Blood flow/hemodynamics Flashcards
What are the five functions of the cardiovascular system?
To transport nutrients, waste, oxygen and CO2; to allow mixing of body fluids, pH, ionic composition and osmolarity regulation; to regulate body temperature; to transport hormones; to defend against infection
What volume of fluid is contained in the circulating plasma?
3 L
____ L of fluid is in the cells
30 L
How much fluid is in the interstitial compartment?
12 L
Define: capacitance of blood flow
The amount of blood stored in a location. I.e. the venous side of the circulatory system has a higher capacitance than the arteriole side. It is a reservoir for blood.
Define: VO2
Metabolic needs of a tissue represented as a percentage of oxygen consumption
What percentage of blood is in systemic circulation? In pulmonary circulation? In the heart?
84% systemic
9% pulmonary
7% the heart
Define: systole
When the heart is most contracted. The number on top in blood pressure
Define: diastole
When the heart is most expanded and it fills with blood. The number on the bottom in blood pressure.
What are the requirements for efficient ventricular pumping?
Synchronized, regular, forceful contractions; valves that open fully and do not leak; ventricles that fill adequately
Define: cardiac output. Give the equation as well
The quantity of blood per time pumped into the aorta by the heart.
CO= SV x HR (stroke volume X heart rate)
What is a typical cardiac output for a normal person at rest
5 L/min
What three things determine stroke volume?
Ventricular preload (length of the muscle before contraction), ventricular afterload (tension of the muscle during contraction) and myocardial contractility
Rank these organs from highest to lowest for percent distribution of blood flow in the resting state: brain, liver/GI, skeletal muscle, kidney, skin
Liver/GI (24%), Skeletal muscle (21%), Kidney (20%), Skin (18%), Brain (13%)
What is Starling’s Law of the Heart?
All other things constant, stroke volume (and thus cardiac output) increases as end-diastole filling increases. Collecting more blood means you can pump more blood.
Is the heart a generator of constant pressure or of constant flow?
Constant pressure
Which vessel in systemic circulation has the greatest resistance to flow?
Arterioles
Define: systolic pressure
The peak arterial pressure reached during ejection of blood by the heart. The top number in a blood pressure reading
Define: diastolic pressure
The lowest arterial pressure during diastole. The bottom number in blood pressure
Define: mean arterial pressure. Give the equation too.
The average pressure during the cardiac cycle. To calculate: MAP= diastolic pressure + 1/3 pulse pressure
Define: pulse pressure
The difference between systolic and diastolic pressure
What is an advantage for the auscultatory measurement for blood pressure? A disadvantage?
It is non-invasive but is not as precise as other means
Describe the method of catheterization to measure blood pressure
To measure arterial pressure, pass a catheter in retrograde (opposite the direction of flow) into an artery or the left ventricle. For venous pressure (and RA and RV), pass the catheter in anterograde.
How would you measure the blood pressure of the left atrium or in a pulmonary artery?
Pass a catheter into it with the direction of flow, inflate a balloon and measure the number at which the vascular pressure equilibrates just past the balloon