G cells - Stomach Antrum Simulus - Gastric distention, Vagus Nerve Via GRP/ Bombesin Inhibition - Inc H conc, Somatostatin Fxn - Increase H ion secretion Growth of Gastric Mucosa

S cells - duodenum Stim H ion, Fatty acids in duodenum Fxn: increase pancreatic HCO3 secretion, counteracts Gastrin

M cells of duodenum jejunum Stim by fasting Stimulates peristalsis, clearing of GI in between meals

Secreted by anorexigenic Neurons Anorexigenic

Orexigenic neurons Increase appetite

Inhibits anorexigenic neurons - stimulate hunger Inhibited by Peptide YU

Anorexigenic Neuron ACTIVATOR Orexigenic neuron INHIBITOR

Constant; no relaxation Spincters Subthreshold slow waves

Periodic contraction an relaxation Mixing and propulsion Spike potentials

Intestinal cells of cajal Slow waves - not true action potential - sodium influx

Gastrointestinal Physiology Flashcards by Oliver Pintor

Myenteric Plexus

Mainly excitatory EXCEPT Pyloric Sphincter and Ileocecal Valve

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10 inches

Esophagus
Duodenum
Urethra

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Absorption

Duodenum

Vitamin C

Iron

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Absorption

Jejunum

Carbohydrate
Fats
Proteins

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Absorption

Ileum

Vitamin B12-Intrinsic Factor (terminal part)

Vitamins ADEK

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Gastrin

G cells - Stomach Antrum
Simulus - Gastric distention, Vagus Nerve Via GRP/ Bombesin
Inhibition - Inc H conc, Somatostatin
Fxn - Increase H ion secretion Growth of Gastric Mucosa

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Secretin

S cells - duodenum
Stim H ion, Fatty acids in duodenum
Fxn: increase pancreatic HCO3 secretion, counteracts Gastrin

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Cholecystokinin

I cells in duodenum jejunum
Stm by FATTY ACIDS
Fxn Gallbladder contraction, Sphincter of Odi relaxation, increase pancreatic enzyme and HCO secretion
INHIBITS GASTRIC EMPTYING

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GIP

Glucose dependent insulinotropic peptide

Aka Incretin GLP-1
K cells of duodenum
Increase insulin secretion
Inhibits gastric emptying

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Motilin

M cells of duodenum jejunum
Stim by fasting
Stimulates peristalsis, clearing of GI in between meals

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Parasumpathetic effects on GI

Contraction of smooth muscles
RELAXATION of sphincters
INC salaivation
INC gastric secretion
INC Pancreatic secretion

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Sympathetic effect on GI

Relaxation of smooth muscles
CONTRACTION of sphincters
INC Salivation

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POMC

Secreted by anorexigenic Neurons

* Anorexigenic

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Neuropeptide Y

Orexigenic neurons

* Increase appetite

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Ghrelin

Inhibits anorexigenic neurons - stimulate hunger

* Inhibited by Peptide YU

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Leptin

Anorexigenic Neuron ACTIVATOR

* Orexigenic neuron INHIBITOR

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Satiety center

Ventromedial hypthalamus

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Hunger center

Lateral hypothalamic area

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GLP

L cells of small intestines

INC Insulin secretion

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Somatostatin

Inhibits release of ALL GI Hormones

Inhibits H+ secretion

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Histamine

By mast cells of GI mucosa
Increase H+
Potentiates Gastrin and Ach

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Tonic Contractions

Constant; no relaxation
Spincters
Subthreshold slow waves

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Phasic contractions

Periodic contraction an relaxation
Mixing and propulsion
Spike potentials

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GI Pacemaker

Intestinal cells of cajal

* Slow waves - not true action potential - sodium influx

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Spike potentials

True AP due to calcium Influx

GI Transit time

Gastric Emptying: 3 hours Pylorus to ileocecal valve: 3-5 hours Ileocecal valve to colon: 8-15 hours

Swallowing center

Medulla

Receptive relaxation of the Orad Stomach

* Vasovagal reflex mediated by VIP * Capacity 1.5L * CCK increases distensibility

Haustra

Saclike segments of Colon due to SEGMENTAL CONTRACTIONS

Structures seen only in colon

Taenia coli, Haustra, Epiploic Appendages

Vomiting center

Medulla

Hormone responsible in absorption of Sodium in saliva at ductal cells

Aldosterone

Parotid gland

Serous secretion | Parasympa supplied by CN IX

Submandibular gland

Mixed secretion, mainly SEROUS | Innervation CN VII

Sublingual gland

Mixed secretion mainly MUCOUS | CN VII

Muscular layers of stomach

* Inner oblique * Middle circular * Outer longitudinal

Chief cell / Peptic cells

Body of the stomach | Pepsinogen

G cells

Antrum | Gastrin

Mucous cells

Body, Antrum | Mucus

Type A gastritis

* Auto immune * Anti parietal cells * Pernicious anemia

Type B gastritis

Secondary to bacteria | Achlorydia

Oxyntic glands

* Body | * Contains Mucus neck cells, Parietal cells and chief cells

Pyloric glands

* Antrum | * Contains G cells, Mucus cells

Enterocromaffin cells

Serotonin

Enterocromaffin like cells

Histamine

Stimulate HCL secretion

Histamine, Ach, Gastrin

Inhibits HCL secretion

Low pH, Somatostatin, Prostaglandin

Increases pancreatic secretions

Secretin, CCK, Ach

How many times the bile is reabsorbed/ recycled before it is excreted

17 times

Carrier for transport of Glucose and Galactose from lumen to intestinal cells

SGLT 1

Carrier for transport of Glucose from lumen to cells of proximal tubules

SGLT 2

Carrier for transport of Fructose from lumen to intestinal cells

GLUT 5

Transfers Glucose, Galactose and Fucose from Intestinal celss to blood

GLUT 2

Main site for water absorption

* Jejunum - 7.5 liters/day | * Large intestine - 1.5 liters/day only

Needed for Vitamin B12 absorption

Intrinsic Factor

Needed for Calcium absorption

Vitamin D

Needed for Iron absorption

Vitamin C

Site of Iron absorption

* Duodenum * Binds to Apoferritin in intestinal cell * Binds to Transferrin in blood

Site of bile acid absorption

Terminal Ileum

Liver lobule

* Hexagonal, Central vein on the center, Portal triad at the borders * Functional unit of liver

Liver acinus model

* Zone 1 - Periportal * Zone 2 - Midzonal * Zone 3 - Centrilobular

Ito cells

* Found in Space of Disse | * Storage of Vitamin A

Kuppfer cells

* Von Kuppfer cells * Seen in Liver sinusoids * Antigen presenting cells

Parietal cells

Body of stomach | Secrete HCL, intrinsic factor