Small Intestine Function Flashcards
Total length of small intestine =
~6 metres (range 4.5 - 9 metres)
Duodenum - length & what occurs in it?
25cm long
- gastric acid neutralisation
- digestion
- iron absorption
Jejunum length - length & what occurs in it?
- 5m long
- nutrient absorption
Ileum length - length & what occurs in it?
- 5m long
- NaCl/H2O absorption => chyme dehydration
What does the intestine have to increase surface area?
Fold, villi, microvilli
Cells change every how many days?
3-5 days, rapidly dividing
What do crypt cells do?
secrete Cl & water
What do villi cells absorb?
NaCl monosaccharides amino acids peptides fats vitamins minerals water
Small intestine secretes how many ml of H2O per day?
1500ml
H2O secretion comes from
epithelial cells lining crypts of Lieberkuhn
H2O secretion is important for normal digestive process as it:
- Maintains lumenal contents in liquid state
- Promotes mixing of nutrients with digestive enzymes
- Aids nutrient presentation to absorbing surface
- Dilutes & washes away injurious substances
2 distinct types of movement in intestinal motility:
- Segmentation
2. Peristalsis
Describe segmentation:
- Happens during meal
- Contraction & relaxation of muscle to move content side to side and mix together
- Helps mix & bring chyme with absorbing surface
Generation of segmentation:
- Pacemakers in longitudinal muscle layer
- Intestinal basic electrical rhythm (BER)
- More AP stronger contraction
BER reduces slightly from intestine to rectum (to move things down slowly) - Parasympathetic increases contraction and sympathetic reduces it (cant be controlled voluntarily)
What is Migrating motility complex (MMC)?
Pattern of peristaltic activity travelling down small intestine (starts in gastric antrum)
