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60 Cards in this Set
- Front
- Back
Stroke Volume is what?
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amount of blood pumped out with every heart beat
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Cardiac output is adjusted by changes in what?
C.O. = ? |
stroke volume, heart rate
CO = SV x HR (ml/min) = (ml/beat) x (beat/min) |
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Stroke volume is regulated by what 3 things?
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1. EDV (preload)
2. total peripheral resistance 3. contractility |
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How are EDV (preload), total peripheral resistance, and contractility proportional to stroke volume?
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EDV/preload and contractility are DIRECTLY proportional
Total Peripheral Resistance is INVERSELY proportional |
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Atrial Reflex adjusts what in response to venous return?
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heart rate
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Stretch receptors in right atrium trigger what through increased sympathetic activity?
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increase in heart rate
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What are 2 Factors that affect EDV (end-diastolic volume)?
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Filling time and Venous Return
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What is Stroke Volume? (formula)
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SV = EDV - ESV
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What is Venous Return?
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rate of blood flow during ventricular diastole
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What is Preload?
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the degree of ventricular stretching during ventricular diastole
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Preload is directly proportional to what?
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EDV
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When are EDV and stroke volume low, and myocardium stretches less?
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at rest
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With exercise, EDV, myocardium, and stroke volume do what?
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EDV increases,
myocardium stretches more, and stroke volume increases |
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The Frank–Starling Principle states what?
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As EDV increases, stroke volume increases
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Ventricular expansion is limited by:
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myocardial connective tissue,
the fibrous skeleton, and the pericardial sac |
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What is End-Systolic Volume (ESV)?
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amount of blood remaining in the ventricle at the end of ventricular systole (heart contraction)
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There are 3 Factors that Affect ESV, what are they?
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Preload, Contractility, and Afterload
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what changes occur in the heart during excercise?
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cardiac output increases:
because heart rate increases and the ventricles contract more forcefully which increases stroke volume; increased SV increases Blood pressure and peripheral resistance increases. |
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What is Contractility?
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force produced during contraction
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what is mean arterial pressure (MAP)?
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Blood pressure
(average blood pressure in aorta) |
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What is Afterload?
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the tension the ventricle produces to open the semilunar valve and eject blood
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what is the formula to determin MAP?
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MAP = CO x PR
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what is cardiac output (CO)?
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the amount of blood pumped by the heart per minute
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what is the formula for determining CO?
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CO = SV x HR
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what is cardiac reserve?
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difference between CO at rest and maximum CO
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what is Peripheral Resistance (PR)?
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PR is total resistance against which blood must be pumped
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As afterload increases, what decreases?
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stroke volume
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what is the formula to determine blood pressure?
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BP = CO x PR
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The difference between resting and maximal cardiac output is called?
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Cardiac Reserve
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what does increased volume in the heart do?
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increases the force of the contraction (Starling's Law)
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Stroke Volume is equal to what percent of end-diastolic volume?
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60%
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Force of contraction of the cardiac myocytes also relates to:
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length of the muscle fiber short = low force of contraction
medium = high force of contraction long - lower force of contraction |
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What is the relationship of stroke volume with EDV and ESV?
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SV = EDV — ESV
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Contraction strength can be intrinsically controlled by:
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Frank-Starling Law
EDV increase causes contraction strength and stroke volume to increase |
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What is Ejection fraction?
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the percentage of EDV represented by SV
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Describe extrinsic control of contractility.
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1. Positive inotropic effect: sympathetic/adrenal norep./ep. increase contractility
2. Negative inotropic effect: Beta-blockers decrease contractility |
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Factors that affect venous return:
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1. Venous Pressure: pressure increases venous return by:
- venule pressure > vena cava pressure - veins become stiff from sympathetic stimulation, decrease volume, pressure increase - skeletal muscle pumps ---> pressure increase - pressure diff between abdominal + thoracic cavities helps venous return 2. Blood Volume |
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Oncotic Pressure
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Oncotic Pressure = difference between the osmotic pressures of blood plasma and interstitial fluid
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what are the intrinsic factors that increase mean arterial pressure?
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increased blood volume, excercise, changing from a standing to a lying down position - increased venous return, increased end-diastolic volume (which increases force of contraction) which increases CO, which increases MAP
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What are the 3 ways that the kidneys regulate LOW blood volume
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1. Anti-Diuretic Hormone from post. pituitary
2. Aldosterone from adrenal cortex (causes H20 reabsorb) 3. Renin enzyme ----> Angiotensin II - Angiotensin II stimulates: vasoconstriction, thirst, aldosterone prod. |
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How does Autonomic Activity affect contractility through sympathetic stimulation?
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– NE released by postganglionic fibers of cardiac nerves
– epinephrine and NE released by adrenal medullae – causes ventricles to contract with more force – increases ejection fraction and decreases ESV |
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How does Autonomic Activity affect contractility through parasympathetic stimulation?
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– acetylcholine released by vagus nerves
– reduces force of cardiac contractions |
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What are 3 Heart Rate Control Factors?
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1. Autonomic nervous system:
sympathetic and parasympathetic 2. Circulating hormones 3. Venous return and stretch receptors |
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What are the ways that the kidneys regulate HIGH blood volume
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Atrial natriuretic peptide: released by atria in response to stretch
- inhibits ADH secretion |
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What does sympathetic stimulation do to the heart?
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Supplied by cardiac nerves, increases heart rate and force of contraction, epinephrine and norepinephrine released
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During rest, under what stimulation is the heart?
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The SA node is slowed down by parasympathetic regulation via the vagus nerve and acetylcholine.
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During exercise, under what stimulation is the heart?
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sympathetic stimulation, Supplied by cardiac nerves, increases heart rate and force of contraction, epinephrine and norepinephrine released
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what does increased sympathetic stimulation do to end systolic volume?
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decreases end systolic volume because more blood is ejected from stronger contractions
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at rest, the ___________ nervous system releases _______ to _________ the heart rate at the SA node.
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parasympathetic
acetylcholine decrease |
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the parasympathetic N.S. ______ heart activity via _________ secreted from the ___________
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decreases
acetylcholine vagust nerve |
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the sympathetic N.S. ______ heart activity via _________ secreted from the _______
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increases
norephinephrine adrenal medulla |
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what happens if there is a sudden increase in pH (a sudden decrease in CO2)
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we want to send less blood to lungs to keep CO2 in the blood longer, so:
increased parasympathetic stim which decreases heart rate, which sends less blood to the lungs, so CO2 increases (pH decreases) |
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at rest, what happens if there is a sudden decrease in pH (a sudden increase in CO2)?
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increased sympathetic stim increases heart rate and SV to increase blood flow to lungs where more CO2 can be blown off and pH will increase as CO2 levels decrease
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at the cardioregulatory center, whenever parasympathetic stim is increased, sympathetic stim is ___________
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decreased
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at the cardioregulatory center, whenever sympathetic stim is increased, parasympathetic stim is ___________
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decreased
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Extrinsic blood-flow control
(entire body - heart/kidney) |
- Sympathetic norepinephrine (constrict)
- Para/sympathetic acetylcholine (dilate) - bradykinin, nitric oxide, prostaglandin I2 (vasodilate) |
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Intrinsic blood-flow control? (heart/kidney only)
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1. Myogenic: smooth muscle in vessels can constrict or dilate on their own (stretch receptors)
2. Metabolic: Vasodilation of vessels due to change in pH, CO2, O2, K+ (chemoreceptors) |
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Coronary blood-flow control?
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Sympathetic norepinephrine: constrict
Adrenergic epinephrine: dilate |
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Heavy exercise blood flow rate (ml/min)?
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20,000 ml/min
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Skeletal muscle blood-flow control?
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Sympathetic acetylcholine: dilate
Adrenergic epinephrine: dilate |