Small Intestine Flashcards
What are the functions of the duodenum
Gastric acid neutralisation, digestion, iron absorption
Function of jejunum
95% nutrient absorption
Ileum function?
NaCl/H2O absorption = Chyme dehydration
What do crypt cells secrete
Cl and H20
How do substances leave lumen to blood
through Na+-coupled secondary active transport
How is h2o secreted into lumen
Passively following active transport of cl into lumen
What does water do in digestion
- Maintains lumenal contents in liquid states
- Promotes mixing of nutrients with digestive enzymes
- Aids nutrient presentation to absorbing surface
- Dilutes and washes away potential injurious substances
Review slide 9**
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two types of intestinal movement :
Peristalsis and segmentation
What happens during meal
segmentation
how does segmentation happen
initiated by depolarisation by pacemaker cells in longitudinal muscle layer) =>
Intestinal basic electrical rhythm produces oscillations in membrane potential => AP induced => contarction
What determines strength and frequency of contraction
Strength : Frequency of AP
Frequency of segmentation : Determined by BER
What is the migrating motility complex
Pattern of peristaltic activity travelling down small intestine (starts in gastric antrum)
MMC acts to:
- Move undigested material into small intestine
2. Limit bacterial colonisation of small intestine
What hormone involved in initiation of mmc
Motilin
