Ex 38

Digestive System

Overview

Alimentary Canalhollow tube from mouth to anusoutside of the bodycovered with mucous membrane

Accessory Digestive Organs

teeth, tongue, gallbladder, salivary glands, liver, and pancreas

Oral Cavity

Tongue and Teeth

Teethincisors, canines, premolars, molars

Oral Cavity

Oral CavitySalivary Glands

secrete salivacontains enzymes for digestioncontains mucous for formation of the bolus

Parotid Glandserousenzymes

Sublingual Glandmucous

Submandibular Glandmixed

demilune

Oral CavitySalivary Glands

secrete salivacontains enzymes for digestioncontains mucous for formation of the bolus

Parotid Glandserousenzymes

Sublingual Glandmucous

Submandibular Glandmixed

demilune

Oral Cavity

Lumen OverviewSerosa

supports, protects, allows viscera to move without frictionepithelium, connective tissue

Muscularis Externacontractions cause peristalsismyenteric plexusouter longitudinal, inner circular

Submucosaarea for nutrition and protectioncarries blood vessels, submucosal plexus, lymph nodules

Mucosasecretes digestive enzymes & mucous, barrier for bacteria, absorption of foodepithelium, lamina propria, muscularis mucousae

Lumen OverviewSerosa

protects, allows viscera to move without frictionepithelium, connective tissue

Muscularis Externacontractions cause peristalsismyenteric plexusouter longitudinal, inner circular

Submucosaarea for nutrition and protectioncarries blood vessels, submucosal plexus, lymph nodules

Mucosasecretes digestive enzymes & mucous, barrier for bacteria, absorption of foodepithelium, lamina propria, muscularis mucousae

Esophagus

Esophagustransports food bolus from oropharynx to the stomach via peristaltic action

Body of the esophagus

Sphinctersupper esophageal sphincterlower esophageal sphincter

defects in sphincter tone can cause disease: GERD and Hiatal Hernia

Esophagus

Esophagustransports food bolus from

oropharynx to the stomach via peristaltic action

Body of the esophagus

Sphinctersupper esophageal sphincterlower esophageal sphincterdefects in sphincter tone can cause

disease: GERD and Hiatal Hernia

Esophagus

Lower Esophageal Sphincter

Made up not only of a muscular band but also forces of the surrounding diaphragm contribute to the lower esophageal tone.

Defects in tone can cause disease

GERD

Hiatal hernia

EsophagusMucosa

nonkeratinized stratified squamous epithelium

Submucosaesophageal glands, submucosal plexus, blood vessels

Muscularis Externaupper 1/3 voluntary striated smooth muscle

middle 1/3 mixed

lower 1/3 involuntary smooth muscle

myenteric plexus

Adventitiano serosa

StomachResponsible for initial

digestion of foodmechanical breakdown through contractions of musculaturesecretion of enzymes (namely pepsin)

Parts of the Stomachlesser curvature

lesser omentumgreater curvature

greater omentumfunduscardiabodyantrum or pylorus

pyloric sphincter

StomachResponsible for initial

digestion of foodParts of the Stomach

lesser curvaturelesser omentum

greater curvaturegreater omentum

funduscardiabodyantrum or pylorus

pyloric sphincterangulusrugae

increases surface area for absorbtion

StomachMucosa

simple columnar epitheliumgastric pits leading to gastric glandsmucous neck cells, parietal cells (HCL), chief cells (pesinogen)

Submucosausual glands, submucosal plexus, blood vessels

Muscularis Externainner oblique, middle circular, outer longitudinalmyenteric plexus

Serosa

StomachMucosa

simple columnar epitheliumgastric pits leading to gastric glandsmucous neck cells, parietal cells (HCL), chief cells (pesinogen)

Submucosausual glands, submucosal plexus, blood vessels

Muscularis Externainner oblique, middle circular, outer longitudinalmyenteric plexus

Serosa

StomachMucosa

simple columnar epitheliumgastric pits leading to gastric glandsmucous neck cells, parietal cells (HCL), chief cells (pesinogen)

Submucosausual glands, submucosal plexus, blood vessels

Muscularis Externa inner oblique, middle circular, outer longitudinalmyenteric plexus

Serosa

Gastric GlandsGastric Pit

mucous neck cellthick, alkaline mucous

parietal cellHCl, intrinsic factor

chief cellpepsinogen, gastric lipase

G cellgastrin

Intestine OverviewSmall Intestine

pyloric sphincter to ileocecal valvebreaks down food so molecules can be absorbed

duodenumjejunumileum

Large Intestinefluid absorbtionsome vitamin production

cecumascending colontransverse colondescending colonsigmoid colonrectum

Small IntestineDuodenum

full chemical mixture for food digestion

bile and pancreatic enzymes enter here

major and minor papillae (spincter of Oddi)

mostly retroperitonealmost absorption occurs here

BulbC-Loop

Small Intestine

Duodenumfull chemical mixture for food digestion

bile and pancreatic enzymes enter here

major and minor papillae (spincter of Oddi)

mostly retroperitonealmost absorption occurs here

BulbC-Loop

Small IntestineDuodenum

full chemical mixture for food digestion

bile and pancreatic enzymes enter here

major and minor papillae (spincter of Oddi)

mostly retroperitonealmost absorption occurs here

BulbC-Loop

Small Intestine

Jejunumplicae circularisfree of mesenteric fat

Small Intestine

Ileumno plicaemesenteric fat partially attachedimportant for iron absorbtion

Small IntestineMucosasimple columnar epithelium folded into villimicrovilli on luminal cell surfacecrypts of Lieberkuhn

Submucosaduodenal glands (brunner)Peyer’s Patches (lymphoid tissue in ileum)

Muscularis Externainner circularouter longitudinalmyenteric plexus

Serosa

Small Intestine

Small IntestineMucosasimple columnar epithelium folded into villimicrovilli on luminal cell surfacecrypts of Lieberkuhn

Submucosaduodenal glands (brunner)Peyer’s Patches (lymphoid tissue in ileum)

Muscularis Externainner circularouter longitudinalmyenteric plexus

Serosa

Small Intestine

Small IntestineMucosasimple columnar epithelium folded into villimicrovilli on luminal cell surfacecrypts of Lieberkuhn

Submucosasubmucosal plexusduodenal glands (brunner)Peyer’s Patches (lymphoid tissue in ileum)

Muscularis Externainner circularouter longitudinalmyenteric plexus

Serosa

Large Intestineileocecal valve

Gateway to the cecum

cecumascending colonhepatic flexuretransverse colonsplenic flexuredescending colonsigmoid colonrectumanus

Ileum

Cecum

Appendixcontains a small lumen, when it is unable to clear debris it becomes infected

Large Intestine

Large Intestine

Tinea Coliouter longitudinal layer is reduced to 3 bands that run longitudinally along the colon

Haustrabulging walls of the colon due to lack of longitudinal muscular support.

Large IntestineMucosasimple columnar epithelium

no villi or microvilli

crypts of Lieberkuhn

goblet cells

Submucosausual glands, submucosal plexus, blood vessels

Muscularis Externainner circular

outer longitudinal in three bands called tinea coli

myenteric plexus

Serosa

Large Intestine

Rectumstorage are for stool

has 3 valves

controls flow of stool/gas

Large Intestine

anusstratified squamous epithelium

internal/external anal sphincters

LiverMain Functions

produces bile

acts as a soap to aid digestion of fat

stores sugar

as glycogen

processes chemicals and toxins

most of the venous return from the digestive system passes through the liver

LiverAnatomy

Lobes

right

left

caudate

quadrate

Falciform Ligament

divides R and L lobes

suspends liver from diaphragm and ant abd wall

gallbladder

Liver

LiverAnatomy

hepatic artery

branches off celiac trunk

LiverAnatomy

Portal Vein

most of the venous return from the digestive system

LiverAnatomy

Hepatic Vein

returns venous blood to IVC

Liver: HistologyVenous Flow Through

LiverPortal Vein

blood coming in from intestines

Sinusoidschannels between rows of hepatic cells

Central Veinsinusoids empty into this structureblood returns to hepatic vein

Bile Canaliculibile produced by hepatocytes travel to bile ducts

Portal Triadportal vein is accompanied by a bile duct and a branch of the hepatic artery

Liver: HistologyVenous Flow Through

LiverPortal Vein

blood coming in from intestines

Sinusoidschannels between rows of hepatic cells

Central Veinsinusoids empty into this structureblood returns to hepatic vein

Bile Canaliculibile produced by hepatocytes travel to bile ducts

Portal Triadportal vein is accompanied by a bile duct and a branch of the hepatic artery

Anatomysnuggled in the C-loop of the duodenumheadbodytail

Pancreas

Pancreasfunctions

produces insulin for control of blood glucose

islets of langerhansreleased into bloodstream

produces digestive enzymes

acinar cellsreleased into duodenum through pancreatic ducts

main (Wirsung)accessory (Santorini)

Pancreas Histologyfunctions

lobular structure much like a salivary gland

acini lined with acinar cells

contain zymogen granules that contain digestive enzymes

islets of Langerhans

produce insulin

Pancreas HistologyPancreatic ducts

secretes bicarb

neutralizes stomach acid

Liver and PancreasBile ducts

R/L hepatic, common hepatic, cystic, common bile duct

the common bile duct and the pancreatic duct usually join just before emptying into the duodenum

PeritoneumPeritoneum

visceral layer (serosa) covers organs

parietal layer lines the walls of body cavity

Peritoneal cavitypotential space containing a bit of serous fluid for lubrication

Parts of the Peritoneum

Mesentery

sheets of visceral peritoneum that are folded over on themselves

stabilize organs’ positions

act as an area where vessels, nerves, lymphatics can get to the organs

Parts of the PeritoneumMesentery

attaches small intestine to abd wall

Mesocolon

attaches large intestine to abd wall

Lesser omentum

peritoneum from liver to stomach

Greater omentum

double sheet of peritoneum from stomach

Greater Omentum, Mesentery & Mesocolon

Lesser Omentum