Lecture 16: CV Biophysics Flashcards
What does the phrenic nerve innervate?
The diaphragm (C3, C4, C5)
What are the functions of the circulatory system?
- Transporting nutrients to tissues
- Transporting waste products away from tissues
- Transporting hormones for signaling
What is the measurement of volume?
Liters; ml
What is the measurement of velocity?
Units of distance/time (e.g., m/s; km/hour)
What is the measurement of pressure?
Force (e.g., mm Hg)
What is the measurement of area?
Size (e.g., cross-sectional area; surface area)
How is blood flow measured?
Volume/time (e.g., ml/min; l/min; ml/sec)
relate vascular resistance and blood flow
Less resistance = greater blood flow (& vice versa)
What does taking a measurement of blood pressure between the source of flow and resistance indicate?
A high blood pressure
What does taking a measurement of blood pressure after a source of resistance indicate?
A lower blood pressure (than if it were in between the heart and the source of resistance)
What drives blood flow?
Pressure
What drives brain blood flow and how is it altered?
CPP drives brain blood flow and is altered by vascular resistance
What is vascular conductance?
How ‘easy’ it is to drive blood flow through some conduit; the inverse of vascular resistance
Differentiate high vascular conductance and low vascular conductance.
High vascular conductance = easier to drive blood through a blood vessel
Low vascular conductance = more difficult to drive blood through a blood vessel
What does Poiseuille’s law relate?
Blood flow, pressure, and vascular resistance into a physics equation
Where is the majority of blood stored in the body?
Systemic veins (84%)
What does adequate cardiac output depend on?
If the veins can bring the blood back to the heart
How does the kidney control overall body volume?
It depends on how much blood we have; if the kidney retains more fluid, it increases blood volume (usually to make up for a deficit)
What is the total resistance in a system arranged in series?
R total = R1 + R2 + R3…
What is the total resistance in a system arranged in parallel?
1/Rtotal = 1/R1 + 1/R2 + 1/R3…
overall the resistance is lower in a system in parallel
What does the internal diameter of a vessel represent?
The cross-sectional area
cross sectional area = Pi x diameter
What happens if the cross-sectional area is a small number?
The blood flow through will be fast (high velocity)
What happens as the distance away from the heart increases in terms of cross-sectional area?
Cross-sectional area increases (e.g., capillaries 2500 cm²)
What happens to blood flow velocity as the distance away from the heart increases?
Blood flow velocity decreases
Contrast the aorta and capillaries in terms of blood flow velocity and cross-sectional area.
The aorta has a low cross-sectional area (2.5 cm²) with a high blood flow velocity (low resistance). The capillaries have a total cross-sectional area (2500 cm²) that is much larger than the aorta, thus creating a much slower blood flow velocity.
What is the formula for velocity of blood flow?
Velocity of blood flow = blood flow/cross-sectional area
Categorize the following vessels from highest resistance to lowest resistance: large arteries, arterioles, small arteries, aorta.
- Arterioles
- Small arteries
- Large arteries
- Aorta
What is the blood pressure measured on the proximal side of a high-resistance vessel?
High blood pressure
What is the blood pressure measured on the distal side of a high-resistance vessel?
Low blood pressure
What are the main resistance vessels that determine blood pressure?
Small arteries & arterioles
What is the blood pressure reading in the capillaries, veins, and right atrium?
10 mmHg
What is the blood pressure reading in the left atrium?
1-5 mmHg
What dictates blood flow through any tissue?
Metabolic rate
What does a high metabolic rate in a tissue indicate?
Low blood pressure (vessels are open) & therefore, we need to expand our blood volume (kidney may retain water to increase blood volume)
What is ideal blood flow?
Laminar Flow
Blood closer to the walls of the vessel meets more resistance; the middle of the blood flow projects faster through the tube due to less wall resistance
What are the characteristics of turbulent flow?
Disorderly; inefficient; blood is pushed into walls of blood vessels causing vasculature remodeling over time.
What can turbulent blood flow cause to aggregate and deposit onto vessel walls?
- Cholesterol
- Ca2+ (calcification)
two C’s
What does Reynolds’ equation measure?
The probability that turbulent flow will occur in a vessel
What percentage of cardiac output do the kidneys receive?
about 20% (or 1 LPM)
Why do kidneys require a high blood flow from the heart?
To be an efficient filter and function properly; the kidneys only partially rely on tissue metabolism for their blood flow.