According to the sources, sebum and sweat are similar because both are secretions from skin glands that function to eliminate certain waste substances from the body . Sweat, produced by sweat glands, is a watery fluid containing NaCl, small amounts of urea, and lactic acid . Sebum, produced by sebaceous glands, eliminates substances like sterols, hydrocarbons, and waxes while providing a protective oily covering . In contrast, the corpus luteum is the transformed remains of a ruptured Graafian follicle and serves an endocrine role , while the Sino-atrial node (SAN) is the heart's pacemaker, which is functionally distinct from the Bundle of His conduction pathway .