5. Regulation of flow and peripheral resistance

Question 1

Describe laminar flow of blood?

Answer 1

Smooth flow in layers with quickest at centre of lumen

In most blood vessels up until “critical velocity”

Question 2

Describe turbulent blood flow?

Answer 2

Disordered, with extensive mixing
Beyond critical velocity or flow past an obstruction
Clotting more likely
Audible, bruits, murmurs and korotkoff sounds

Question 3

Describe vascular resistance when blood vessels are in series?

Answer 3

Different categories of vessels

More resistances in series, the greater total resistance

Question 4

Describe vascular resistance when blood vessels in parallel?

Answer 4

Within a vascular bed, similar categories of vessels are arranged in parallel
More resistances in parallel, lower total resistance

Question 5

Where does vasodilation occur?

Answer 5

In metabolically active tissue mainly in arterioles and pre cap sphincters

Question 6

What is a certain condition that must be present for vasodilation?

Answer 6

It must be against a background of increased cardiac out put to maintain BP in the face of the opening of these vessels