Small Intestine Structure and Function Flashcards
What is the function of the duodenum?
Gastric Acid Neutralisation, Iron Absorption and Digestion
What is the function of the jejunum?
Nutrient absorption
What is the function of the ileum?
NaCl/H2O Absorption –> Chyme dehydration
Describe the basic electrical rhythm
Is initiated by depol generated by pacemaker cells in the longitudinal muscle layer. The intestinal BER produces oscillations in membrane potential which will eventually reach threshold, generate an AP which will initiate contraction
What determines the strength of contraction?
The frequency of the action potential
What determines the frequency of segmentation?
BER
What happens to BER as we move from intestine to rectum?
BER decreases
Describe segmentation
Contraction and relaxation of short intestinal segments. Contraction moves chyme into areas of relaxation. Relaxed areas contract and push chyme back.
What is the function of segmentation?
This process mixes chyme with digestive enzymes and brings chyme into contact with the absorbing surface
When does segmentation occur?
During a meal
When does peristalsis occur?
After segmentation
Where does peristalsis begin and end?
Antrum of stomach to terminal ileum
What initiates an MMC?
Motilin
What is the effect of vagus stimulation on contraction?
Contraction increases
What is the effect of sympathetic stimulation on contraction?
Contraction decreases