Microcirculation

1. Microcirculation
Dr. Sara Sadiq
(MBBS, M.Phil)

2. 1. Classification of blood vessels with
example?
2. Effect of high right atrial pressure
on peripheral venous pressure?
3. Effect of high intra-abdominal
pressure on venous pressure of leg?
4. Effect of gravitational pressure on
venous pressure?

3. Microcirculation
• Blood flow through blood vessels smaller than 100µm
 arterioles,
 capillaries,
 venules
• Function  Transport of cells, oxygen and other substances to/from the tissues
 Regulation of body temperature

6. Flow of Blood In Capillaries
• Vasomotion  Intermittent flow because of precapillary sphincter and
metarterioles
• Average function of capillary system  average rate of blood flow
 average capillary pressure
 average transfer of substance

8. Structure of Capillary Wall

9. Special Types of Pores in Capillaries
• Brain  Tight junction  extremely small molecules
(Water, Oxygen, Carbon dioxide)
• Liver  wide cleft  all dissolved substances
• GIT  midway between liver and muscles
• Kidney  fenestrated  small openings to increase filtration through
glomerulus

11. • Lipid soluble substance diffuse directly through cell membrane
(Oxygen, Carbon dioxide)
• Water soluble substance diffuse through intercellular pores
(Na, Cl, Glucose)
• Effect of concentration difference on net rate of diffusion through
capillary membrane
• Effect of molecular size on passage through pores

13. Interstitium and Interstitial Fluid

14. • Gel in the Interstitium  because of proteoglycans filaments and
fluid entrapped within them, the consistency that of a gel. The
fluid diffuses but not flow.
• Free fluid in the Interstitium  usually ≤1%, unless there is edema
and then it expands rapidly.

17. Thank You