Physiology Flashcards
What are the layers in the stomach
Mucosa (Epithelium, Lamina propria, Muscularis mucosae)
Submucosa (blood vessels and submucosal nerve plexus)
Muscularis externa (Circular and longitudinal muscle and myenteric nerve plexus)
Serosa
Where are the two places nervous system sits in the gut?
1) Submucosal plexus
2) Myenteric plexus
**They control whole gut contractions and are highly vascular
Function of each of the regions in the GIT
1) Salivary glands- chop up food
2) Stomach- acid steriliser, reservoir- digestion, mixing and metering
3) Pancreas- supplies enzymes (for carbs) and bicarbonates
4) Liver- supplies detergent (for fats)- digestion and excretion
5) Duodenum- Equilibration, digestion and absorption
Jejunum- Digestion, mixing and absorption
6) Colon- dessicator, pelletor and residue combustor
Then, emission control device
How does motility of GIT change with function?
1) Propulsive to deliver
2) Stationary to mix
3) Spinchter constriction and relaxation to compartmentalise
Absorption
Movement of nutrient across apical and basal membranes of the enterocyte to blood and lymph
Mechanical digestion
Gentle wave like motion, peristaltic waves to create CHIME
Phasic pace-maker
Displays continual slow intrinsic electrical activity- Basal electrical rhythm (BER)
Migrating motor complexes
These start at the stomach and occur in non-fed state to produce propulsive motility to squeeze everything through
After absorption, MMC migrates to the small intestine and towards large intestine.
Regulation of peristalsis
Myenteric nerve plexus –> cholinergic motor neuron –> retrograde signal to circular muscle CONTRACT and anterograde signal to circular muscle RELAX
Ileocaecal valve
Restricts reflux bug movement
Opens with increased pressure of ileum
Closes with increased pressure of colon
Metering in GIT- valves
Upper oesophageal Lower oesophageal Pyloric Ileocaecal Anal
Enteric nervous system
Myenteric plexus- mechanical digestion
Submucosal plexus- chemical digestion
