Intro

Question 1

What are the 3 components of the cardiovascular system?
What are they comprised of?

Answer 1

1. Heart: 2 separate pumps, 4 chambers, 4 valves.
2. Blood Vessels: Arteries, arterioles, capillaries, venules, veins.
3. Blood: Erythrocytes (RBC), leukocytes (WBC), platelets.

Question 2

What is blood comprised of?

Answer 2

Plasma: 55% of blood. Comprised of water, ions, proteins, hormones, etc.
Hematocrit: 45% of blood. Comprised of erythrocytes.
Leukocytes & platelets: Remaining 5%.

Question 3

How much blood do we have?

Answer 3

Approximately 1% of body weight is from blood.
Hydration levels, recent blood loss, doping, exercise frequency, altitude, and many other factors can influence blood volume levels.

Question 4

Where in the circulatory system does most of the blood reside?

Answer 4

84% of total volume is in systemic circulation. About 64% of this is in veins, with the remaining 13% in arteries, arterioles and capillaries.
7% of total volume is in the heart.
9% of total volume is in pulmonary vessels.

Question 5

What are the different functions of each blood vessel?

Answer 5

Arteries: High pressure transport to organs.
Arterioles: Control and distribution of flow.
Capillaries: Exchange of nutrients, electrolytes, hormones, etc. with tissues.
Venules: Blood collection from capillaries.
Veins: Blood transport back to the heart.

Question 6

What is compliance?

Answer 6

The volume change per unit pressure.
(Slope of a pressure volume graph)
C= Δ V / Δ P

Question 7

What is pulse pressure?

Answer 7

Systole - Diastole.

Question 8

How does compliance affect pulse pressure?

Answer 8

Compliance serves as a dampening system, absorbing some of the pulse pressure. This reduction in pressure in capillaries lowers the chances of bursting.

Question 9

What are the different types of blood flow?

Answer 9

Laminar flow: Streamlined, orderly.
Turbulent flow: Chaotic, disorganized. Can hear turbulent flow (korotkoff sounds).
Shear rate: Friction caused by fluid against the boundary. Depending on the density & velocity, more or less friction may occur.

Question 10

Explain the relationship between flow pattern and velocity of flow.

Answer 10

Turbulent flow is influenced by initial blood velocity. Higher velocities = More turbulent flow. Yet we lose velocity with turbulence, as energy is lost.
Different velocities can also occur within a vessel, friction from vessel walls can result in slower velocity closer to the walls.

Question 11

What is the equation for flow velocity?

Answer 11

Velocity = Flow rate (Q) / Cross sectional area (A)

Q: Volume of blood in L/min, cm^3/min, etc.
A: Measured typically in cm^2.

Question 12

What is Ohm’s law?

Answer 12

Flow = Δ Pressure / Resistance

Question 13

Explain the relationship between pressure and flow.

Answer 13

Blood flows from regions of high pressure (P) to low pressure. Flow occurs only if a positive pressure gradient (Δ P) is present.

Question 14

Why is the pressure drop greatest at the arterioles?

Answer 14

Arterioles have the most increase in resistance among blood vessels.

Question 15

What is resistance?

Answer 15

Opposition to flow due to friction (inverse relationship).
Depends on tube length (L), tube radius (r), and viscosity (thickness) of fluid (η).

Question 16

Resistance increases as ___ and ___ increase, and as ___ decreases.

Answer 16

As tube length and viscosity increase, and as radius decreases.

Question 17

What is the equation for resistance?

Answer 17

R = 8Lη / πr^4

Question 18

What is Poiseuille’s law?

Answer 18

Blood flow = ΔPπ r^4 / 8ηl
Primary determinant of blood flow. Changes in radius can drastically change P and R.

Question 19

What is the major determinant of vascular resistance and how is it regulated?

Answer 19

The radius of the vessel.
It is physiologically regulated.