How may cells be specialised to their function?

Despite animal cells all having a nucleus (for genetic information storage and reproduction), a cytoplasm (for structure), mitochondria (for aerobic respiration), ribosomes (for protein synthesis) and a cell membrane (to control passage of molecules into and out of the cell), cells are often specialised for their function. For example ciliated (meaning, they have cilia) epithelium (lining tissue) found in the lung facilitates the removal of foreign particles and debris from the lung. These cilia beat in a coordinated fashion to move molecules from the lower respiratory tract up to the trachea. They therefore require more energy (as ATP) and so these cells will have extra mitochondria to facilitate this. Another example is the intestinal epithelium (the lining tissue found in the gut, in the small intestine) which have villi and microvilli which greatly increases the surface area of the gut to enable more diffusion and active transport from the substances within the gut to the blood stream. Although not a direct adaptation of the cells itself, intestinal epithelium is related very closely to capilaries and has a massive capillary network to aid this diffusion.