Lecture 15 - Blood flow in arteries 1

Question 1

What is Poiseuille’s law?

Answer 1

says that the volume of a homogeneous fluid passing per unit time through a capillary tube is directly proportional to the pressure difference between its ends and to the fourth power of its internal radius, and inversely proportional to its length and to the viscosity of the fluid

Question 2

Poiseuille Formula?

Answer 2

Q = -[piR^4/8mu] * [dp/dx]

Question 3

Poiseuille’s law assumptions?

Answer 3

Steady and fully developed

Laminar

Incompressible

Viscous - Newtonian

Question 4

Application of Poiseuille’s formula.

Answer 4

It proves that the most effective factor controlling blood flow is the blood vessel radius.

Question 5

Stress distributions in endothelial cells?

Answer 5

• Surface is wavy with hills and valleys
• no-slip condition must be applied on
  cells membranes facing the blood
• non-uniform shear stress distribution!!!
• Inside the individual endothelial cells,
  there is world of structures and materials
• Intracellular mechanics at smaller and smaller scales

Question 6

What are endothelial cells?

Answer 6

Endothelial cells are very flat, have a central nucleus, are about 1-2 µm thick
and some 10-20 µm in diameter. They form flat, pavement-like patterns on the
inside of the vessels and at the junctions between cells there are overlapping
regions which help to seal the vessel.