L40: Small Intestine Flashcards
What are the three components of the small intestine?
- Duodenum;
- Jejunum;
- Ileum.
What are the primary functions of the s. intestine?
Digestion and absorption
What structure supports the s. intestine in place?
Parietal peritoneum
What structure gives rise to the lubricating layer of the peritoneum?
Mesothelium (serous membrane) comprised of mesothelial cells
What is the mesentery?
A fold of membrane that attaches the intestine to the abdominal wall and holds it in place
What is the omentum?
A double fold of peritoneum connecting the stomach with other organs
Where are Brunner’s glands and what are their purpose?
In the duodenum, produce an alkaline secretion to neutralise the acid from stomach
Where is the sphincter of Oddi and what is its purpose?
Located in the duodenum (major duodenal papilla), controls the amount of bile and pancreatic juice secreted into the duodenum
What is CCK and what does it stimulate?
- A hormone, chole-cysto-kinin;
- Released by the duodenum in response to fat and protein;
- Stimulates contraction of the gall bladder;
- Relaxation of the sphincter of Oddi.
What supplies blood to the duodenum?
- Coeliac trunk;
- Superior mesenteric artery.
What drains blood from the duodenum?
Inferior vena cava
Where does the duodenum end?
Duodenojejunal junction
Where does digestion primarily occur in the s. intestine?
Duodenum
What digestive processes occur in the jejunum?
Digestion (and absorption)
What digestive processes occur in the ileum?
Absorption
How is the jejunum specialised to continue digestion?
Brush border enzymes
How is the s. intestine specialised to carry out its functions?
Microvilli across the entire surface area of the intestinal tract, finger-like projections which increase the surface area 5000x
What are Peyer’s patches?
- Found in the ileum;
- Collections of inflammatory tissue which monitor snd prevent unwanted bacterial activity of the gut.
What are enterocytes?
- Simple columnar epithelial cells;
- Microvilli (brush border)
- Brush border enzymes;
- Carrier proteins.
How is chyme moved along the gut?
- CILO;
- Circular: local breakdown of food through constriction;
- Outer: passes food along through shortening.
What is Meckel’s diverticulum?
- An out-pouching of the ileum;
- Rule of 2’s;
- 2% of pop., 2+, 2ft from valve.
What are intestinal crypts (of Leiberkuhn)?
Intestinal glands found along the epithelium lining (invaginations), secrete intestinal juice
