What causes bones to decrease during adolescence?

People whose genetic makeup triggers a later-than-average start to puberty have lower bone mineral density, especially in their lower spine. Because adolescence is a critical period for accruing bone, this effect may increase a person's risk of osteoporosis and bone fractures later in life.

when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.