Buccinator

Sublingualgland

Wharton’sduct

Stensen’s duct

Masseter muscle

Parotid gland

Mandible

SubmaxillaryGland

Buccal Cavity: Primary Salivary Glands

• Filtration: In the Acinus is Primarily Passive

Acinar cells

Myoepithelial cell

Ductal cells

Acinus

Myoepithelial cell

Intercalated duct Striated duct

Organization of the “Salivon”

• Digestive: -Amylase: Starch Digestion

- pH optima 7.0; Active in Proximal Stomach

- Ligual Lipase: Fat Digestion

- pH optima ~4.0; does not require bile salts

• Lubrication/Protection:

- Anti-Bacterial: I -, SCN -, Secretory IgA,Lysozyme and Lactoferrin

- Anti-Corrosive: HCO3 to buffer pH; F- Ca2+.

- Lubrication: Mucus- Mucopolysaccharides, H2O

- Coat the Food to Aid in Swallowing-Taste Prevent Abrasion

Functions of Saliva: Digestion, Protection-Lubrication

• Filtration: In the Acinus is Primarily Passive

Organization of the “Salivon”

Acinar cells

Myoepithelial cell

Ductal cells

Acinus

Myoepithelial cell

Intercalated duct Striated duct

Capillaries

SP

Acetylcholine

SP: Substance P

Stomach Anatomy

Gastric LumenGastric Pits

Columnar Epithelium

Lamina Propria

Gastric Gland

Lymph Node

Lymphatics

Mucosa

Sub-Mucosa

Mucularis

Serosa

Gastric Pits and Glands

Gastric Lumen

Mucus

Superficialepithelial

cells

Mucusneckcells

Parietalcells

Pepticcells

(Oxyntic)

GASTRIC

GLANDS

Gastric Pits

The Epithelial Protective Barrier

Tight Junctions between Adjacent Cells

Mucus and Bicarbonate Secretion

Rapid Turnover – Cell Migration and Proliferation

: All Appear to be Driven by Prostaglandins

Oxyntic Gland Secretions

• Peptic Gastroferrin Iron Binding Protein P• Pepsin-ogen Protease D

• Mucus Neck Mucopolysaccharides; HCO3 P

• Oxyntic Intrinsic Factor B12 Binding D Protein

• HCl Digestion/ P/D

“denaturation”

Cell Type Component Function: (P/D)

P- Protective; D- Digestive

• Protein Digestion : - Activates Pepsin - Denatures and Solubilizes Tissue

• Protective: Kills Bacteria

Roles of HCl in the Stomach

ATP

K+

K+

K+

H+H+

Na+

Cl-

Cl-

Cl-

HCO3-

H2CO3CO2

HCO3-

Na+

Lumenof gland

ATP Canaliculus

Metabolism

Cl-

CA

CA – Carbonic Anhydrase

Baso-Lateral

The Oxyntic Cell

CO2 + H2O H2CO3 HCO3- + H+

Role of Carbonic Anhydrase

CA

Key Players: HCl Secretion

• H+ / K+ ATPase : Lumenal Omeprazole

• Carbonic Cytosolic Acetozolamide Anhydrase

• Na/K ATPase Basolateral Ouabain

• K+ / Cl- cotransport : Lumenal Cl- / HCO3 antiport: Basolateral

Location Inhibitor

Acetylch

oline

Gastrin

Histamine

Ca2+

Ca2+La2+

H+

A

A

CMCM

CM

A

ATP cAMPAdenylate

Cyclase

BlocksDoes not block

Ca2+

IP3

A - ATROPINE

Ln2+- Lanthanum

CM - Cimetidine

H+ Secretion

Phases of Secretion

• Cephalic Smell, Taste Central reflexes

• Gastric Chyme Enters Stomach Distension, Local

Effects Amino Acids

• Intestinal Chyme Enters Local Feedback the Intestine

• Inter-Digestive Histamine Basal Release

Phase Stimuli Pathway

Primary Mechanisms for Inhibiting HCl Secretion

• Antrum Acidification pH < 3 Somatostatin Inhibition (Gastric) Maximal pH < 1 of Gastrin Secretion

• Duodenum Distension Enteric (Local) Reflexes (Intestinal) pH < 6

Fat and Peptides Entero-gastrone?

Location (Phase) Stimuli Pathway

AchAch

AchGRP

Vagus nerves

GastrinGastrin

Cell

Somato-statinCell

DigestedProtein H+

+

Regulation of G-Cell Secretion

Myenteric

Plexus

Antrum

Body ECL