F - Microcirculation and Special Circulations - Ballam

Question 1

What does the Starling equation calculate?

Answer 1

The flow of water either out of the capillary (+) or drawing it into the capillary (-)

Question 2

What is the Starling equation?

Answer 2

J = (Pc - Pi) - (pc-pi)
J = (forces moving fluid out) - (forces moving fluid in)

Question 3

What does it mean if the Starling equation is positive?

Answer 3

This would predict a net movement of fluid out of the capillary

Question 4

How are Starling values changed in edema?

Answer 4

Pc - elevated venous pressure (heart failure)
Pi - restricted lymphatic flow
pc - decrease in albumin (starvation, liver failure)
pi - restricted lymph flow or inflammation

Question 5

3 Types of local control?

Answer 5

Metabolic - active or reactive hyperemia
Myogenic control
Shear

Question 6

Active hyperemia

Answer 6

Increasing interstitial concentration of CO2, H+, K+, lactate, adenosine, or reduction in O2
-causes relaxation of smooth muscle increasing flow through area

Question 7

Reactive hyperemia

Answer 7

Vascular obstruction causes build up of metabolites leading to vasodilation
-if obstruction is removed, area flooded with blood

Question 8

Myogenic control

Answer 8

If BP elevated arterial walls become stretched and that causes vasoconstriction

Question 9

Shear

Answer 9

Local control
If vascular bed dilates due to metabolic demand the flow through upstream arterioles and small arteries would increase.
This increases shear friction = release of NO

Question 10

What areas of the body have the most local control?

Answer 10

Heart, brain, skeletal muscle

Question 11

Histamine and bradykinin

Answer 11

Arteriolar vasodilation
Increases cap porosity allowing escape of large molecules
Causes edema in response to tissue damage

Question 12

Serotonin

Answer 12

Vasoconstriction in response to tissue damage

Question 13

Coronary circulation

Answer 13

Largely under metabolic control

Question 14

Skin and circulation

Answer 14

Symp vasoconstriction to baroreceptor reflex

Symp inhibition and dilation of shunt pathway to excessive body temp

Question 15

The highest pressures of pulmonary vascular system?

Answer 15

RV (24 to 0) and pulmonary a. (24 to 10)

Question 16

Distribution of blood flow in lung zones?

Answer 16

zone 1 - collapses
zone 2 - cap open part of cardiac cycle
zone 3 - cap always open

Question 17

Is arterial system more compliant than systemic arteries?

Answer 17

Yes
Small changes in mean pressure will significantly dilate arteries, reduce resistance and help maintain pressure low in face of large changes in flow

Question 18

Right to left shunt

Answer 18

Systemic v to systemic a without passing through functional lung tissue
Foramen ovale - RA to LA
Ductus arteriosis - pulmonar a to aorta

Question 19

Left to right shunt

Answer 19

blood from systemic a to systemic v without passing through a cap bed for substance exchange

Question 20

Umbilical v.

Answer 20

O2 blood from placenta to fetus

Connects fetal IVC in the liver

Question 21

Post-parturition changes

Answer 21

Umbilical a and v clamped = increased fetal total peripheral resistance.
Ductus venosus closes
Lungs expand and pulmonary resistance falls

Question 22

Ductus arterioles after birth

Answer 22

Left pressure greater than right, flow reverses through ductus arterioles and passes from aorta into pulmonary a generating a left to right shunt
Hormonal changes will close it

Question 23

What 2 major factors cause a change in blood flow pattern following birth?

Answer 23

Systemic vascular resistance is increased due to removal of placental circulation
Decreased resistance of the pulmonary circulation due to expansion and oxygenation