GEP (Life Maintenance) Week 3 Flashcards
What are the content of the foregut, midgut and hindgut
**Foregut: **oesophagus, stomach, proximal duodenum, liver, gallbladder, pancreas, spleen
Midgut: ilium, jejenum, caecum, 2/3 of transverse colon
**Hindgut: **1/3 of transverse colon, descending colon, sigmoid colon, rectum and anus
What are the boundries and Blood supply of the Foregut, Midgut and Hindgut
What is the small intestines: how is it broken down
- Duodenum -> Jejenum -> ileum
- Jejenum begins at duojejenal flexure
- No clear boundary between jejenum and ileum
- Ileum ends at ileoceacal valve.
- Neurovasculature runs inthe mesentery
- Large surface area – plicae circulares + villi + microvilli for absorption of nutrients
What is the histology of the small intestines
**Histology: **simple columnar epithelium with villi and microvilli. Contains Goblet cells, Paneth (neuroendocrine) cells, Brunner’s glands (duodenum only).
-Brunner’s glands – secrete alkaline fluid to neutralise stomach acid.
-Peyer’s patches – clusters of lymphatic tissue (GALT). For immune surveillance
Paneth cells reside at the bottom of the crypts, intermingled with the stem cells. The intestinal epithelium absorbs nutrients yet serves as a natural barrier to constrain the complex bacterial flora within the lumen (12). Peyer’s patches (PPs) are secondary immune organs located in the mucosa of the gut (21).
What are the main differences between Jejunum and Ileum in the small intestines
What is the the large intestines: how is it broken down
- Ileocaecal junction to anus
- Absorbs water and salt
- Contains the microbiome
- Features: haustra,taeniae coli
- Appendix: McBurney’s point – lateral 1/3 of line from ASIS to umbilicus
- Sigmoid colon: most common place for diverticulosis
What is the histology of the large intestines
Histology
* Colon and rectum: columnar epithelium
* Above pectinate line: columnar epithelium
* Below pectinate line: stratified squamous epithelium
What is the blood supply for the large intestines
What is the anatomy of the rectum and Anus
what is the histology of the rectum and anus
Histology
Above pectinate line: columnar epithelium
Below pectinate line: stratified squamous epithelium
What is the blood supply to the rectum and anus
What is the blood supply, innervation and nodes present above and below the pectinate line
What is the peritoneum
- The peritoneum is the continous membrane that lines the abdominal cavity, covering the organs.
- Contains blood vessels and lymphatics
- There are 2 layers and inbetween the 2 layers is the peritoneal cavity with small amount of fluid.
-Parietal
-Visceral
Describe further what the 2 laters of the peritoneum are
**Parietal: **lines the internal surface of the abdominopelvic wall. Inflammation -> well localised
**Visceral: **covers the surface of organs. Inflammation -> poorly localised pain following dermatomal pattern
What are the specific names of the folds of the peritoneum and what are thier roles
- They are known as the mesentery and omenta.
-
Omenta: visceral peritoneum that extend from the stomach/proximal part of the duodenum to other organs
* The mesentery: double fold of peritoneum that connects anintraperitoneal organ to the abdominal wall, carryingneurovasculature
‘The mesentery’ = mesentery of the small intestine
Others: Egtransverse mesocolon,sigmoid mesocolon*
Intraperitoneal: Within the peritoneal cavity (the area that contains the abdominal organs).
What are the 2 main omentums and thier attachments
**Lesser omentum: **lesser curvature of stomach and D1 -> liver
**Greater omentum: **greater curvature of stomach and D1 -> anterior surface of transverse colon
What does retroperitoneal mean and the organs in it
Retroperitoneal is the area in the back of the abdomen behind the peritoneum
The best way to remember this is via the mnemonic SAD PUCKER
Secondary Retroperitoneal are: pancreases except the tail, Asc and Desc colon and finally 2nd and 3rd part of duodenum.
How are Carbohydrates absorbed by the body
- Carbohydrates: breaking down starch into disaccheridesvia amylases. Brush border enzymes then break down these disaccherides into monosaccherides (glucose, fructose etc). These monosaccherides are then moved across the membrane into the enterocytes in different ways, depensdng on what they are.
- Salivary and pancreatic amylase break down starch into disaccharides in the mouth and small intestine respectively
- Glucose and galactose absorbed via SGLT1 (secondary active transport) with Na+
- Fructose absorbed via GLUT5 (facilitated diffusion)
The brush border domain at the apex of intestinal epithelial cells is the primary site of nutrient absorption in the intestinal tract and the primary surface of interaction with microbes that reside in the lumen.
How are proteins broken down by the body
- Pepsin in stomach followed by brush border enzymes/pancreatic enzymes in the small intestine
- Amino acids absorbed via a Na+ cotransporter and then transported across the basolateral membrane via facilitated diffusion
- Di-and tripeptides are absorbed via H+ cotransporters, inside cells they are hydrolysed to amino acids.
The brush border domain at the apex of intestinal epithelial cells is the primary site of nutrient absorption in the intestinal tract and the primary surface of interaction with microbes that reside in the lumen.
How are fats absorbed by the body
- 10% via gastric/lingual lipases
- Bile helps emulsify fat into small micelles
- Absorbed in the jejunum with fat soluble vitamins (ADEK) via lacteals
What are the signs and symptoms of Malabsorption
Signs and symptoms:
* Chronic diarrhoea
* Steatorrhoea – increased fat excretion in the stool. Pale, oily, floating.
* Weight loss
* Anaemia
-Howell-Jolly bodies on blood film – nuclear remnants in reticulocytes, which have been released early to compensate for an anaemia
* Flatulence
* Abdominal pain
* Vitamin and mineral deficiencies + associated abnormalities on bloods
What are the reasons for malabsorbtion
What are the definition, cause and investigations of acute and chronic diarrhoea
What is the management of Diarrhoea
What is the management of IBS
- Faecal calprotectin to test for IBD vs IBS
- Diet advice – figuring out if anything triggers it or if there are other underlying intolerances e.g. dairy/gluten
- Lifestyle = stress reduction, avoiding triggers, exercise
What is the pathophysiology of Coeliac disease
Coeliac disease is mediated by a Type IV hypersensitivity reaction.
1) Deaminated gliadin bind to antigen presenting cells (APCs). More specifically to the HLADQ2/HLADQ8 molecules on APCs.
2) Gliadin is then presented to CD4+ T cells which triggers inflammatory cytokine release.
3) This also leads to B cells releasing antibodies (anti-TTG and anti-endomysial) which recruits CD8+ T cells and they damage the enterocytes in the small intestine.
Diagnosing Coeliac Disease
What are the different presentations of coeliac disease between Adults and Children
What are the anatomical locations of where Crohns and Ulcerative colitis affects
Crohns can affect from mouth to rectum, but mostly occurs in the ileum and colon. Characterised by skip lesions with transmural inflammation. The rectum is often spared.
UC starts in the rectum and moves up the colon withouth interruption with diffuse inflammation of ther mucosa and does not affect the small intestines
What are the differences macroscopic features for both Crohns and Ulcerative colitis (UC)
What are the differences microscopic features for both Crohns and Ulcerative colitis (UC)
What are the difference in management of UC and crohns disease.
