| [ Summary ] |
The structure of the peritoneum may be the parietal peritoneum and the visceral peritoneum. The peritoneal serous membrane consists of a monolayer of flat cells on a basement membrane, and a layer of loose connective tissue, blood vessels and lymphatic vessels. The mesothelium is an important layer for the prevention of inflammation and the secretion of substances. The mesothelial microvilli have the function of protecting abdominal organs and facilitating exchanges between cells and the peritoneal fluid. Connective tissue contains many blood vessels that mainly play a function in solute transport and ultrafiltration. There is an enormous abundance of pinocytotic vesicles, which along with the macromolecules play a role in transportation within endothelial cells. There is a complex network of lymphatics in the peritoneum. Stomata in the peritoneum , in proximity to the diaphragm, help in the drainage of solutes, protein and blood cells. There is a cytokine network composed of immune reacting cells : macrophages, mast cells, plasma cells, leukocytes and fibroblasts in the peritoneum. The distribution of peritoneal fluid is not uniform, some of the characteristics which demonstrate this are that the peritoneal cavity may experience an outbreak of bolus residual peritoneal fluid and abscesses around liver and/or spleen. Peritoneal solute transport is thought to take place through a three pore system, (1) the small pores : mainly related to the low molecule transport, (2) the large pores: involved in the transport of macromolecules, (3) the ultrasmall pores : supports transcellular water transport, named the water channel. Fluid transport consists of water transport from the peritoneal capillaries into the peritoneal cavity by trans capillary ultrafiltration and by fluid loss out of the peritoneal cavity. Hydrostatic factors include, the colloid osmotic and the crystalloid osmotic pressure gradients which exert an influence on transcapillary ultrafiltration. Fluid loss out of the peritoneal cavity is coupled to lymphatic absorption and back filtration by colloid osmosis. |