Lecture 15

Question 1

Physical principles that govern blood flow.

Answer 1

Hemodynamics

Question 2

Two things needed for blood to flow:

Answer 2

1. Path to travel.

2. Pressure gradient (energy gradient)

Question 3

The greater the pressure difference from point A to point B…

Answer 3

The GREATER the volume of flow.

Question 4

In the body, pressure is created by:

Answer 4

The heart or gravity.

Question 5

Q (volume flow rate) is affected by:

Answer 5

Viscosity
Friction
Inertia

Question 6

The fluids thickness or stickiness.

Answer 6

VISCOSITY

UNITS: Poise

Question 7

Blood viscosity is about _____ that of water.

Answer 7

Quadruple.

Question 8

What can change viscosity of blood?

Answer 8

Anemia = low resistance to flow and low viscosity

Polycythemia = high resistance to flow and high viscosity

Question 9

Resistance to motion because of two moving objects touching each other.

Answer 9

FRICTION.

Question 10

Vessel walls and flowing blood produce:

Answer 10

Friction.

Question 11

The longer the vessel, the more fiction, the…

Answer 11

greater the resistance to flow.

Question 12

Tendency of an object to maintain its “status quo”

Answer 12

INERTIA.

Question 13

Inertia can affect:

Answer 13

The volume of flow.

Question 14

Pressure must rise to a level that:

Answer 14

will overcome inertia.

Question 15

Poiseuille’s Equation predicts:

Answer 15

Volume flow rate (Q) in long straight tubes and assumes laminar flow.

Question 16

Poiseuille’s Equation explains relationship between:

Answer 16

Q = volume flow rate
P1 P2 = pressure gradient
r = radius of vessel
L = length of vessel
n = viscosity of fluid

Question 17

Poiseuille’s Mathematical Equation

Answer 17

Q = P/urR

OR

Q = (P1 - P2) pie r^4/ 8nL

Question 18

When pressure increases, volume flow:

Answer 18

increases, vice versa.

Question 19

When radius increases, volume flow:

Answer 19

increases, vice versa.

Question 20

When viscosity increases, volume flow:

Answer 20

decreases, vice versa.

Question 21

When vessel length increases, volume flow:

Answer 21

decreases, vise versa.

Question 22

• Blood velocity uniform across lumen.

- Occurs at entrance of large vessels.

Answer 22

Plug flog

Question 23

PULSATILE FLOW - ARTERIES

Answer 23

• HEART CONTRACTION - change in pressure and velocity

- arteries offer resistance to blood flow.

Question 24

Steady flow - Veins

Answer 24

• Pressure and flow depend on PHASICITY (RESPIRATION) and HYDROSTATIC PRESSURE (GRAVITY).
• Hold large amounts of blood w/o change in resistance and pressure.

Question 25

• Diaphragm descends.
• Intra-abdominal pressure increases
• Pressure gradient changes
• Lower extremity venous flow decreases.

Answer 25

INSPIRATION.

Question 26

• Diaphragm ascends.
• Intra-abdominal pressure decreases
• Pressure gradient changes
• Lower extremity venous flow increases.

Answer 26

EXPIRATION.

Question 27

• Weight of a column of blood from the heart to the point where the pressure is measured.
• Venous pressure changes between supine and standing.

Answer 27

HYDROSTATIC PRESSURE.

SUPINE - 15 mm/Hg
STANDING - 102 mm/Hg