L33 and L34: Intro to GI, Esophagus, and Swallowing Flashcards
What are the 6 processes of the GI tract?
Ingestion Propulsion Mechanical digestion Chemical digestion Absorption Defecation
Name the layers of the GI tract (outermost to inner most)
Serosa Longitudinal muscle Myenteric plexus Circular muscle Submucosa Submucosal plexus Mucosa
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Name the 3 layers of the Mucosa (out to in)
Muscularis mucosae
Lamina Propria
Epithelium
What is the benefit for parallel blood flow of splanchnic circulation?
Allows for regulation of flow to individual organs
What is the benefit for series blood flow of splanchnic circulation?
Liver is exposed to all absorbed substances.
What comprises the enteric nervous system? How does this interact with the autonomic nervous system?
Enteric NS = Myenteric plexus + Submucosal plexus
Afferent modulates the ENS, but ENS does NOT require ANS input to carry out most functions (send afferents to eachother)
What does the myenteric plexus innervate? What does it control?
Innervates longitudinal and circular smooth muscle layers
-Control of GUT MOVEMENT
What does the submucosal plexus innervate?
Innervates glandular epithelium, endocrine cells, and submucosal blood vessels
-Control of INTESTINAL SECRETION
The effect of the SNS on the GI organs is _____.
Inhibitory (NE)
The effect of the PNS on the GI organs is _____.
Excitatory (Ach)
Preganglionic projects directly onto gut
GI endocrine cells are not concentrated into ____. They are ____ in the GI tract.
glands
dispersed
Name the site of secretion and stimuli for secretion of Gastrin.
Site of secretion: G cells of stomach
Stimuli for secretion: Small peptides, AA, distention of stomach, Vagal stimulation (GRP- Gastrin releasing peptide)
What is the action of Gastrin? (2)
- Increased H+ secretion
- Stimulates growth of gastric mucosa
Name the site of secretion and stimuli for secretion of Cholecystokinin (CCK).
Site of secretion: I cells of duodenum and jejunum
Stimuli for secretion: Small peptides, AA, and FA
What is the action of CCK? (5)
- Increases pancreatic enzyme secretion
- Increases pancreatic HCO3- secretion
- Stimulates contraction of the gallbladder and relaxation of the sphincter of Oddi
- Stimulates growth of the exocrine pancreas gallbladder
- Inhibits gastric emptying
Name the site of secretion and stimuli for secretion of Secretin.
Site of secretion: S cells of duodenum
Stimuli for secretion: H+ in the duodenum, FA in the duodenum
What is the action of Secretin?
- Increases pancreatic HCO3- secretion
- Increases biliary HCO3- secretion
- Inhibits gastric H+ secretion
- Inhibits trophic effect of Gastrin on gastric mucosa
Name the site of secretion and stimuli for secretion of GIP (glucose-dependent insulinotropic peptide).
Site of secretion: Duodenum and jejunum
Stimuli for secretion: FA, AA, Oral glucose
What is the action of GIP?
- Increases insulin secretion from pancreatic Beta cells
- Decreases gastric H+ secretion
Paracrines act ____ and are carried by ____ or _____.
Locally (while hormones can act at distant locations)
Carried by capillaries or by diffusion
What are the 2 paracrines of the GI tract?
Somatostatin
Histamine
Somatostatin is released from _____ and inhibits the release of _____.
D cells
all gut hormones
What are the 4 neurocrines? State whether they come from the PNS and SNS.
Ach (PNS)
Norepi (SNS)
Vasoactive intestinal peptide (VIP) (PNS, ENS)
Gastrin releasing peptide (GRP) (PNS)
Increases secretions
Relaxes sphincters
Increases contraction of wall smooth muscle
What is this neurocrine?
Ach
