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Cardiovascular physiology

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ACE inhibitors and angiotensin II antagonists reduce hypertension by what mechanism?

reduce angiotensin II, aldosterone, decrease blood volume

Acetylcholine activates which channels while simultaneously affecting cAMP?

inward rectifier K channels

Acetylcholine binding to muscarinic cholinergic receptors antagonizes the effects of ____________ and decreases generation of __________.

norepinephrine, cAMP

Afferent signals elicted by increased arterial pressure are sent to the cardiovascular centers via the ______________ and _______________.

carotid sinus, vagus nerves

ANF is secreted by the atria of the heart in response to what?

high blood volume/high arterial pressure

Angiotensin II is a vasodilator or vasoconstrictor?


Aside from the force-length diagram, what other phenomenon explains the fact that pre-load affects contractility?

fibers which are stretched more have a higher affinity for Ca (different isoform of troponin than skeletal muscle)

At ~21 days, blood is flowing in a _________ to _______ direction

caudal to cranial

At ~21 days, the sinus venosus is receiving blood from which three venous locations?

vitelline, umbilical, and cardinal

At what day does vasculogenesis begin?


Atropine has what effect on the heart?

it antagonizes acetylcholine, and therefore increases heart rate

b-adrenergic blockers (propranolol) reduce hypertension by what mechanism?

reduce cardiac contractility

Baroreceptor sensing of high arterial pressure will have what effect on heart rate?


Based on the vascular function curve, arterial constriction will have what effect on cardiac output?


By what mechanism does angiotensin II work?

increasing concentration of Ca in cytoplasm

By what molecular mechanism does ANF work?

increasing levels of cGMP

Ca channel blockers, a-adrenergic antagonists (phentolamine), and K channel openers act to reduce hypertension by what mechanism?

relaxing smooth muscle

CO2 acts directly and locally on blood vessels as a ______________, but in response to cerebral ischemia, it acts as a ______________.

vasodilator, vasoconstrictor

Concentric hypertrophy would follow from which pathological conditions?

hypertension, strength training

Correlate the outflow track, inflow track, and ventricular cells with their corresponding progenitor regions in the primitive streak.

outflow track - cranial, inflow track - caudal, ventricular cells - midstreak

Definition of stroke volume?

volume of blood ejected from the ventricle with each beat

Differentiate between the mechanisms of Ca+ release from the SR in skeletal versus cardiac muscle

skeletal - dihydropyridine receptors are mechanically linked to an SR gate, cardiac - influxed Ca opens the SR gate

diurectics (furosemide, thiazides) reduce hypertension by what mechanism?

increase urine output, decrease blood volume

During isovolumetric ventricular relaxation and contraction, all valves are _______.


During large losses of blood volume (hemorrhage), large amounts of ___________ are secreted, causing peripheral vasoconstriction.

vasopressin (antidiuretic hormone)

Eccentric hypertrophy would follow from which pathological condition?

aortic insufficiency

Even though the forces generated in the R ventricle are smaller than the L, stroke volume is approximately the same because ________________

pulmonary resistance is low

Formula for stroke volume

end diastolic volume - end systolic volume

From wher edoes the vasomotor center receive signals?

higher center (emotions) and baroreceptors in the aorta and carotid arteries

fusion of the ____________results in the pericardial cavity

2 coelomic cavities

Fusion of the endocardial tubes forms the __________

primitive heart tube

How do you calculate mean arterial pressure?

1/3 systolic + 2/3 diastolic OR diastolic + 1/3 pulse pressure

How do you calculate total peripheral resistance?

[arterial pressure - venous pressure]/cardiac output

How will a blood transfusion effect the vascular function curve?

Shift up

How will a change in blood volume and a change in arterial resistance change the vascular function curve?

shift the curve, change the slope

How will arterial dilation effect the vascular function curve?

Decrease slope

If both the SA and AV nodes fail, the _________ can act as emergency pacemakers because they have a slow but present _______________.

Purkinje fibers, diastolic phase 4 depolarization

If the SA node was damaged due to ischemia, the AV node could take over, but the AV node beats at approximately _______ beats/min as opposed to _______ beats/min from the SA node

44-50, 70

In cardiac muscle, the resting tension is much _______ at normal fiber lengths than in skeletal muscle.


In pressure overlaod hypertrophy, there is predominantly an increase in ______________ which is called ________________.

wall thickness, concentric hypertrophy

In response to decreases in blood pressure, the kidneys will secrete what?


In volume overload hypertrophy there is a predominant increase in ______________, which is called________________.

radius, eccentric hypertrophy

In what layer does vasculogenesis begin?

splanchnic layer of extraembryonic mesoderm

Increased cardiac output will have what effect on venous pressure?


Increasing total peripheral resistance will have what effect on cardiac and vascular function curves?

reduce the slope of both

Is ANF a vasodilator or vasoconstrictor?


K channel blocking drugs mimic the effects of what cardiac syndrome?

Long QT syndrome (mutations of select K channels(

Mural stress of the ventricular wall is directly proportional to the _______ of the ventricular chamber and inversely proportional to the __________.

radius, thickness Normal Aortal pressure

Normal blood pressure in R Ventricle


Normal L Ventricular pressure


Normal mean L atrial pressure

5 - 10

Normal mean pressure in Right Atrium


Normal mean pulmonary wedge pressure

5 - 10

Normal pressure in pulmonary artery


Pacemaker channels are directly activated by which molecule?


Parasympathetic action on the heart is mediated by what neurotransmitter?


Propanolol has what effect on the heart?

it antagonizes the effects of norepinephrine, and therefore decreases the heart rate

Regarding the action potentila of ventricular myocytes, inward rectifier K channels are _________ at rest, causing the cell to ___________.

open, remain at rest

Sympathetic stimulation has what effect on arterioles?

constriction due to b-adrenergic stimulation of smooth muscle cells

The _____________ serves as a shunt enabling oxygenated blood to pass from right to left atria

foramen primum

The beginnings of the muscular ridge for the IVS form from the ________ wall of the endocardium and myocardium.


The Ca channels are structurally similar to _________ channels.


The counteractive force on the depolarization by voltage gated Ca channel opening is ____________ via _______ channels

K+ efflux via voltage gated K channels

The incomplete partition between atria formed by the overlap of the upper and lower limbs of the septum secundum is known as the __________________.

foramen ovale

The initial repolarization of the ventricular myocyte is aided by the inactivation of _______ channels.


The initial repolarization of the ventricular myocyte is initiated by opening of the _________ channels

voltage activated K

The initial repolarization of the ventricular myocyte is slowed into a plateau due to the opening of ____________ channels.

voltage gated Ca

The main function of the baroreceptor system is ____________

To keep arterial pressure constant and maintain cardiac output in the short term

The major effect of norepinephrine on the heart is to increase the rate of ____________

diastolic depolarization

The neurotransmitter involved in sympathetically increasing the heart rate is


The phase 3 repolarization in the AP at the SA node is due to what 3 factors?

voltage gated K channels opening, Ca channels inactivating, and Ca channels deactivating bc of hyperpolarization

The precardiac mesoderm becomes the ________ during cranial-caudal-lateral-folding

tubular heart

The propagation through the atria and ventricles requires time because of the ________________, whereas the time taken to traverse the SA and AV nodes are long because of the ____________.

large distance, low velocity

The rate of beating of the Purkinje fibers is _____beats/min.


The SA and AV nodes have _____ maximal rates of depolarization (______), whereas the Purkinje fibers depolarize at __________.


The septum primum grows _________ from the ________wall of the atrium toward toward the _________ to divide the primitive atria.

downward, dorsal, fusing AV cushions

The sinus venosus is the primitive ________ tract


The spread of the action potential over the entire heart requires about _____ milliseconds.


The strength of ventricular contraction dependce on the volume at what time?

The end of diastole

The upstroke of the action potential in the SA node is initiated by ________ channels because there are no _________ channels.

Ca, voltage gated Na

The vasomotor center in the medulla of the brain is responsible for what aspect of blood pressure control?

autonomic control of arterial pressure

The ventricular myocyte AP begins when _____ channels open, allowing ___ to rush in.


There are fewer inward rectifier K channels in the ___________

SA node

Two parallel endocardial tubes form by _______ in the rostral splanchnic mesoderm


Upstroke velocity is dependent on ___________

types and number of voltage gated ion channels

Usually, positive inotropic effects are accounted for by what?

Inreased availability of Ca for the contractile machinery

What are the 2 effects of acetylcholine on the AP of the SA node?

1) reduce the rate of diastolic depolarization, 2) make the maximal diastolic potential more negative

What are the 3 main effects of angiotensin II?

increasing peripheral resistance by vasoconstriction, promoting synthesis of aldosterone, increasing salt and fluid reabsorption in the proximal nephron

What are the 3 major differences between SA node action potentials and ventricular myocyte Aps?

1) SA node has slower upstroke, 2) plateau phase is less distinct if even existent, 3) no steady resting potential

What are the 3 mechanisms for returning cytoplasmic Ca to low levels during repolarization?

Na-Ca exchanger in plasma membrane, ATP driven Ca effluxer in plasma membrane, ATP driven Ca effluxer in SR

What are the axes of the vascular function curve, and what does the slope correspond to?

x axis - cardiac output, y axis - venous pressure, slope - peripheral resistance

What are the non-Ca mediated mechanisms of norepinephrine''s positive inotropic effect?

phosphorylation of myosin binding protein C, PKA stimulation

What are two ways to increase stroke volume and stroke work?

Increase contractility, increase filling pressure/filling time

What effect does aldosterone have on the kidney?

reabsorption of salt and fluid in the distal nephron

What happens to the Starling curve upon addition of sympathetic stimulation?

shifts up

What hormone acts in opposition to angiotensin II?


What is a positive inotropic effect on the heart?

Anything that increases the contractility

What is afterload?

Wall stress required for ejection, estimated as systolic aortic pressure

What is cardiac output?

stroke volume x heart rate

What is Laplace''s Law?

total force that tends to stretch the ventricle is equal to the ventricular wall forces that oppose the stretch

What is normal approximate mean arterial pressure?


What is preload?

wall stress that balances ventricular pressure just before contraction begins - estimated as ventricular end diastolic pressure

What is pressure diuresis?

When arterial pressure increases, the kidneys increase the amount of fluid excreted as urine

What is pulse pressure?

systolic pressure - diastolic pressure

What is the Bainbridge reflex?

Baroreceptors in the atrium sense atrial stretch and increase venous return, thus eliciting a signal from the ANS to increase HR

What is the definition/formula of ejection fraction?

stroke volume/end-diastolic volume

What is the equation for mural stress?

mural stress = Pr/2d

What is the location of the cellular precursors for the coronary arteries?


What is the location of the cellular precursors for the epithelium and connective tissue of the pericardium, the epicardium, and the intersititial connective tissue of the myocardium?


What is the mechanism of caffeine-mediated positive inotropic effects?

causes release of Ca from the SR through a direct effect on Ca release channels

What is the mechanism of digitalis''s positive inotropic effect on the heart?

inhibition of Na/K pump increases cellular Na, decreases activity of the Na/Ca exchanger, increasing cellular Ca (both cytoplasmic and SR)

What is the molecular mechanism by which norepinephrine increases contractility?

(via cAMP -> PKA) activates plasma membrane Ca channels, Ca release channels in SR, and Ca pump in SR

What is the normal resting value of cardiac output?


What is the normal resting value of stroke volume?


What is the normal resting value of the ejection fraction?

.5 - .7

What is the order of locations for intraembryonic hematopoeisis?

1st - paraortic clusters in splanchnic mesoderm of AGM region, then liver, then bone marrow

What is the staircase effect?

Increasing the rate of contraction increases the force of contractility

What is the velocity of AP conduction through the SA node, atria, AV node, His/Purkinje fibers, and ventricles?

SA - .05, atria - 1, AV - .03, His/Purkinje - 3.5, ventricles - .4

What kinds of cells form blood islands?

angioblasts (differentiated from mesenchymal cells)

What molecule is primarily responsible for regulation of the SR Ca pump?

phospholamban (PL)

What phenomenon ensures that fibers always operate in the region where tension increases with length?

resting tension increases sharply as the fiber approaches optimal length for contraction

What ratio do Na-Ca exchangers exhibit?

3 Na to 1 Ca

When Na rushes into the cell during the upstroke, ____________ channels close.

inward rectifier K channels

When voltage gated Ca channels open, Ca rushes in or out?


When voltage gated K channels close at the SA node, what happens and why?

phase 4 depolarization because of a lack of inward rectifier K channels and presence of pacemaker channels

Where is the mesoderm that surrounds epithelial cells of the yolk sac derived from?

EMT from the yolk sac epithelium

Which cells are the first to produce erythrocytes?

yolk sac cells

Which measurement/parameter is useful in determining ventricular fiber length?

Central Venous Pressure

Which vessels have the highest aggregate resistance?


Why does increasing peripheral resistance help during cerebral ischemia?

vessels supplying blood to the brain do not respond strongly to autonomic signals

Why does the cardiac curve have a reduced slope when peripheral resistance increases?

Greater force is required to maintain the same cardiac output

Why does the vascular function curve have a reduced slope when peripheral resistance increases?

Greater arterial-venous pressure differences are required to maintain the same cardiac output

Why is the myocyte in an absolute refractory phase during most of the ventricular AP?

Na channels are inactivated at membrane potentials near zero