Lecture 1: Review & CV Function (Exam I) Flashcards
What is Clearance?
What units would be used to denote this concept?
- How much plasma is cleared of a substance per unit of time ( ex. mL/min )
What is free water clearance?
What would a high free water clearance indicate?
What is an example of a situation that would necessitate a high free water clearance?
- How much H₂O is cleared from the blood.
- ↑ free H₂O clearance = getting rid of water
- Ex. Hypervolemia
What would the normal pulse pressure in large arteries be?
How would this change in the aorta and why?
- 40mmHg
- PP would be less in the aorta due to increased aortic compliance.
What would be considered “stiffer”, the aorta or large arteries?
What would the result of stiffness be on the measured pulse pressure?
- Larger Arteries = stiffer = less compliance.
- ↑ stiffness = ↑ pulse pressure
What is the formula for compliance?
- C = ΔV / ΔP
What are the three benefits of increased aortic compliance?
- Increased “stretchability” allows for more pumped blood to fill up aorta.
- Decreases LV afterload.
- Functions as “rebound” secondary pump.
What is a healthy CVP and where is it measured?
- 0 mmHg measured right outside of the right atrium.
The addition of lots of volume with relatively little pressure increase would indicate a _____ compliance system.
high
The addition of little volume but relatively large pressure increases from the volume addition would be considered a ____ compliance system.
low
What is a normal pressure in the left atrium?
- 2 mmHg
What is a normal pressure in the right atrium?
- 0 mmHg
What vessel group has the greatest total cross-sectional area?
- Capillaries (4500 cm²)
What vessel has the lowest total cross-sectional area?
- Aorta (4.5 cm²)
What is the formula for blood velocity?
- Flow / Area
What structure governs blood flow into the capillaries?
- Arterioles & precapillary sphincters
What would trigger arteriole relaxation?
Why would this occur?
- H⁺, CO₂, & adenosine (metabolic byproducts)
- Arteriole relaxation = ↑ flow & movement of metabolic products.
What is the normal hydrostatic pressure at the beginning of a capillary system?
What about at the end?
What would the average pressure be throughout the capillary system?
- 30mmHg to 10mmHg
- 20mmHg
What is the plasma colloid osmotic pressure (πCAP) ?
- 28 mmHg
What would a normal interstitial fluid pressure be?
- -3mmHg
What would a normal interstitial fluid colloid osmotic pressure be?
- 8mmHg
What portion of the vascular system has a lack of innervation?
Why is this?
What neurotransmitter is secreted to cause vasoconstriction?
- Capillaries
- No smooth muscle is present.
- Norepinephrine
Where does lymphatic return to the venous system occur?
- Subclavian Vein
What are the effects of gravity on the blood pressure of a standing person?
- 1mmHg BP increase for each 1.36cm below the heart.
Where in the body can one experience negative blood pressure?
Why is this?
What would the relevance of this be in a trauma situation?
- Cerebral sinuses
- No one-way valves and hard venous walls.
- With traumatic injury to the cranium, one could potentially get air into the CV system due to exposed negative pressure of the sinuses.
Why is the pressure in the jugular veins negative in a standing person?
- Trick question. The pressure won’t be negative, the jugular veins will collapse and pressure effectively becomes 0 mmHg.
If a person is standing or sitting what would you expect blood pressure taken at the arm be in relation to a perfect isogravimetric position?
- BP in arm should be a bit higher due to gravitational effects on the blood pressure.
What drug class prevents venous return? (as discussed in lecture).
Why is this?
- NMBs
- Lack of muscle movement and basal resting tone lead to lack of venous blood movement.
Are veins or arteries more distensible?
- Veins
What is distensibility? What is the formula for vascular distensibility?
- How expandable a container is.
- Distensibility = Increase in volume / (increase in pressure x original volume)
What is the formula that predicts turbulence?
- Re = (v · d · ρ) / η
Increases in what factors would increase the likelihood of turbulent flow?
Where is the likeliest vessel we’d see turbulent flow?
- Velocity, viscosity, density, diameter
- Aorta
An Re value greater than or equal to 2000 would indicate what?
- Turbulent flow
If 1 is considered a normal arterial BP waveform, what would you expect 2 to indicate in the figure below?
- Arteriosclerosis.
If 1 is considered a normal arterial BP waveform, what would you expect 3 to indicate in the figure below?
- Aortic stenosis
If 1 is considered a normal arterial BP waveform, what would you expect 6 to indicate in the figure below?
- Aortic regurgitation
What occurs with pulse pressure as one ages?
Why does this occur?
- Pulse pressure widens with age due to increasing vessel rigidity.
Describe what has occurred in the graph below as well as why.
- Drop in BP from loss of arterial tone from sympathetic chain blockade from spinal anesthesia.
Low compliance systems would be indicated with a steep or slight slope on a graph?
- Low compliance = steep slope
What are the four phases of cardiac contraction?
- Filling period
- Isovolumetric contraction
- Ejection period
- Isovolumetric relaxation
What would a sloped line on the isovolumetric parts of a pressure-volume loop of the cardiac cycle indicate?
- Volume loss (isovolumetric plots should be essentially vertical)
When does the Mitral valve open?
When does this valve close?
- MV opens at end of isovolumetric relaxation and beginning of filling period.
- MV closes at end of filling period and beginning of isovolumetric contraction.
When does the aortic valve open?
When does the aortic valve close?
- AV opens at the end of isovolumetric contraction and the beginning of the ejection period.
- AV closes at the end of the ejection period and the beginning of the isovolumetric relaxation.
What would occur if both carotids were clamped? Why is this?
- The arterial pressure would rise significantly.
- Loss of baroreceptor signaling allowing for NTS control of BP.
