The immune system is a complex network that finds pathogens, removes damaged cells, and launches immune responses to protect the body from infection. White blood cells drive this defense: phagocytes ...

The nervous system consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (motor nerves, sensory nerves, cranial and spinal nerves, autonomic ganglia, and ...

Vikki Velasquez is a researcher and writer who has managed, coordinated, and directed various community and nonprofit organizations. She has conducted in-depth research on social and economic issues ...

Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Robert Kelly is managing director of XTS ...

The musculoskeletal system is an organ system comprising the bones, muscles and connective tissues (including cartilage, tendons and ligaments) that bind tissues and organs together. The main ...