Gastro-Intestinal 1 Flashcards
What is mastication?
Chewing
Briefly describe the course of digestion of food.
Mouth- amylase and lipase allow mastication and swallowing.
Swallowing creates a bolus which passes through the larynx and oesophagus into the stomach.
Enzymes and acid in the stomach chemically and physically disrupt the bolus to form a chyme.
The chyme leaves the stomach into the duodenum. Here it is neutralised and further digested thanks to secretions from the liver and pancreas that enter the duodenum.
Absorption occurs in the more proximal small intestine.
The large intestine reabsorbs water and remaining electrolytes and forms faecal matter.
Faeces remain in the colon and are propelled to the rectum periodically for expulsion.
How can swallowing be compromised?
What is a consequence of this?
By anaesthesia and neurological deficits.
Can lead to aspiration of food into the lungs.
Define dysphagia.
Difficulty swallowing.
How does the stomach protect itself against its acid? (2)
- producing mucus
- producing hydrogen carbonate
What can cause acid reflux to occur?
Weakening of the gastro-oesophageal sphincter.
Describe Barrett’s oesophagus.
It is a metaplasia of the stratified squamous lining of the oesophagus to simple columnar epithelia (like that of the stomach). This is due to acid reflux of the stomachs contents into the oesophagus; usually because the gastro-oesophageal sphincter is weak.
What does the liver produce and transport to the duodenum? How?
It produces bile, which is transported to the gallbladder to be stored, before travelling along the bile duct to the duodenum.
What is the role of bile in digestion?
Fat digestion
What are gallstones? What are the consequences of gallstones?
Gallstones are precipitations of bile acids and cholesterol in the gallbladder.
They can block the bile duct, causing a back up of bile into the liver and consequent liver damage and jaundice (as bilirubin also builds up)
Where is the appendix located? Describe the change in pain location in appendicitis.
The appendix is located in the lower right quadrant of the abdomen.
In appendicitis, pain is initially felt centrally over the abdomen and later becomes localised to the LRQ. This is because there is no proper somatic innervation to the gut, so it is initially felt generally. Localisation occurs because the peritoneum does have somatic innervation.
Describe our total intake of food/fluid into the gut.
Total= 14L. We ingest 1kg, Mouth- 1.5L of saliva Stomach- 2.5L of gastric secretions Small intestines- 9L of water/alkali
Describe the expulsion figures from the gut.
Small intestine- absorbs 12.5L
Large intestine- absorbs 1.35L
Faeces- 0.15kg
What are the two intrinsic nerve plexuses of the gut and where are they located?
The myenteric nerve plexus- between muscle layers of the gut wall
The submucosal nerve plexus- beneath the submucosa
What are the four layers of the gut wall Histologically?
Mucosa- epithelia, lamina propria, muscularis mucosa,
Submucosa
Muscularis externa- circular and longitudinal smooth muscle
Serosa- connective tissue and epithelia.
