Heamodynamics and microcirculation

Question 1

What is Total Peripheral Resistance? TPR

Answer 1

resistance to flow of blood in systemic circuit

Question 2

What does MAP equal?

Answer 2

Cardiac output * TPR

Question 3

What is Darcy’s Law?

Answer 3

flow is linearly proportional to pressure difference between 2 points

Question 4

What is mean velocity?

Answer 4

Flow/ Total cross sectional area

Question 5

What are the 3 types of blood flow in vessels?

Answer 5

Laminar- arteries/veins
Turbulent
Single file flow - capillaries

Question 6

Where does turbulent flow occur?

Answer 6

ventricles

Question 7

What is TPR equation?

Answer 7

8nL/ Pir^4
L- tube length r= radius
n= fluid viscosity

Question 8

What is Poiseuille Law equation for Fluid Flow? Q

Answer 8

Pressure difference/Resistance

Question 9

How are vessels of the same type arranged ?

Answer 9

Parallel but aorta/Pulmonary trunk arent

Question 10

When does total resistance in circuit increase?

Answer 10

when series unit added

Question 11

What is Compliance?

Answer 11

Volume/ change in distending Pressure

Question 12

What is distending pressure?

Answer 12

pressure inside minus pressure outside

Question 13

Why is artery a shallow gradient on Compliance graph?

Answer 13

when pressure applied, volume doesn’t increase by much

Question 14

Why does Vein have large compliance?

Answer 14

thin walls and store volume well

Question 15

What is LaPlace equation for Tension?

Answer 15

T= Pt *r/ u
u= wall thickness             Pt= trans mural 
r= radius

Question 16

What is Trans Mural pressure ? Pt

Answer 16

pressure along entire wall

Question 17

What is Autoregulation?

Answer 17

adjustment of blood flow to specific tissue

Question 18

How is blood flow changed?

Answer 18

diameter of arterioles change

Alter contraction of sphincters

Question 19

How is oxygen a factor of metabolic autoregulation?

Answer 19

hypoxia when not enough 02 to meet metabolic demand

Question 20

How is low 02 supply increased?

Answer 20

Arteriolar smooth muscle vasodilate

Question 21

What happens in vasodilation?

Answer 21

resistance decreases so inc. blood flow so inc. 02

Question 22

What metabolic products diffuse into surrounding tissue and relax smooth muscle?

Answer 22

CO2
H+
Adenosine
K+

Question 23

What substances in endothelium mediate vasodilation in smooth muscle?

Answer 23

Prostacyclin

Nitrogen oxide- Endothelium derived relaxing factor

Question 24

What happens when Perfusion Pressure increases?

Answer 24

inc. stretch of smooth muscle> constriction>inc. Resistance so decreased flow then NEG. feedback

Question 25

What is long term autoregulation of low 02 delivery?

Answer 25

increase Microcirculatory vessels

enlargement of vessels

Question 26

What is an example of when long term autoreg.?

Answer 26

high altitudes

Question 27

What do clefts in capillary endothelium allow?

Answer 27

hydrophobic solutes

water/ ions

Question 28

How is exchange of fluid between capillaries and tissues?

Answer 28

• hydrostatic pressure highest at arterial end

- net osmotic pressure gradient favours fluid absorption by capillary

Question 29

What is net fluid movement?

Answer 29

• fluid out at arterial end

- fluid in at venous end

Question 30

What is lymph ?

Answer 30

fluid with white blood cells and waste

Question 31

What are lymph nodes in the head?

Answer 31

Parotid
Submental
Submandibular

Question 32

What carries excess fluid from capillary beds?

Answer 32

lymphatic vessels w/ smooth muscle to venous system

Question 33

What does right lymphatic duct drain into?

Answer 33

internal jugular vein

Question 34

What does left lymphatic duct drain into?

Answer 34

Subclavian vein