Process Control Block (PCB, also called Task Controlling Block, Task Structure or Switchframe) is a data structure in the Operating System kernel containing the information needed to manage a particular process.The PCB is the manifestation of a process in an Operating System.

1. Excretion is the process in which all metabolic wastes are passed out of the body. Excretion in humans occurs in several processes through various organs and internal organs of the body.

2. Diffusion is the most common process of excretion in lower organisms. The human body is an extraordinary machine, where various life-processes (respiration, circulation, digestion, etc.) occur simultaneously. As a result, many of the waste products produced in our bodies are in various forms including carbon dioxide, water, and nitrogenous products such as urea, ammonia, and uric acid.