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62 Cards in this Set

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The ____ wave represents the depolarization of the atria.
P wave
Where does depolarization begin in the heart?
SA node
Is atrial repolarization seen in a normal ecg?
No...it is buried in the QRS complex
The ________ interval is the time from the initial depolarization of the atria to the initial depolarization of the ventricles.
PR interval
The PR segment corresponds to an isoelectric (flat) portion signaling _____ _____ conduction.
AV node
outline the conduction pathway of a normal action potential through the heart...
SA node (automatic)

Left atrium depol.

Right atrium depol.

AV node (very delayed--allows ventricles to fill completely)

Bundle of His

Left and Right bundle branches

left and right purkinje fibers

**note that the conductile anatomy is slightly more complicated than the above outline...not likely testable
What is the sympathetic effect on the conduction velocity through the AV node? Parasympathetic?
Symp = faster

Para = slower
The QRS waves collectively represent ______________.
depolarization of the ventricles
The ____ wave represents repolarization of the ventricles.
T wave
The _____ interval represents first ventricular depolarization to last ventricular repolarization.
QT interval
The ____ segment corresponds to the plateau of the ventricular action potential.
ST segment
________ is the volume of blood ejected by the ventricle on each beat.
stroke volume
___________ is the fraction of the end-diastolic volume efected in each stroke volume...a measure of ventricular efficiency.
Ejection Fraction
_______ is the total volume ejected by the ventricle per unit time.
Cardiac Output
What is an ~ normal EF?
55%
Ejection Fraction = _____/______
Stroke volume/ end-diastol. vol.
What is an ~ normal cardiac output?
5L/min
Cardiac output = _______ x ________.
Stroke Volume x HR
Cardiac output is determined by ________ and _______
CO determined by HR and stroke volume
________Is the highest pressure during the cardiac cycle and is determined by stroke volume and compliance
Systolic pressure
___________ Is the lowest pressure during the cardiac cycle and is determined by heart rate and total peripheral resistance
Diastolic pressure
What contributes to arterial pressure?
Cardiac output

Total peripheral resistance
What contributes to stroke volume?
LVEDV

LVESV
What contributes to LVEDV?
Ventricular compliance

Ventricular filling pressure
What contributes to LVESV?
Vent. Ejection
Ventricular ejection is dependent on ___________________________?
Coronary blood flow

Sympathetic discharge
What are the 2 steps that influence heart rate?
Pacemaker freq.

Symp vs. para influence
What determines total peripheral resistance?
Local factors

neurohumoral
Blood pressure = __________ x ________________
Cardiac output

TPR
dPressure = ______ x ______
dP = flow x resistance
Consider vascular blood flow, where is there no net flow (location/zone)?
against the wall
Reynolds # helps to determine what kind of flow...>2000
Turbulant flow
Compliance is determined by?
d Volume

d pressure
Arteries or veins have the most compliance?
Veins
What contributes to transmural pressure?
Pi and Po

inside and outside pressures
Which vascular structure(s) represent the greatest total surface area?
Capillaries
Which vascular structure(s) have the slowest blood flow velocity?
Capillaries
Which vascular structure/systems contains the greatest proportion of total blood volume?
Venous
In which vascular structure(s) do you see the greatest drop in pressure? Why?
Arterioles

greatest resistance here...
Why would arterial pressure be higher with arteriosclerosis? Lower with Aortic stenosis?
Arteriosclerosis is narrowing of radius of vessel and decrease in compliance...thus higher pressure.

Aortic stenosis would have lower pressure because decreased stroke volume and normal compliance.
What is the difference in resistance for series and parallel?
Series:
Flow through any segment in series is the same. i.e. = to total flow


Parallel:
Pressure drop across system is equal, but flows vary for each bed.

Pi = Po
What factors contribute to tension on a vessel wall?
total pressure

Radius of vessel
What is the most common type of capillary in the body?
Continuous caps
Capillary _____ improves diffusion.
recruitment
What are the local mechanisms of vasodilation?
hyperpolarization

increase cAMP or cGMP
What are the local facotrs that cause vasodilation?
Hypoxia

Adenosine

CO2 local acidosis

EC K+

Autocoids
The heart has mostly what kind of adrenergic receptor?
Beta 1
What is the only way to increase oxygen to the heart?
Increase coronary blood flow
As oxygen consumption increases, _______ increases.
Coronary blood flow
Where are the arterial baroreceptors?
Carotid sinus

Aortic arch
Discuss the cascade produced by stretching baroreceptors in the carotid sinus....
cues cardiac decelerator

parasympathetic surge

inhibitory to SA node
Discuss the cascade produced by a decrease in arterial pressure...baroreceptors...
decreased stretch on baro

decrease parasymp. to heart

increased HR

increase contractility

increase TPR

venous constriction: decrease venous volume--increase venous return

Arterial pressure normalizes
_____ = prolonged P-R interval
first degree heart block
_______ = dropped beat---
Second degree heart block
What would you expect to see on the ECG of a pt with third degree HB?
A fair distribution of P waves, BUT NO QRST....Missing beats
SA node falters, and a subsidiary pacemaker takes over
Escape beat
Ectopic focus within the ventricular muscle, the QRS complex is wide, bizarre, and unrelated to a preceding P wave
Ectopic Beat
Which are the inferior leads?
II

III

aVF
Which are the lateral/left leads?
I

aVL

V5

V6
Which are the Right sides leads?
aVR

V1
How many Precordial/chest leads are there?
6
Which are the anterior leads?
V2

V3

V4