Med Physio (5, B9) - GI

Flashcards to review key concepts from the GI Structure and Innervation lecture.

What are the two possible outermost layers of the GI tract?

Serosa/Adventitia

Which outermost GI layer is found in the esophagus and retroperitoneal regions?

Tunica adventitia

Which outermost GI layer is found in intraperitoneal regions?

Tunica serosa

Name the two layers of the Muscularis externa.

Circular, Longitudinal

Which muscle layer of the muscularis externa controls lumen diameter?

Circular muscle

Which muscle layer of the muscularis externa controls the length of the GI segment?

Longitudinal muscle

Which muscularis externa layer is primarily responsible for propelling contents?

Longitudinal

Which muscularis externa layer primarily narrows the GI lumen?

Circular

What is the effect of parasympathetic ANS activity on GI motility?

Increases

What is the effect of sympathetic ANS activity on GI motility?

Decreases

The vagus nerve provides what type of autonomic innervation to the GI tract?

Parasympathetic

Splanchnic nerves provide what type of autonomic innervation to the GI tract?

Sympathetic

What is the effect of parasympathetic ANS activity on GI secretions?

Increases

What is the effect of sympathetic ANS activity on GI secretions?

Decreases

Where is the Myenteric plexus (Auerbach's plexus) located within the GI wall?

Between muscle layers

Where is the Submucosal plexus (Meissner's plexus) located within the GI wall?

Submucosa

What is the primary function of the Myenteric (Auerbach's) plexus?

Motility regulation

What is the primary function of the Submucosal (Meissner's) plexus?

Secretion regulation

What is a secondary function of the Submucosal (Meissner's) plexus related to blood flow?

Blood flow regulation

What does ENS stand for?

Enteric Nervous System

Name two excitatory neurotransmitters of the ENS.

ACh, Substance P

Name two inhibitory neurotransmitters of the ENS.

VIP, NO

What is the effect of ACh on GI smooth muscle?

Contraction

What is the effect of Substance P on GI smooth muscle?

Contraction

What is the effect of VIP on GI smooth muscle?

Relaxation

What is the effect of NO on GI smooth muscle?

Relaxation

Which neurotransmitters stimulate propulsive contractions in the GI tract?

ACh, Substance P

Which neurotransmitters are responsible for receptive relaxation in the GI tract?

VIP, NO

GI hormones exert their effects at what site, and via what medium?

Distant via blood

GI paracrines exert their effects at what site, and via what mechanism?

Local diffusion

GI neurocrines exert their effects at what site, and via what mechanism?

Nerve endings release

What type of GI peptide is Gastrin?

Hormone

What type of GI peptide is CCK?

Hormone

What type of GI peptide is Secretin?

Hormone

What type of GI peptide is GIP?

Hormone

What type of GI peptide is GLP-1?

Hormone

What type of GI peptide is Somatostatin?

Paracrine

What type of GI peptide is Histamine?

Paracrine

What type of GI peptide is ACh, in the context of GI regulation?

Neurocrine

What type of GI peptide is VIP, in the context of GI regulation?

Neurocrine

Which class of GI peptides includes secretin?

Hormone

Which class of GI peptides acts via local diffusion?

Paracrine

What cells are the source of Gastrin?

G cells

Where are Gastrin-producing G cells primarily located?

Gastric antrum

Are proteins a stimulus for gastrin release?

Yes

Is gastric distention a stimulus for gastrin release?

Yes

Does an increase in gastric pH stimulate gastrin release?

Yes

What is Gastrin's action on HCl secretion by parietal cells?

Increases HCl

What is Gastrin's action on ECL cells?

Stimulates histamine

What is Gastrin's effect on gastrointestinal mucosal growth?

Stimulates

What is the specific receptor for Gastrin on parietal cells?

CCK-B receptor

What is the specific receptor for Gastrin on ECL cells?

CCK-B receptor

Zollinger-Ellison Syndrome is caused by a tumor secreting what hormone?

Gastrinoma

What cells are the source of CCK?

I cells

Where are CCK-producing I cells primarily located?

Duodenum, jejunum

Are fatty acids a stimulus for CCK release?

Yes

Are amino acids a stimulus for CCK release?

Yes

Are small peptides a stimulus for CCK release?

Yes

What is CCK's action on the gallbladder?

Contraction

What is CCK's action on pancreatic enzyme secretion?

Secretion

What is CCK's action on the rate of gastric emptying?

Decreases rate

What is CCK's action on the sphincter of Oddi?

Relaxes

What is the specific receptor type for CCK (e.g., on the gallbladder)?

CCK-A receptor

What cells are the source of Secretin?

S cells

Where are Secretin-producing S cells primarily located?

Duodenum

Is duodenal acid a stimulus for secretin release?

Yes

Are fatty acids a stimulus for secretin release?

Yes

What is Secretin's action on pancreatic bicarbonate (HCO_3^-) secretion?

Increases secretion

What is Secretin's action on bile bicarbonate (HCO_3^-) secretion?

Increases secretion

What is Secretin's action on gastric acid secretion?

Decreases

What is Secretin's effect on mucosal trophic action?

Inhibits

What cells are the source of GIP?

K cells

Where are GIP-producing K cells primarily located?

Duodenum, jejunum

Are fatty acids a stimulus for GIP release?

Yes

Is glucose a stimulus for GIP release?

Yes

What is GIP's action on insulin release from the pancreas?

Stimulates

What is GIP's action on gastric acid secretion?

Decreases

What is another name for GIP that describes its function?

Glucose-dep Insulinotropic Polypeptide

What type of muscle forms the upper esophagus?

Striated

What type of muscle forms the lower esophagus?

Smooth

Which muscle type (striated or smooth) is under voluntary control?

Striated

Which muscle type (striated or smooth) is under involuntary control?

Smooth

What controls the Upper Esophageal Sphincter (UES)?

Skeletal muscle

What primarily controls the Lower Esophageal Sphincter (LES)?

Smooth muscle tone

LES relaxation is initiated by what type of vagal fibers?

Vagal inhibitory fibers

Name the two key neurotransmitters responsible for LES relaxation.

VIP, NO

What is the clinical defect in Achalasia regarding the LES?

LES fails to relax

What is the underlying cause of Achalasia at a neuronal level?

ENS neuron degeneration

What is a prominent symptom of Achalasia related to swallowing?

Dysphagia

What localized injection can be a treatment option for achalasia?

Botox injection

What is the surgical treatment for achalasia?

Heller myotomy

What is the defect in Diffuse Esophageal Spasm related to contractions?

Uncoordinated contractions

Name two common symptoms of Diffuse Esophageal Spasm.

Dysphagia, chest pain

What esophageal condition is characterized by a 'corkscrew' appearance on imaging?

Diffuse esophageal spasm

Which regions constitute the orad part of the stomach?

Fundus, proximal body

Which regions constitute the caudad part of the stomach?

Distal body, antrum

What is the primary function of the orad stomach?

Relaxation, storage

What is the primary function of the caudad stomach?

Mixing, grinding

What is a secondary function of the caudad stomach related to emptying?

Emptying regulation

What stimulus triggers receptive relaxation of the stomach?

Swallowing