Lecture 35: Lower GI Histology II Flashcards
Where does carbohydrate digestion begin?
The mouth
What is the role of amylase?
Hydrolyzes starch to form sugars; present in saliva and also secreted by pancreas
Where are disaccharides broken down into monosaccharides?
Brush border of small intestine; then monosaccharides are taken up by enterocytes
Where does protein digestion begin?
The stomach, where proteins are hydrolyzed into peptides (requires pepsin)
What steps of protein digestion occur in small intestine?
Polypeptides broken down into peptides by several enzymes; at brush border, oligopeptides broken down into amino acids and transported into enterocytes via carrier-mediated process
Where does lipid digestion begin?
Small intestine, where fats enter as triglyceride droplets
Pancreatic lipase
Emulsifies large triglyceride droplets and releases fatty acids, glycerol
Micelles
Transport fatty acids, glycerol, phospholipids, vitamins A and K, etc. across enterocyte apical plasma membrane via passive diffusion (requires FABPs)
Chylomicrons
Formed from proteins and triglycerides; fuse to plasma membrane, taken up by lacteals where they will dump into lymphatic network and eventually enter blood
Cholecystokinin
Secretion site: upper intestinal mucosa of duodenum in response to gastric contents
Acts on pyloric sphincter to slow emptying of stomach, stimulates release of bile from gallbladder and secretion of pancreatic enzymes
Gastrin
Secretion site: pyloric-antral portion of stomach
Stimulates HCl production by parietal cells, gastric motility, promotes growth of gastric mucosa, stimulates release of insulin by beta pancreatic cells
Secretin
Secretion site: epithelial cells of duodenum in response to acid contents of stomach
Enhances release of insulin by beta pancreatic cells, stimulates release of bicarbonate from pancreas
Identify epithelium and musculature present in anal canal
Epithelium: stratified squamous
Musculature: skeletal muscle (external anal sphincter)
Which of the following best describes the olfactory mucosa?
A. Stratified columnar epithelium with goblet cells and distinct basement membrane
B. Simple ciliated columnar epithelium with goblet cells and distinct basement membrane
C. Stratified, non-keratinized epithelium lacking goblet cells with thick basement membrane
D. Pseudostratified columnar epithelium lacking goblet cells with no distinct basement membrane
D. Pseudostratified columnar epithelium lacking goblet cells with no distinct basement membrane
Which of the following is NOT a necessary part of the respiratory membrane?
A. Pneumocyte I B. Basal lamina of pneumocyte I C. Dust cells D. Basal lamina of endothelial cells E. Endothelial cell
C. Dust cells
Which of the following is characteristic of an arteriole?
A. Thick tunica adventitia and large lumen
B. Thick tunica media in relation to size of lumen
C. Thin tunica media with relatively large lumen
D. Large blood-filled lumen
E. Large amounts of elastic fibers in tunica media
B. Thick tunica media in relation to size of lumen
Where in the body of a normal, healthy individual would you expect most erythrophagocytosis to be occurring?
A. Marginal zone of spleen B. Medulla of thymus C. Hematopoietic cord in bone marrow D. Cord of Billroth in spleen E. Paratrabecular sinus in lymph node
D. Cord of Billroth in spleen
Which of the following sequences best describe the flow of RBCs through the spleen?
A. Trabecular arteries, central arteries, splenic arteries, penicillus, venous sinuses
B. Splenic artery, central arteries, trabecular arteries, venous sinuses, penicillus
C. Trabecular arteries, splenic arteries, central arteries, penicillus, venous sinuses
D. Splenic artery, trabecular arteries, central arteries, penicillus, venous sinuses
D. Splenic artery, trabecular arteries, central arteries, penicillus, venous sinuses
The simple cuboidal epithelium of this portion of the kidney tubule is composed of cells in the form of truncated pyramids which are characterized by basal striations that mark the location of mitochondria
A. Proximal convoluted tubule
B. Descending thin segment of loop of Henle
C. Ascending thick segment of loop of Henle
D. Distal convoluted tubule
E. Collecting ducts
A. Proximal convoluted tubule
Renin is secreted by which of the following
A. Liver B. Macula densa C. Atrial cells of the heart D. Mesangial cells E. Juxtaglomerular cells
E. Juxtaglomerular cells
