An acid (from the Latin acidus/acÄre meaning sour) is a chemical substance whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals (like calcium) to form salts.he Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen ions (H +) or protons in 1884. An Arrhenius acid is a substance that, when added to water, increases the concentration of H + ions in the water.
The surface of the inner wall of all of the body cavities is lined by a serous membrane which consists of a single layer of flat epithelium with a thin underlying propria (connective tissue). Within the thoracic cavity, this is known as the pleura. The visceral pleura which coats the outer surface of the lung is derived from the splanchnic mesoderm.
Serous membranes have specific names in three locations of the body: Peritoneum-the serous membrane that lines the abdominal cavity and the organs within it. Pleura-the serous membrane that surrounds the lungs. Pericardium-the serous membrane that surrounds the heart.erous membranes are continuous but when the membrane covers the wall of the body cavity it is called parietal and when the serous membrane lines an organ within the body cavity it is called visceral (viscus is Latin for organ). The word serous means watery.