Nutrients…• substances in food that provide

energy and materials for cell development, growth, and repair.

Classes of Nutrient - Organic

CarbohydratesCarbohydrates: main source of energy

ProteinsProteins: used for growth.  FatsFats: provide energy (stored) helps body absorb vitamins

VitaminsVitamins: organic nutrients that help your body to use other nutrients.

Classes of Nutrients - Inorganic MineralsMinerals: Inorganic nutrients that

regulate many chemical reactions

WaterWater: Enables chemical reactions to take place in your cells.

Enzymes - Reviewspeed up the rate of

chemical reactions

They do this without being changed or used up.

speed up reactions by reducing amount of energy necessary for a chemical change to begin.

Digestive Enzymes

AMYLASE secreted in the mouth; breaks down carbohydrates (starches).

PEPSIN, found in the stomach, breaks down proteins.

Lipase made in pancreas; breaks down fats

Additional Chemical Digestives

• Gastric Juice – found in stomach; very acidic; (3 million times more acidic than your bloodstream) a combination of HCL and Pepsin; breaks proteins

• Bile – made in liver; first process in breaking fats.

Digestion Processes

• Chemical: chemicals in the body break large molecules into smaller ones

• Mechanical: physical, using teeth or muscle to help break food down

The Alimentary CanalMouth - chemical digestion •glands in mouth produce saliva, which contains amylase, which breaks down starch

Mouth• Mechanical Digestion:

– Teeth and tongue break food into smaller pieces

Digestive System

Esophagus: muscular tube connects throat to stomach.

Moves food down by squeezing (peristalsis)

Peristalsis• Rhythmic contraction of esophagus to move

food to stomach.• https://www.youtube.com/watch?v=rJS-Kh5wCQU

Your Digestive SystemStomach: muscular bag

Chemical Digestion: pepsin; gastric acid

Mechanical Digestion: stomach contractions; food stays here ~2-6 hours,

End Product:chyme: afood sludge

Digestive SystemLiver: produces bile; stored in

gallbladder. Bile breaks up large particles of fats into

smaller particles.

Some of Liver’s Jobs

• filters the blood coming from the digestive tract

• detoxifies chemicals and metabolizes drugs.

• secretes bile (breaks down fats)

• makes proteins important for blood clotting

Your Digestive System

Gall Bladder: small sac that stores bile produced by liver (breaks down fats)

Your Digestive SystemPancreas: • produces substances that stop the action of

stomach acid• produces lipase which breaks fats

Pancreas’ Other Jobs• excretes enzymes to break down the

proteins, lipids, carbohydrates, and nucleic acids in food.

• as an endocrine gland, secretes the hormones insulin and glucagon to control blood sugar levels throughout the day.

Digestive SystemSmall Intestine:

digestive juices from liver and pancreas are added

villi increase surface area for absorption of nutritents from chyme

Villi

Small Intestines

• absorbs about 90% of the nutrients from the food we eat.

• only 1 inch in diameter, making it less than half the diameter of the large intestine.

https://www.youtube.com/watch?v=CFjlRhs1rR8

3 Parts of Small Intestine - FYI

• duodenum – connects to the pyloric sphincter of the

stomach.

• Partially digested food, or chyme, from the stomach is mixed with bile from the liver and pancreatic juice from the pancreas to complete its digestion in the duodenum.

3 Parts of Small Intestine - FYI

• The jejunum is the middle section; primary site of nutrient absorption

• The ileum is the final section and completes the absorption of nutrients that were missed in the jejunum.

Digestive System

•Large Intestine: absorbs (removes) water from undigested food; – unabsorbed

materials become more solid (waste - poop).

Your Digestive SystemRectum: where muscles control

the release of wastes from the body

https://www.youtube.com/watch?v=Ujr0UAbyPS4

The Human Digestive System

http://www.dnatube.com/video/8362/Digestive-System-Animation