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60 Cards in this Set

  • Front
  • Back
Stroke Volume is what?
amount of blood pumped out with every heart beat
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)
Stroke volume is regulated by what 3 things?
1. EDV (preload)
2. total peripheral resistance
3. contractility
How are EDV (preload), total peripheral resistance, and contractility proportional to stroke volume?
EDV/preload and contractility are DIRECTLY proportional
Total Peripheral Resistance is INVERSELY proportional
Atrial Reflex adjusts what in response to venous return?
heart rate
Stretch receptors in right atrium trigger what through increased sympathetic activity?
increase in heart rate
What are 2 Factors that affect EDV (end-diastolic volume)?
Filling time and Venous Return
What is Stroke Volume? (formula)
What is Venous Return?
rate of blood flow during ventricular diastole
What is Preload?
the degree of ventricular stretching during ventricular diastole
Preload is directly proportional to what?
When are EDV and stroke volume low, and myocardium stretches less?
at rest
With exercise, EDV, myocardium, and stroke volume do what?
EDV increases,
myocardium stretches more,
and stroke volume increases
The Frank–Starling Principle states what?
As EDV increases, stroke volume increases
Ventricular expansion is limited by:
myocardial connective tissue,
the fibrous skeleton,
and the pericardial sac
What is End-Systolic Volume (ESV)?
amount of blood remaining in the ventricle at the end of ventricular systole (heart contraction)
There are 3 Factors that Affect ESV, what are they?
Preload, Contractility, and Afterload
what changes occur in the heart during excercise?
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.
What is Contractility?
force produced during contraction
what is mean arterial pressure (MAP)?
Blood pressure
(average blood pressure in aorta)
What is Afterload?
the tension the ventricle produces to open the semilunar valve and eject blood
what is the formula to determin MAP?
what is cardiac output (CO)?
the amount of blood pumped by the heart per minute
what is the formula for determining CO?
CO = SV x HR
what is cardiac reserve?
difference between CO at rest and maximum CO
what is Peripheral Resistance (PR)?
PR is total resistance against which blood must be pumped
As afterload increases, what decreases?
stroke volume
what is the formula to determine blood pressure?
BP = CO x PR
The difference between resting and maximal cardiac output is called?
Cardiac Reserve
what does increased volume in the heart do?
increases the force of the contraction (Starling's Law)
Stroke Volume is equal to what percent of end-diastolic volume?
Force of contraction of the cardiac myocytes also relates to:
length of the muscle fiber short = low force of contraction
medium = high force of contraction
long - lower force of contraction
What is the relationship of stroke volume with EDV and ESV?
Contraction strength can be intrinsically controlled by:
Frank-Starling Law
EDV increase causes contraction strength and stroke volume to increase
What is Ejection fraction?
the percentage of EDV represented by SV
Describe extrinsic control of contractility.
1. Positive inotropic effect: sympathetic/adrenal norep./ep. increase contractility
2. Negative inotropic effect: Beta-blockers decrease contractility
Factors that affect venous return:
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
Oncotic Pressure
Oncotic Pressure = difference between the osmotic pressures of blood plasma and interstitial fluid
what are the intrinsic factors that increase mean arterial pressure?
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
What are the 3 ways that the kidneys regulate LOW blood volume
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.
How does Autonomic Activity affect contractility through sympathetic stimulation?
– 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
How does Autonomic Activity affect contractility through parasympathetic stimulation?
– acetylcholine released by vagus nerves
– reduces force of cardiac contractions
What are 3 Heart Rate Control Factors?
1. Autonomic nervous system:
sympathetic and parasympathetic
2. Circulating hormones
3. Venous return and stretch receptors
What are the ways that the kidneys regulate HIGH blood volume
Atrial natriuretic peptide: released by atria in response to stretch
- inhibits ADH secretion
What does sympathetic stimulation do to the heart?
Supplied by cardiac nerves, increases heart rate and force of contraction, epinephrine and norepinephrine released
During rest, under what stimulation is the heart?
The SA node is slowed down by parasympathetic regulation via the vagus nerve and acetylcholine.
During exercise, under what stimulation is the heart?
sympathetic stimulation, Supplied by cardiac nerves, increases heart rate and force of contraction, epinephrine and norepinephrine released
what does increased sympathetic stimulation do to end systolic volume?
decreases end systolic volume because more blood is ejected from stronger contractions
at rest, the ___________ nervous system releases _______ to _________ the heart rate at the SA node.
the parasympathetic N.S. ______ heart activity via _________ secreted from the ___________
vagust nerve
the sympathetic N.S. ______ heart activity via _________ secreted from the _______
adrenal medulla
what happens if there is a sudden increase in pH (a sudden decrease in CO2)
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)
at rest, what happens if there is a sudden decrease in pH (a sudden increase in CO2)?
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
at the cardioregulatory center, whenever parasympathetic stim is increased, sympathetic stim is ___________
at the cardioregulatory center, whenever sympathetic stim is increased, parasympathetic stim is ___________
Extrinsic blood-flow control
(entire body - heart/kidney)
- Sympathetic norepinephrine (constrict)
- Para/sympathetic acetylcholine (dilate)
- bradykinin, nitric oxide, prostaglandin I2 (vasodilate)
Intrinsic blood-flow control? (heart/kidney only)
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)
Coronary blood-flow control?
Sympathetic norepinephrine: constrict
Adrenergic epinephrine: dilate
Heavy exercise blood flow rate (ml/min)?
20,000 ml/min
Skeletal muscle blood-flow control?
Sympathetic acetylcholine: dilate
Adrenergic epinephrine: dilate