The lungs' alveoli and the inner walls of arteries are examples of what kind of tissue?

This type of tissue contains cells widely separated by an extracellular matrix secreted by living cells.

As bone grows, the osteocytes (bone-producing cells) secrete a hard, calcified matrix that forms thin, concentric layers called ___________, giving bone its characteristic appearance.

As an adult, you have a fixed number of ____ cells in your body. Depending on your diet, metabolism, and exercise regimen, these cells can only enlarge or shrink, but you can never get rid of them.

In mammals, as erythrocytes mature, their nuclei are ejected from the cells, giving them a limited life span of around ______ days.