The Digestive The Digestive SystemSystem

Topic OutlineTopic OutlineAnatomy of the digestive system

◦Accessory organs

Physiology of digestion◦Digestive processes◦Control mechanisms

anatomy of the digestive system

digestive systemGastrointestinal (GI) tract

◦Ingestion, digestion, absorption and defecation

Accessory organs◦Assistance in digestive breakdown

The Gastrointestinal TractThe Gastrointestinal Tract

The Gastrointestinal TractThe Gastrointestinal TractMouthEsophagusStomachSmall intestineLarge intestine

mouthAka, oral cavityAnterior opening: lipsLateral walls: cheeksRoof: hard and soft palateFloor: tongue

esophagusAbout 25 cm longPassageway for foodRuns from the pharynx through

the diaphragm to the stomach

stomach Is a muscle that can contract to digest

food.

It produces enzyme and Hydrochloric acid (HCl) to chemically digest food.

The pH of your stomach can be as low as 2

Digested food in the stomach is called “Chyme”

small intestineExtends from the stomach to the large intestines

Major digestive organ

2-4 m in length

small intestineStructures that increase the surface

area for absorption

Microvilli◦ Tiny projections off each villi

Villi◦ Fingerlike projections into the small

intestines

large intestine1.5 m in length

Extends from the small intestines to the anus

Absorption of water and elimination of undigested food

accessory digestive organs

accessory organsSalivary glandsTeethPancreasLivergallbladder

salivary glandsSaliva: mixture of mucus and

water and enzymes

teethFirst set: deciduous (milk) teeth

◦20 teethSecons set: permanent teeth

◦32 teeth

pancreasProduces enzymes that breaks

down all categories of digestible food

◦It also produces Insulin, which controls blood sugar levels and is tied to Diabetes

liverLargest gland

Digestive function: production of bile

Bile: Digestion of Fats

It is stored in the Gall Bladder

physiology of digestion

digestive process1. Ingestion: voluntary process

(eating)

2. Mechanical digestion: physical process of digestion

3. Chemical digestion: large molecules are broken down into their building blocks- catalyzed by enzymes

digestive process5. Absorption: bringing

nutrients into the bloodstream- small intestine: major absorptive site

6. Defecation: elimination of indigestible food (feces)

stomach2-3 L of gastric juice produced

everyday

HCl: activates pepsinogen to pepsin (protein digesting enzyme)

Ulcer: breach in the mucosa caused by increased acid production

Gastric UlcerGastric Ulcer

Questions?Questions?