Cardiovascular Physiology - Exam 1 Flashcards by Liz Jarzembowski

Atrial and ventricular syncytium can be attributed to each side having _ _

gap junctions

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Which side of the heart has lower pressures?

right
-hence PE, clots, etc

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What anatomical structure allows the atria to fully contract before the ventricles?

fibrous insulator

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What helps keep the blood flow in the heart unidirectional?

valves

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Cardiac muscle is comprised of _ and _ filaments

myosin and actin

-much lower resistance to conduction than cell membranes

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RMP of cardiac muscle is _-_mV, and the action potential is _ mV

-85 to -95mV
105mV

-plateau lasts longer than skeletal musc ~0.2-0.3sec

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Action potential of cardiac muscle results in _

depolarization

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Ventricular Muscle Action Potential
-phases

0-Fast Na+ channels open, slow Ca++ channels open too
1-K+ channels open
2-Ca ++ channels open more
3- K+ channels open more
4-resting membrane potential

-K+ channels opening is pretty transient bc Ca++ channels open wider and offsets K+ leaving cell

-the latter K+ is vent repolarization occurring

-biggest diff from skeletal musc is in phase 2 with Ca++ channels opening wider

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T/F Vent conduction AP is the same process as pacemaker cells

false

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The _ refractory period does not allow the ventricle’s cardiac muscle to be re-excited again

absolute

-an AP is currently occurring

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The _ refractory period can allow the ventricle’s cardiac muscle to be re-excited again

relative

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The absolute refractory period of ventricular AP is - sec and _ sec in atria

0.25-0.3sec
0.15sec

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On an EKG, the P wave represents conduction prior to _ _

atria contracting

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On an EKG, the QRS complex represents conduction prior to _ _

ventricular depolarization
-this is SYSTOLE!
-this also is masking the atria repolarizing

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On an EKG, the T wave represents electrical conduction of _ _

ventricular repolarization
-vent diastole
-vents stay contracted a few milliseconds after T wave

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S1 heart sound is heard when the _ valves close

AV
-@ START of vent systole

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During atrial systole, which valves are open?

Tricuspid and Mitral

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During ventricular systole, which valves are open?

Pulmonic and Aortic

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In the vent pressure/volume curve, isovolumetric relaxation occurs:

AFTER T wave

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S1 heart sound is heard when the _ valves close

AV (tricuspid and mitral)
-@ START of vent systole

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In the vent pressure/volume curve, isovolumetric contraction occurs:

DURING QRS complex

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S2 heart sound is heard when the _ and _ valves close

aortic and pulmonic
-@ END of vent systole

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On a vent pressure/volume curve, an “a” wave represents:

atrial cx

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On a vent pressure/volume curve, a “c” wave represents:

vent cx (AV valves bulge)

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On a vent pressure/volume curve, a "v" wave represents:

blood flowing back into atria

What does a dicrotic notch(incisura) represent?

sudden stop of back flow toward L vent

Aortic pressure must overcome _ pressure to allow blood forward

systemic (SVR)

_ _ accounts for 25% of filling in the ventricle during diastole

atrial systole -"atrial kick"

Normal Values End diastolic volume (EDV)

120mL -max volume at end-diastole -directly proportional to SV and CVP -higher CVP increases EDV which increases SV ; (good; more volume on the receiving end, so SV is more forceful and more blood is readily replenishing chambers)

Normal Values End systolic volume (ESV)

50mL -directly proportional to afterload (SVR) and INversely proportional to SV -increased SVR increases ESV which decreases SV ; (heart is pushing against too strong of a force and it's leaving volume behind and making the stroke weaker)

Normal values Ejection volume (SV)

SV= EDV - ESV ~70mL

Normal values Ejection fraction

EF= SV / EDV normally ~60%

EDV-ESV =

_ is the total volume of blood going thru the heart in 1 min

If HR increases, SV will _

decrease -helps maintain CO, compensatory

Normal values CO

~5L/min

Chordae tendinae are attached to which valves?

Resting cardiac muscle stretch is _ than skeletal muscle

less

T/F Afterload should be > LV pressure

false

_, or venous return, is important to the Frank-Starling curve because it causes the optimal stretch for maximum contraction.

preload/CVP

Preload is synonymous with _ and _ _ _

CVP and end diastolic pressure (EDP)

T/F High afterload is from HTN coming from the heart

false, this is systemic~SVR

CO will only increase when HR is elevated if _ also increases

Sympathetic activity would _ CO

increase -increased HR and contractility

Vagal fibers mainly go to the _

atria

PNS stimulation would cause CO to _

decrease -slows HR and slightly decreases SV

During a normal cardiac cycle, the impulse is delayed in the _ _

AV bundle -lets atria fully contract

Which structure brings the cardiac impulse into the ventricular area?

AV bundle

Which structure brings the cardiac impulse to each part of the ventricles?

R and L Purkinje bundles

Normal rate of discharge -sinus node

70-80bpm

Normal rate of discharge -AV node

40-60bpm

Normal rate of discharge -purkinje fibers

15-40bpm -think about a heart block pt and how low their rates can be. Their conduction doesn't work thru the SA and AV node so Purkinje takes over and old man Purkinje is slow

Valve areas -aortic

2.5-3.5cm^2 -same as mitral! crit=0.7cm^2

Valve areas -pulmonic

4-6cm^2

Valve areas -mitral

2.5-3.5cm^2-same as aortic crit=<1cm^2

Valve areas -tricuspid

8-10cm^2

Normal chamber pressures -RA

0-6mmHg very similar to CVP...

Normal chamber pressures -RV

15-30 Systole 0-6mmHg Diastole "Quarter over a nickel"

Normal chamber pressures -LA

6-12mmHg

Normal chamber pressures -LV

100-140mmHg Systole 6-12mmHg Diastole LV works hard and doesn't like to relax

Normal chamber pressures aorta

100-140 mmHg Systole 60-80mmHg Diastole kinda like a normal BP....

Normal chamber pressures PA

15-30 mmHg Systole 6-12mmHg Diastole "A quarter over a dime"

Normal PR interval

0.16sec

Normal QT interval

0.4sec

If alterations in the _ _ pump occur, could change EKG

Na/K+ ATPase pump -I'm looking at you, Digoxin (rate control, inc contractility)

T/F No potential is recorded when vent muscle is either depolarized or repolarized

true

T/F QRS complex has positive deflections only

false, has both -deflection depends on which lead you are looking at

Lead II and _ have opposite QRS deflections

HR counting methods -high

if 2 R-R waves are seperated by one box =300bpm if 2 boxes = 150bpm, etc.

HR counting methods -low

count R waves in 6 sec, x by 10

HR counting methods -irregular/high

if strip is 10 sec, count R waves and x 6 if strip is not 10sec, count how many R waves in 6 sec and x10

T/F Repolarization of atria occurs rapidly follows depolarization and occurs during PT segment

true

T/F Depolarization of vents = QRS and repolarization is T wave

true

When a depolarization wave spreads towards the electrode, the deflection will be _ and when if depolarizes away from the electrode it will be _

positive negative -when current flows obliquely towards the lead it will deflect up a little less (occurs with bipolar impulses)

The cardiac cycle is coordination of 5 things:

-electrical changes -ions -pressure changes in LA, LV, and aorta -ventricular volume changes -cardiac valves

Which lead is best to look at for ischemia?

12 lead ekg -3 bipolar limb leads

I, II, and III

12 lead -3 augmented voltage leads

aVR, aVL, aVF

12 lead -precordial leads

V1-V6

Frank Starling mechanism

-heart will pump blood that comes to it without damming veins TO A CERTAIN POINT... -extra stretch on cardiac myocytes makes actin and myosin interdigitate to more optimal degree of force generation (actin and myosin adjust to accommodate stretch to allow for forceful contraction) -think about yourself (volume) jumping on a trampoline (contractility). If your trampoline is a perfect size and is working well, you can get a good bounce off it. Your older brother joins and you can bounce higher on it bc he's bigger (adding more volume to same system). Systolic issue: At a certain point, too many people (too much volume) on the trampoline will break it and you wear it out and you all can't bounce as high. Diastolic issue: Similarly, if you have a small trampoline or if it's too stiff (less contractility) you won't bounce as well either

ABV -premies

95mL/kg

ABV -full term neonate

85mL/kg

ABV -infants

80mL/kg

ABV -men

75mL/kg

ABV -women

65mL/kg

Pulse pressure is _ - _ and normal value is _mmHg

SBP - DBP 40mmHg

Factors affecting pulse pressure -SV

Direct relationship increased SV = increased PP decreased SV = decreased PP

Factors affecting pulse pressure -arterial compliance

inverse relationship higher compliance = lower PP lower compliance = higher PP

Factors affecting pulse pressure -arteriosclerosis

decreases compliance = increases PP

Factors affecting pulse pressure -PDA

-low diastolic and high systolic pressures = net INCREASE in PP

Factors affecting pulse pressure -aortic regurg

backflow causes low diastolic and high systolic pressures = INCREASE in PP

Factors affecting pulse pressure -aortic stenosis

low BF thru aortic valve causing low systolic pressure = decreased PP

RAP correlates with which hemodynamic measurement?

CVP

Normal value CVP

0mmHg -can be as high as 20-30mmHg

Factors that increase RAP/CVP

-increased blood volume -increased venous tone -dilation of arterioles -decreased cardiac function

Increased SNS activity would _ CVP

increase

Increased CVP can be useful to increase _ but detrimental if too high and cause _ edema

SV peripheral

Local blood flow in the heart is controlled via _

autoregulation -via catecholamines and hyperemia from increased tissue demand

Resistance equation

R= change in P (pressure difference in 2 points in vessel) mmHg / Q (mL/min-flow)