Exam 1 - Lecture 5 Flashcards
Right Vagus nerve is the
SA node
Left vagus nerve is the
AV node
Sympathetic innervation is where on the heart?
widespread, more on the ventricle tissue.
If you take away sympathetic nervous system, HR goes to
60bpm
Transparent layer on top of heart is ___ and what is it for?
Serous pericardium, visceral layer. thin membrane for things to move without friction.
Inner layer of parietal layer over heart?
Serous pericardium - parietal layer.
outer layer of parietal layer over heart?
Fibrous pericardium - External layer.
Most important ion for gap junctions in heart?
sodium since its small, calcium is pretty big.
Cusps are also called
leaflets
Cusps are attached to
Chordae tendineae
chordae tendineae are attached to the
papillary muscles
How can you tell its the left or right ventricle?
Right ventricle wall will be much thinner
When the ventricle muscles contract, the ___ will too.
papillary muscles
whats the purpose of contraction of papillary muscles?
prevents AV valves from blowing back into atria from pressure in ventricles when pressure is really high in ventricle.
If you have an MI that takes out papillary muscles, this will cause an
AV valve problem.
normal ejection fraction for our class is
70 of 120 (58.3%)
What can damage structure of valves?
infection that immune system will attack that it shouldnt, and high cholesterol gets stuck to valves.
How many cusps/leaflets do aortic valve and pulmonary valve have?
3 each.
where are the coronary arteries fed blood?
from aorta, on left and right cusps.
how do the coronary arteries get help for increased blood flow?
The cusps of the aortic valve act as cups, and when the valves close the “cup” collects blood and the high pressure in the aorta and also the aorta expanding then recoiling allows the blood to flow into the coronary artery.
What is yet another problem aortic stenosis when you consider the coronary blood flow?
Less pressure for the coronary arteries to get perfused if blood isnt pooling in the cusps.
what is the functional split between the electrical activity happening in atria and ventricle?
Cardiac cartilaginous ring.
doesnt conduct electrical activity well, so it keeps the electrical activity separate (between the muscles).
What does the cartilaginous ring have in the middle?
opening for bundle of his
the one spot for the electrical system to talk to eachother, allows AV node to talk to ventricles and send action potentials.
Forgotten about third cusp of left ventricle is
commissural cusp, really just a part of the posterior cusp.
Vast majority of patients have back of heart supplied by
right coronary artery
but some people it can be the circumflex artery (which branches off left coronary artery)
Huge vein on posterior heart?
Great cardiac vein
The great cardiac vein empties into the
coronary sinus -> right atrium
Coronary blood flow is typically (how much blood?)
70mL/min/100g of muscle
which comes out to 225mL/min
this means, the heart is typically 321g
When is coronary blood flow highest?
during diastole, with least amount of pressure because pressure forces them to collapse
Diastole is the only time that ______ parts of the heart are being perfused.
High pressure
What spots in the heart are perfused during systole?
Low pressure spots
The superficial vessels are called
epicardial vessels
The vessels that are deeper in the heart are called
endocardial or subendocardial blood vessels
Which side of the heart is higher pressure therefore less blood flow during systole?
Left ventricle and interventricular septum.
Which section of heart is low pressure throughout cardiac cycle and always getting blood flow?
right side of heart and the atrias.
Atria also dont use alot of energy so dont need alot of blood flow
Which coronary artery feeds the high pressure, and which feeds low pressure?
Not clear cut… but in general:
Left coronary: high pressure
Right coronary: low pressure
Which coronary artery blood flow is more continous throughout cardiac cycle?
Right coronary
Which coronary artery can be negative blood during cardiac cycle? Which part of cycle?
Left coronary from high pressure squeezing it. Early systole.
How is delta P configured for coronary blood flow?
Aortic pressure - Left ventricular pressure (wall pressure)
How is coronary perfusion calculated?
Delta P x (Diastolic) Time = coronary perfusion
Diastolic time is important d/t thats when high pressure areas are being perfused
If you increase the HR in someone who has partially blocked coronaries, why is this bad? isnt increased cardiac output good?
Its bad bc less time for diastolic, so less time for coronary perfusion.
If there is a healthy heart, why isn’t there a concern about tachycardia decreasing diastole?
It just gets rid of the middle phase, which is after the initial filling and before the atrial kick, where there’s hardly any filling. So it’s not a big deal for a healthy heart. A healthy heart also doesn’t need extra time for the coronary arteries to perfuse, unlike an unhealthy heart.
How does aortic stenosis cause perfusion issues with the left wall?
Since the left ventricle has to pump harder to work against the stenosis, it raises metabolic demand and raises the pressure in the wall so now it is harder to perfuse.
Normal blood pressure with aortic stenosis?
PP narrows, ~110/90
What happens to aortic pressure with aortic regurgitation?
Since blood goes back into ventricle, the diastolic is lower than normal resulting in a widened pulse pressure
What happens to atria pressure during systole when there’s mitral regurgitation?
Pressure rises as blood is shot back into the atria from the ventricle. Doesn’t get high at first cause it was empty, but as time goes it gets fuller and fuller
How does cardiac output change with spinal anesthesia? If circulation stays normal? What if it also affects venous return?
Very small decrease in CO, d/t taking away the very little sympathetic stimulation from heart that it has at baseline.
Then it would change a lot more, down to roughly 3L/min
Atrial pressure: A wave
Result of atrial contraction
Atrial pressure: C wave
Function of AV valves bulging back (papillary muscles)
Atrial pressure: V wave
Result of atrial filling while the AV valves are closed (towards end of systole)
CVP: X descent
Atrial relaxation right after the C wave (contraction) stops bulging on the atria and its really empty before it starts filling again.
CVP: Y descent
Right after V wave; when the AV valves open and fill the ventricle, leaving the atria.
Range for cardiac output is
4.0 - 6.5
Systemic vascular resistance has to be a lot higher than
PVR
SVR range and units
800-1600 dynes x sec/cm5
Formula for SVR
((MAP - CVP) / CO) x 80 = (dyne x sec/cm-5 OR (mmHg/L/min)
PVR formula
((MPAP - PAWP) / CO) x 80 = ~16mmHg/L/min OR Dyne x sec/cm-5
PAWP is what and measured where
Pulmonary arterial wedge pressure: A wedge that gives us an estimated pressure of the left atria
Will pulmonary capillary pressure be higher or lower than PAWP?
Higher since its upstream of the heart
PVR range
40-180 dynes x sec/cm5
What is a CGS unit
Centimeters/grams/seconds
PRU
Peripheral resistance unit
What is the PRU formula
Delta P / Flow (cardiac output), but use cardiac output per second, not minute..
100 - 0 mmHg / 83.3mL/sec = x
But round it up to 100mL/sec….. 100/100 = 1 PRU (normal PRU, aka PVR or SVR????) or mmHg/mL/sec
If you need to convert PRU to CGS, how do you do it?
Times PRU by 1333
What’s the comparison of pulm circulation to systemic circulation?
Pulm circulation is 0.14 PRU, which is 1/7th of systemic.
If we make thoracic pressure low, it will ____ cardiac output
Help
When chest pressure is high, this will do what to cardiac output
Decrease
What you see in the pulmonary artery pressure will be a similar pattern to
Aortic pressure
On inspiration, what happens to CVP?
The negative pressure in the chest will initially lower the CVP almost to 0, because the veins are thin walled and compliant. This means more blood is pulled into the thorax, filling up the veins with blood, theeen fills up the heart with blood. Initially, this lowers cardiac output since pressure is reduced outside the heart, but once the pressure returns to normal it fills the heart. I dont fucking know man.
During inspiration, this will do what to the venous walls?
PULL ON THEM. WHICH ALLOWS MORE BLOOD IN. BUT THIS REDUCES PRESSURE/PRELOAD, AND MAY EVEN PULL BLOOD FROM RIGHT ATRIUM
On inspiration, what is the result of cardiac output on right heart and left heart?
RH: one arrow decrease
LH: 2 arrow decrease
We have established what happens to preload with inspiration, but what about afterload for right heart?
Also decreases.
Are aorta pressures affected by thoracic pressures?
No
Afterload and preload affect for left side of the heart during inspiration?
Afterload stays the same but preload is reduced, therefore CO is reduced a lot more than the right side (both loads reduced over there)
How long are the cardiac output changes after inspiration?
First beat or two.
