Chapter 18

Question 1

Flow

Answer 1

indicates the volume of blood moving at a particular time

units: volume/time ex. liters/mm “how much?”

Question 2

Velocity

Answer 2

indicates the speed of a fluid moving from one location to another
units: distance/time ex. 200cm/sec

Question 3

3 Basic Forms of Blood Flow

Answer 3

pulsatile
phasic
steady

Question 4

Pulsatile Flow

Answer 4

occurs when blood moves with variable velocities, accelerates and decelerates from cardiac contraction and appears in the arterial circulation

Question 5

Phasic Flow

Answer 5

occurs when blood moves with variable velocities, accelerates and decelerates from respiration and appears in venous circulation

Question 6

Steady Flow

Answer 6

occurs when blood moves at a constant velocity, steady flow is present in the venous circulation when individuals stop breathing for a moment
ex. of steady flow, water running through a garden hose

Question 7

Laminar Flow

Answer 7

when the flow streamlines and is parallel, layers of blood travel at individual speeds, commonly found in normal physiological states

Question 8

2 Forms of Laminar Flow

Answer 8

plug flow

parabolic flow

Question 9

Plug Flow

Answer 9

when all the layers of blood cells travel at the same velocity (center of river)

Question 10

Parabolic Flow

Answer 10

velocities are highest in the center and gradually decrease to the minimum at the vessel wall (has a bullet-shaped profile)

Question 11

Plug and Parabolic Flow are…

Answer 11

Laminar and associated with normal physiology. Laminar flow is silent.

Question 12

Reynolds number

Answer 12

predicts whether flow is laminar or turbulent
laminar flow is less than 1,500
turbulent flow is more than 2,000

Question 13

Turbulent Flow

Answer 13

chaotic flow patterns in many different directions and at many different speeds
hurricane-like, also called an eddy current or vortex

Question 14

Turbulent Pathology

Answer 14

associated with cardiovascular pathology and elevated blood velocities
may be seen downstream from stenosis in a vessel

Question 15

Turbulent Flow converts flow energy into..

Answer 15

sound and vibrations

Question 16

Turbulence associated with sound

Answer 16

is called murmur or a bruit

Question 17

Turbulence associated with vibrations

Answer 17

is called a thrill, also described as a palpable murmur, you can feel it with your fingertips

Question 18

Where can turbulent flow be detected?

Answer 18

1 cm after the stenosis

Question 19

Energy Gradient

Answer 19

blood moves from regions of higher energy to lower energy

Question 20

What event provides energy to the circulating blood?

Answer 20

energy is imparted to blood by the contraction of the heart during systole

Question 21

Forms of energy associated with blood

Answer 21

kinetic
pressure
gravitational

the total energy at a specific location with the circulation is the sum of all 3 energy forms

Question 22

Kinetic Energy

Answer 22

is associated with a moving object

determined by 2 factors: object’s mass and the speed at which it moves

Question 23

Pressure Energy

Answer 23

stored or potential energy, has the ability to perform work

pressure is a major form of energy in the circulation system, creates flow by over coming resistance

Question 24

Gravitational Energy

Answer 24

stored or potential energy (like pressure energy), associated with any elevated object (use of gravity)

identical objects at the same height have the same gravitational energy

Question 25

Energy is lost 3 ways during circulation

Answer 25

viscous loss frictional loss inertial loss

Question 26

Viscous loss

Answer 26

associated with thickness of the blood, energy is lost by overcoming its internal thickness

Question 27

Viscosity is measured in units called...

Answer 27

Poise

Question 28

Viscous energy loss in blood is determined by the.. .

Answer 28

Hematocrit, % of blood made up of red blood cells.

Question 29

Frictional Energy loss

Answer 29

energy is lost when flow energy is converted to heat | blood sliding across the vessel walls

Question 30

Inertial Energy loss

Answer 30

energy is lost when the speed of the fluid changes, regardless is the fluid accelerates or decelerates

Question 31

Inertia

Answer 31

relates to the tendency of a fluid to resist changes in its velocity

Question 32

Inertial Energy loss occurs during 3 events

Answer 32

pulsatile flow phasic flow velocity changes at a stenosis

Question 33

velocity increases...

Answer 33

when the vessel is at its narrowest

Question 34

velocity decreases...

Answer 34

when the blood flows out of a stenosis into the normal vessel diameter

Question 35

Stenosis

Answer 35

is a narrowing in the lumen of a vessel

Question 36

5 affects of a Stenosis

Answer 36

``` change in flow direction increased velocity as vessel narrows turbulence downstream from the stenosis pressure graident across the stenosis loss of pulsatility ```

Question 37

Bernoulli's Principle

Answer 37

describes the relationship between velocity and pressure in a moving fluid principle of conservation of energy- with a steady flow, the sum of all energy is the same everywhere

Question 38

The relationship between flow resistance and pressure gradient is defined by what equation?

Answer 38

flow X resistance = pressure gradient

Question 39

Pressure gradient increases when..

Answer 39

flow increases | resistance increases

Question 40

Flow increases when...

Answer 40

pressure gradient increases | resistance decreases

Question 41

Ohm's Law

Answer 41

current X resistance = voltage

Question 42

Ohm's is...

Answer 42

electrical resistance

Question 43

Fluids

Answer 43

pressure flow resistance

Question 44

Electricity

Answer 44

voltage current resistance (ohms)

Question 45

What is the typical resistance of veins?

Answer 45

low resistance

Question 46

How do veins adapt to increased inflow during periods of exercise?

Answer 46

the cross section shape of the vein changes from hourglass to oval and then to round

Question 47

Hydrostatic Pressure

Answer 47

pressure related to the weight of blood pressing on a vessel measured at a height above or below the heart level

Question 48

Units of Hydrostatic Pressure

Answer 48

mmHg

Question 49

What is the hydrostatic pressure when an individual is supine?

Answer 49

Zero, all parts of the body are at the same level as the heart

Question 50

Respiration affects venous flow for 2 reasons

Answer 50

the venous system is low pressure | muscles responsible for respiration alter pressures in the thorax and the abdomen

Question 51

Breathing affects 2 venous flows

Answer 51

venous flows in the legs venous return to the heart, which comprises venous flow from the head, arms and flow from the inferior vena cava to the heart

Question 52

Venous flow in the legs correlates with movement of the...

Answer 52

diaphragm

Question 53

Downward movement of the diaphragm...

Answer 53

decreases venous flow in the legs | downward-decrease

Question 54

Upward movement of the diaphragm...

Answer 54

increase venous flow in the legs | upward-increase

Question 55

When venous flow in the leg decreases...

Answer 55

venous return to the heart increases

Question 56

When venous flow in the leg increases...

Answer 56

venous return to the heart decreases