Nonpolar and small polar molecules<span> can pass </span>through the cell membrane<span>, so they diffuse </span>across<span> it in response to concentration gradients. Carbon dioxide and oxygen are two </span>molecules<span> that undergo this simple diffusion </span>through<span> the </span>membrane<span>. The simple diffusion of water is known as osmosis.</span>
Spongy bone has trabecular which serve as reinforcing plates against a force. The loss of spongy bones causes weakening of the internal support that the compact bone requires and the entire bone breaks.
