Physiology - Final - Part 2

davidwurbel7's version from 2015-08-18 04:15

GI Structure

Question Answer
Causes mechanical breakdown of food & propulsion of food through gutGastrointestinal Motility
Release of enzymes, water & ionsGastrointestinal Secretion
Plexus of neurons and synapses ( located within the wall of GI tract). Enteric nervous system consists of the Submucosal and Myenteric plexusesIntrinsic component
Nerve supply from the Autonomic Nervous system (ANS) - Sympathetic & ParasympatheticExtrinsic component
Lies between the submucosa and the circular muscle. Controls secretory functions of GITSubmucosal plexus (Meissner's plexus)
Lies between the circular muscle and the longitudinal muscle. Controls motor functions of GITMyenteric plexus (Auerbach’s plexus)
Vagus nerves (X CN) and pelvic nerves (S2-S4)Parasympathetic Nerve Supply
Usually excitatory – increases gastrointestinal secretions and motilityParasympathetic Signaling
Originate from lateral horn cells of spinal cord, T5-L2Sympathetic nerve supply
Usually inhibitory – decreases gastrointestinal secretions and relaxes smooth musclesSympathetic Signaling
Secreted by G cells in the antrum of the stomachGastrin
Increases H+ secretion by the Gastric parietal cells. Stimulates growth of gastric mucosa by stimulating protein synthesisGastin
It is caused by a Gastrin-secreting tumor or Gastrinoma (usually in the non-β-cell pancreasZollinger - Ellison Syndome
Signs and symptoms include duodenal ulcers caused by the increased secretion of H+. Increased H+ secretion inactivates pancreatic lipase. As a result, dietary fats are not adequately digested or absorbed, and fat is excreted in the stoolZollinger - Ellison Syndrome
Secreted by I cells of the duodenal and jejunal mucosaCholecystokinin
Partially digested fats and proteins in duodenum and jejunum stimulate secretion ofCholecystokinin
Causes the contraction of gall bladder & relaxation of sphincter of Oddi. Secretion of Pancreatic enzymes. Secretion of HCO3- from Pancreas. Slows down Gastric emptying, ensuring adequate time for intestinal digestion & absorptionCholecystokinin
Secreted by S cells of duodenumSecretin
[H+] concentration in the lumen of the duodenum. Fatty acids in the lumen of duodenum. Secreted whenever the pH of small intestinal content is less than 4.5Secretin
Stimulates bicarbonate secretion from pancreas & in the bile. Purpose is to neutralize H+ and increase pH of intestinal contents. This neutralization is essential for fat digestion because Pancreatic Lipases are inactivated at acidic pH. Inhibits H+ secretion from stomach. Inhibits trophic effects of gastrin on gastric mucosaSecretin
Also known as Glucose dependent Insulinotropic peptide. Secreted by K cells of the duodenal & jejunal mucosaGastric Inhibitory Peptide (GIP)
Stimulates insulin secretion by beta cells of pancreas. This explains why oral glucose is a more powerful stimulant for insulin secretion than the intravenous glucose. Inhibits H+ secretion from the stomach (its name implies this)Gastric Inhibitory Peptide (GIP)
Only GI hormone that is secreted in response to end products of digestion of all nutrients, namely, glucose, amino acids and fatty acidsGastric Inhibitory Peptide (GIP)
Secreted by D cells of GI mucosaSomatostatin
Acid directly stimulates release from D cells which in turn acts on parietal cell to decrease acid secretionSomatostatin
Secreted by Enterochromaffin like cells (ECL) of antral region of stomach. Along with Ach and Gastrin, Stimulates H+ secretion by gastric parietal cellsHistamine

Salivary Sectetion

Question Answer
Initial saliva is secreted by these cells which is isotonic and has the same electrolyte composition as plasmaAcinar Cells
These cells modify the initial saliva by reabsorption of Na+, Cl- & secretion of K+ and bicarbonateDuctal Cells
Initial starch digestion by salivary enzymeα-Amylase
Initial triglyceride digestion by salivary enzymeLingual Lipase
Lubrication of ingested food by mucus for its easy passage through the esophagus. Protection of mouth & esophagus by dilution and buffering of ingested foods. Helps articulation and speech by keeping oral cavity moistSaliva
Located in body of stomach. Secrete HCl and Intrinsic factorParietal (Oxyntic) Cells
Located in body of stomach. Secrete pepsinogenPeptic (Chief) Cells
Located in antrum of stomach. Secrete hormone, gastrin into circulation. Gastrin is NOT present in the gatric juiceG Cells
Located in antrum of stomach. Secrete mucus, bicarbonateMucus Neck Cells
Gastric secretion is influenced by various stimuli before food reaching the stomachCephalic Phase
Gastric secretion is influenced by stimuli when food is in the stomachGastric Phase
Gastric secretion is influenced by stimuli arising from the intestineIntestinal Phase
Blocks the H+ - K+ pump in the stomachOmeprazole
Blocks M3 receptors in the stomachAtropine
Blocks H2 receptors for histamine in the stomachCimetidine
Somatostatin and Prostaglandins inhibit secretion ofHCl
Stimulates muscus and bicarbonate production in the stomachProstaglandins
Acts on ductal cells increasing secretion of HCO3 -Secretin
Acts on acinar cells increasing secretion of pancreatic juice CCK
Pancreatic secretion is rich in enzymes, poor in bicarbonate and of small volumeCCK
Pancreatic secretion is poor in enzymes, rich in bicarbonate and of large volumeSecretin
Essential for the digestion and absorption of lipids in the small intestineBile Salts
These are conjugated with amino acids, glycine and taurine to form bile salts which are more water soluble than bile acids in the intestineCholic Acid and Chenodeoxycholic Acid

Digestion and Absorption

Question Answer
Chief source of amylase for starch digestion comes fromPancreas
Dextrins, maltotriose and maltose are the intermediate break down ofStarch
α- Dextrin -> glucoseDextrinase
Maltose -> glucoseMaltase
Sucrose -> glucose + fructoseSucrase
Lactose -> glucose + galactoseLactase
Maltotriose -> glucoseSucrase
This is required for the proper absorption of glucose in the small intestineSodium
Trypsinogen, Chymotrypsinogen, Proelastase, Procarboxypeptidase A, Procarboxypeptidase B are secreted in inactive form from thePancreas
Trypsinogen is activated to trypsin byEnterokinase
Chymotrypsinogen, Proelastase, Procarboxypeptidase A, Procarboxypeptidase B are all activated byTrypsin
Iron is absorbed at this part of the GI tractDuodenum
Folate is absorbed at this part of the GI tractJejunum
Due to malabsorbed nutrients or poorly absorbed electrolytes that retain water in the lumenOsmotic Diarrhea
Due to secretion of excess fluid by intestinal cellsSecretory Diarrhea