Figure 14 13. Blood pressure in different vessels of the systemic circulation 0 Left Large ventricle arteries E Capillaries Venules veins 120 100 P Resistance vessels Exchange Capacitance vessels vessels
4. Precapillary Sphincter muscle Partially determines Arteries the amount of blood flowing through a Metarterioles act as a Precapillary bypass channel and sphincters regulate flow into particular capillary Arteriole capillary beds Venule wall is bed smooth Capillaries muscle Allow only 5% 10% of the venule capillary in bed skeletal muscles Arteriovenous bypass Precapillary sphincters to be open at rest
➢ Partially determines the amount of blood flowing through a particular capillary bed ➢ Allow only 5% - 10% of the capillary in bed skeletal muscles to be open at rest. 4. Precapillary Sphincter muscle-
Vein Artery Bed open Precapillary sphincter venule Arteriole S -Throughfare channel Capillary Muscle fibers (cells) Bed closed
5. Exchange Vessel-Capille heart. Notice the thin intercellular channel (middle lett) and the >the walls are composed some of the many pinocytotic vesicles of only one cell layer )-a simple squamous epithellum, or endothelium >permits a more rapid transport of materials between the blood and the tissues
5. Exchange Vessel – Capillary ➢the walls are composed of only one cell layer ➢– a simple squamous epithelium, or endothelium. ➢permits a more rapid transport of materials between the blood and the tissues
Make Up of Blood Vessels: Capillaries (a)Continuous capillaries Basement have leaky junctions Transcytosis vesicles Endothelial cell junctions Nucleus allow water and sma‖l dissolved solutes to pa Endothelial cells beneath basement (b) Fenestrated capillanes have large pores Transcytosis vesicles Fenestrations Fenestrated or pores pores Endothelial cel Basement membrane(cut) membrane Transcytosis brings proteins Some vesicles may and macromolecules across fuse to create endotheliun temporary channels
Make Up of Blood Vessels: Capillaries