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45 Cards in this Set
- Front
- Back
What are the 3 functions of the heart? and there sub-functions?
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1. Transportation
- respiratory - nutritive - excretory 2. Regulation - hormonal - temperature 3. Protection - clotting - immune |
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what side of the heart is considered pulmonary?
Why? |
right
Because it pumps blood to the lungs |
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what side of the heart is consdiered systemic?
Why? |
left
Because it pumps blood to the body |
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During systole, does blood pressure rise or fall?
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rises
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What vessel(s) deliver deoxygenated blood to the heart from the body?
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superior/inferior vena cava
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Blood pressure does what during diastole?
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falls
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Describe the structures that the blood travels through from the superior and inferior vena cavas to the lungs.
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Vena cavas ---> right atrium ---> right atrioventricular (tricuspid) valve ---> right ventricle ---> pulmonary semi-lunar valve ---> pulmonary artery ---> lungs
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Describe the structures oxygenated blood travels through from the lungs to the body.
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Lungs ---> pulmonary vein ---> left atrium ---> left AV (bicuspid/mitral) valve ---> left ventricle ---> aortic semi-lunar valve ---> aorta ---> body
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When heart rate increases, what happens with all the phases of cardiac cycle?
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they shorten, especially diastole
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Identify the layers of the heart wall
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Name/Describe the 2 phases of systole
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1. Isovolumetric Contraction:
- Blood is not moving in or out of ventricle - All valves are closed - Pressure is building 2. Ejection: - AV valves are closed - Ventricular pressure causes semilunar valves to open - Blood is ejected |
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Name/Describe the 1st phase of diastole
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Isovolumetric relaxation:
- Semilunar valves close - Ventricles/Atria relaxed - Ventricular/Atrial pressure drops |
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What is Heart Murmur?
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sounds produced by regurgitation through valves
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Name/Describe the 2nd phase of diastole
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Rapid Filling:
- Ventricular pressure drops below that of the atria - AV valves open - Blood rushes into ventricles |
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Name/Describe 3rd phase of diastole
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Atrial Contraction (atrial systole):
- Pressure in atria now lower than that of ventricles - Atria contract to deliver the remaining blood - Immediately after atrial contraction, Isovolumetric Relaxation, and hence the cardiac cycle, start all over again. |
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what is the main way that the ventricles are filled?
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passive ventricular filling during diastole
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During diastole:
the chordae tendineae tension is _______ the papillary muscle is ________ the cardiac muscle is _________ the ventricle is _______ the AV valves are ________ and the semilunar valves are |
low
relaxed relaxed dilated open closed |
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What is adjusted by the autonomic nervous system or hormones?
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heart rate
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During systole:
the chordae tendineae tension is _______ the papillary muscle is ________ the cardiac muscle is _________ the ventricle is the AV valves are ________ the semilunar valves are _______ |
high
contracted contracted contracted closed open |
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what are the two ways the AV valves stay closed?
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the cusp shape causes them to close as blood fills them
the chordae tendineae put tension on them to close them |
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Do the atria and/or ventricles work together or separately?
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Atria: work as one
Ventricles: work separately from each other |
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The Vagus nerves (X) carries what to small ganglia in cardiac plexus?
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parasympathetic preganglionic fibers
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does the nervous sytem cause the heart to contract?
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no
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Explain the electrical impulse cycle in the SA node
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1. Pacemaker Potential: Drives the self-generated firing of Pacemaker Cells
Preceding action potential completes ---> cell is hyperpolarized -60mV ---> Na/K channel opens ---> Na comes in fast ---> K goes out slowly ---> slow net depolarization to -40mV threshold 2. Action Potential -40mV causes Ca2+ channels to open ---> Ca2+ influx causes upward phase of action potential ---> at top of action potential (+20mV) K+ channels open ---> repolarization ---> new cycle begins |
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Explain how the spontaneous SA node depolarization can be modulated
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1. Epinephrine/Norepinephrine:
- Increases cAMP production - cAMP keeps Na+ (HCN) channels open - Faster pacemaker potential 2. Acetylcholine: - Secreted by parasympathetic neurons - Opens K+ channels. - Slows pacemaker potential |
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Describe the path of electrical signals
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Sinoatrial (SA) node ---> Electrical channels ---> atrioventricular (AV) node ---> Bundle of His ---> Left/Right Bundle Branches ---> Purkinje Fibers (which start at the base and travel up outer walls)
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Why is the Pacemaker Potential also called the Diastolic Depolarization
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Because the pacemaker potential represents the non-contracting time between heart beats (diastole)
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Describe the Myocardial Action Potential
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- Myocardial cell rests at -85mV
- Action potential from SA node brings MC cell to threshold - Voltage gated Na+ channels open, potential shoots straight up (undefined slope) to +15mV - Plateau for 200-300ms due to a balance of Ca influx and K efflux. - More K+ channels open, repolarization occurs. |
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ACh (parasympathetic stimulation) speeds or slows the heart?
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slows
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NE (sympathetic stimulation) does what to the heart?
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speeds it up
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what is the primary ion that causes depolarization in cardiac myocytes?
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sodium (Na+)
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What is the difference between what happens in the SA node and in other cardiac myocytes?
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The SA node has a faster action potential: sodium causes slight depolorazation until threshold when Ca+ channels open and Ca+ rushes in causing a very fast depolarization.
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Membrane potential of pacemaker cells are higher or lower than other cardiac cells?
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lower
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what causes repolarization of cardiac myocytes?
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potassium leaving the cells
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what is the same about skeletal and cardiac muscle?
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depolarization caused by sodium entering the cell and repolarization caused by potassium leaving the cell
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what is different about cardiac muscle cells from skeletal?
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The plateau phase: the depolarization of the cardiac muscle causes Ca+ channels to open letting Ca+ into the cell (which makes cell go positive) - at the same time, K+ is leaving the cell (which makes cell go negative) - so the movements of these two ions cancel each other out for a time, causing a longer contraction in the cardiac muscle cell.
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Increased heart rate (by sympathetic stimulation of SA node) is cause by what hormones?
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epinephrine (E), norepinephrine (NE), and thyroid hormone
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How does the cardiac myocyte repolarize?
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after plateau phase, the L-type Ca+ channes close while K+ continues leaving, making the cell more negative (repolarization)
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describe what the refractory period in cardiac myocytes is and why it is necessary
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a period of either complete or reduced sensitivity to additional stimulation
Prevents tetanic contraction - allows movement of AP to progress down the heart from the SA node rather than go back up right away. |
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what does the P wave represent?
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atrial depolarization spreading
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what does the QRS complex/wave represent? Immediately after?
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spread of depolarization into ventricles
immediately after QRS is heart sound 1 "Lub" |
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- what does the S-T segment represent?
- what 2 events does the T wave represent? |
plateau phase of the action potential
ventricle repolarization, heart sound 2 "Dub" |
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which valves are closed during diastole?
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semilunar valves (bicuspid and tricuspid) - keeps blood that has left the heart from leaking back into the ventricles.
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