Digestive System

Objectives:1. What are the nutrients that the body uses2. What is the purpose of digestion3. Identify the organs of the Digestive System

Nutrients of the Body

Carbohydrates – Provide energy for the body– Fiber – helps food move through your digestive

tract– Starch – Complex carbohydrate– Sugar – Simple carbohydrate. It is the building

block of all carbohydrates

Nutrients of the Body

Fats - Provides energy for the body when carbohydrates are not available

– Fatty acids and glycerol – building blocks of fats

– Saturated – from animals mainly– Unsaturated – from plants mainly

Nutrients of the Body

Proteins - Provides energy for the body when fats and carbohydrates are not available.

– Used to build and repair the body– Amino acids – building blocks of proteins

Nutrients of the Body

• Minerals -- Helps your body function properly (ex. Keeps muscle, bones, nerves healthy)

• Vitamins – needed for chemical reaction to occur in the body (ex. Aids in blood clotting)

• Water – chemical reactions of the body take place in water.

Digestive System• Purpose of the digestive system is to fuel the

body with energy from nutrients.

• Types of Digestion– Mechanical – physical action of breaking

food down into smaller pieces (done in mouth and stomach)

– Chemical – food is broken down into the essential nutrients the body can use with the help of chemicals such as enzymes

“Lock and Key” System

+ =

carbohydrate enzyme

Sugars

“Lock and Key” System

• Enzymes– Chemicals that help break down substances

(foods)– Often end in “ase”

• Examples:– Amylase carbohydrates– Protease proteins– Lipase fats (lipids)

What’s missing?

Organs of the Digestive SystemMouth Salivary glands

• Food is mechanically digested with the help of the teeth and tongue

• secretes saliva into the mouth (chemical)

• Food is chemically digested with the help of saliva and the enzyme amylase

• Food doesn’t enter the salivary glands

• Saliva breaks down carbohydrates into sugars

• Chyme is the name of the chewed food in your mouth

Organs of the Digestive SystemEsophagus Stomach

• transports food to the stomach (mechanical)

• produces gastric juice to breakdown proteins into amino acids (chemical)

• Smooth muscles push food through the digestive tract, this is known as peristalsis

• A layer of mucus protects the stomach lining from gastric juice

• Churns food with strong muscles (mechanical)

Organs of the Digestive SystemLiver Gall Bladder

• produces bile that chemically digests food in the small intestine

• small sac underneath the liver which stores bile - mechanical

• Bile breaks down fats into fatty acids

• Food doesn‘t enter the liver

• Food doesn’t enter the liver

Organs of the Digestive System

Pancreas• Known as the “super gland”

• Produces pancreatic juice that chemically digests food in the small intestine

• Pancreatic juice breaks down carbohydrates, fats, and proteins

• Food doesn’t enter the pancreas

Organs of the Digestive System

Small Intestine Villi

• most important digestive organ (22-24ft long); absorption of nutrients through villi - mechanical

• Fingerlike projections inside small intestine; increase the surface area for nutrient absorption

• Bile and pancreatic juice digest food in the small intestine - chemical

• Absorption = mechanical digestion

• Intestinal juice breaks down carbohydrates and protein – chemical

Organs of the Digestive System

Large Intestine• Water is reabsorbed in the large intestine (3-4 ft. long) -

mechanical

• Waste products are collected in the large intestine (feces) and are stored in the rectum - mechanical

• Wastes are expelled from the body through the anus - mechanical

• No nutrients are absorbed in the large intestine