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35 Cards in this Set
- Front
- Back
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What nerve aids the stomach in accommodation?
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The vagus.
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Why do the pressure waves for the stomach look different in different locations in the stomach?
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The pacemaker cells begin below the fundus.
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What regions of the stomach are dependent on gastric slow waves for contraction?
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All but the fundus.
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What determines when the stomach empties?
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Gastric volume
Osmolarity of gastric contents Acid conditions in the duodenum Caloric content of the meal-- uniform empytying of calories per unit time (fat delays emptying) Particle size |
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What effect does acid in the duodenum have on gastric emptying? How?
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It slows emptying via the enterogastric reflex and release of secretin.
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During what time period are slow waves happening?
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Continuously.
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What is special about the slow waves in the phase III of the migrating motor complexes?
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Every wave is associated with a contraction.
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What happens to particles that don't empty during gastric emptying into the duodenum?
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Evacuate during the fasting motor phases.
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What might occur if the MMC don't occur?
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Bacterial overgrowth.
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What happens during contraction orad, relaxation caudad?
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Orad: Circular muscle contracts, longitudinal muscle relaxes.
Cuadad: Circular muscle relaxes, longitudinal muscle contracts. |
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What is the vago-vagal reflex pathway?
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A reflex stimulated by gastric distention
causes relaxation of proximal stomach and secretion of HCl and gastrin. |
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What is the vago-vagal reflex pathway?
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A reflex stimulated by gastric distention
causes relaxation of proximal stomach and secretion of HCl and gastrin. |
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How do smooth muscle cells communicate?
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gap junctions!
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The role of secretin is primarily on what cells?
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pancreatic duct cells
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Secretion of CCK is regulated by what?
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CCK-RP in response to fatty and amino acids and by a monitor peptide
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CCK primarily effects what cells?
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Pancreatic acinar cells by binding to CCK-A receptors on basolateral membranes.
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Transcellular movement of water is linked to to absorption of nutrients through which transporter?
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SGLT-1
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How do sodium,chloride and potassium pass into the lumen of the small bowel?
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paracellularly
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What hormones regulate removal of potassium from the blood?
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Insulin
Aldosterone Epinephrine |
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How do we absorb calcium?
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Passively, paracellularly
Actively, in the duodenum through a transporter. |
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Does vitamin D affect the active or passive transport of calcium?
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active
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Where does active absorption of magnesium occur?
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In the ileum
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Which vitamin facilitates the absorption of iron?
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Vitamin C, because it aids in the reduction of Fe3+ to Fe2+
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Which trasnporter is responsible for bringing heme into the cell?
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HCP1
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What is the unstirred layer?
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A layer of fluid lining the villi of the small intestine. It separates the bulk of intestinal contents from the mucosal cell surface.
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What type of junctions exist between enterocytes? What transmembrane proteins are crucial in these junctions?
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Tight junctions
Claudins. They allow regulated transport of paracellular substances. |
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What is the net absorption of calcium per day?
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~175 mg
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What exchange of ions is responsible for the net absorption of chloride?
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Cl-HCO3 exchange
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What are the sources of potassium for the body?
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Food (avocados!), gastric, pancreatic, and biliary secretions
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What are the sources of potassium for the body?
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Food (avocados!), gastric, pancreatic, and biliary secretions
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Which transporter brings both reduced iron and H+ into the enterocyte?
Under what conditions does this transporter have optimal function? |
DCT1
When the pH of the intestinal lumen is more acidic than intracellular pH |
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Who transports iron across the basolateral membrane? Who carries the Fe3+ in the blood?
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IREG1
Transferrin |
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Will demand for iron adjust the amount of iron that is absorbed?
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Yes. Iron transport proteins are upregulated when plasma iron levels are low.
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Cobalamin (B12) requires another protein to bind to it for absorption. What is this protein and where does the conjugation occur?
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Intrinsic factor, in the duodenum.
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Who transports glucose, galactose, and fructose across the basolateral membrane?
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GLUT2
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