Cardiac Physiology Pt. I Flashcards
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
The cardiac cycle
\_\_\_\_ Volume \_\_\_\_ Valves \_\_\_\_ EKG
pressure
electrical triggers
heart sounds
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
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
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
Boyle’s Law
• Pressure inversely proportional to ____ at constant mass, ____
– As volume expands, pressure decreases
– As volume shrinks, pressure rises
volume
temperature
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
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
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
The cardiac cycle
* Changes in \_\_\_\_ and volume > largely what you're looking at for cardiac cycle * \_\_\_\_ pressure > most important (red)
pressure
ventricular
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
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%
____: atrial contraction – squeezing an extra 20%
p-wave
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
close
pressure
____
– ventricular contraction
• QRS event > electrical event in ventricles ○ Relates to mechanism of increased contraction of muscles in the ventricles
QRS wave
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
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
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
2
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
