EXAM 1: Lecture 2 Flashcards
What is represented by A in the context of blood flow?
A represents a normal artery
What type of flow is represented by B?
B represents laminar flow
What characterizes turbulent flow as represented by C?
Blood is moving in all different directions, with massive amounts of energy being wasted and an increased risk of clotting
What effect do hardened arteries with plaque deposits have on blood flow?
They create high resistance, leading to wasted energy and turbulent flow
Where is turbulent flow most commonly found in the cardiovascular system?
In the aorta and large arteries due to high velocity
What conditions increase the risk for turbulent flow?
- Increased velocity
- Wide diameter
- Increased density
What is the Reynolds number and its significance?
A hypothetical number with no units; a Reynolds number greater than 2000 indicates turbulent flow
What is the formula for calculating Reynolds number?
Reynold’s number = V x D x P / n
Where V = velocity, D = diameter, P = density, n = viscosity
How is density defined?
Density = mass/volume
What is viscosity?
The thickness of fluids like blood, water, gas, and air
What distinguishes density from viscosity?
Density is mass per volume, while viscosity refers to thickness, like molasses or oil
What type of flowmeter is described as an implanted ultrasonic flowmeter?
A device that is not commonly used due to the need for implantation around a blood vessel
How does the electromagnetic probe in a flowmeter work?
It measures flow by detecting changes in the magnetic field created by blood flowing through a sensor
What is the purpose of a pressure transducer in measuring blood pressure?
To connect to a needle attached to a tube in the cardiovascular system for continuous blood pressure measurement
What happens during phase 1 of the pressure volume loop?
The mitral valve opens, allowing passive filling of the left ventricle, starting at 50mL and increasing to 120mL
What is left ventricular end diastolic volume (LVEDV)?
The total volume in the left ventricle at the end of filling, which is 120mL
What role does preload play in heart filling?
Preload refers to the pressures leading into the heart, affecting the rate of filling
What is the atrial kick?
The small increase in pressure and volume (10mL) due to atrial contraction at the end of phase 1
What defines phase 2 of the pressure volume loop?
Isovolumetric contraction, where volume remains constant but pressure increases from 5 to 80mmHg
What occurs in phase 3 of the pressure volume loop?
The aortic valve opens, allowing blood ejection, decreasing left ventricular volume from 120mL to 50mL
What is stroke volume?
The difference between left ventricular end diastolic volume (LVEDV) and left ventricular end systolic volume (LVESV), which is 70mL
What is the significance of phase 4 in the pressure volume loop?
Isovolumetric relaxation, where volume remains the same while pressure decreases from 100 to about 2mmHg
What is the general definition of systole?
The period of ejection when blood is moving into the aorta from the left ventricle
What is diastole?
The period of filling when the heart is preparing for the next contraction
What is systolic pressure?
The pressure in the arteries during ventricular systole
What is diastolic pressure?
The pressure in the arteries during ventricular diastole
What does S1 represent in the cardiac cycle?
The closure of the AV valves; systolic murmur associated with mitral and tricuspid regurgitation
What does S2 represent?
The closure of the pulmonic and aortic valves; diastolic murmur associated with aortic and tricuspid regurgitation
What is S3 heart sound indicative of?
Rapid blood rush from atria to ventricle; associated with conditions like CHF and pulmonary hypertension
What does S4 heart sound indicate?
Contraction of the atria into a stiff ventricle; associated with left ventricular failure
What does the area within the pressure volume loop represent?
The external work done by the heart
What is the significance of the Carl J Wiggers diagram?
It plots volume and pressure against time during the cardiac cycle
What happens during the P wave on the ECG?
It represents atrial contraction, occurring before the pressure changes in the ventricle
What is indicated by the lowest point in the intraventricular volume graph?
The start of filling at 50mL
What happens to aortic pressure during the cardiac cycle?
It peaks during phase 3 and is lowest when the aortic valve opens at the end of phase 2
What does a phonocardiogram display?
The heart sounds related to valve closures
What is the characteristic of atrial pressure in the diagram?
It remains low and does not exceed single digits
What starts the beginning of phase 4 in the heart cycle?
The closure of the aortic valve in the left ventricle.
What does a phonocardiogram show?
Heart sounds.
What is the first heart sound related to?
The closing of the AV valves (tricuspid and mitral).
What is the second heart sound related to?
The closing of the aortic valve.
What is atrial pressure during contraction?
Low, typically not above single digits.
What happens to atrial pressure when the mitral valve closes?
Atrial pressure rises because it prevents further filling of the ventricle.
What is the effect on atrial pressure during systole?
There is a slight increase in atrial pressure.
What happens to atrial pressure when the mitral valve opens?
Atrial pressure drops quickly.
What is the cardiac output at normal right atrial pressure of 0mmHg?
5L/min.
What happens to cardiac output as right atrial pressure increases?
It increases significantly until it plateaus at higher pressures.
What is the maximum cardiac output for a healthy person during intense exercise?
22-25L/min.
How high can the cardiac output get for elite athletes?
35-40L/min.
What does a hypereffective heart do to right atrial pressure?
Reduces right atrial pressure and shifts the curve to the left.
What happens to cardiac output in a heart that is hypoeffective?
Increases right atrial pressure and shifts the curve to the right.
What is the effect of parasympathetic stimulation on cardiac output?
Reduces pumping effectiveness of the heart.
What characterizes the cardiac output curve for a person with CHF?
It is much lower than normal curves.
What is the mean systemic filling pressure (PSF)?
7mmHg.
What does a higher PSF do to venous return?
Increases venous return.
What is the resistance to venous return (RVR)?
How easy or difficult it is for blood to return to the heart.
What happens to venous return if right atrial pressure increases?
Venous return decreases.
What can cause the collapse of large veins filling the right atrium?
Significantly low right atrial pressure.
What is the Bainbridge reflex?
A system that increases heart rate to accommodate higher filling pressure.
What does a right atrial pressure of 4mmHg indicate for venous return?
Venous return drops to about 2L/min.
What is the effect of increased thoracic pressure on venous return?
It can lower the venous return curve.
What happens to venous return when PSF is halved?
Venous return also halves.
Fill in the blank: Cardiac output depends on the conditions of the ______ and the ______.
[circulatory system], [heart]
True or False: A normal circulatory system with a weak heart will have a positive atrial pressure.
True.
What is the relationship between cardiac output and right atrial pressure?
As right atrial pressure increases, cardiac output can increase until it plateaus.
What is the right atrial pressure when CO/venous return is 5L/min?
0mmHg
What is the CO/venous return at maximal sympathetic stimulation with a right atrial pressure of 0mmHg?
6L/min
What happens to CO/venous return when PSF is increased to 20mmHg while keeping filling pressure the same?
13L/min
What is the CO/venous return when PSF is 20mmHg and right atrial pressure is increased to 1mmHg?
22L/min
Fill in the blank: If right atrial pressure is 0mmHg and PSF is 7mmHg, CO/venous return is _______.
5L/min
True or False: Increasing PSF to 20mmHg while keeping right atrial pressure at 0mmHg results in a CO/venous return of 6L/min.
False
What is the PSF when the right atrial pressure is maintained at 0mmHg and CO/venous return is maximized at 6L/min?
7mmHg
What is the relationship between PSF and CO/venous return based on the given data?
Higher PSF leads to higher CO/venous return
