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.
SSC CGL asks 2-3 questions on human body systems. Common topics include blood groups, vitamins, hormones, and organ functions. Questions often test which organ produces what hormone or which vitamin deficiency causes which disease.
Use the mnemonic 'CRED-MEN-LI' for major systems - Circulatory, Respiratory, Excretory, Digestive, Muscular, Endocrine, Nervous, Lymphatic, Integumentary.
Identify the function - insulin controls blood sugar.
Recall endocrine glands - pancreas, thyroid, pituitary, adrenals.
Match function to gland - pancreas produces digestive enzymes AND insulin. Answer: Pancreas (specifically beta cells in islets of Langerhans). WORKED EXAMPLE 2: Question - How many chambers does human heart have?
Recall heart structure - divided into upper and lower chambers.
Count chambers - 2 atria (upper) + 2 ventricles (lower) = 4 total.
Remember blood flow - right side pumps to lungs, left side pumps to body. Answer: 4 chambers (2 atria, 2 ventricles). FORMULA SHORTCUTS: Blood pressure = Systolic/Diastolic (normal = 120/80 mmHg). Heart rate = 72 beats/minute average. Body temperature = 98.6°F or 37°C. BMI = Weight(kg)/Height²(m²). Normal breathing rate = 16-20 breaths/minute.
Students confuse arteries and veins. Remember: Arteries carry blood AWAY from heart (both words start with 'A'). Veins carry blood TO heart.
Exception: Pulmonary artery carries deoxygenated blood to lungs, pulmonary veins carry oxygenated blood to heart. Another trap: confusing endocrine and exocrine glands. Endocrine glands release hormones directly into blood (ductless).
Exocrine glands release substances through ducts (like sweat glands). The pancreas is both - releases insulin into blood (endocrine) and digestive enzymes through ducts (exocrine).
18graded MCQs · easy to hard · full solution & trap analysis