Regulation of acid production and motility Flashcards
What are the 3 different types of GIT control
Autonomic, enteric and hormonal
What are the 3 types of Gastric Acid secretion?
Cephalic, Gastric and intestinal phase
What does sight, smell and taste trigger?
Cephalic phase - increase HCL
What does gastric distension and peptides trigger?
Gastric Phase - increase HCL
What does acid in duodenum trigger?
Intestinal phase - feedback inhibition of HCL via secretin
What drives gastric acid secretion?
Gastrin, histamine and ACh
What inhibits gastric acid secretion?
Somatostatin, secretin and prostaglandins
What creates a pressure gradient towards ileo-caecal sphincter?
Pacemaker activity not being the same along the lengthy of the GIT
Is the fundus rhythmic?
no
How are slow waves generated?
Interstitial cells of Cajel (ICC) - PNS
Describe properties of the ICCs?
Gap junctions with smooth muscle
Close to nerve terminals
Postulated to have conductive function
Kit positive
What impairs GIT motility?
Blocking Kit with antibodies
What is the function of slow waves?
Increase probability of opening for voltage-dependent Ca2+ channels
Increases resting membrane potential
What generates these slow waves
ICCs
What two things increase the force of contraction in the stomach?
Slow waves + increased membrane polarisation
What does gastric distension do?
Accelerates emptying rate
What types of food empty faster than others?
Liquids > carbohydrate rich meals > protein rich meals > fatty meals
What is the feedback inhibition involved with gastric distension?
Duodenal feedback: negative enterogastric reflex triggered by vagal sensory fibres
What do the vagal sensory fibres detect?
pH, osmolality, fatty acids and amino acids
What effect do secretin and CCK have on gastric emptying rate?
Decreases it
What is a gastro esophageal reflux disease symptom?
Heartburn
Barrett’s esophagus can develop
Define vomiting
Rapid removal of potential harmful material
What are the 2 phases of vomiting?
Prodromal and expulsive phase
What are traits of the prodromal phase?
Nausea, pallor, sweating, salivation and tears
What are the traits of the expulsive phase?
Giant retrograde contraction from jejenum
Abdominal wall contraction & glottis closes
Relaxation of LOS/LES
Esophageal shortening – longitudinal muscle
Diagram contracts – crural diaphragm relaxes
(except during retching)
