Cardiovascular System: Principles of Flow

Helpfulness: 0
Set Details Share
created 8 years ago by dantetaraba
78 views
Grade levels:
Graduate school
Subjects:
physiology
show moreless
Page to share:
Embed this setcancel
COPY
code changes based on your size selection
Size:
X
Show:
1

rate of diffusion depends on

concentration gradient

2

In a circulatory system, the rate of exchande with interior celss if proportional to

rate of blood flow

3

To determine the flow (Q) of blood through a given resistance (R) use:

Ohm's law Q = Change (P)/ R

4

Mean Arterial Pressure (MAP)

Pressure on the arterial blood (typical value is 85 mmHg)

5

The resistance of the systemic circulation

Total Peripheral Resistance (TPR)
expressed in unit of pressure/flow or
mmHg/(ml/sec)...named peripheral resistance units (PRU)

6

flow of blood through the system

cardiac output (CO)
CO = MAP/TPR (note CO = SV X HR)

7

Two forces that fluids face when flowing through a vessel

Pressure (push) vs. Friction (slows down)

8

Laminar flow

layers near wall slowly (due to friction) while layers near center quickly (due to pressure)

9

the resistance of a single vessel is determined by

poiseuille's law: R = 8nl/pi r^4

10

Factors that increase resistance

increase in vessel length (l)
increase in blood viscosity (n)
decrease in vessel radius (r)...has the most influence over resistance which is why the body manipulates it often

11

blood flows through each vessel in turn and must flow through all to reach the end

series resistance (has greater resistance than parallel)

12

blood has mucltiple possible paths it can follow to reach end

parallel resistance (has less resistance than series)

13

T/F: Arterioles and precapillary sphincters are the points of highest resistance int he CV system

TRUE

14

4 factors that determine pressure

Cardiac Output (CO)
Compliance
Gravity
Location

15

the rigidity or stretchy state of a vessel that helps determine pressure

compliance
high compliance = vessel strtchy = low pressure
low compliance = rigid vessel = high pressure

16

T/F: Arteries have low compliance

True...creates greater pressure

17

T/F: Veins have high compliance

True...hold large volumes of blood without much pressure (most of blood in body lies in systemic veins)

18

Capillary pressure (Pc) will be closer to venous pressure (Pv) when:

Rpost < Rpre...because most of the pressure drops during Rpre

19

Capillary pressure (Pc) will be closer to arterial pressure (Pa) when:

Rpost > Rpre...because there's less relative pressure drop at Rpre

20

If capillaries have smallest radius, why are arterioles the main site of resistance in the CV system?

because there is an increased number of capillaries which leads to greater conductances

21

what two key mechanisms of veins helps drive blood back to the heart?

1.venomotor tone: causes veins to contract (actually move forward through muscle pump)
2. venous valves: prevent blood from moving backwards

22

Why do veins need reinforcement in their walls if blood pressure is so low?

because of wall tension (T)...where T is the force that the vessel must exert to resist splitting open
use Laplace's law: T = change P x r

veins have about 140 times more wall tension than capillaries, therefor need thicker walls

23

why does blood flow at lower velocity in capillaries that the rest of the vascular system?

becuase of gas exchange...capillaries increase their cross sectional area in order to decrease blood velocity in order to exchange material with tissues (flow (Q) remains the same)

24

what is one key result of 65% of blood volume being in the systemic veins?

serves as a blood volume reserve in case theres a sudden increased need for cardiac output

25

T/F: blood pressue drops continuously as it flows from arteris to capillaries to veins

True

26

the process where large proteins are actively transported across cells is known as:

transcytosis (requires a lot of energy)

27

the tightly sealed separtation between blood and brains tissue is:

blood-brain barrier

28

T/F: exchange of solute in capillaries occrus mostly by diffusion

True

29

the main goal of the CV system is to maximize the exchange between blood and tissues (Ex)...what are two ways to Maximize Ex?

1. maximal difference between blood and tissue concentrations (keep nutrients high and wastes low in the blood)
2. maximal flow (Q)

30

What are two ways that the body maximizes cross-sectional area of flow?

short term: increase number of open capillaries
long term: grow new capillaries

31

what are the four forces (capillary pressure, interstitial fluid pressure, osmotic pressure of capillaries, and osmotic pressure of interstitial fluid) known as?

the Starling forces

32

what do the combination of all Starline forces yield?

Net Filtration Pressure (NFP)
NFP = (P(c)+Pi(if)) - (P(if)+Pi(c))
If NFP is positve, net pressure is outward and if NFP is negative, net pressure is inward

33

What are typical values for NFP?

arterial end= (38+0)-(1+25) equals 12 mmHG outward
venous end= (16+0)-(1+25) equals -10 mmHg inward

34

In regard to exchange of solutes between blood and tissue what are the forces of osmotic pressure and pressure on capillary and interstitial fluid

(Pi)c is pressure pulling water into the capillary and (Pi)if is pressure pushing water out of the capillary
Pc is pressure pushing water out fo the capillary and Pif is pressure pulling water into the capillary

35

the accumulate of water in lower legs and feet when standing for long periods of time is known as

edema

36

a type of venous blockage caused by liver cirrhosis is known as

ascites

37

decreased blood protein can lead to increased water flow into tissues...this is known as

kwashiorkor