Cardiac Physiology Pt. I Flashcards by J L

Why do we need to pump blood?
• Blood delivers oxygen and nutrition
• Blood removes \_\_\_\_ and waste
• Must ensure it gets to the tissues
• Cross sectional area \_\_\_\_ proportional to velocity

• Go to capillaries > CSA inversely proportional to velocity
	○ Blood goes quickly through initial vessels, and then want blood to slow down during the \_\_\_\_

CO2
inversely
gas exchange

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The cardiac cycle

\_\_\_\_
Volume 
\_\_\_\_
Valves
\_\_\_\_
EKG

pressure
electrical triggers
heart sounds

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Ventricular systole and diastole

• Systole: a drawing together or a ____. – Ventricular systole – squishing out blood
• Diastole: separation, ____
– Ventricular diastole – dilation, blood flows in

• Most of cardiac cycle is spent in \_\_\_\_
	○ Much \_\_\_\_and more passive
• Systole (contraction) is much \_\_\_\_

contraction
expansion
diastole
slower
faster

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Diastole filling - 80% - ____ filling

Blood flows into right ventricle
Open ____ Valve

Blood flows into left ventricle
Open ____ Valve

Closed pulmonary artery and aortic valves – ____

Pressure higher for input Input valves open
Exit valves ____

* Pressure is higher in input valves then it is in ventricular spaces; because of pressure gradient > tricuspid and mitral valves open; blood passively fills the ventricles
* Pressure is \_\_\_\_ in aorta/pulm artery > these valves are then closed

passive
tricuspid
mitral
semilunar
closed

higher

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Active filling - atrial contraction
80% - Passive filling
20% - ____ filling

Squeezing more blood into ventricle
____ Tricuspid Valve

____ Mitral Valve

____ pulmonary and aortic valve

• 80% full there is a slight squeezing in the \_\_\_\_ compartments > forces a little bit more blood in
	○ Pressure in ventricle is lower than in aorta and pulm vessels; the valves are still open

active
open
open
closed

atrial

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Boyle’s Law

• Pressure inversely proportional to ____ at constant mass, ____
– As volume expands, pressure decreases
– As volume shrinks, pressure rises

volume

temperature

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Isovolumic contraction - squeeze with valves closed

____ Tricuspid Valve

____ Mitrial Valve

____ Pulmonic Valve

____ Aortic Valve

Muscle contracts, same amount blood, smaller space, ____ rises

Pr pressure higher in ____ than ventricle – SL valves closed

Pr pressure higher in ____ than atrium – AV valves close

* After the contraction, the pressure in atrium is lower than in ventricle; pressure differential closes tricuspid and mitral
* Pressure in the output (exit in aorta) is still higher than in ventricles > both input and output valves are closed > the beginning of contraction of cardiac cycle
* As muscles contract > make space smaller > pressure inside ventricle increases > until it's greater than the pressure in \_\_\_\_ > ejection of systole

closed
closed
closed
closed

pressure
aorta
ventricle

aorta/pulm vessel

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Systole: Ejection

____ Pulmonic Valve

____ Aortic Valve

____ pressure>aortic pressure Valves open, blood ejected

____ - Rapid ejection
____ – Reduced ejection

• Pressure is so high > valves open and blood moves
	○ 2/3 rapid; 1/3 reduced ejection
• Valves opening depends on relative pressure of the \_\_\_\_

open
open
ventricular
2/3
1/3
three compartments

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Diastole starts again

Stroke Volume=
____ – End Systole Volume

In typical resting male, =120 ml-50 ml=____ ml=____ oz (TSA compliant)

Ejection fraction = ____/ End Diastole Volume
=70ml/120 ml x100= ____

SV = EDV – ESV 
EF = SV / EDV

• Now begin the \_\_\_\_ filling of diastole
• SV
	○ \_\_\_\_ of blood that gets pumped out (when start to squeeze, and how much you have when you squeeze it out)
• EF
	○ What \_\_\_\_ of blood can you pump w each contraction
	○ Increase efficiency can increase your health; problems if decreased too much

end diastole volume
70
1.7

stroke volume
58%

passive
amount
portion

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The cardiac cycle

* Changes in \_\_\_\_ and volume > largely what you're looking at for cardiac cycle
* \_\_\_\_ pressure > most important (red)

pressure

ventricular

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Start of diastole, ventricular blood volume ____

Ventricular volume ____ ml at lowest.
Blood flowing into atrium and ventricles, passive flow

* Diastole > passive filling of blood
* \_\_\_\_ valve opening > volume increases and ventricular pressure drops

lowest
50
AV

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Pressure-volume curves for diastole

• Increase is due to squeezing and contraction of \_\_\_\_ > atrial kick
	○ \_\_\_\_ extra volume that comes from squeezing of contraction from atrial muscles

atria

30%

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____: atrial contraction – squeezing an extra 20%

p-wave

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Pressure volume curves for diastole

• At this point pressure in ventricle is greater than inside atrium > valves \_\_\_\_ > isovolumetric contraction > big increase in \_\_\_\_, no change in volume > both valves are closed > contraction with no change in volume

• At a certain point here (B)
◦ we see that the pressure inside the ventricle is greater than the aortic pressure
‣ that is when these valves open

pressure

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____
– ventricular contraction

• QRS event > electrical event in ventricles
	○ Relates to mechanism of increased contraction of muscles in the ventricles

QRS wave

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Ventricular contraction, ejection

Ventricular pressure rises, shuts ____ valve, pressure increases rapidly

____ rise as valves closed, no blood moves

Aortic valve ____, blood squeezed out, volume falls
____ -wave ventricular contraction

Aortic valve closes

* Rapid decrease in volume > slows down > most blood exits ventricle
* Pressure rises at first > volume goes down > pressure drops > when less than aortic pressure > the valves close
* Isometric relaxation > both valves closed > muscle is relaxing > decrease in pressure from within the \_\_\_\_
* All changes in volume are due to physical changes in contraction due to \_\_\_\_ and differential pressure is due to \_\_\_\_ of the valves

AV
isovolumetric pressure
opens
QRS

ventricles
electrical signals
opening/closing

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Pressure, valves & ventricular volume

Isovolumetric contraction

Pressure rises enough to open ____ valves, blood flows out

Ventricle relaxes, pressure falls, ____ valve opens

* Opening/closing of valves > important in allowing \_\_\_\_ to go up; ventricular relaxation > \_\_\_\_ valve opens and allows filling to begin again
* Valves, pressure and volume are intimately related

SL
AV
pressures
AV

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Pressure & Aortic Flow

Aortic valve only opens when ____ pressure higher than aortic pressure – pushes valve open

• Pressure at which aortic valves open > blood pressure value
	○ \_\_\_\_ > ventricles have to be greater then to push the valve open

ventricular

120/80

CARDIAC CYCLE SUMMARY

KNOW ME!

• Ejection portion
	○ Mitral is \_\_\_\_, aortic valve is \_\_\_\_ > pressure of LV/aortic pressure > continues to increase then decreases > continues to increase as the contraction goes through > as the volume decreases >  you begin to see in both the ventricle and aortic pressure as the bolus is passed through > the pressure goes \_\_\_\_
• Filling portion
	○ Initial diastole portion
	○ Mitral valve is \_\_\_\_ > mitral is open, aortic is \_\_\_\_ > LV is increasing, AP is decreasing (slowly going down), volume of LV is increasing (filling period)

closed
open
down

open
closed

Heart Valves: TPMA

Aortic ____ valve
Pulmonary ____ valve
____ valve
____ valve (mitral

semilunar
semilunar
tricuspid
bicuspid

Cardiac valves

Mitral – 2 Tricuspid – 3 Pulmonary – 3 Aortic - 3 Why 2 cusps in Mitral? Developmental twisting?

• Developmental twisting in \_\_\_\_ > mitral valve with \_\_\_\_ cusps

embryonic development

Increased pressure closes valves, prevents backflow

• Valves open only in ____ direction after blood pushed through – prevent backwash
• Example:
– Left Atrial Pressure > Ventricle Pressure
Mitral Valve is ____
– Left Atrial Pressure < Ventricle Pressure
Mitral Valve is ____

Papillary muscles contract and ____
tighten, prevent inversion into atria

• Not just pressure, but also \_\_\_\_ contracting > chordae tendon maintain the shape of the valves

one
open
closed
chordae tendinae
muscles

Cardiac cycle & heart sounds

* Heart sounds > reflection of closing of the \_\_\_\_ > useful diagnostic tool > allow auditory input into how valves are functioning
* Heart sound 1 > closing of \_\_\_\_ valve
* Heart sound 2 > closing of \_\_\_\_ valve

valves
mitral
aortic

Heart sound S 1 (LUB)
long and loud

Closure of ____ valves
Onset of ____
____
Longest (____sec)
Mitral v : ____ mid- clavicular
Tricuspid v : ____ of sternum

closure
systole
loudest
0.14
5th ICS
5th ICS left

Heart sound S 2 (DUB) higher * Closure of ____ valves * Onset of ____ * Higher ____ – because SL valves more taut * Lower ____ * Listen at the ____ * Aortic v : ____ right of sternum * Pulmonary v : ____ left of sternum • Higher pitch > structure of the valves ____ to one another

``` semilunar diastole frequency intensity base 2nd ICS 2nd ICS relative ```

Heart sound S3 and S4 * “____ Gallop” • * Middle 1/3 of ____ • * Rapid ____ filling * Dull&lowpitched * Normal in ____ * May indicate ____ or cardiomyopathy in adults ____ "gallop" Corresponds to ____ contraction Rarely a normal finding Associated with "stiff", ____ ventricle * Normally not heard * Can be indicative of benign changes, or can indicate pathology * S4 occurs just before S1; S2 right before S3

ventricular diastole children congestive heart failure (CHF) atrial atrial hypertrophied

Balancing the electrical and chemical gradients across the membrane • both the chemical and electrical gradient drive ____ in ◦ both the chemical and electrical gradient for ____ drive it into the cell ◦ the cell is very ____ ◦ but the ____ gradient for potassium drive it in ‣ because potassium is positively charged and the cell is negatively charged ‣ but there is a lot of potassium inside the cell and not very much outside • this forces/will push potassium ____ of the cell

``` sodium calcium negative electrical out ```

Because PK>PNa, PCl, Vm close to ____ The greater the ____, the more influence an ion has on the membrane potential!

Ek permeability

Goldman-Hodgkin-Katz equation Time-dependent changes in the permeability to ____ and ____ underlie the neuronal action potential • AP dictated by a ____ change…

Na+ K+ time-dependent

Heart beat coordinated through impulses * Pacemaker cells in ____ * Pass through cells to right atrial muscle and left atrial muscle * ____, bundle of His, Purkinje Fibers • Efficiency of pumping blood is dependent on having one contraction of all muscle; do not want different parts contracting at different times/out of order • SA node ○ Primary pacemaker of the cardiac signal > pass to contraction of atrial muscle > and then slowly to the AV node > leads to ____ of the right and left signals > AP passed to the ____ > into the left and right bundles > purkinje fibers > contraction of ventricular muscle

sinoatrial node AV node unification bundle of His

The cardiac conduction system * Time (in sec) after SA node signal * ____ right to left atrium * Built in delay top to bottom so atria empties before ____ contract * L&R ventricle ____ * SA node drives because it has ____ discharge rate – overrides pacemaking of AV node, Purkinje fibers • Bundle of His > the contraction of L/R ventricles occur simultaneously > driving from bottom to top to squeeze blood through aorta • SA node > drives contraction because it is the fasted; AV node pacemaking activity and in PF ○ ____ period; AP originating at SA node and through AV node through heart > dominates and drives the contraction; very important you only have one contraction

delay ventricles faster AP/refractory

Pacemaker potential Depolarized and leaking * Pacemaker resting potential ____V, then “leakiness” of ____. Then ____ brings potential to threshold without additional input * Slower to peak than myocytes, but myocytes with ____ • PP > change in membrane potential > without additional input > AP oscillations • Have to have an AP generating without any other input > contribution of different ion channels ○ The membrane potential is ____ depolarized > -55mV ○ A lot of leakiness > in pacemaker cells, Na+ goes through (leaks) channels > depolarizes the membrane > achieve threshold > AP § PM depolarization is slower to peak than in the myocytes (these are all-or-none) § PM AP > ____ Ca+ open first, then the ____ Ca+ > AP, the ____ channels open > hyperpolarize the MP > brings it back down > leaking Na+ channels that allows us to have a continuous depolarization

-55m Na+ Ca++ plateau more T type L type K+

Cardiac myocyte AP/contraction longer than nerve or skeletal muscle Don’t want a ____ twitch Influx - ____ Na+, ____ Ca2+, then ____K+ efflux • Peak potential of ____ and myocyte is same; but depolarization of the myocyte achieves a long plateau > want a long contraction because you need to have a steady control to squeeze that blood out ○ ____ situation; all fibrils have to contract and it has to be coordinated • -90 mV resting > Na+ enters depolarizes > entry of Ca+ maintains the plateau > with a delay > K+ increases and repolarization ○ Delayed opening of K+ ○ Presence of Ca++ to allow ____ contraction

quick fast slow delated nerve all-or-none long

Ionic conductance changes ventricular AP ____ Ca2+ conductance and ____ K+ conductance allow for prolonged contractions • Na+ driven > big ____ in Na+ permeability; then an increase in Ca+ and decrease in K+ > allows for the plateau

increased decreased increase

Refractory periods maintain ventricular AP - can be modified to change heart rate Effective RP vs Relative RP modify rate • ERP > initial part ○ ____ period in contract muscle • RRP ○ Can use ____ to modify (faster or slower) • Change HR by changing the amount of time the myocyte AP takes to ____

fastest drugs recover

Cardiac muscle a syncytium * ____ connect the end of cell so action potential spreads to all cells. Coordinated contraction: all at once. * Atrial vs. ventricular syncytium; separated by ____ fibers • Gap junctions at end of fibers > allow cardiac muscles to act as syncytium > enhance cardiac efficiency when it's time to beat ◦ by coupling the muscle fibers electrically through these gaps junctions ‣ you make sure that these action potentials signals pass rapidly from one cell to another • ____ coupling allows for much faster spreading in a coordinated conduction • Atria/ventricle chambers > depends on there being different contraction times > having non-conductive fibers that separated atria from ventricles > electrical signal going through AV and bundle of His passing through the NCF

gap junctions non-conductive gap junction

Excitation contraction in cardiac muscle – influx of Ca2+ key * The same Ca2+ influx through ____ VDCC that underlies plateau also triggers release of calcium-dependent calcium release through ____ channels on sarcoplasmic reticulum * More Ca2+ maintained in ____ than for skeletal muscle, bound to ____ • Influx of Ca+ is critical to the cardiac muscle • Larger T tubules > more Ca++ is bound within ○ ____ bind Ca++ so there is enough Ca++ to enter the cardiac muscle > AP comes along > transmitted into T tubule > opens Ca channel > Ca enters (electrochemical gradient mandates that it open) > Ca++ dependent Ca release cahnnels on SR (ryanodine channels) > secondary release of Ca (much more here) > contraction § Two sources > ____ signal and ____ controls the signal; ensure a solid and firm contraction, and to control the time ○ Entry of ____ is critical for contraction and actin-myosin cross bridge sitation

L-type ryanodine T tubule mucopolysaccharides mucopolysaccharides magnifies temporally Ca++

Ca++ channel blockers demonstrate the importance of Ca++ influx for contraction * Show that cardiac muscle relies on extracellular calcium * Force generation can be modulated by calcium ____ of the cell * ____® * Verapamil® * ____® * Increase cxn of drug > plateau phase of muscle is ____ > cardiac muscle depends on extracellular calcium coming in * Forces in mN over time > the ____ is also decreased by the blocker

``` outside diltiazem nifedipine reduced force ```

When plateau ends, cytoplasmic Ca2+ levels return to normal – end contraction * ____ Ca2+ channels close, no more influx * Na/Ca & Na/K transporters actively transport ____ to outside (remember primary and secondary active transport?) * Ca2+ actively transported back into SR by ____ • We talked about how important this is to have important temporal control over the contraction ◦ this applies to not just the beginning of the contraction but also the end • Removing calcium is how we limit the contraction ◦ this is done in a couple of ways: • SERCA ATPase > uses energy of ____ to actively pump Ca++ out of the cytoplasm into the SR to refill the stores again ○ Energy dependent aspect of muscle contraction* • Na/Ca exchangers > pump Ca++ outside (from cyto to EC space and loaded into ____) • Primary > ____: ◦ ATP binds here (Na/K channel) so that we have a driving force to bring that sodium back in ‣ that driving force bringing Na in across the myofibril is what allows us to pump ____ out • The closing of those calcium channels and the time has come for them to close is critical to reduce this as well ◦ the uptake into the SERCA depends on ____ ◦ the Ca/Na exchanger (secondary active transport pushing calcium outside the cell based ultimately on the ____ pump) and have the channels closed so no more calcium comes in

L-type Ca++ SERCA-ATPase ATP T tubule NaK ATPase Ca+ ATP ATP

Electrocardiogram ``` P = ____ depolarization QRS = ____ depolarization T = ventricular ____ ``` ECG=EKG Elektrokardiographie German / American

atrial ventricular repolarization

EKG and cardiac cycle • ____ – atrial depolarization/ contraction • ____ ventricular depolarization/ contraction • ____ – ventricular repolarization • P wave depolarization > leads to additional ____

p wave QRS T-wave

Polarity of EKG vs. cells • ____ different from cell membrane potential – it’s complicated • Phase I > corresponds to ____ The T wave ◦ corresponds to the repolarization ( ____) • They are both ____ waves on the EKG ◦ One represents a depolarization (QRS) and one represents a ____ (T wave)

``` tissue potential QRS phase III positive hyperpolarization ```

EKG - intervals and segments * P-Q(R) interval: ____ contraction, ____ sec * Q-T interval: contraction of ____, ____ sec * S-T segment: ____ depolarized, ____ sec * ____Interval = heart rate, 1/0.9 sec =1.11 bps x60 = 66 BMP • the R is the largest ____ that you are going to see on the EKG • RR > interval of ____ • QT > ____contraction ○ Delay the plateau > increase the ____ • PQR > time in between ____ and ventricular contraction • ST > ____ phase

``` atrial to ventricular 0.16 ventricle 0.35 ventricular myocytes 0.1 1/RR ``` ``` depolarization HR plateau interval atrial contraction ```