Heart Phys yo Flashcards
Which walls are fed by the L coronary artery?
lateral wall
anterior wall
Which walls are fed by the R coronary artery?
inferior wall
posterior wall
(I’m pretty sure these are right - please tell me if I’m wrong!)
Where is the worst place to have an infarction?
anterior wall
What are the 3 types of heart cells?
myocardial
pacemakers
specialized conducting cells (e.g. bundle of his, purkinje fibers)
What happens during a normal action potential?
(there is a picture on the other side)
What happens during the action potential of the SA/AV nodes?
(another picture)
What is the term for when no stimulation will depolarize cells?
absolute refractory period
What is the term for when only a very strong stimulus will depolarize cells?
relative refractory period
What are the parasympathetic HRs for the SA node, AV node, and Purkinje fibers?
SA - 60-100
AV - 40-60
Purkinje - 20-40x/min
Does conduction velocity occur faster in the LBBB or RBBB?
LBBB
What causes ventricular myocytes to depolarize?
Na entering the cell
Which wall is opposite to the inferior wall?
Lateral wall
Which ion is primarily responsible for depolarizing the AV node?
calcium
Which system inc HR, inc conduction velocity, and inc the force of contraction?
With what neurotransmitters?
sympathetic
NE, EPI
Which system dec HR and dec conduction velocity?
With what neurotransmitter?
parasympathetic
Ach
Do you have a lower threshold at rest or exercise?
rest
how do waves of depolarization and repolarization travel across the cells?
gap junctions
What kind of a deflection do you get when a vector travels toward a + electrode?
a - electrode?
toward + electrode = + EKG
toward - electrode = - EKG
What does the EKG look like when a vector travels @ 90 degrees of it
biphasic
Starting with the AV valve closing, what is the order of events with regards to the opening and closing of the AV valve/aortic valve and the filling of the ventricles?
1) AV valve closes
2) Ventricles are filled and begin isovolumic contraction
3) Aortic valve opens
4) Ventricles eject blood into aortic valve (systole)
5) Aortic valve closes
6) Isovolumetric relaxation occurs in the ventricles
7) AV valve opens
8) Diastole occurs (blood fills the ventricles)
When the AV valve closes, what is happening:
a) to the atrial pressure?
b) to the ventricular pressure?
c) to ventricular volume?
a) atrial pressure slightly increases (due to slamming shut)
b) ventricular pressure greatly increases (isovolumic contraction occurs)
c) ventricular volume is highest
When the aortic valve opens, what is happening:
a) to the aortic pressure?
b) to the atrial pressure?
c) to the ventricular pressure?
d) to ventricular volume?
a) aortic pressure increases
b) atrial pressure starts to decrease (because the ventricles aren’t pushing up on them as they eject)
c) ventricular pressure continues to increase (as it squeezes)
d) ventricular volume greatly decreases
When the aortic valve closes, what happens:
a) to the aortic pressure?
b) to the ventricular pressure?
c) to ventricular volume?
a) aortic pressure starts increasing again
b) ventricular pressure is decreasing
c) ventricular volume is lowest
When do you hear S1?
When the AV valve closes
(onset of ventric contraction)
When do you hear S2?
When the aortic valve closes
(onset of ventric relaxation)
When is ventricular peak end volume?
After atria contract - after diastole
What is systolic volume in terms easy enough for a simpleton like me?
After the ventricles contract, it is what is left in the heart.
S3, or a ventricular gallop, is heard when?
If middle-aged, associated with heart failure.
Can be normal in younger people, as long as it goes away before middle age.
S4, or atrial gallop, is heard with what condition(s)?
when there is a stiff or hypertrophied ventricle
Why is it important that the pulmonary circulation is low pressure?
Slower - allows for better exchange of gases
What is the term for the amount of blood that the heart pumps each minute?
cardiac output
What is cardiac output determined by?
stroke volume (amount of blood pumped with each beat)
heart rate
what is the term for the maximum percent increase in cardiac output that can be achieved above resting?
cardiac reserve
What is preload?
basically the volume of blood that fills the heart to be pumped (based on how much the heart stretches)
What is afterload?
the pressure that the heart must generate to pump blood against the resistance and into the aorta
Which heart layer is a fibrous covering around the heart that holds it in a fixed position?
pericardium
Which heart layer also lines the vessels and valves?
endocardium
In what areas of the heart is the conduction very slow?
SA and AV nodes
What is the purpose of having a slower velocity of AP through the SA and AV nodes?
allows the atria to complete their ejection before ventricular contraction begins
What initiates this slow response?
Calcium
What happens if the tranmission of impulse is blocked through the AV junction?
ventricles beat independently from the atria
Which ion plays a key role in the contraction of cardiac cells?
calcium
Where in the heart is there a fast electrical response?
What ion causes this?
normal myocardial cells and Purkinje fibers
caused by fast Na influx
What do catecholamines do to HR?
increases heart rate (increase the rate of depol)
What does Ach do to HR?
decreases HR (slows depol)
What term is used to describe the difference between the end-diastolic and end-systolic volumes?
stroke volume (is approx 70ml)
What term is used to describe the percentage of diastolic volume that is ejected from the heart during systole?
ejection fraction
what can ejection fraction assess?
how severe was a patient’s MI?
(the lower it is, the worse it is)
When do the atria fill, during systole or diastole?
Both! (no valves before atria)
Basically, what does the Frank-Starling mechanism describe?
That there is an ideal amount of stretch for the heart to have maximum contraction, based on how the myosin heads line up
(too much or too little stretch = weaker contraction)
What do epi and NE* do to blood vessels?
vasoconstrict
What is the Bainbridge reflex?
baroreceptors in your atria tell your heart whether to inc or dec the HR based on pressure
what type of control is the frank starling mechanism and bainbridge reflex?
intrinsic (within the heart)
What type of control is NE and Angiotensin II?
extrinsic control
an increase in end diastolic volume does what to stroke volume?
increases it (intrinsic control)
an increase in venous return does what to end diastolic volume?
increases it. thus it also increases stroke volume
