Explore how narrow, branched capillary networks and permeable one-cell endothelium deliver substances and form tissue fluid in IB Biology HL B3.2.1.
Explain how the structure of capillaries relates to their functions.
capillary walls are thin/one cell thick for better diffusion;
the lumen has a small diameter/narrow lumen so capillaries can fit into small spaces/between cells;
the small diameter gives greater surface area for molecular exchange;
pores between cells of the walls allow plasma to leak out;
pores between cells of the walls allow phagocytes/immune components to enter tissues;
only one red blood cell passes at a time for efficient oxygen uptake;