Karteikarten
BMS13-1056 - Gastrointestinal Secretions and their Control
Karten in diesem Stapel (46)
- 1In 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 - 2What is the tonicity of primary secretion of saliva?Isotonic to plasma
- 3How 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 - 4How does flow rate impact the modification of saliva?Higher flow rate=less modified
- 5What 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 - 6Where 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
- 7What 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 - 8Which salivary gland has the highest basal flow rate?Submandibular gland
- 9Which salivary gland has the highest stimulated flow rate?Parotid
- 10How does the proportion of amylase and mucus differ in saliva from the parotid, submandibular and sublingual glands?Parotid: Amylase>mucus
Submandibular: amylase - 11How does increased PNS affect saliva?Increases fluid/electrolyte component
- 12How does increased SNS affect saliva?Increased release of macromolecular components
- 13What 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 - 14Which cell secretes pepsinogen? Where is it located?Chief cell
Located in the lumen of the stomach - 15Which cell secretes HCl and Intrinsic factor? Where is it located?Parietal cell in the lumen of the stomach
- 16What does HCl do?Creates acidic environment in stomach, activates pepsinogen to pepsin
- 17What does intrinsic factor do?Allows for absorption of B12
- 18What 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 - 19What reaction does carbonic anhydrase speed up?CO2+H20-->H2CO3
- 20How is acid secretion increased?Upon stimulation, proton pump fuses with canaliculi to increase SA for HCl secretion
- 21What 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) - 22What 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) - 23What are the two targets of SST?1. ECL cell to lower histamine release
2. Parietal cell to lower HCl secretion - 24How does gastrin affect stomach secretion? What increases/inhibits its secretion?Increases gastric secretions/motility
Increases: increased proteins, alcohol, coffee etc.
Decreases: Low gastric pH - 25How does CCK affect stomach secretion? What is its release stimulated by?Lowers gastric secretions/motility
Released from duodenum wall by increased fats - 26How does secretin affect stomach secretion? What is its release stimulated by?Lowers gastric secretions
Released from duodenum wall from increased acid - 27How 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 - 28What do crypt cells secrete in the SI?Isotonic saline
- 29What do Brunner's Glands secrete in the SI?Alkaline mucus
- 30What do enterocytes secrete in the SI?Bicarbonate rich fluid with digestive enzymes
- 31What must relax for pancreatic/bilary secretions to go through? What causes this to relax?Sphincter of Oddi
CCK - 32What 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 - 33What 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 - 34What 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 - 35What 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
- 36What produces bile? What secretes it?The liver
The gallbladder - 37What does bile initially contain before modifications?1. Bile salts/acid for fat emulsification
2. bilirubin from RBC - 38What secondary modifications are made to bile? What stimulates these modifications?H20+HCO3- added in bile duct
Stimulated by secretin - 39What gut hormone stimulates insulin release?GIP from SI
- 40What gut hormone stimulates insulin, inhibits glucagon and promotes satiety?GLP-1 from Ileum/colon
- 41What gut hormone promotes satiety?CCK from SI
- 42What gut hormone promotes appetite?Ghrelin from stomach
- 43What is the main function of the colon?Water reabsorption
- 44What are the three secretions of the colon?Mucus
HCO3-
Some K+ secretion - 45How is K+ secreted from the colon?Lumenal Na+ channels absorb Na+
Creates negative charge in lumen
K+ enters lumen via paracellular pathway - 46What are dysfunctions associated with 1. Saliva 2. Gastric Secretions 3. Pancreatic secretions 4. Bile1. Dry mouth, enamel damage, lowered immunity
2. Anaemia, acid, ulcers, malabsorption
3. Malabsorption, cystic fibrosis can impact
4. Malabsorption
Informationen
- Beschreibung
- Understand: - Saliva production and its function - Parietal cells's production of HCL and its function - Secretion of pepsinogen, mucus, intrinsic factor, gastric lipase and regulation - Regulators/roles of gastrin, CCK/PZ, and secretin - source and roles of GLP-1 & GIP - secretions of small intestine enterocytes - exocrine secretions of the pancreas (composition, source, main stimuli) - bile - consequences of dysfunction of gastrointestinal tract secretions
- Erstellt von
- Evian Chai
- Aufrufe
- 18
- Tags
- Bewertung