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56 Cards in this Set
- Front
- Back
3 layers of heart
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endothelium, myocardium, endocardium
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Largest layer of heart that contracts
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myocardium
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Innermost layer of heart
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endothelium
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Pressure is greater in atria than in the ventricles, what valve opens?
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AV valves
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When the ventricle starts to contract, what happens to the AV valves and why?
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slam shut to prevent backflow into atria
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When the ventricle contracts more, what valves opens?
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semilunar valves
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The pressure in the aorta and pulmonary arteries is greater than the ventricle, what happens?
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semilunar valves slam shut
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AV valve is between what?
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Atria and ventricle
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The Chordae tendinae does/does not open and shut AV valve
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does not, it prevents backflow
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Where do you find semilunar valves
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juncture where major arteries leave ventricles
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When ventricular pressure is greater than arterial pressure, what happens
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semilunar valves open
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When do semilunar valves slam shut?
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When arterial pressure is greater than ventricular pressure
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Are there valves between the atria and veins?
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no
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2 types of cardiac muscle cells
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autorhythmic, contractile
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Do autorhythmic cells contract? What is their function?
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No, Specialized for initiating and conducting action potentials responsible for contraction of working cells
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What cells do the mechanical work of pumping?
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contractile
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Do contractile cells initiate their own action potentials?
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No
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autorhythmic action potential process
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Potassium channels close, potassium leaks out, funny sodium channels (are always open) and sodium goes in, cell depolarizes and channels open,, calcium channels open, calcium in, potassium channels open, potassium out, hits "rest"
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autorhythmic cells have ___ sodium channels, two types of ____ channels which are ___ and ____.
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funny (stay open), calcium, T-type (transient), L-type (long-lasting)
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SA node controls contractions of ___ and av node controls contractions of ____
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atria, ventricle
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Spread of Excitation
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interarterial pathway, internodal pathway, AV node transmission, ventricular excitation
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What contracts first in ventricle?
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apex
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Similarities between skeletal and cardiac muscle
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both are striated, sarcomeres, both use troponin and tropomyosin, both have T-tubules (spread quickly), sarcoplasmic reticulum, oxidative fibers
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Differences between skeletal and cardiac muscle
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intercalated disks (w/ gap junctions), desmosomes for stretching, innervated by Autonomic, influenced by hormones, calcium comes from ECF and sarcoplasmic reticulum
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Does summation or tetanus occur in cardiac muscle? Why or why not?
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No, because of the long refractory period and plateau phase
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L-Type calcium channels cause long ____ ____ in cardiac muscle
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refractory period
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What 3 ways is calcium removed from the cytosol?
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Ca ATPase in SR, Ca ATPase on plasma membrane, Na-Ca exchanger on plasma membrane
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Which is longer, diastole or systole
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diastole
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Mechanical activity consisting of alternate periods of_____ which is _____ and ______ which is _______
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systole, contraction, diastole, relaxing
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Four phases of Cardiac Cycle
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Ventricular filling, Isovolumetric ventricular contraction, Ventricular ejection, and Isovolumetric ventricular relaxation
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SV = EDV -ESV. When you increase End diastole volume, you ____ stroke volume. When you increase end systole volume, you _____ stroke volume
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increase, decrease
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First heart sound
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AV valves closing
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Second heart sound
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Semilunar valves closing
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Which sound is louder and why?
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Second heart sound because semilunar valves are under more pressure
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AV closing is at the beginning of isovolumetric ____ ____ , whereas the semilunar closing is at the beginning of the ____ ____ ____
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ventricular contraction, isovolumetric ventricular relaxation
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Formula for Cardiac output
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CO = HR X SV
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What is the main determinant of Cardiac output
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heartrate because you can change heartrate more than stroke volume
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What parts of the heart does the parasympathetic system innervate?
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SA node, AV node to slow heartrate
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What parts of the heart does the sympathetic system innervate?
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SA node, AV node to speed heartrate, ventricular myocardium
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Without parasympathetic, what would the heartrate be?
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100
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Effects of sympathetic ns on heart rate
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increased sympathetic activity, Beta adrenergic receptors on SA node, increase funny Na channels and opens Ca channels, increased rate of depolarization, increased hr
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Effects of sympathetic ns on heart rate
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increased parasympathetic activity, muscurinic cholinergic receptors in SA node, increase open state of K channels and closed state of Ca channels, decrease in spontaneous depolarization, decreased hr
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Stroke volume is influenced by 2 types of controls, ___ and ___ which are ___ and ____ respectively
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intrinsic, extrinsic, changes in end diastolic volume, sympathetic ns and hormones
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an increase of ___ ___ by increasing ____ ____
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stroke volume, contraction strength
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drop in arterial pressure will cause a/an ____ in stroke volume
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increase
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___ controls heart rate and sa node whereas ____ only controls heart rate
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sympathetic, parasympathetic
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Which part of the heart has the greatest musculature?
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Ventricle
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The opening of the AV and semilunar valves is driven by what?
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pressure differences
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The rising phase of the action potential that spontaneously occurs in the autorhythmic cells is due to
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Opening of L-type Ca channels
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What do L-type Ca channels do in the contractile cell?
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cause plateau phase
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99% of myocardial cells are
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contractile
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What is the conduction pathway through the heart?
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SA node, AV node, Bundle of His, Purkinje system
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Why can't tetanus of the heart occur?
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long refractory, prolonged plateau, ensure alternating contraction and relaxation
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During which phase of the cardiac cycle are both AV valves and semilunar valves open
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never
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what is occuring during ventricular ejections
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semilunar valves open, ventricle is contracting, blood is leaving the ventricle
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What would decrease cardiac output?
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CO = SV * HR
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