In order to warm the body up when cold: vitamin D is synthesized sudoriferous glands release sweat sebaceous glands release oil the arrector pili muscles contract to stand hairs upright melanin is produced. Which moist epithelial membrane lines body cavities that open to the exterior: synovial cutaneous mucous serous peritoneum Serous fluid reduces friction: in movable joints such as the knee between organs and the cavities in which they reside inside the lungs as food is chewed around the brain
