Enteric Nervous System Flashcards
What is the enteric nervous system?
3rd division of the ANS
Doesnt involve CNS to function (no brain required)
What does the ENS do?
Carries out intrinsic innervation of the walls of the GI tract
Where is the ENS functioning?
Walls of GIT from oesophagus to rectum
What is the myenteric plexus?
Runs for the full length of the GI tract
What is the submucosal plexus?
Runs in the stomach and intestines only
What types of neurone are involved in the ENS?
Sensory neurones - Mechano/chemoreceptors
Interneurones - Coordinate input and output
Efferent Neurones - innervate motor and secretory effectors (smooth muscle)
What are the excitatory and inhibitory neurotransmitters for motor effectors of the ENS?
Excitatory - ACh, 5-HT
Inhibitory - NO, VIPI, ATP
What are the excitatory and inhibitory neurotransmitters for secretory effectors of the ENS?
Excitatory - ACh or VIP (excitatory)
What is the function of the ENS?
Controls motility, secretion and blood flow in the GI tract Motor reflex (peristalsis)
What is the role of the myenteric plexus in motor reflex in the GIT?
Mucosal stimulation of food (bolus)
Distention
Causes excitatory Nts to act constricting smooth muscle behind bolus
Causes inhibitory Nts to relax smooth muscle in front of bolus
What is the role of the submucosal plexus In the secretory reflex of the GIT?
Food Sensory receptors (mechano/chemo) ENS (submucosal plexus) Secretory neurones Secretion (mucus, enzymes, acid)
What regulates blood flow in the GIT?
Myenteric plexus releasing vasoactive neurotransmitters
How does the ENS integrate with the CNS?
ENS <=> symp/p.symp NS <=> CNS
CNs influence varies along the GIT
Oesophagus - no control
Rectum - high control
What are some clinical diseases associated with the ENS?
Hirschprungs disease
Chagas disease
IBS
What is Hirschprungs disease?
Congenital absence of ENS neurones in the colon
Leading to peristaltic contractions being halted and therefore faecal build up
