DIGESTIVE SYSTEMDIGESTIVE SYSTEM

Through stomach

Overall Digestive ProcessOverall Digestive Process

IngestionMovementDigestion (mechanical & chemical)Absorption (into blood/lymph vessels)Elimination = Defecation

GI OrganizationGI Organization

Digestive tract = canal Gastrointestinal tractAlimentary canalAccessory Structures – outside of the tract

Microstructure - generalMicrostructure - general

Mucosa– Mucous membrane– May have villi and microvilli

Submucosa– Very vascular

MuscularisSerosa = Visceral Peritoneum

PeritoneumPeritoneum

Parietal peritoneumVisceral peritoneumPeritoneal cavity

Folds of PeritoneumFolds of Peritoneum

Binds organs together, anchors them, suspends vessels

Mesentery proper (SI-Dorsal BW) Mesocolon & Mesorectum (LI-Dorsal BW Falciform ligament (Li-Ventral BW) Lesser omentum (Lesser curvature/duodenum-Li) Greater omentum (Greater curvature-Dorsal BS

Oral CavityOral Cavity

LabiaLabial frenulumHard palateSoft palate

– Uvula

Tongue (accessory)Tongue (accessory)

Glosso-Lingu-Skeletal muscle covered by mucous

membraneLingual frenulum

TongueTongue

PapillaeTaste Zones

– Sweet, Salt– Sour, Bitter

Function– Bolus formation

Salivary Glands (accessory)Salivary Glands (accessory)

ParotidSubmandibularSublingual

SalivaSaliva

1-1 ½ liters/day99% waterMucinsAmylaseLysozyme – anti-microbial

Saliva Secretion ControlsSaliva Secretion Controls

Nervous System – Medulla oblongata & Pons

ANSSmell, thought, sight, irritationDehydration, Fear

Teeth (accessory)Teeth (accessory)

GingivaeCrownRootNeck

Tooth ComponentsTooth Components

Periodontal ligamentDentinPulp cavity & pulpApical foramenEnamelCementum

TeethTeeth

Deciduous – 20Permanent - 32

Teeth - shapeTeeth - shape

IncisorCaninePremolarMolar

Dental TerminologyDental Terminology

LabialBuccalLingualPalatalOcclusal

Digestion in Oral CavityDigestion in Oral Cavity

IngestionMasticationChemical digestionDeglutition

PharynxPharynx

Already did under Respiratory

EsophagusEsophagus

HiatusSphinctersFunction

– Peristalsis– Heartburn is actually esophageal “burn”

Stomach (gastric)Stomach (gastric)

Anatomy– Cardia– Fundus– Body– Pylorus and Pyloric Sphincter– Greater Curvature– Lesser Curvature

Digestion in StomachDigestion in Stomach

Stores foodChymeMotility, Mixing & EmptyingPeristalsisTo Pyloric Sphincter, to DuodenumPacemaker cells make smooth muscle

contract about 3x/minute when food present

Controls of Stomach MotilityControls of Stomach Motility

2-6 hours to emptyControls include volume & distentionGASTRIN

– Hormone released by pyloric cells in response to distention. Stimulates gastric motility.

– Caffeine stimulates gastrin release

Controls of Stomach MotilityControls of Stomach Motility

ENTEROGASTRIC REFLEX– As duodenum distends, it inhibits gastric

motility

SECRETINCHOLECYSTOKININGASTRIC INIHIBITORY PEPTIDE

Gastric SecretionGastric Secretion

“Juice”Zymogenic Cells make PepsinogenParietal Cells make HCl

– Alkaline blood following a meal

Mucus Cells make protective mucus

Controls of Stomach SecretionControls of Stomach Secretion

GASTRINCephalic, Gastric & Intestinal phase of

seeing and eating foodENTEROGASTRIC REFLEXGIP, CHOLECYSTOKININ, SECRETIN

Stomach PhysiologyStomach Physiology

Very little absorption