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48 Cards in this Set
- Front
- Back
- 3rd side (hint)
What are the names of the 3 phases of digestion and absorption? |
1. Cephalic 2. Gastric 3. Intestinal |
1. C 2. G 3. I |
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What controls the Cephalic Phase? What is its primary function? |
1. By resources via the ANS 2. Stimulates saliva formation |
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What initiates the cephalic phase? Relays info to? |
1. Sensory receptors pick up the sight, smell and taste of food. 2. Salivatory nuclei in medulla |
1. Stimulation of... 2. Nuclei. |
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The Salivatory nuclei sends the signal for... |
Parasympathetic Efferent Response; Vagal Stimulation for Acetylcholine Secretion. |
PER, ACh |
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What does the Parasympathetic stimulation lead to? |
1. Secretion of ACh & VIP by nerve endings which stimulates the Antrum's G-Cells. 2. Increased blood flow (Kallikrien & Bradykinin) |
1. Neurotransmitters 2. Vasodilation |
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What initiates Gastric Secretion? What kind of reflexes occur? |
1. Distention of the stomach 2. Vago-vagal & local reflexes |
1. Distention: State of being stretched normal normal dimensions. 2. Controls the contraction of the gastrointestinal muscle layers in response to distension of the tract by food. |
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What is the function of the Vago-vagal reflex? |
It allows for the accommodation of large amounts of food in the gastrointestinal tracts. |
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What does ACh from the cephalic phase do? This leads to... |
1. Causes Gastrin secretion from G-cells (stomach). 2. HCL Gastric Secretion from Parietal Cells |
1. Secretion from pyloric Antrum 2. HCL |
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What regulates Gastric Secretion? |
1. Secretion of Secretin, CCK, GIP (Gastrin Inhibitory Peptide) by duodenum (intestinal phase) 2. Secretion of ACh by nerve endings |
1. Inhibit G-Cells & Parietal Cells; secretions by S-cells, I-cells and K-cells 2. Stimulates Gastric Secretion |
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What is the cause of Secretin, CCK and GIP being secreted in the Intestinal Phase? |
Protein Digestion products in the duodenum trigger the secretion. |
Protein related |
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What 3 factors allow enzyme-rich secretions by Acinar cells? |
1. ACh secretion 2. VIP (Vasoactive Intestinal Peptide) secretion with ACh & Gastrin 3. CCK secretion by I-cells in Intestinal Phase |
1. Cephalic phase's Parasympathetic Vagal activity. 2. By G-cells in Antrum in the Gastric Phase. 3. I for Intestinal |
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Low pH in the duodenum causes the secretion of... What is the action of this hormone? |
1. Secretion of Secretin by S-cells. 2. Secretion of Bicarbonate-rich fluid by duct cells |
1. Secretin 2. Alkaline to counter acidity |
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What agents does the Pancreas secrete? Where are they stored? |
1. Proteolytic 2. Amylolytic 3. Lipolytic 4. Zymogen granules |
Enzymes Note: they are secreted in an inactive form: zymogen (e.g. Trypsinogen) |
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What are the functions of Trypsin? |
1. Cleaves peptide bonds 2. Activates other enzymes |
1. Protease 2. Activator 3. Along with Chymotrypsin Zymogen: Trypsinogen activated by: Enteropeptidase |
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What is Pancreatitis? What are the mild and severe case symptoms? |
1. Inflammatory disease with high incidence rate among alcoholics. 2. Interstitial oedema 3. Acinar cell Necrosis 4. Acini destruction (leads to Steatorrhoea) |
1. General definition 2. Mild 3. Severe 4. Chronic |
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What causes cystic fibrosis? |
1. Duct cells & other epithelial cells have atypical AMP-activated Cl- channels. 2. Loss of channel function reduces bicarbonate & water secretion. 3. The protein-rich secretion thickens leading to duct blockage. |
1. Lots of a channel function 2. HCO3 & H2O 3. Primary secretion thickens |
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Where are the key sites of nutrition absorption? |
1. Duodenum 2. Jejunum 3. Ileum |
Small intestines |
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Where are lipids primarily absorbed? Via? |
1. Jejunum 2. Diffusion, transporters and solvent drag |
1. Across a leaky epithelium 2. Osmotic forces are important |
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What is the function of Bile? Where does Bile Acid absorption occur? |
1. Emulsifies lipids into droplets for more Surface Area for Pancreatic Lipase Action. 2. Mostly in Ileum but also Duodenum, Jejunum and Ascending Colon |
Small intestine with a part of three large intestine as well. |
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Where is Cobolamin absorbed? |
Ileum |
Part of the small intestine. |
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How are carbohydrates digested? |
Firstly by Salivary Amylase, then by Pancreatic Amylase. |
Involves the cephalic phase and exocrine function of the Pancreas. Both are secreted in active form. |
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How does alpha-amylase carry out its function? |
Endoenzyme action on linear 1,4 linkages between glucose residues. |
Alpha glucose only! |
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Most monosaccharides are absorbed... Via... |
1. In the first 20% of the Small Intestine. 2. Enterocytes' Oligosaccharidases |
1. SI; Microvilli (Brush border) 2. oligosaccharidases have catalytic domains facing the lumen. I.e. Lactase, Maltase (glucoamylase), Sucrase (sucrase-isomaltase) |
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Glucose & Galactose can... |
Compete to bind and be transported by apical SGLT-1. |
SGLT-1: Sodium-Glucose Linked Transporter |
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What is the function of GLUT-2? Location? |
1. When glucose in the lumen is high, GLUT-2 is inserted into the apical membrane to further facilitate transport. 2. Apical membrane of Enterocytes. |
Remember that GLUT-2 has a low affinity for Glucose |
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What normally transports Fructose? |
Apical GLUT-5 |
Glucose Transporter also found on enterocyte |
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How are proteins digested in the Stomach? In the Pancreas? |
1. Gastric enzymes (Pepsin) 2. Pancreatic Enzymes (Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B) |
Both are secreted in inactive forms. Pepsin: an endopeptidase from Pepsinogen. |
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What do Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B give rise to? |
1. Procarboxylase A&B give rise to exopeptidase enzymes 2. The rest do endopeptidase enzymes |
Endo our Exo? |
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How are proteins digested? |
Firstly by Gastric enzymes (Pepsin), then by Pancreatic Enzymes (Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B) |
Both are secreted in inactive forms. Pepsin: an endopeptidase from Pepsinogen. |
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What do Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B give rise to? |
1. Procarboxylase A&B give rise to exopeptidase enzymes 2. The rest do endopeptidase enzymes |
Endo our Exo? |
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Define Endopeptidase and Exopeptidase. |
1. Enzymes which break peptide bonds other than the terminal ones in a peptide chain. 2. Enzymes which break terminal peptide bonds in a peptide chain. |
Breakage of terminal peptide bonds. |
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What is the location and function of Peptidases? Where does the digested protein go? |
1. Exist on the brush-border 2. Hydrolysis of oligopeptides into amino acids 3. Intestinal capillaries |
Brush border consists of microvilli composed of Enterocytes |
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What are Enterocytes? Function? |
1. Simple columnar epithelial cells 2. Degrade lysosomes 3. Uptake of proteins, carbohydrates, lipids, water and ion in the intestines. 4. Uptake of Vitamin B12 Cobolamin. |
1. Epithelial cell; forms microvilli on villi of intestines 2. Degradation 3. Uptake of everything 4. Uptake of a vitamin |
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What is the location and function of M-cells (Microfold Cells)? |
1. Line Peyer's Patches and BALT 2. Package proteins into vesicles and transport organisms & particles from gut lumen to immune cells. |
1. Peyer & Bronchus Associated Lymph Tissue 2. Packaging & transportation |
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94% of Bile salts that enter the intestines... |
Are reabsorbed. |
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What is the location and function of M-cells (Microfold Cells)? |
1. Line Peyer's Patches (lymphoid nodule of ileum) and BALT 2. Package proteins into vesicles and transport organisms & particles from gut lumen to immune cells. |
1. Peyer's Patches are unique to ileum. BALT: Bronchus Associated Lymph Tissue 2. Packaging & transportation |
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94% of Bile salts that enter the intestines... |
Are reabsorbed. |
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What are the 3 functions of the Gall Bladder? |
1. Acts as a Bile Reservoir 2. Concentrates Bile 3. Emptying mainly by CCK |
1. Storage 2. Concentration 3. Empties |
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What is the major factor of Bile regulation? |
1. Return of Bile salts is the major factor. 2. Cholesterol Gall stones |
1. Secretin enhances Bicarbonate-rich watery fluid by duct cells. 2. Excess cholesterol causes crystal formation; acts as Ca2+ & PO4 salts' nuclei |
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Lipids are digested by... MOA? Limitation? |
1. By Salivary, Gastric and Pancreatic Lipase. 2. Splits bonds linking FA to 1st & 3rd Carbons of glycerol. 3. Limited action without colipase. |
1. Mouth, stomach & Pancreas 2. Triacylglycerol 3. Colipase |
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Name and describe the MOA of 2 Pancreatic Lipases. |
1. Pancreatic Phospholipase A: breaks down Lecithin 2. Pancreatic Cholesterol Esterase: breaks 2-ester linkages of TAG |
1. Lecithin a.k.a phosphatidyl Choline, needs Ca2+ and bile salts 2. TAG ester bond |
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Lipids pass across brush border... If they are big /small... |
1. And are re-esterified in Enterocytes' smooth ER. 1. Big lipids are secreted as fat droplets across bilateral membrane and enter lacteals via exocytosis 2. Small lipids enter intestinal capillaries. |
1. Small intestine has villi with micro villi (brush border) which is made up of Enterocytes. 2. Lacteals (lymphatic capillaries) 3. Intestinal capillaries |
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How are Vitamins Digested? |
1. Fat-soluble Vitamins (ADEK) USE the same pathway as fat absorption. 2. Water-soluble use diffusion/carrier mediated transport. |
1. Fat:lipid 2. e.g. B1 (thiamin) & C (ascorbic acid) use Na+-dependant carriers |
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Vitamin B12 (Cobolamin) is released from food... |
Via Pepsin Action |
Enzyme |
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Cobolamin then binds to... It is then released from degraded H_ and binds to... |
1. Haptocorrin at low pH 2. Intrinsic Factor |
1. Found in saliva; condition protects it from Gastric Juices. 2. IF is secreted by parietal cells |
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Vitamin B12 (Cobolamin) is released from food... |
Via Pepsin Action |
Enzyme |
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Cobolamin then binds to... It is then released from degraded H_ and binds to... |
1. Haptocorrin at low pH 2. Intrinsic Factor |
1. Found in saliva; condition protects it from Gastric Juices. 2. IF is secreted by parietal cells |
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The Cobolamin-IF complex is absorbed... Enterocyte processing binds Cobolamin to... |
1. By the Ileum 2. Transcobalamin II |
1. Absorption is Ca2+ dependant. |