Term
| (05-06) In the mouth, what begins carbohydrate digestion? What are the end products? |
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Definition
| Amylase in the saliva breaks starch and glycogen into maltose or limit dextrins |
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Term
| (05-06) In the stomach, what happens to amylase? What does this mean for carbohydrate digestion? |
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Definition
| Amylase is denatured, leading to no further carbohydrate digestion |
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Term
| (05-06) In the duodenum, what happens to carbohydrates? |
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Definition
| Pancreatic amylase breaks down extra starch and glycogen into maltose and limit dextrins. |
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Term
| (05-06) Can maltose be absorbed? |
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Definition
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Term
| (05-06) What finally breaks down maltose into absorbably molecules? |
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Definition
| Brush border enzymes – specifically, maltase. |
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Term
| (05-06) What are the brush border enzymes? |
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Definition
| Sucrase, lactase, maltase, isomaltase. |
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Term
| (05-06) What breaks down limit dextrins? |
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Definition
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Term
| (05-06) How do glucose and galactose enter a cell? Why does this work? |
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Definition
| A secondary active transport that moves two sodium for every one sugar. The sodium-potassium pump is constantly pumping sodium out of the cell, allowing the secondary active transport to move sodium along its concentration gradient. |
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Term
| (05-06) How is fructose moved across the brush border into cells? |
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Definition
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Term
| (05-06) How do glucose and galactose exit a cell into the bloodstream? |
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Definition
| Glut2 (carrier-mediated exit) |
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Term
| (05-06) Glucose vs. fructose: Which requires ATP to move into and out of a cell? |
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Definition
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Term
| (05-06) How does fructose exit a cell? |
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Definition
| Facilitated transport through Glut4 |
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Term
| (05-06) In lactose intolerance, what enzyme is missing? Where is this enzyme normally found? |
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Definition
| Lactase; brush-border enzyme |
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Term
| (05-06) What is secreted in the stomach to encourage protein digestion? What is secreting it? |
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Definition
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Term
| (05-06) On exposure to stomach acid, what happens to pepsinogen? What happens next? |
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Definition
| A semi-active form of pepsinogen. This can then autocatalysis and remove 44 amino acids to become pepsin. |
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Term
| (05-06) Why doesn’t pepsin eat your duodenum? |
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Definition
| Pepsin is deactivated in alkaline conditions. |
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Term
| (05-06) Are there proteases in the mouth? |
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Definition
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Term
| (05-06) What organ is the main area of protein digestion? |
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Definition
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Term
| (05-06) What are the pancreatic zymogen endopeptidases? |
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Definition
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Term
| (05-06) What are the pancreatic zymogen exopeptidases? |
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Definition
| Carboxypeptidase and aminopeptidase |
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Term
| (05-06) What are the limits to endopeptidases? |
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Definition
| They are limited to certain amino acid internal bonds. |
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Term
| (05-06) What is the function of exopeptidases? |
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Definition
| They can cleave end bonds and finish digestion of proteins |
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Term
| (05-06) What are polypeptides broken down into in the pancreas? |
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Definition
| Amino acids and short peptidases |
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Term
| (05-06) What activates trypsinogen? |
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Definition
| Enterokinase to create trypsin |
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Term
| (05-06) What does trypsin do? |
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Definition
| It activates chrymotrypsin and carboxypeptidase. |
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Term
| (05-06) What do fats begin as when eaten? What are they converted to? |
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Definition
| Triglycerides, phospholipids, cholesterol are converted to fattyacids and monoglycerides |
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Term
| (05-06) Define emulsification. |
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Definition
| The combination of two immiscible liquids (oil and water – mayonaise!) |
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Term
| (05-06) In the mouth, what begins lipid digestion? |
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Definition
| Lipases beginthe process of breaking down fats |
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Term
| (05-06) In the stomach, what enzyme works on lipids? |
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Definition
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Term
| (05-06) Where are bile salts made? |
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Definition
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Term
| (05-06) Where do bile salts begin to work on lipids? |
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Definition
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Term
| (05-06) Are bile salts nonpolar, polar, or amphipathic? Why? |
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Definition
| Amphipathic; the polar and nonpolar bits assist in the mixing of lipid and water |
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Term
| (05-06) Emulsified fat can be acted on by _____ in the presence of _____. |
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Definition
| Pancreated lipase and colipase |
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Term
| (05-06) Why is colipase important? |
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Definition
| Bile salts repel lipase unless colipase is present. |
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Term
| (05-06) What does lipase break triglycerides into? |
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Definition
| A monoglyceride and two fatty acids |
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Term
| (05-06) How do we get lipids into the bloodstream? |
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Definition
| Lipids diffuse into enterocytes and enter right into the endoplasmic reticulum. Next, triglycerides move to the Golgi apparatus to be packed into chylomiccrons. The chylomicrons are then spit out into interstitial fluid, where they move into lacteals of the lymphatic system and to the blood. |
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Term
| (05-06) What’s important to remember when wondering how a lipid passes through a cell? |
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Definition
| The membrane of cells is made out of lipids, so the lipid wanting to pass can just diffuse right across |
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Term
| (05-06) Define chylomicrons |
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Definition
| Lipids and proteins bound together – lipoproteins |
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Term
| (05-06) Why do chylomicrons enter the lacteals instead of right into the bloodstream? |
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Definition
| These molecules are too big to go straight into the bloodstream. |
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Term
| (05-06) How are fat-soluble vitamins absorbed? |
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Definition
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Term
| (05-06) How must B12 move into the blood? |
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Definition
| B12 must bind to intrinsic factor (pernicious anemia is the malfunction disease) |
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Term
| (05-06) Define enteric nervous system. |
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Definition
| The gut’s “brain” that allows it to detect and respond to stimuli locally, without CAN input |
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Term
| (05-06) What are the two main parts of the ENS? |
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Definition
| Submucosal (secretion) and myenteric (motility) |
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Term
| (05-06) What type of neurotransmitters does the enteric nervous system use? |
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Definition
| All the normal ones – Ach, dopamine, etc. |
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Term
| (05-06) What are the two pathways of the ENS? |
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Definition
| Short reflex pathway and long reflex pathway |
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Term
| (05-06) What are the three main receptors in the ENS? |
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Definition
| Chemoreceptors, osmoreceptors, and mechanoreceptors |
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Term
| (05-06) What does the short reflex pathway do? |
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Definition
| Activates the ENS, which either stimulates effector cells or the release of hormones. |
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Term
| (05-06) What does the long reflex pathway do? |
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Definition
| Activates the CNS, which effects the ENS via the autonomic nervous system. ENS then either stimulates effector cells or the release of hormones. |
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Term
| (05-06) What’s the overall product of the short reflex and long reflex pathways? |
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Definition
| Increase in endocrine and exocrine secretion and/or increase in GI motility. |
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