Enteric Nervous System Flashcards
What is the ENS
3rd division of ANS
Intrinsic innervation of GIT
Degree of independence from brain
Where is the ENS and what does it do
Submucosal plexus (nearer lumen) - stomach and intestine only = Secretory reflex Myenteric Plexus (in between muscle) - full length of GIT = motor reflex Plexuses extensively connected
What sensory neurones are involved in ENS
Mechanoreceptors
Chemoreceptors
What is the role of the interneurones
Coordinate input and output
Excitatory = ACh
Inhibitory = many
What are the different types of efferent neurones
Motor effectors
Sensory Effectors
What is special about the motor effectors
Excitatory = ACh Inhibitory = NO, VIP, ATP
What is the excitatory molecule for secretory efferents
ACh or VIP
What plexus is responsible for blood flow
Myenteric and Submucosal plexus produce vasoactive neurotransmitters
How does ENS interact with CNS
Long reflex = ENS ride on SNS/PNS fibres to CNS
How does CNS influence GIT
Can shut down ENS
CNS influence varies along GIT (Suppress distension of anus to prevent defaecation)
What occurs in peristalsis
Bolus of food (distension) - mucosal stimulation
Myenteric plexus = + = contract smooth muscle behind bolus
Myenteric plexus = - = relax smooth muscle in front of bolus
What is IBS
Irritable Bowel Syndrome
Dysfuntional interaction between CNS and ENS
What is Chagas disease
Typanosome parasite lives in gut, releases toxin to paralyse ENS (neurone death)
