21620742
Beschreibung
Karteikarten von Evian Chai, aktualisiert more than 1 year ago
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Erstellt von Evian Chai
vor mehr als 4 Jahre
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| Frage | Antworten |
| In an acinar cell, what is the role of the Na+/K+ pump on the basolateral side of the cell? | It pumps Na+ OUT of the cell into saliva Cl- leaves via channel alongside Na+/H20 Creates primary secretion |
| What is the tonicity of primary secretion of saliva? | Isotonic to plasma |
| How is saliva modified as it passes down the duct? What is reabsorbed and what is added? What is the final tonicity? | Na+/Cl- reabsorbed K+/HCO3- added Creates a HCO3- rich hypotonic secretion |
| How does flow rate impact the modification of saliva? | Higher flow rate=less modified |
| What are 3 other components in saliva? | 1. Ions (Ca2+, phosphate) 2. Large molecules released via exocytosis by acinar cells (eg. mucins, glycoproteins, lysozymes, amylase) 3. Immununoglobulin A |
| Where is immunoglobulin A made and what does it bind to in an acinar cell? | Made in B lymphocytes, bind to receptor on basolateral side of acinar |
| What are the 4 main functions of saliva? | 1. Lubrication of food 2. Starch digestion (amylase) 3. Antimicrobial 4. pH/mix of Ca2+ and phosphate prevent demineralisation |
| Which salivary gland has the highest basal flow rate? | Submandibular gland |
| Which salivary gland has the highest stimulated flow rate? | Parotid |
| How does the proportion of amylase and mucus differ in saliva from the parotid, submandibular and sublingual glands? | Parotid: Amylase>mucus Submandibular: amylase<mucus Sublingual: mucus |
| How does increased PNS affect saliva? | Increases fluid/electrolyte component |
| How does increased SNS affect saliva? | Increased release of macromolecular components |
| What are the three phases of digestion? | 1. Cephalic Phase: -Thinking about food increases salivary secretions - Chewing + amylase secretion 2. Gastric phase - Stomach secretes pepsinogen/acid - Mechanical breakdown of food - Start of protein digestion 3. Intestinal phase - Hormones inhibit gastric secretion - Hormones induce bile/pancreatic secretions - Digestion + absorption |
| Which cell secretes pepsinogen? Where is it located? | Chief cell Located in the lumen of the stomach |
| Which cell secretes HCl and Intrinsic factor? Where is it located? | Parietal cell in the lumen of the stomach |
| What does HCl do? | Creates acidic environment in stomach, activates pepsinogen to pepsin |
| What does intrinsic factor do? | Allows for absorption of B12 |
| What is the mechanism of acid secretion? | 1. In the parietal cell, CO2+H20-->H2CO3-->HCO3- + H+ 2. H+ pumped against concentration gradient into lumen via H+/K+ exchanger (using ATP) 3. HCO3- exits into blood via Cl-/HCO3- exchanger |
| What reaction does carbonic anhydrase speed up? | CO2+H20-->H2CO3 |
| How is acid secretion increased? | Upon stimulation, proton pump fuses with canaliculi to increase SA for HCl secretion |
| What are the 4 factors impacting HCl secretion by parietal cells? | 1. Ach from the vagus (ENS) nerve (neural) 2. Histamine from ECL cell (endocrine) 3. Gastrin from G cell (gastric) 4. SST from D cell (neural inhibition) |
| What are the three targets of Ach from the vagus nerve to impact acid secretion? What is the primary mechanism? | 1. Parietal cell directly 2. Increases histamine secretion from ECL cell (primary) 3. D cell to stimulate SST release (lower secretion of acid) |
| What are the two targets of SST? | 1. ECL cell to lower histamine release 2. Parietal cell to lower HCl secretion |
| How does gastrin affect stomach secretion? What increases/inhibits its secretion? | Increases gastric secretions/motility Increases: increased proteins, alcohol, coffee etc. Decreases: Low gastric pH |
| How does CCK affect stomach secretion? What is its release stimulated by? | Lowers gastric secretions/motility Released from duodenum wall by increased fats |
| How does secretin affect stomach secretion? What is its release stimulated by? | Lowers gastric secretions Released from duodenum wall from increased acid |
| How does GLP (SI) and GLP-1 (Ileum/colon) affect stomach secretion? What is its released stimulated by? | Inhibits gastric secretions Stimulated by increased fats/chyme in lumen |
| What do crypt cells secrete in the SI? | Isotonic saline |
| What do Brunner's Glands secrete in the SI? | Alkaline mucus |
| What do enterocytes secrete in the SI? | Bicarbonate rich fluid with digestive enzymes |
| What must relax for pancreatic/bilary secretions to go through? What causes this to relax? | Sphincter of Oddi CCK |
| What are the two components of the pancreatic secretion and which cells secrete them? | 1. Alkaline fluid rich in HCO3- from pancreatic duct cells 2. Digestive enzymes (eg. endopeptidases, carboxypeptidases, amylase, lipase etc.) from acinar cells and stored in zymogen granules |
| What are the two regulators of pancreatic secretion and what do they do? | CCK- increases secretions in response to fats Secretin- increased HCO3- release in response to chyme |
| What is the mechanism of alkaline fluid secretion from the pancreas? | 1. CO2 from blood -->H2CO3-->H+ + HCO3= 2. Energy from Na+ pump on basal side of cell 3. HCO3= efflux into duct via HCO3-/Cl- exchanger |
| What is the negative feedback loop between acid and HCO3-? | Acid increases secretion, which increases plasma secretion, which increases HCO3- from duct cells, which inhibits secretion+neutralises acid |
| What produces bile? What secretes it? | The liver The gallbladder |
| What does bile initially contain before modifications? | 1. Bile salts/acid for fat emulsification 2. bilirubin from RBC |
| What secondary modifications are made to bile? What stimulates these modifications? | H20+HCO3- added in bile duct Stimulated by secretin |
| What gut hormone stimulates insulin release? | GIP from SI |
| What gut hormone stimulates insulin, inhibits glucagon and promotes satiety? | GLP-1 from Ileum/colon |
| What gut hormone promotes satiety? | CCK from SI |
| What gut hormone promotes appetite? | Ghrelin from stomach |
| What is the main function of the colon? | Water reabsorption |
| What are the three secretions of the colon? | Mucus HCO3- Some K+ secretion |
| How is K+ secreted from the colon? | Lumenal Na+ channels absorb Na+ Creates negative charge in lumen K+ enters lumen via paracellular pathway |
| What are dysfunctions associated with 1. Saliva 2. Gastric Secretions 3. Pancreatic secretions 4. Bile | 1. Dry mouth, enamel damage, lowered immunity 2. Anaemia, acid, ulcers, malabsorption 3. Malabsorption, cystic fibrosis can impact 4. Malabsorption |
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