tailieunhanh - Ebook Anatomy, histology and cell biology (4th edition): Part 2

Completely revised and small enough to fit in a lab coat pocket, these reviews for subjects tested on the USMLE Step 1 feature 500 board-style questions, including many in clinical vignette format, with answers and explanations. All questions are reviewed by recent USMLE Step 1 test-takers. | Gastrointestinal Tract and Glands Answers 200. The answer is d. Ross p 63. Kumar pp 858. Mallory bodies are derived from keratin intermediate filaments within hepatocytes. Hepatic stellate cells answer a secrete the collagen that replaces normal liver parenchyma in cirrhosis. Kupffer cells answer b are the macrophages of the liver. Vimentin answer c is the intermediate filament protein found in cells of mesenchymal origin the liver and hepatocytes are epithelial in origin. Desmin answer e is the intermediate filament protein associated with muscle. ALT SGPT and AST SGOT are hepatic aminotransferases when their blood levels are elevated it is indicative of liver damage. 201. The answer is c. Johnson pp 1123-1124. Mescher pp 264 266-269. Ross pp 528-530. In the resting parietal cell the proton pump H K -ATPase is found in the tubulovesicle membranes that are located intracellularly answer a . The sequestration of the proton pump in intracellular tubulovesicles in the resting state prohibits secretion. On activation of the parietal cell through Ca and diacylglycerol second messengers the tubulovesicle membranes fuse with the plasma membrane by exocytosis. Histamine answer e along with gastrin and acetylcholine activate the parietal cell. Na K -ATPase located in the basal membrane and the chloride channel answer b of the apical plasma membrane maintain the appropriate ionic gradients to facilitate acid secretion. Carbonic anhydrase a cytoplasmic enzyme catalyzes the formation of carbonic acid H2CO3 from carbon dioxide which is the source of protons in the parietal cell and other cell types such as the osteoclast that also depend on a proton pump answer d . After dissipation of the stimulus ie gastrin acetylcholine or histamine or exposure to an HZ blocker the parietal cell returns to the resting state by recycling endocytosis of membrane to reform the tubulovesicular arrangement within the cytoplasm. 202. The answer is a. Mescher pp 83 264-266 268-269 275. Kumar pp .