Human Biology and Health Basics

Vitamin K is essential for blood clotting as it helps produce clotting factors in the liver. Vitamins B1 and B2 are involved in energy metabolism, and Vitamin D helps with calcium absorption. Without adequate Vitamin K, blood cannot clot properly.

Red blood cells (erythrocytes) are produced in the bone marrow through a process called erythropoiesis. In adults, this primarily occurs in the vertebrae, sternum, ribs, and pelvic bones. The liver produces blood cells only during fetal development, while kidneys and heart have no role in RBC production.

Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and transports it to tissues throughout the body. Each hemoglobin molecule can carry four oxygen molecules. The other options are incorrect - hemoglobin does not destroy bacteria (white blood cells do), prevent anemia (it causes anemia when deficient), or utilize energy directly.

The skin is the largest organ in the human body by both weight and surface area, covering approximately 22 square feet and accounting for about 16% of body weight. It provides protection, temperature regulation, and sensation. The liver is the largest INTERNAL organ, but skin is overall the largest.

The liver is the largest gland in the human body, weighing about 1.5 kg in adults. It performs over 500 functions including detoxification, protein synthesis, and bile production. The thyroid and pancreas are much smaller endocrine glands. The liver is both a gland and the largest internal organ.