Peripheral Vascular system Flashcards Preview

Crrab 1 > Peripheral Vascular system > Flashcards

Flashcards in Peripheral Vascular system Deck (31):
1

What are some factors that affects diffusion?

1. conc. diff
2. Surface area for exchange
3. distance of diffusion
4. perm of capillary wall to substance

2

What some other factor besides diffusion that affects fluid movement?

Pores
Hydrostatic pressure- fluid pushed
Osmotic pressure - water attracted

3

What is starling hypothesis?

Describes the relationship between opposing hydrostatic and oncotic forces on net bulk flow
- either filtration or resorption
Net flow= K[(Pc-Pi)-(Pie(c)-Pie(i))]
also (Pplasma-Pif)-(Pieplasma-Pieif)

4

What is Pc?

Hydrostatic pressure of intracapillary fluid

5

Whta is pie(c)?

Oncotic pressure of intracapillary fluid

6

What are Pi and Pie(i)?

Same quantities for interstitial fluid

7

What is K?

Constant expressing how readily fluid can move across capillaries

8

What is filtration and what is its starling flow?

Net movement of solutes and fluid out into the interstitial fluid
- Positive net pressure gradient

9

What is reabsorption and what is its starling flow?

Net movement of solutes and fluid into the capillary from IF
- Negative net pressure gradient

10

Where does filtration and reabsorption happen?

Arteriole
Venule- oncotic pressure usually doesn't change

11

What is an exception to the oncotic pressure rule? How does it work?

Release of histamine
-Increase cap perm and protein leak into IF (lowers oncotic pressure)

12

What is the role of the lymphatic system?

Keeping IF protein conc. low
- Very porous
- Collects particles and moves to LN where particles are removed and fluid is returned to venous system

13

What is the resistance across vessels in series?

Total resistance is sum of individual resistances
- Rs=R1+R2+R3
- pressure with highest R will have greatest impact of pressure and flow

14

How does one compare vessels in parallel?

Resistance of vessels in parallel is not determined by diameter by total cross sectional area of all capillaries
1/Rp= 1/R1+1/R2+1/R3

If all the same Rp=Rx/n

15

What is the relationship between flow and flow rate?

Since vessels have diff total cross sectional area and thus diff resistance something must change to keep flow (Liters/Min) the same
- Flow velocity changes (mm/sec)

16

What the purpose of the peripheral venous system?

Serve as a reservoir (60%) blood here
- secondary is central venous system

17

What consists of the central venous system?

Great veins of thorax and right atrium

18

When peripheral veins constrict what happens?

Blood is displaced and enters central system
- raises venous volume, pressure and cardiac filling
- thus more in and more out (starling)

19

Where does blood pressure decrease the most?

Pulsatile nature disappears across arterioles

about 25 mmHg in Caps

20

What is the pressure in the central venous system?

0 mmHg

21

What compensates for increased resistance in arterioles? Why?

Pressure drop Q= ^P/R
- flow must remain the same
- arterioles have increase resistance and to keep flow the same pressure drop must do so to compensate

22

What determines the resistance of organs?

Typically arterioles since greatest resistance
- lumen diameter is regulated to adjust resistance

23

What is total peripheral resistance?

Overall resistance to flow through the entire systemic circulation
- organs are in parallel

24

What are 2 ways to decrease resistance TPR?

1. Add another organ system
2. Decrease resistance in any organ

25

What is compliancy?

How much pressure in response to volume change
C=^V/^P
- Large shifts in blood into/out of PVS has only small changes in pressure

26

What counters blood pooling?

Active venous constriction

27

What is the purpose of the elastic properties of arteries?

1. Convert pulsatile flow coming from heart into smooth steady flow before entering vascular bed]

2. Store pressure energy during expansion to push blood through the periphery

28

What is mean arterial pressure?

Average effect pressure that drives the blood through the systemic organs

Pa=Co*TPR

also Pa=2/3Pd+1/3Ps
Pd+1/3(Ps-Pd)

29

how does one calculate the arterial pulse pressure?

Systolic minus diastolic
Pp=Ps-Pd

30

What determines arterial pulse pressure?

Stroke volume and Compliance
Pp=SV/Ca

31

Does atrerial pulse pressure change with aging?

Yes
- increase volume
- decrease Ca
- leads to increase in pulse pressure and mean arterial pressure