Physiology Flashcards
When does the mitral valve closes?
When the intraventricular pressure rises above that of the atrium
What is the period between the closure of the mitral valve and the opening of the aortic valve?
Isovolumetric contraction phase
What is the Windkessel Effect?
During diastole, arterial pressure is maintained by elastic recoil on the walls of the aorta
What is the isovolumetric relaxation phase?
Interval between aortic valve closure and mitral valve opening
What represents the first (small bump) on the Wiggers Diagram?
Atrial contraction to fill the ventricle
On the Wiggers Diagram, why is there a plateau between the systolic and diastolic phase? What is the name of this plateau?
Incisura/diacrotic notch
It represents the aortic blood flow going backwards to fill the aortic leaflets (cusps)
What is the ejection fraction?
Stroke volume
_____________
End-distolic volume
What is an normal ejection fraction?
55-70%
What is systolic blood pressure?
Highest arterial pressure at peak ventricular contraction
What is diastolic blood pressure?
Lowest recorded blood pressure at the end of diastole
Systolic BP - Diastolic BP =
Pulse pressure
Mean arterial pressure =
Diastolic BP + 1/3 Pulse pressure
On the pressure-volume loop, the curve [aortic valve closing]-[mitral valve opening]-[mitral valve closing] is what?
Diastole
On the pressure-volume loop, the curve [mitral valve closing]-[aortic valve opening]-[aortic valve closing] is what?
Systole
What is EDPVR?
End-diastolic pressure-volume relation (pressure-volume relation during cardiac filling)
What is ESPVR?
End-systolic pressure-volume relation (pressure-volume relation at aortic valve closure)
If left ventricle is less compliant, EDPVR curve will…
Shift upward
End diastolic volume (EDV) - End systolic volume (ESV) =
Stroke volume
What are the three determinants of stroke volume?
Ventricular prepload
Ventricular afterload
Ventricular contractility
What is Frank-Starling’s Law?
Ceteris Paribus, stroke volume increases as cardiac filling increases
Increase in preload leads to what?
Higher end-diastolic volume
Higher stroke volume
Decrease in preload leads to what?
Less end-diastolic volume
Less stroke volume
Afterload (wall stress) is proportional to what?
Mean arterial pressure
Pressure in ventricle x Radius
________________ =
2x wall thickness
Afterload
Hypertension and aortic valve stenosis is associated with
High afterload
Increase in afterload leads to what?
Decrease stroke volume
Decrease in afterload leads to what?
Increased stroke volume
What is contractility?
Strength of heart’s contraction during systole
With respect to contractibility, norepinephrine will…
Increase contractibility
Increased contractibility will lead to what?
Decreased end-systolic volume
Higher stroke volume
Decreased contractibility will lead to what?
Higher end-systolic volume
Decreased stroke volume
Positive chronotropic effect leads to what?
Higher heart rate
Positive inotropic effect leads to what?
Higher contractibility
What is Fick’s formula?
Cardiac output = VO2/(ConcO2a-ConcO2v)
Usinf the thermodilution method, the cooler the blood…
The smaller the cardiac output
Diffusion coefficient x Concentration gradient =
Flux (flow per unit area)
Diffusion coefficient x ((ConcOut - ConcIn)/thickness) =
Flux
What is 1 unit of blood?
450ml
What is the usual cardiac ouput?
5L/min
Hydrostatic pressure =
Density (p) x Height x Gravity
Perfusion pressure/Resistance =
Flow
Within a vessel, where is the blood the fastest?
At the center
Mean arterial pressure/Cardiac output =
Total periphery resistance
According to Poisseule’s Law, with respect to resistance, the higher the radius…
The lower the resistance
Who recorded the first heart’s current?
Einthoven
Normally, what is the polarity of a cell?
The inside of a cell is negative, and the outside is positive
The T-wave refers to what?
Repolarization
If the recording is negative, what does that mean?
The flow of polarization went from negative to positive
Lead aVR goes from where to where?
From the center of body to right arm
Lead aVL goes from where to where?
From the center of the body to left leg
Lead aLA goes from where to where?
From the center of the body to left arm
Lead I goes from where to where?
From right arm to left arm
Lead II goes from where to where?
From right arm to left leg
Lead III goes from where to where?
From left arm to left leg
What is the name of the first downward deflection, after the P wave?
Q-wave
What is the name of the first upward deflection, after the P wave?
R-wave
What is the name of the downward deflection after the Q or R wave?
S-wave
ST segment is normally isoelectric (it’s a the baseline level). If it moves up or downwards, what does it mean?
The heart is lacking oxygen
A sinus rhythm of less than 60beats/min is a sign of what?
Sinus bradycardia
A sinus rhythm of more than 100beats/min is a sign of what?
Sinus tachycardia
From a birds view, what is the angle of the lead V1?
100
From a birds view, what is the angle of the lead V2?
80
From a birds view, what is the angle of the lead V3?
75
From a birds view, what is the angle of the lead V4?
60
From a birds view, what is the angle of the lead V5?
30
From a birds view, what is the angle of the lead V6?
0
Mean systemic filling pressure =
Peripheral venous pressure
What are the characteristics of central venous compartments?
Small system compared to peripheral venous compartments
Intrathoracic
Includes venae cava and right atrium
Which has the bigger volume, peripheral or central venous compartments?
Peripheral venous compartments
Which is most compliant, peripheral or central venous compartments?
Peripheral venous compartments
What is the name of the actual pressure that would exist throughout the system in the absence of flow?
Mean systemic filling pressure
What is the name of the rate at which blood gets to central venous compartment?
Venous return (normally equal to cardiac output)
Rising the central venous pressure will temporarely do what?
Increase cardiac output
Decrease venous return
Peripheral venous press - central venous press
_____
Venous resistance
Flow
What happens if central venous pressure falls below the intrathoracic pressure?
Thin-walled veins in the thorax will collapse
What happens to the venous function curve when peripheral venous pressure increases?
Shifts upwards and to the right
What happens to the venous function curve when peripheral venous pressure decreases?
Shifts downward and to the left
What is the instrument that allows the assessment of the left atrial pressure?
Swan-Ganz catheter (aka pulmonary artery catheter)
Variation of volume
____
Variation of pressure
Compliance
When someone stands up, the arterial pressure drops momentarily. What does it do with respect to cardiac output, contractility and stroke volume?
Decrease cardiac output
Decrease stroke volume
Increase contractility
When someone stands up, the arterial pressure drops momentarily. What does it do with respect to central blood volume, heart rate and total peripheral resistance?
Decrease central blood volume
Increase heart rate
Increase peripheral resistance
Is there a venodilatation when someone stands up?
No. There’s venoconstriction
Cardiac ouput x total periphery resistance =
Mean arterial pressure
What happens to plasma volume when you stand up?
You lose plasma volume (which explains why you lose central blood volume)
During exercise, after correction, what happens to heart rate, cardiac output and mean arterial pressure?
All three increase
During exercise, after correction, what happens to stroke volume?
Stroke volume increase slightly, but will decrease at high heart rate
During exercise, after correction, what happens to total periphery resistance and arteriovenous oxygen difference?
Decreased total periphery resistance
Increase arteriovenous oxygen difference
Will endurance training increase the maximum heart rate?
No
Exercise will increase blood flow to which systems?
Skin
Skeletal muscle
Heart
