Regulation of gut Flashcards
What is the enteric nervous system
Neurons found in the walls of the GI tract-around 100million. Arranged in plexuses of ganglia and connected by unmyelinated fibres
Can function idenpendently-and works to integrate the motor and sensory activity
What kind of neurons connects the ENS ganglia?
Unmyelinated neurons-non of ENS is
What are the main causes of ENS dysfunction?
Inflammation (chrons), Post operative injury, IBS, ageing (constip)
What does the ENS regulate?
Motility, blood flow, water intake, MORE
What types of neurons are found in the ENS?
Sensory-mechanical, thermal, osmotic, chemical. Motor-terminate at SMC. Interneurons-neurons between neurons that integrate outputs and outputs
Where are the main plexuses found in GI?
Myenteric plexus-sandwiched between circular and longitudinal muscle layers-control movements
Submucosal plexus-in Submucosa-senseing environement in lumen, regulate blood flow, endocrine
Minor plexuses-number of different ones
What is the intrinsic nervous system and extrinsic nervous system?
Intrinsic is ENS, extrinsic is ANS
SNS-Where do thoraxic splanchic nerves and Lumbar splanchic nerves innervate?
SNS-short pre-gagnlionic, then connect in thoracic thrunkThoracic carries to fore and midgut, lumbar to hindgut/rest In emergencies (fight/flight)-gut is trying to be shut down Main neurotransmitter is noradrenaline
PSNS-what is the main nerve to the GI tract
Vagus-uses acetyl choline-activates GI tract (rest and digest)
How does the ANS and PSNS connect to the ENS?
PSNS uses vagus nerve to talk to ENS. SNS talks also (through SNS ganglia) to ENS, but also has a direct impact on blood vessels-CNS overrides the ENS
The outputs usually come out from ENS
Inputs go back (local afferents) to ENS/GI plexuses, or directly to the CNS
What are the types of extrinsic innervation of the GI?
Efferent (cooredination of SNS/PSNS and afferent (pain, nausea, etc)
Where can endocrine system of the GI be found?
It’s a diffuse endocrine system-not a large collection, but has some dotted around (around 1%)-are in mucosa and submucosa of stomach, intestine and pancreas. Can be paracrine, endocrine or neurocrine (go through blood, OR as neuron)
Remember-different subtypes of cell will produce different hormones
What are the endocrine cells of the GI?
APUD cells-columnar-in the crypts of lebraukans-flask shape (finger in cytoplasm-with receptors sensing whats in the gut)-chemosensitive. Larger bottom over capillary ready to release hormones
Eg: I, K and L cells
What are some functions of endocrine system?
Control of post absorbative processes (like glucose regulation), control of long term processes like development (GLP2 changes gut size)
What are exemples of paracrine GI activities?
Histamine released from stomach to increase HCL release. Or somatotrophin to inhbit some
What are the hormones found in the stomach?
Gastrin, Ghrelin, Somatostatin, histamine
Gastrin regulated by mechanoreceptor, things in stomach and vagus
