Gut Feelings- Signalling

Question 1

Enteric neurones function

Answer 1

▪️control motility
▪️secretion
▪️blood flow
▪️mucosal growth

Question 2

Gut derived pain

Answer 2

▪️nociception:
-hyperalgesia-increased response to painful stimulus eg, banging leg on table and feeling a sharp pain
-allodynia-painful response to a normally innocuous stimulus eg, rubbing a bruise and feeling pain
▪️acid-peptic related:
-heartburn- reflux of acid into oesophagus
-peptic ulcer-in GIT
▪️distension:
-mechanoreceptors respond to stretch above threshold
▪️inflammatory bowel disease:
-Crohns, ulcerative colitis- sensitises neurones in SI
▪️irritable bowel syndrome:
-feelings of distension, bloating, swelling- constipation or diarrhoea in both LI and SI

Question 3

Meal/hunger cycle

Answer 3

▪️hunger
▪️meal
▪️satiation-promotes termination of eating
-controls amount of food in one sitting
▪️satiety-fullness that persists after eating
-controls length of time between meals
▪️snack

Question 4

Enteroendocrine cells (EECs)

Answer 4

▪️ 12 different types within SI eg I-cells for CCK
▪️respond to different nutrients fed into the stomach
▪️nutrients act as ligands in cells eg, fibre is broken down by microbiome into short chain fatty acids
▪️SCFA then lead to release of gut hormones which act on vagal afferent receptors to increase satiation

Question 5

Gut hormones for increase in satiation

Answer 5

▪️peptide YY
▪️pancreatic polypeptide 
▪️glucagon-like peptide 
▪️ghrelin 
▪️CCK

Question 6

Role of CCK in GIT

Answer 6

▪️regulates SI digestion
▪️as fat and proteins enter SI CCK is produced which:
-stimulates pancreatic enzyme secretion
-stimulates gallbladder contraction
-reduces food intake and gastric emptying via vagus nerve
▪️during obesity, vagal afferent nerves are insensitive to CCK therefore brain does not reduce food intake or gastric emptying

Question 7

Role of GLP-1 in GIT

Answer 7

▪️regulator of nutrient utilisation
▪️as glucose, fat and protein enter SI GLP-1 is released which:
-stimulates insulin section from pancreas
-inhibits food intake and gastric emptying via vagal afferent neurones

Question 8

Role of ghrelin in GIT

Answer 8

▪️stimulator of nutrient intake
▪️secretion highest in blood immediately before a meal from body of stomach
-stimulates food intake and gastric emptying
-works on vagal afferent neurons and hypothalamus
-inhibits CCK on VAN