目b. Facilitated diffusion(易化扩散) o(transporter-mediated diffusion) ccarriers D. endocytosis transporters) exocytosis into or out of o Involving specific carriers(transporter) cells o Energy-independent o Saturability o Competition with other drugs o Concentration gradient(down-hill) 口(3) Endocytosis/ exocytosis(入胞/出胞)b. Facilitated diffusion（易化扩散） (transporter-mediated diffusion) Involving specific carriers (transporter) Energy-independent Saturability Competition with other drugs Concentration gradient(down-hill) (3) Endocytosis/exocytosis（入胞/出胞）