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