Enteric nervous system Flashcards
What does the enteric nervous system supply
intrinsic nerve supply of the gut from the oesophigas to the anal canal
What does the enteric nervous system supply
- Peristalsis in outer ring
- Glandular secretion in inner ring
What are the two networks of interconnected ganglia along most of the length of the gut
MP= controls peristalsis - outer ring
Submucosal plexus = glandular secretion - inner ring
What is hirshprung’s disease causes
- Bursting of the large intestine (colon)
- absence of enteric neurons in the rectum ( extend throughout the colon)
- absence of myenteric and submucosal plexus
- leads to swollen colon and shrunken rectum
- lack of ganglionic cells in the bowel- do relaxation of bowel- stops it from passing stool
What is the symptopms of Hirshsprung disease
- vomitting
- chronic constipation
- swollen tummy
- weight gain
- slow growth in first 5 years
- poor feeding
- explosive or difficult bowel movements
What are the roles of extrinsic regulation
- preparation of food
- evacuation of faeces
- up or down regulating gut function for metabolic demands
What are some excitatory and inhibitory neurotransmitters in the gut
Excitatory - acH, Substance P, serotonin
Inhibitory- NO, VIP, ATP
Ascending excitatory reflec
Descending inhibitory reflex
Descending exciatory reflex what happens?
PERISTALSIS
AER - detect the stretch with Ach on NIc receptors it will send signals to oral end sending contractions in the oral end
DIR - At the same time DIR= send electrical signals to anal end to trigger relaxation inhibitory neurotransmitters
DEF - Also have to have DEF to activate the signals to progress to the anal end just like sliding your hands up the toothpaste
What is gastric acid secretion
- input from the para (vagus) and symp NS excitatory and trigger pariental cell to secrete stomach acid
- hormonal and neuronal systems regulating acid secretion within gut wall
- histamines are important to regulate acid secretion
- acid secretion stimilates within pyloric gland- signal back to parietal to regulate acid
- proteglandins decrease acid secretion
What drugs decrease acid production
- protein pump inhibitor (targets parietal cell ) = OMEPRAZOLE
- Histamine H2 receptor antagonists = RANITIDINE
- Prostaglandin analogue (mimics prostalandins)= MISOPROSTAL
What technique has fallen out of use because of the success of acid secretion drugs
- : highly selective vagotomy (functions of vagus nerve that control stomach acid)
- muscarinic antagonists which will stop the secretion of Ach to activate the parittal (in stomach) cell for acid secretion
Which part of the body do most vomiting drugs work on
- work on the brain instead of the gut
- Anti- emetics are centrally acting for example H1 receptor antagonist (cyclizine)
What drug has been used to increase gut activity but is not used anymore
- 5HT4 receptor antagonist= CISAPRIDE
- increases ACh release and was used to treat gastro-oesophegeal reflux
- assosiated with serious cardiovascular side effects
What are antimuscarinic drug receptors and what does it do to gut activity
- decreases excitatory action of Ach so slows down gut activity
- HYOSCINE, ATROPINE
How do opiate agonists acting on enkephalin decrease gut activity
- agonists act on brain and reduce release of ACh - reduce motility by inactivation of enkephalin which is a neurotransmitter (endogenous opioid receptor activation)
- mostly opiate receptor in gut
