Microcirculation and Special Circulations
Start with the big picture
Arterioles, capillaries, and venules form the microcirculatory pathway: arterioles regulate resistance, while capillaries are the principal sites of exchange. Precapillary sphincters produce vasomotion in response to metabolic and myogenic signals. Fluid movement reflects Starling forces, with lymph returning excess interstitial fluid; changes in capillary pressure, plasma oncotic pressure, permeability, or lymph drainage can contribute to edema. Diffusion and permeability also vary across tissues. Regional circulations have specialized controls: for example, coronary flow is greatest during diastole, cerebral flow is autoregulated, and pulmonary vessels constrict in response to hypoxia. The topic also connects tissue activity and shear stress with local blood-flow responses.
What you'll learn
- Describe the roles of arterioles, capillaries, and venules in microcirculation.
- Explain how vasomotion and local signals regulate capillary perfusion.
- Relate Starling forces and lymphatic return to fluid balance and edema.
- Compare key regulatory features of major regional circulations.
- Distinguish functional from reactive hyperemia and summarize endothelial shear responses.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
