Digestive System

Anatomy & PhysiologyAnatomy & Physiology

Alimentary CanalOne-way digestive tract through the body

Lumen of digestive tract

is externalenvironment

1-way flow ishighly effi cient

Body

Alimentarycanal

Digestive Processes

Digestive Organs

Mesentary

Peritonitis

                                                            

Oral Anatomy Lateral View

Cadaver Midsaggital Section of Oral Structures

Oral Anatomy Anterior View

Tongue Anatomy

Taste Bud Anatomy

Salivary Glands

Cadaver ___ Gland

Tooth Anatomy

                                                                               

Tooth Eruption

             

                  

Impacted Molar

Gingiva

Universal Tooth Numbering System

Tooth Faces• Lingual (Nearest Tongue)Lingual (Nearest Tongue)

• Facial (Farthest from tongue)Facial (Farthest from tongue)

• Mesial (Closest to the Mesial (Closest to the incisors)incisors)

• Distal (Farthest from the Distal (Farthest from the incisorsincisors

• Occlusal (Grinding surfaceOcclusal (Grinding surface

Splanchnic Circulation

25% of Cardiac Output

Endoscope

Larynx

Esophageal Reflux

G.E.R.D. (GastroEsophageal Reflux

Disease)

Gastric Fundus

Gastritis due to Helicobacter Pylori

Gastric Diverticulum

Gastric Polyps

Gastric Carcinoma

Duodenal Mucosa

Duodenal Ulcer

Proctologist

Testing for Occult Blood

Colonoscopy

Colonoscopy Administration

                                    

Caecal Diverticula

Descending Colon

Tapeworms

Ulcerative Colitis (Sigmoid Colon & Rectum)

Rectum

Anal Hemorrhoids (Piles) Caused by Inflammation of

the Superior & Inferior Hemorrhoid Veins

Scope Comparison

Barium Enema

Colostomy& Stoma

Colostomy Bag

Peristalsis

27 Year Old Male

81 Year Old Male

Swallowing

Gastric Regions

Gastric Anatomy

Gastric Cells

Gastric Cell FXN’s

• Goblet cells – produce alkaline mucusGoblet cells – produce alkaline mucus• Mucus Neck cells – produce acidic Mucus Neck cells – produce acidic

mucusmucus• Parietal cells – produce HCl & Intrinsic Parietal cells – produce HCl & Intrinsic

FactorFactor• Chief cells – produce pepsinogenChief cells – produce pepsinogen• Enteroendocrine cells – produce gastrin, Enteroendocrine cells – produce gastrin,

pepsin, cholecystokinin, & somatostatinpepsin, cholecystokinin, & somatostatin

Gall Bladder & Pancreas Empty Contents into

Duodenum

Liver & Pancreas Secretions

Liver FXN’s

• Synthesizes bile (bile salts, Synthesizes bile (bile salts, biliruben, & cholesterol)biliruben, & cholesterol)

• Stores glucose as glycogenStores glucose as glycogen

• Stores fat soluble vitamins ADEKStores fat soluble vitamins ADEK

Gall BladderFXNFXN• Stores bileStores bile• CCK contracts gall bladder secretion of pancreatic CCK contracts gall bladder secretion of pancreatic

juice & relaxation of the sphincter of Oddijuice & relaxation of the sphincter of Oddi

PathophysiologyPathophysiology• Gall stones – too much cholesterol or too few bile Gall stones – too much cholesterol or too few bile

salts resulting in cholesterol crystal accumulationsalts resulting in cholesterol crystal accumulation

• Obstructional jaundice – bile duct becomes Obstructional jaundice – bile duct becomes obstructed & bilirubin increases in bloodobstructed & bilirubin increases in blood

Gallstones

Bile Salt

PancreasFXNFXN• Secretes basic pancreatic juice (pH 7.5-8.0)Secretes basic pancreatic juice (pH 7.5-8.0)

Pancreatic Juice (p.j.)Pancreatic Juice (p.j.)• Bicarbonate rich p.j. neutralizes HCl in the duodenum Bicarbonate rich p.j. neutralizes HCl in the duodenum

(Stimulated by secretin when HCl enters the duodenum)(Stimulated by secretin when HCl enters the duodenum)

• Enzyme rich p.j. stimulated by CCK when fatty or protein Enzyme rich p.j. stimulated by CCK when fatty or protein rich foods enter the duodenumrich foods enter the duodenum

NoteNote• Hormones released in inactive form so they don’t digest Hormones released in inactive form so they don’t digest

the pancreasthe pancreas

Accessory Organ Ducts & Sphincter

H2O

CO2

H2CO3

H+

Na+

HCO3-

Na+

Blood capillary

Pancreaticacinar

cell

Pancreatic duct

Pancreatic secretion ofNaHCO3 (sodium bicarbonate)

[simplified]

Water & minerals• No need f or digestion• Water absorbed by osmosis

8.5 liters/ day• Minerals absorbed by

– Active transport– Facilitated diff usion

Water & Mineral Digestion

Absorption of…

Vitamins – Vitamins – • A,D,E,K fat soluble (diffuse into blood)A,D,E,K fat soluble (diffuse into blood)• B & C water soluble (diffuse into blood)B & C water soluble (diffuse into blood)• B12 requires intrinsic factor for diffusion…leads to B12 requires intrinsic factor for diffusion…leads to

pernicious anemiapernicious anemia

• Electrolytes (NaElectrolytes (Na++, K, K++, HCO, HCO33--, Cl, Cl--))

• Iron – binds to ferratin in mucosal cells & transferrin in Iron – binds to ferratin in mucosal cells & transferrin in the blood for transportthe blood for transport

• Calcium – PTH increases ionic calcium & vitamin D aids in Calcium – PTH increases ionic calcium & vitamin D aids in absorptionabsorption

Lipid Emulsification

Lipid Digestion

Carbohydrate Digestion

Na/K Symport

Protein Digestion

Brush Border

Villi

Small Intestine

Large Intestine with Mesentery

Cecum

Anal Sphincter

Control

Hormonal Control of Digestion

(Produced in stomach)• Gastrin - HCl secretion & gastric emptyingGastrin - HCl secretion & gastric emptying• Serotonin – Contracts gastric muscleSerotonin – Contracts gastric muscle• Histamine – HCl release from parietal cellsHistamine – HCl release from parietal cells• Pepsinogen – Pepsinogen – inactive form of pepsin (HCl activated) inactive form of pepsin (HCl activated)

catabolyzes proteincatabolyzes protein

• Somatostatin – Inhibits:Somatostatin – Inhibits: gastric secretionsgastric secretions gastric emptyinggastric emptying pancreatic secretionspancreatic secretions intestinal absorptionintestinal absorption gall bladder contraction (bile release)gall bladder contraction (bile release)

Hormonal Control of Digestion (Produced in

Duodenum)• Secretin - pancreatic juice secretion & bile outputSecretin - pancreatic juice secretion & bile output

• Cholecystokinin - pancreatic juice output, contracts gall Cholecystokinin - pancreatic juice output, contracts gall bladder, & relaxes sphincter of Oddibladder, & relaxes sphincter of Oddi

• Gastric inhibitory peptide – inhibits gastric secretion & Gastric inhibitory peptide – inhibits gastric secretion & motilitymotility

• Vasoactive intestinal peptide – dilates intestinal Vasoactive intestinal peptide – dilates intestinal capillaries & inhibits HCl productioncapillaries & inhibits HCl production

Hormonal Control of Digestion

(Produced by pancreas)• Trypsinogen – Inactive form of trypsin (activated by Trypsinogen – Inactive form of trypsin (activated by

enterokinase) catabolyzes protein to peptidesenterokinase) catabolyzes protein to peptides

• Amylase – catabolyzes polysaccharidesAmylase – catabolyzes polysaccharides

• Lipase – catabolyzes lipidsLipase – catabolyzes lipids

• Carboxypeptidase – catabolyzes protein to amino acidsCarboxypeptidase – catabolyzes protein to amino acids

• Chymotrypsin – catabolyzes protein to peptidesChymotrypsin – catabolyzes protein to peptides

Metabolic statesThe absorptive state•During & for several hours after a meal•Insulin

glucose uptake by cells (from blood)

glycogenesis in liver cells lipogenesis in fat cells lipolysis in fat cells

Continues until . . .

Metabolic statesThe postabsorptive state•Begins several hours after a meal•Glucagon

glycogenolysis gluconeogenesis lipolysis in fat cells lipogenesis in fat cells

Feces may indicate health issues

•Motility / timing•Diarrhea•Constipation

•Color / consistency•Gray = lack of bile•Black/tarry = bleeding (upper)

•Black = PeptoBismol•Red = bleeding (lower)

Digestion of Alcohol