Page 258 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Structure of the small intestine (schematic)
10 13 14 15
7 Mucus
8, 9
12

1
2
3
4 11 Kerckring’s fold
5
6 8 9 Epithelial cells
11 Small Intestinal Function

16 12 Intestinal villus
Small intestine
B. Peristaltic reflex
Contracted
Stretch sensor Longitudinal Plate 10.10
(stimulated by muscles
previous passage Myenteric
of bolus) Relaxed plexus
Circular
muscles
Relaxed
Bolus Lumen

Neuron Transmitter
Sensory (+) ?
Movement Interneuron (+) Serotonin
Disinhibition Interneuron (–) ? ACh (After J.D.Wood)
Contracted Interneuron (+) ACh
Motor, type 2 (+)
Motor (–) VIP
C. Slow waves and spikes D. Pacemaker rate
Continuous
Spike discharge Non- Maximal rate of the respective
pacemaker situated
0 bursts excitable towards the anus
–10
Membrane potential (mV) –30 2 3 Non-excitable, Rate of slow potential waves Pacemaker
–20
1
Threshold
–40
potential
zones
–50
–60
–70 1 Slow waves atonia Intrinsic rate 2 3 (After Dimant & Borthoff)
0 6 12 18 24 30 36 42 48 54 Proximal Distal 245
Time (s) (After Guyton) Distance in small intestine
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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