Gastrointestinal System

(Digestive System)

Purpose

Main Function:Main Function: Digest food and Digest food and

make nutrients make nutrients available for the available for the rest of the body. rest of the body.

Feedback loops

Muscles use Muscles use energyenergy

Brain tells GI Brain tells GI system to Brake system to Brake down food faster down food faster and make more and make more energy available. energy available.

You feel “Hungry”You feel “Hungry” Need to replace Need to replace

used energy used energy stores. stores.

Mouth

Digestion beginsDigestion begins Saliva - EnzymesSaliva - Enzymes MasticationMastication

Prepares food for Prepares food for next voyagenext voyage

Peristalsis

Muscular Muscular contraction in the contraction in the GI system that GI system that moves food moves food through the bodythrough the body

Reverse Reverse Peristalsis:Peristalsis:

when food comes when food comes back out.back out.

Esophagus

Tube that leads Tube that leads from Mouth to from Mouth to Stomach.Stomach.

Lined with Lined with involuntary involuntary musclesmuscles

No digestion or No digestion or absorption takes absorption takes place here. place here.

Epiglottis

Stomach

Begins chemical Begins chemical digestiondigestion More enzymes More enzymes

and acidsand acids Low pH levels, kill Low pH levels, kill

off bacteriaoff bacteria Mechanical Mechanical

digestiondigestion Churning, Churning,

squeezingsqueezing

Heartburn

The heart is not The heart is not involved.involved.

When acid from When acid from stomach travels stomach travels up the up the esophagus.esophagus.

Esophagus is not Esophagus is not protected from protected from acid, and it begins acid, and it begins to burn the lining to burn the lining of muscle.of muscle.

Small Intestine

22 feet long!22 feet long! Further Further

breakdown of breakdown of food with bile.food with bile.

Begins nutrient Begins nutrient absorption.absorption.

3 Parts3 Parts DuodenumDuodenum JejunumJejunum IleumIleum

Villi

Wrinkles in lining of Wrinkles in lining of small and large small and large intestineintestine

Purpose:Purpose: Increase surface areaIncrease surface area

Microvilli: each villus Microvilli: each villus is covered in even is covered in even smaller wrinklessmaller wrinkles

Purpose:Purpose: Increase surface areaIncrease surface area

Large Intestine

Most responsible Most responsible for absorptionfor absorption Water from Water from

indigestible foodindigestible food Any nutrients the Any nutrients the

SI didn’t getSI didn’t get Rectum stores Rectum stores

waste to be waste to be expelled through expelled through anus. anus.

Summary

The GI system plays an important The GI system plays an important role in our bodies.role in our bodies.

It provides the rest of the body It provides the rest of the body with nutrients and energy.with nutrients and energy.

It connects with the nervous It connects with the nervous system to inform us of when to system to inform us of when to eat.eat.

The nervous system can also The nervous system can also inform the GI system to prepare inform the GI system to prepare for incoming food. for incoming food.