::coordinated}} contraction of muscles
Published	01/14/2024	A(n) {{c1::triad}} is a structure found in {{c2::skeletal}} muscle which contains 1 {{c3::T-tubule}} with 2 {{c3::terminal cisternae}}
Published	01/14/2024	A(n) {{c1::dyad}} is a structure found in {{c2::cardiac}} muscle which contains 1 {{c3::T-tubule}} with 1 {{c3::terminal cisterna}}
Published	01/14/2024	The first step of muscle contraction occurs when the {{c1::somatic motor}} neuron depolarizes, opens {{c2::Ca2+}} channels and {{c3::ACh}} is released…
Published	01/14/2024	The second step of muscle contraction occurs after {{c1::ACh}} has been released by the motor neuron and binds to {{c2::nicotinic cholinergic}} recept…
Published	01/14/2024	In muscle contraction, after the muscle cell is depolarized, the action potential travels down the {{c1::T-tubule}} and to the {{c2::dihydropyridine r…
Published	01/14/2024	Once a(n) {{c1::conformational}} change is induced in the {{c2::dihydropyridine receptor::long name}}, it opens the {{c3::ryanodine receptor}} which r…
Published	01/14/2024	After the {{c1::ryanodine}} receptor is opened, the Ca2+ that is released binds to {{c2::troponin C}}. This induces a conformational change that moves…
Published	01/14/2024	In muscle contraction, the {{c1::power stroke}} occurs when myosin binds to actin after releasing Pi
Published	01/14/2024	During muscle contraction:- the {{c1::H}} and {{c1::I}} bands, and distance between Z bands, are shortened- the {{c2::A}} band remains the same length
Published	01/14/2024	After the power stroke in muscle contraction, binding of a new {{c1::ATP}} molecule causes {{c2::detachment}} of the {{c3::myosin head}} from the acti…
Published	01/14/2024	After myosin binds a new ATP molecule in muscle contraction, hydrolysis of the new ATP molecule to ADP allows the myosin head to adopt a(n) {{c1::high…
Published	01/14/2024	Type {{c1::I}} muscle fibers are also known as slow twitch muscle fibers
Published	01/14/2024	Slow twitch muscle fibers are {{c1::red::color}} due to {{c2::increased}} myoglobin concentration
Published	01/14/2024	Fast twitch muscle fibers are {{c1::white::color}} due to {{c2::decreased}} myoglobin concentration
Published	01/14/2024	Slow twitch muscle fibers perform more {{c1::oxidative phosphorylation}} due to increased {{c2::mitochondria}}
Published	01/14/2024	Fast twitch muscle fibers perform less {{c1::oxidative phosphorylation}} due to decreased {{c2::mitochondria}}
Published	01/14/2024	Type {{c1::II}} muscle fibers are also known as fast twitch muscle fibers
Published	01/14/2024	Type {{c1::I}} muscle fibers are increased in proportion after endurance training
Published	01/14/2024	Type {{c1::II}} muscle fibers are increased in proportion after weight/resistance training and sprinting
Published	01/14/2024	{{c1::Acetylcholine}} and {{c2::bradykinin}} are stimuli for {{c3::NO}} production in endothelial cells
Published	01/14/2024	{{c1::NO}} is synthesized from {{c2::L-arginine}} via {{c3::NO synthase}}
Published	01/14/2024	{{c4::Ca2+}} enters smooth muscle cells via {{c3::L}}-type {{c4::Ca2+}} channels and binds to {{c1::calmodulin}}, leading to smooth muscle {{c2::contr…
Published	01/14/2024	NO upregulates {{c1::guanylyl cyclase}}, which converts GTP to cGMP
Published	01/14/2024	cGMP stimulates {{c1::myosin-light-chain phosphatase}}, which {{c2::dephosphorylates}} myosin and {{c2::relaxes}} smooth muscle
Published	01/14/2024	The Ca2+-calmodulin complex upregulates {{c1::myosin-light-chain kinase}}, which {{c2::phosphorylates}} myosin and {{c2::contracts}} smooth muscle
Published	01/14/2024	The intermediate filament Desmin is found in {{c1::muscle}} cells
Published	01/14/2024	Glycogenolysis and skeletal muscle contraction are synchronized via intracellular accumulation of {{c1::Ca2+}} following neuromuscular stimulation
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