Development of the human body used to approximately judge a child's age based on physical development. Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a boy. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult
The Inner Life of the Cell The Inner Life of the Cell The Inner Life of the Cell is an 8.5-minute 3D computer graphics animation illustrating the molecular mechanisms that occur when a white blood cell in the blood vessels of the human body is activated by inflammation (Leukocyte extravasation). It shows how a white blood cell rolls along the inner surface of the capillary, flattens out, and squeezes through the cells of the capillary wall to the site of inflammation where it contributes to the immune reaction. When teaching biology, professors will often generate 3D animations to demonstrate certain concepts to their students in a