GI 1. Flashcards
(31 cards)
What is the main functions of the GI system
- ingestion
- mechanical processing
- digestion
- secretion
- Absorbtion
- excretion
What is Absorbtion
The movement of organic substrates, electrolytes, vitamins and water across the epithelium to the interstitial fluid of the digestive tract
What is excretion
Removal of indigestible material and waste via body fluids
What are the accessory digestive organs
- parotid salivary gland
- teeth
- tongue
- sublingual/submandibular salivary gland
- liver
- gallbladder
- pancreas
What part of the digestive process has a conscious decision part
Ingestion
What makes the fluid less acidic for the duodenum from the stomach
Bile,
it also emulsifies parts of the bolus - from the liver
What does the pancreas empty into the duodenum
Lipases
to break down fats
What is the peritoneum
Lining of the abdominal cavity - the parietal peritoneum
Covers the organs - visceral peritoneum
They form mesentries, where the perituneum becomes double layered (which suspend, support, secretes peritoneal fluid - lubrication, keep them from tangling)
Mesentries also carry blood vessels and nerves and lymphatics
What is the embryological tube of the Gi tract divided into
Foregut -> stomach/liver/spleen
Midgut -> duodenum/small intestinal loop/ part of transverse colon
Hindgut -> last bit of transverse colon to anus
Where do all the blood vessels of the gut stem from?
The abdominal aorta - 3 main arteries - coeliac trunk, superior mesentries artery, inferior mesenteric artery
What happens with venous drainage from the gut
- portal venous system (drains into hepatic portal vein)
- goes to liver first
- blood containing metabolants is metabolised at liver
- blood drains into vena cava
artery supplying the Foregut
where does this branch from the AORTA
Coeliac artery T12
what does the Superior mesenteric artery
where does this branch from the AORTA
Feeds the midgut
L1
What does the hind gut get fed by? Artery wise? where does this branch from the AORTA
Inferior mesenteric artery
L3
What is the histological organisation of the digestive tract
Innermost to outermost:
- mucosa (epithelium, lamina propria, muscularis mucosae)
- submucosa
- muscularis externa (circular then longitudinal)
- serosa (areolar connective tissue, epithelium = part of the peritoneum)
What does the serosa contain
Connective tissue and epithelium
Where are the microvilli
Small intestine
What is a hemidesmosome
Anchors cell to basement membrane
Where would you find tight junctions in the digestive tract
Stomach to stop acid leaking between the cells:
Otherswise inflammation and peptic ulcers
What do desmosomes do?
Hold epithelial cells next to one another adjacently
What do tight junctions do
Prevent movement of solutes between epithelial cells next- only goes to intestinal apical mucosal membrane
What is net flux -
What is net flux - how much were excreting and absorbing
Absorb active flux - Secretory flux
What are the two types of secretion and Absorbtion?
Trancellular
Paracellular (if no tight junctions)
