The human body is a complex biological machine with multiple organ systems working together. For SSC CGL, focus on the 11 major organ systems and their functions. The circulatory system pumps blood through a 60,000-mile network of blood vessels.
The respiratory system exchanges gases 20,000 times per day. The digestive system breaks down food in a 30-foot tube from mouth to anus. The nervous system contains 86 billion neurons processing information at 268 mph.
The skeletal system has 206 bones in adults, while babies are born with 270 bones that fuse over time. The muscular system has over 600 muscles, with the heart being the strongest. The endocrine system produces hormones that regulate growth, metabolism, and reproduction.
The excretory system filters 180 liters of blood daily through kidneys. The reproductive system ensures species continuation. The integumentary system (skin) is the largest organ, covering 20 square feet.
The lymphatic system fights infections and maintains fluid balance.