🦴 Skeletal — 206 bones, support & protection
💪 Muscular — 600+ muscles, movement
❤️ Circulatory — heart, blood, vessels
🧠 Nervous — brain, spinal cord, nerves
🫁 Digestive — stomach, intestines, liver
🫁 Respiratory — lungs, trachea, diaphragm

• Your brain uses 20% of your energy
• Your small intestine is 6m long
• You have 60,000 miles of blood vessels
• Your heart beats 100,000 times/day
• Bones are stronger than steel (per weight)
• You blink 15-20 times per minute