Arteries, Veins, and Microcirculation Flashcards Preview

Cardiovascular > Arteries, Veins, and Microcirculation > Flashcards

Flashcards in Arteries, Veins, and Microcirculation Deck (25):
1

WHat vessels have the highest wall thickness to lumen diameter?

precapillary spincters

arterioles are close

2

elastic modulus

force per unit area that is required to stretch a material to 2x its original length or the slope of the stress/strain relationship to the right

3

What happens to arterial compliance with age?

decreases with age

less elastin and mroe collagen

4

Windkessel effect

the walls of the aorta act as a secondary pump by stretching out during systole and then continuing to pump blood during diastole

this effect wears off with age

5

Laplace's law

the pressure inside a cylindrical or spherical vessel exerts a distending force on the wall proportional to the magnitude of the pressure and the radius

T = (Pi - Pt)/h

Pi = intravascular pressure

Pt = tissue pressure

6

pulse pressure

systolic pressure - diastolic pressure

7

physical factors that affect arterial blood pressure

arterial blood volume and compliance

8

factors affecting diastolic presssure

resistance - run off rate

compliance of the aorta

systolic pressure

heart rate

9

mean arterial pressure equation

MAP = CO x TPR

10

runoff

blood flowing away from the heart to the peripheral arteries and tissues

the greater the runoff, the lower the pressure

11

What is the relationshi between wave frequency of blood flow and dampening?

low frequency waves move more slowly but undergo less dampening

high frequency waves move faster but undergo more dampening

12

What does decreasing distensibility do to rate of flow and dampening?

it increases rate of flow and causes more dampening

13

metarterioles

discontinuous single layer of vascular smooth muscle cells generally not innervated

14

characteristics of blood flow through capillaries

low velocity

intermittent due to vasomotion

changes direction due to pressure gradients

not uniform

Roleaux formation

15

Roleaux formation

"stack of coints" arrangement of RBCs

16

vasomotion

spontaneous contraction and relaxation of precapillary sphincters

increased metabolic activity increases the time that precapillary sphincters are open

decreased oxygen delivery has the same effect

17

capillary hydrostatic pressure (Pc)

major determinant of fluid movement

determined by arterial pressure, venous pressure, and the ratio of venular to arteriolar resistance

Pc = [(Rv/Ra)*Pa + Pv]/[1 + (Rv/Ra)]

18

How does increasing pre/post pressure affect capillary hydrostatic pressure?

decrease

19

How does decreasing pre/post pressure affect capillary hydrostatic pressure?

increased

20

interstitial hydrostatic pressure

changes only slightly except in cases of lymphatic blockage or increased capillary permeability

normally around -1 mmHg

21

osmotic pressure

favors absorption

about 25 mmHg for water to enter the capillary due to the higher concentration of plasma proteins

pi = sRT (CI - CO)

22

What protein contributes the most of the plasma oncotic pressure

albumin - 51%

disproportionately large based on concentration

23

Starling's Law for capillary fluid movement

fluid movement = k[(Pc + pii) - (Pi + pip)]

normally the first half fluid leaves (20L) and the second half is reabsorption of water (18L)

the remainder draings through the lymphatics

24

lymph

fluid and other plasma proteins that accumulate in the extravascular space

composition similar to plasma

flow depends on interstitial hydrostatic pressure

25

factors that predispose one to edema

increased capillary pressure

increased capillary permeability

decreased plasma protein concentration

excessive protein excretion, excess salt and fluid retention

lymphatic blockage