Cardiovascular Physiology Flashcards by Marnie Reimer

Arteries

Carry blood away from heart

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Veins

Carry blood towards heart

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Blood flow across pressure gradient

Flows down pressure gradient

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Blood pressure

Generated by the pressure that blood exerts on the walls of blood vessels

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Driving pressure for systemic flow is created by the…

Left ventricle

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Blood vessel constriction

Increases BP

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Blood vessel dilation

Decreases BP

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Blood flows from ____ pressure to ____ pressure.

High –> low

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If there is no pressure gradient, blood…

Will not flow

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Mean arterial pressure is equivalent to

Cardiac output x peripheral resistance

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Peripheral resistance

Function of radius of vessel; smaller diameter= more resistance

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Effect of narrowness of vessel on flow velocity

More narrow = faster velocity

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Velocity =

Flow rate/cross-sectional area

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Pericardium

Membranous fluid-filled sac that surrounds the heart; protects and anchors the heart

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The heart is mainly comprised of this cell type

Myocardium

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Heart valves ensure

One-way flow

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Right heart valves

Tricuspid, pulmonary semilunar

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Left heart valves

Bicuspid, aortic semilunar

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Cardiac muscle vs. skeletal muscle

Cardiac muscle smaller, 1 nucleus per fiber, have intercalated disks, smaller sarcoplasmic reticulum (Ca2+ store)

Intercalated disks

Allow for transfer of force (desmosomes) and electrical connections (gap junctions)

AV node

Routes the direction of electrical signals, delays transmission of action potentials

SA node

sets the pace of the heartbeat (70 bpm); pacemaker cells in the right atrium

What other heart structures can set the pace of the heartbeat?

AV node (50 bpm), Purkinje fibers (25-40 bpm); only under certain conditions

Major waves of electrocardiogram

P wave, QRS complex, T wave

Stroke volume

Amount of blood pumped by one ventricle during a contraction

Cardiac output

Volume of blood pumped by one ventricle in a given period of time

Cardiac output

Volume of blood pumped by one ventricle in a given period of time

Average cardiac output

5 L/min

Systole

time during which the heart contracts

Diastole

time during which the heart relaxes

EDV, ESV

End-diastolic volume, End-systolic volume

Stroke volume=

EDV - ESV

1st heart sound

Closure of AV valves

2nd heart sound

Closure of semilunar valves

How do valves close in the heart?

Closed by backflow of blood

P wave

Atrial depolarization (SA node)

PR segment

Atria contract, conduction through AV node and bundle down towards apex

Q wave

Depolarization moves to apex

R wave

Depolarization spreads upwards

S wave

Depolarization of ventricle

ST segment

Ventricles contract

T wave

Ventricular repolarization

EDV

End-diastolic volume, the amount of blood pumped into the ventricles from the atria

EDS

End-systolic volume, the amount of blood left in the ventricle after contraction (not all blood is forced out)

Stroke volume increases when

EDV increases

Effect of norepinephrine and epinephrine on cardiac output

Stimulate more forceful contraction, shorten duration of contraction

Heart rate is determined by

rate of depolarization in pacemaker cells