Final answer:
Membrane surface area in absorptive cells is increased through the expansion of microvilli on the apical membrane, enhancing nutrient absorption by increasing the diffusion rate.
One way that membrane surfaces area is increased in absorptive cells is through increasing the microvilli apical membrane.
Step-by-step explanation:
One way that membrane surface area is increased in absorptive cells is through increasing the microvilli on the apical membrane. Microvilli are tiny, finger-like projections that extend from the plasma membrane of absorptive cells such as those lining the small intestine. They serve to greatly enhance the surface area available for absorption by creating more space on the plasma membrane which faces the lumen — the cavity from which nutrients and other substances are absorbed. This increased surface area facilitates the absorption of nutrients and substances, such as amino acids and glucose, into the cells using various transport mechanisms like symport, antiport, active transport, and facilitated diffusion.
The concept of surface area and plasma membrane thickness is crucial in understanding the efficiency of absorption. A greater surface area, provided by microvilli, increases the diffusion rate, which allows for more efficient transfer of substances across the membrane. Conversely, a thicker membrane would reduce the rate of diffusion, thereby affecting the cell's ability to absorb substances.