1. Longest bone in human body - Femur (thigh bone)
  2. Smallest bone - STAPES the middle ear
  3. Hardest material in the human body Tooth - enamel
  4. Strongest muscle - Jaw muscle
  5. Largest external organ - Skin
  6. Largest internal organ - Liver
  7. Smallest gland - Pituitary
  8. Largest artery - Aorta
  9. Smallest blood vessel - Capillary
  10. Element most common in human body - Oxygen (65%)
  11. Mineral most common in human body - Calcium
  12. Compound most common in human body - Water
  13. Pigment which gives a dark colour to the skin - Melanin
  14. Nails are modification of EPIDERMIS (external layer of skin)
  15. Muscles are attached to bones by connective tissues called - Tendons
  16. Bones are attached to bones by - Ligaments
  17. Sebaceous glands in human body secrete - Sebum or oil
  18. Lachrymal glands in human body secrete - Tears
  19. The volume of blood in an adult is - 4.7 to 5 litres
  20. The total number of bones in human body is - 206
  21. The most common type of blood group is - Type O