Lower GI system Flashcards
Where does the small intestine start and finish?
Starts at the pyloric sphincter and ends at the ileo-ceacal valve
How long and wide is the small intestine?
5-9m long
2.5cm wide
List the 3 sections of the small intestine
- Duodenum
- Jejunum
- Ileum
What epithelium lines the small intestine?
Simple columnar epithelium
Where are the brunner’s glands found and what is their function?
They are found in the submucosa of the small intestine
secrete alkaline juices to neutralise the stomach acid in the chyme
What is the superficial layer of the small and large intestine?
Serosa
List 4 cell types found in the epithelium of the small intestine and what do they produce?
Absorptive cells - posess microvilli
Goblet cells - secrete mucus
Paneth cells - secrete lysosyme
Enteroendocrine cells - secrete hormones into the gut
What are the circular folds called in the small intestine?
Plicae circulares
Give 3 ways in which the small intestine is adapted to have a larger surface area?
Villi
Microvilli (brush border )
Plicae circulares
What is the length and width of the large intestine?
1.5m
6cm wide
Explain the structure of the large intestinal wall
It has 3 bands of smooth muscle called the Taenia coli that run around the colon forming Haustrations in the colon.
List the 8 sections of the large bowel:
1.Caecum
2.Ascending colon
3. Hepatic flexure
4. Transverse colon
5. Splenic flexure
6. Descending colon
7. Sigmoid colon
8. Rectum
How long is the colon?
15cm
What is the function of the large intestine?
- absorption of water and electrolytes
- produce and absorb vitamins
- forming and storage of faeces
- bacteria present to break down food
What is the function of the appendix?
It contains lymphatic tissue, plays a role in the immune system .
What is the peritoneum and list the two types?
A serous membrane that lines the abdominal cavity and separates the abdo organs from organs in the pelvis.
Visceral peritoneum - covers organs in the abdo
Parietal peritoneum - binds organs to the abdo wall so they remain in position.
Fluid between layers to allow slight movement in the abdo cavity.
Name 4 non-malignant bowel conditions:
- Diverticulitis
- IBS
- Haemorrhoids
- ulcerative/ischaemic colitis
What is the 10 yr survival for colorectal cancer?
53%
Give 5 causes/risk factors of colorectal cancer
- Old age
- Diet (too much red/processed meat, not enough fibre)
- Family history
- Polyps
- Bowel conditions
What is the most common histology for colorectal cancer?
Adenocarcinoma
Where does colorectal cancer most commonly metastasise to?
Lungs,
Liver,
Brain
Name the nodes that commonly drain fluid from the colorectal region
Epicolic,paracolic nodes
List 5 signs and symptoms of colorectal cancer:
- Abnormal bowel motions (diarrhoea, loose stools, constipation)
- rectal bleeding, blood in stools
- Pain in the abdomen
- lump in the abdominal region
- Bowel obstruction
Give 3 ways in which colorectal cancer may be diagnosed
- Digital rectum examination
- Feacal immunochemical test
- Colonoscopy
- CT colonography
What is the name of the procedure where the bowel opening is at the surface of the abdominal wall?
Colostomy
Stoma - is the opening at the abdominal wall
How is colon cancer normally treated?
Surgery is primary treatment followed by chemotherapy
Chemotherapy can be given before.
Radiotherapy is never used unless treating palliative.
How is rectum cancer normally treated
Surgery and radiotherapy (with or without chemo)
Radiotherapy is either given before or after (more common to be given before surgery)
List 3 chemotherapy drugs used to treat colorectal cancer
5FU, capecitabine, cetuximab
What is the name of the surgical procedure for colon cancer and rectum cancer?
Colon -
small - local resection (of the colon lining)
large - Colectomy - removal of all or part of colon
Rectum-
small - Total mesorectal excision (TME)
large - Transanal endoscopic microsurgery (TEM)
What is the pre op long course, pre op short course and post op course of radiotherapy for rectum cancer?
Pre op short - 25Gy in 5#
Pre-op long 45-50 in 25-28#
Post op with chemo - 45-54Gyin 20-30#
