UPPER GI Flashcards
where are the vallate papillae found on the tongue
vallate papillae lie in a single row just anterior to the v-shaped sulcus terminalis that divides the tongue into an anterior 2/3 and a posterior 1/3. There are roughly 8-12 vallate papillae in humans. they are separated from one another by considerable distances.
which end of the esophagus do you think will have smooth muscle in its muscularis externa and which will have skeletal? why
The upper portion has skeletal muscle in the muscularis externa, while the lower portion has smooth. This makes sense because the upper end is continuous with the pharynx whose walls contain skeletal muscle while the lower end is continuous with the stomach which contains only smooth muscle. The midsection of the esophagus has a mixture of skeletal and smooth muscle in the muscularis externa.
where are the epithelial stem cells located in the stomach
In the neck of the glands. If you look in this region, you will be able to see mitotic figures. The same stem cell population gives rise to the surface mucous cells, enteroendocrine cells and gastric gland cells. That means that some differentiating cells move up toward the surface of the stomach and others move down into the glands in a well-orchestrated procession.
why do parietal cells have an intensely eosinophilic cytoplasm?
because they have so many mitocondria. The many proteins in the membranes of a mitochondrion cause it to be extremely eosinophilic.
What accounts for the basal basophilia of the cheif cells?
The RNA in the ribosomes of their extensive RER. These cells secrete large amounts of enzymes including pepsinogen and, in humans, lipase.
Older individuals sometimes report that their mouth feels very dry. This is because the volume of saliva that is produced decreases gradually with age. What change occurs in the morphology of the aging parotid glad that could contribute to a decrease in secretory volume
much of the mass of the parotid in an older person is occupied by adipocytes rather than by secretory cells. Therefore there are fewer secretory acini available to produce saliva.
what is the embryological origin of the cells that produce tooth enamel? Of the cells that produce predentin and dentin?
ameloblasts produce enamel. They are derived from part of the enamel organ (the inner enamel epithelium), which originates from the oral ectoderm. Odontoblasts produce dentin. They develop from the mesenchymal cells of the dental papilla, which are of neural crest origin.
why do we have to visit the dentist if we have a serious defect in the enamel in one of our teeth? what can’t teeth produce more enamel to repair the defect?
ameloblasts, which produce enamel, are present only durin tooth development. During development they lie in the outer surface of the enamel layer, but they are lost during the process of tooth eruption, leaving the enamel as the outermost layer. Therefore, once the tooth has erupted there are no cells left that are capable of making more enamel. This is in contrast to the situation with odontoblasts, which persist in mature teeth and retain the ability to make predentin and dentin.
how would you distinguish between the upper, lower, and middle portion of the esophagus?
the most reliable feature would be the type of muscle found in the muscularis externa. It should be skeletal muscle in the upper portion of the esophagus, smooth in the lower portion, and a mixture of both in the midportion. If you see muscous glands in the lamina propria (esophageal cardiac glands) this suggests that you are either at the upper or lower end of the organ.
why are the esophageal glands that are located in the lamina propria called esophageal cardiac glands?
they are given this name because they resemble the cardiac glands of the stomach, which are also mucous glands and are also located in the lamia propria. This can help you remember in which layer the esophageal cardiac glands are found.
what is the morphological difference between a serosa and an adventitia
the outer most layer of most hollow organ is either an adventitia or a serosa. an adventitia is a connective tissue layer. It has no epithelium covering its outer surface. If fact the reason for having an adventitia is so that this layer can blend with the connective tissue surrounding structure to bind them together and thus provide support. Blood vessels have an adventitia that binds them to surrounding connective tissue and holds them in place. A serosa is a connective tissue layer that has a mesothelium covering its outer surface and separating it from surrounding structures or more often surrounding spaces. The stomach has a serosa that separates it from peritoneal cavity. The lung has a serosa that separates it from the pleural cavity.
intraperitoneal organs are suspended directly or indirectly from the body wall by a mesentery. What is the function of a mesentery other than to keep our intraperitoneal organs from sloshing around randomly? Describe the histology of a mesentery
in addition to providing some support, mesenteries serve as the pathways through which nerves and blood vessels supply intraperitoneal organs. A mesentery is a thin sheet-like structure with a core of connective tissue, in which the blood vessels and nerves are embedded, along with lymphatics, and sometimes lymph nodes. Both surfaces of this sheet are covered by mesothelium. In the simplest arrangement, the mesentery connects the intraperitoneal organ directly to the body wall. Its mesothelium is continuous at one end with the serosa of the intraperitoneal organ, and at the other end with the mesothelium that lines the body cavity.
what is the structural relationship between a gastric pit and a gastric gland
if you were looking down onto the surface of the stomach, each circular opening you saw would be the entrance to a pit. If you went down one of these pits, at the bottom of it you would several more openings, each one leading to a gastric gland.
how can you distinguish the cardiac stomach from the fundic or pyloric stomach?
important features include the depth of the pits, the length of the glands, the degree to which the glands are coiled, and the major cell types present in the glands. The three regions can be characterized as follows:
- cardiac stomach: has the shortest pits, and short highly coiled mucous glands.
- pyloric stomach: has the longest pits, and coiled mucous glands that are usually somewhat longer than cardiac glands
- fundic stomach: has the longest and straightest glands: the glands contain mainly parietal cells and chief cells. Notice that in all three regions, surface mucous cells line the lumen and also the pits, so that these features are not useful in distinguishing between regions.
what are the functions of parietal cells and chief cells
parietal cells secrete HCL and intrinsic factor. they have large numbers of mitochonria to supply the ATP that they need for ion pumping. Intrinsic factor is required for vitamin B12 uptake, which occurs in the ileum. Chief cells in humans secrete pepsinogin and lipase.
Oxyphils (parathyroid glad) and parietal cells (fundic stomach) both contain unusually large numbers of mitochondria. How could you distinguish between them in a medium magnification electron micrograph?
If you see intracellular canaliculi you know it was a parietal cell since oxyphils don’t have canaliculi. Similarly, if you could see a lumen it would be a parietal cell since parathyroid does not have a lumen. always remember to look at the object of interest and at the structures around it.
human dental formula
(incisors: canine: premolar: molar)
adult: 32 teeth (2:1:2:3)
deciduous: 20 (2:1:2)
parts of tooth 4
- crown: above gum line, dentin covered by enamel, cusps= raised peaks or ridges at the occlusal surface of the crown
- root: below gum line, holds tooth in the alveolus, dentin covered by cementum
- neck (cervix): where crown and rot meet at CEJ
- pulp: internal part of tooth, CT with blood vessels, lymphatics and nerves that supply tooth (enter at apical foramen). important in formation of dentin. surrounded by dentin from crown to root apex.
