Flashcards in Physiology Deck (200)
The large intestine is the principal site of dietary nutrient reabsorption. True/False?
Small intestine is the principle site of dietary nutrient absorption
What are the main functions of the large intestine?
Reabsorbs fluid + electrolytes
Stores faecal matter
The exocrine and endocrine "parts" of the pancreas are both part of the GI system. True/False?
Only the exocrine pancreas is part of the GI system
Name some accessory structures of the GI tract
Which muscle - smooth or skeletal - is predominant in the motility of the GI tract?
Which parts of the GI tract are under skeletal muscle control?
Mouth + pharynx
External anal sphincter
Name two polysaccharides
Name two disaccharides
Name three monosaccharides
What are proteins broken down into?
The apical membrane of an enterocyte faces the lumen. True/False?
Which membrane of an enterocyte faces the blood?
What are the 4 main layers of the GI tract wall, from innermost to outermost?
What is the function of epithelial cells in the mucosa?
What is the importance/function of the muscularis mucosa?
Can change shape/SA to facilitate absorption
What does contraction of circular muscle do to the lumen of the digestive tract?
Makes it narrower and longer
What does contraction of longitudinal muscle do to the lumen of the digestive tract?
Makes it shorter and fatter
What is the function of gap junctions between adjacent smooth muscle cells?
Enable slow wave of contraction to spread across smooth muscle sheet
Which cells drive slow wave electrical activity?
Interstitial cells of Cajal (ICCs)
What type of cells are ICCs?
What must happen for ICCs to produce contraction?
Slow wave amplitude must reach threshold to trigger an action potential
The upstroke of the AP generated by ICCs is mediated by Na+ influx. True/False?
Mediated by Ca++ influx through Ca++ channels
The force of contraction in the GI tract is related to the number of action potentials discharged from ICCs. True/False?
The more APs fired, the greater the force of contraction
What determines the basal electrical rhythm of the digestive tract?
Slow wave electrical activity
All slow waves trigger contraction. True/False?
Threshold must be reached first
What is the net direction of luminal contents in the small intestine? Why?
Fduodenum greater than Fileum
What is the net direction of luminal contents in the large intestine? Why?
Fdistalcolon greater than Fproximalcolon in order to allow some reabsorption to take place
What connects myenteric and submucosal plexi?
Interganglionic fibre tracts
What is the nervous system of the gut called?
Enteric nervous system