Physiology Gi Tract

Front 1

Divisions of the Extrinsic Nervous System

Back 1

1) Parasympathetic 2) Sympathetic

Front 2

GI and Parasympathetic Nervous System: Nerves

Back 2

1) Vagus nerve 2) Pelvic nerve

Front 3

Vagus Nerve Innervation

Back 3

Innervates: 1) Esophagus 2) Stomach 3) Small intestine 4) Upper colon

Front 4

Pelvic Nerve Innervation

Back 4

Innervates: 1) Descending colon 2) Sigmoid colon 3) Rectum 4) Anal canal

Front 5

Vagovagal Reflex

Back 5

1) Information from receptors in mucosa and smooth muscle relayed to CNS via vagus nerve afferents 2) Triggers a response that is carried back to GI tract via vagus nerve efferents

Front 6

GI and Sympathetic Nervous System: Innervation

Back 6

1) Nerve fibers typically synapse outside GI tract in prevertebral ganglia 2) A few innervate blood vessels and secretory cells directly.

Front 7

Enteric/Intrinsic Nervous System Function

Back 7

1) Relay information to and from gut via extrinsic system 2) Stimulus in one part of GI tract can produce response in another part in absence
of extrinsic nervous system

Front 8

Enteric/Intrinsic Nervous System Structure

Back 8

Networks formed by myenteric and submucosal plexuses

Front 9

Enteric/Intrinsic Nervous System Innervation

Back 9

Innervate: 1) Blood vessels 2) Smooth muscle 3) Secretory cells 4) Endocrine cells

Front 10

G Cell Secretion

Back 10

Gastrin

Front 11

Parietal Cell Secretion

Back 11

Gastric acid (HCl)

Front 12

Steatorrhea

Back 12

Excess fat in stools

Front 13

CCK

Back 13

1) Cholecystokinin 2) Secreted by I cells 3) Released in response to: A) Small peptides B) Amino acids C) Fatty acids D) Monoglycerides (containing 8 or more carbon atoms) 4) Stimulates: A) Gallbladder contraction B) Pancreatic enzyme secretion 5) Potentiates pancreatic bicarbonate secretion 6) Inhibits gastric emptying

Front 14

I Cell Secretion

Back 14

CCK

Front 15

Reason Fatty Meals Empty More Slowly than Non-Fat Meals

Back 15

CCK, released in response to fatty acids, inhibits gastric emptying

Front 16

Secretin

Back 16

1) Released by S cells 2) Stimulates: a) Bicarbonate b) Water secretion in: i) pancreas ii) liver 3) Increases bile production 4) Inhibits gastric acid secretion 5) Released in response to acid

Front 17

S Cells

Back 17

1) Duodenum 2) Secretes secretin in response to acid

Front 18

GIP

Back 18

1) Glucose-dependent insulinotropic peptide 2) Secreted by K cells 3) Released in response to: A) Fat B) Protein C) Carbohydrate 4) Stimulates insulin release from pancreas

Front 19

K Cells

Back 19

1) Duodenum and jejunum) 2) Secretes GIP in response to: A) Fat B) Protein C) Carbohydrate

Front 20

Why Is Oral Glucose Load More Effective than IV Glucose in Causing Insulin Release?

Back 20

1) IV glucose circulates through the blood and therefore fails to stimulate the GIP secreting K cells of the small intestine which stimulate insulin release from pancreas 2) Oral glucose passes through the small intestine, stimulating GIP and insulin release

Front 21

Motilin

Back 21

1) Released cyclically about every 90 minutes from upper small intestine (duodenum and jejunum) during fasting
2) Stimulates migrating myoelectric complex in: A) Stomach B) Small intestine 3) Release abolished by eating

Front 22

Gastrointestinal Peptides: Types

Back 22

1) Hormones 2) Paracrines 3) Neurocrines

Front 23

Gastrointestinal Peptides: Hormones

Back 23

1) Gastrin 2) CCK 3) Secretin 4) GIP 5) Motilin

Front 24

Gastrointestinal Peptides: Paracrines

Back 24

1) Somatostatin 2) Histamine

Front 25

Gastrointestinal Peptides: Neurocrines

Back 25

1) VIP 2) GRP 3) Enkephalins

Front 26

Somatostatin

Back 26

1) Secreted by D cells 2) Inhibits: A) Gastric acid secretion B) Release of gastrin C) Release of all GI hormones

Front 27

D Cells

Back 27

1) Throughout GI tract 2) Release somatostatin in response to acid in lumen

Front 28

Histamine

Back 28

1) Secreted by ECL cells 2) Increases gastric acid secretion: A) Directly B) Potentiating effects of: a) gastrin b) ACh 3) Releaser: gastrin

Front 29

ECL Cells

Back 29

1) Enterochromaffin-like cells 2) Located in acid secreting portion of stomach 3) Secrete histamine in response to acid

Front 30

VIP

Back 30

1) Vasoactive intestinal peptide 2) Released from nerves in: A) Mucosa B) Smooth muscle of GI tract 3) Relaxes smooth muscle of GI 4) Stimulates: A) Intestinal secretion B) Pancreatic secretion 5) Secreted from pancreatic islet cell tumor

Front 31

Gastrin

Back 31

1) Secreted by G cells 2) Released in response to: A) Peptides B) Amino acids C) Distension of stomach D) Vagal stimulation 3) Stimulates HCl secretion 4) Increased in Zollinger-Ellison syndrome

Front 32

Gastrinoma

Back 32

1) Tumor in the pancreas or duodenum that secretes excess of gastrin 2) Implicated in Zollinger-Ellison syndrome

Front 33

GRP

Back 33

1) Gastrin-releasing peptide or bombesin 2) Released from nerves in gastric mucosa in response to vagal stimulation 3) Stimulates gastrin release

Front 34

Gastric Mucosa

Back 34

1) Contains nerves that release GRP 2) Responds to vagal stimulation

Front 35

Enkephalins

Back 35

1) Secreted from: A) Nerves of mucosa and smooth muscle of GI tract 2) Stimulate GI smooth muscle contraction: A) lower esophageal B) Pyloric C) Ileocecal sphincters 3) Inhibit intestinal secretion of: A) Fluid B) Electrolytes

Front 36

Slow Wave Contraction Couplet

Back 36

Slow waves without contractions, but not contractions without slow waves

Front 37

Slow Waves

Back 37

1) Smooth muscle cell potential rhythmically depolarizes and polarizes 2) Also called Basic Electrical Rhythm (BER) 3) Not action potentials

Front 38

Cells of Cajal

Back 38

1) Generate slow waves 2) Interstitial

Front 39

Slow Wave Dispensation

Back 39

1) Begin in cells of Cajal 2) Spread to other cells via gap junctions

Front 40

Slow Wave Generation: Depolarization Phase

Back 40

Ca++ influx

Front 41

Slow Wave Generation: Plateau Phase

Back 41

Ca++ influx

Front 42

Slow Wave Generation: Repolarization Phase

Back 42

K+ efflux

Front 43

Slow Waves: Requirement for Contraction

Back 43

Plateau phase must exceed threshold

Front 44

Slow Waves: Plateau Exceeds Threshold

Back 44

1) Voltage-gated Ca++ channels open 2) Ca++ enters 3) AP initiated

Front 45

Slow Waves: Function of Action Potential

Back 45

1) Increase strength and duration of contraction 2) Required for contraction everywhere except stomach

Front 46

Slow Waves: Stomach Contractions and Action Potential

Back 46

1) May occur in absence of AP 2) AP almost always present

Front 47

Slow Waves: Affect of Neural and Hormonal Input on Frequency

Back 47

Little affect on frequency of slow waves

Front 48

Smooth Muscle Action Potentials: Neural and Hormonal Input

Back 48

Influence variations in membrane potentials: 1) Produce AP, thus contractions 2) Inhibit AP 3) Determine strength of contractions

Front 49

Slow Waves: Frequency

Back 49

Sets maximum frequency for contraction of given part of GI tract

Front 50

G Cell Location

Back 50

Stomach

Front 51

Parietal Cell Location

Back 51

Stomach

Front 52

Signals for CCK Release

Back 52

1) Small peptides 2) Amino acids 3) Fatty acids 4) Monoglycerides (containing 8 or more carbon atoms)

Front 53

CCK Stimulates

Back 53

1) Gallbladder contraction 2) Pancreatic enzyme secretion

Front 54

CCK Releasing Cell

Back 54

I cell

Front 55

CCK Inhibits

Back 55

Gastric emptying

Front 56

CCK Potentiates

Back 56

Pancreatic bicarbonate secretion

Front 57

I Cell Location

Back 57

Proximal small intestine: duodenum and jejunum

Front 58

Secretin Stimulates

Back 58

Bicarbonate and water secretion in liver and pancreas

Front 59

Secretin Increases

Back 59

Bile production

Front 60

Secretin Inhibits

Back 60

Gastric acid secretion by parietal cells

Front 61

Signals for Secretin Release

Back 61

Acid