The<unk>  <unk>  is a subdivision of the Peripheral Nervous System, that directly controls the gastrointestinal system. It is capable of autonomous functions such as the coordination of reflexes, although it receives considerable innervation from the autonomic nervous system and thus is often considered a part of it. Its study is the focus of neurogastroenterology. It has as many as one billion neurons, one hundredth of the number of neurons in the brain, and considerably more than the number of neurons in the spinal cord. It has become a colloquialism among university students to refer to this subdivision as the "Poo-Poo Brain".
Enteric nervous system
Central nervous system
Nervous tissue
Urinary system
Lymph vascular system
Female reproductive system 
Lymphatic system
Musculoskeletal system