Lecture 36-37- Regulation of GI Function Flashcards
What is the name of the section of the hypothalamus that is the main location for energy control?
Arcuate nucleus
What are the two types of neurons within the arcuate nucleus and their function
Orexigenic neurons- induce appetite
Anorexigenic neurons- reduce appetite
What stimulates the stomach to send negative feedback to food intake?
Volume (mechanoreceptors)
What hormone is released from the stomach to increase appetite?
Ghrelin
When are ghrelin levels highest?
Before a meal
What medication is a ghrelin agonist?
Entyce
Where is Cholecystokinin (CCK) released and what does it do?
Released by the epithelial cells of the small intestine
Short-lived induction of satiety to stop eating the current meal
Where is Peptide YY released and what does it do?
Released throughout the intestinal tract, especially distally
Continues satiety several hours after a meal
Where is insulin releaased and what does it do?
Released by the pancreas
Supresses appetite while nutrient levels are high
Where is leptin released and what does it do?
Released by adipose tissue
Decreases hunger and increases metabolism
Can make it difficult to lose weight
What parasympathetic neurons control salivation?
Glossopharyngeal to parotid
Facial to submaxillary and sublingual
What is the difference between the saliva of ruminants and nonruminants
Nonruminant saliva has a neutral pH
Ruminants have basic saliva pH to prevent rumen acidosis
Is swallowing voluntary or involuntary
Both
What are the two phases of swallowing
Oropharyngeal- voluntary
Esophageal- involuntary
What is intrinsic nervous system control of the GI tract?
The enteric nervous system
Two main enteric nervous system plexuses name and function
Submucosal plexus- near lumen, controls local blood flow
Myenteric plexus- superficial, controls musscle activity
Branches that allow enteric neurons to affect multiple target cells at once
Varicosities
What do these enteric epithelial cells do
Enterocytes
Goblet cells
Paneth cells
Enteroendocrine cells
Enterocytes- absorb nutrients
Goblet cells- secrete mucous
Paneth cells- secrete antimicrobials
Enteroendocrine cells- secrete hormones
What type of cells secrete Secretin
S cells
What is the function of secretin?
Regulate pH in the duodenum and promote bile secretion
What is the function of Gastrin and what produces it
Produced by G cells in the pylorus duodenum and pancreas
Increases motility and HCl production
What produces CCK and what does it do
Produced by epithelial cells in the small intestine and neuronal cells
Increases satiety by slowing digestion triggered by fatty acids/aminoacids
What produces Glucose-dependent insulinotropic peptide and what does it do?
Stimulated by glucose in the duodenum
Stimulates insulin secretion
What produces motilin and what does it do
Secreted between meals to stimulate fundus contraction/emptying
Stimulated migrating motor complex
What neurons are primarily responsible for detecting pathology in the GIsystem
Splanchnic nerves
What extrinsic hormone affects the GI system and what does it do
Aldosterone stimulate water and sodium reabsorption from the gut
