- The lining in a person’s stomach is replaced every 4 to 5 days to prevent it from digesting itself.
- Human semen normally contains 1 to 8 billion sperm per fluid ounces (140-300 million sperm per millimeter).
- Adult humans spend about 33% of their lives asleep.
- An adult’s skin weighs between 8 to 11 pounds (3.6 to 5.0 kg). Its surface area is about 18-22 square feet (1.7 to 2.0 sq. m) which is the size of the floor in a one-person.
- A human heart is roughly the size of a large fist.
- Human heart has 4 chambers; two upper chambers (The Atria) and two lower once (The ventricles).
- The right atrium and the right ventricle together make up the “Right heart”.
- The left atrium and the left ventricle together make up the “Left heart”.
- A wall of muscle called the septum separates the two sides of the heart.
- The heart circulates blood through two pathways; the pulmonary circuit and the systemic circuit.