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Introduction 
Any activity in our life is under control of one of the main control systems: 
1- Endocrine system: This controls the slow action by hormones.II. The parasympathetic nervous system:  
o This arises from the 2nd, 3rd and 4th sacral segments of the 
spinal cord as well as from the nuclei of some cranial nerves 
III, VII, IX and X cranial nerves (Cranio-sacral outflow).The regulation of blood pressure, gastrointestinal responses to food, 
contraction of the urinary bladder, focusing of the eyes, and 
thermoregulation are just a few of the many homeostatic functions 
regulated by the ANS. 31 segments (8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 
coccegeal).o Divided into:  3 cervical, 12 thoracic, 4 lumber, 4 = sacral.- Inferior mesentric ganglion.????