PROCESS OF DIGESTION

PROCESS OF DIGESTION

Chapter 38-2Biology 392

Digestive System1. Function2. Structure3. Movement4. Processes

a. Digestioni. Mechanicalii. Chemical

b. Absorption5. Disorders

FUNCTIONBreaking down large food molecules into smaller nutrients.

INGESTIONDIGESTIONPERISTALSISABSORPTIONDEFECATION

STRUCTURE“FOOD TUBE”

• Mouth• Pharynx• Esophagus• Stomach• Small Intestine• Large Intestine

ACCESSORY ORGANS

• Teeth• Salivary Glands• Pancreas• Liver• Gall bladder

MOVEMENT• Mouth Moistens & tears food, results in

BOLUS “chewed clump of food”• Esophagus Bolus moves through tube by

PERISTALSIS rhythmic contractions• Sphincters tight rings of muscles that close

and open to separate the different organs– CARDIAC SPHINCTER

• Stomach after churning, food is liquefied = CHYME

– PYLORIC SPHINCTER

MOVEMENT (cont.)• Peristalsis movement through small intestine• Absorption through villi of small intestine into

blood stream nutrients travel everywhere!Go to all cells of body (brain is the priority) Proteins & Carbs go into blood Most fats go into lymphatic system

• Water is absorbed in large intestine• Undigested material passes through rectum • Leaves body through anus

PROCESS OF DIGESTIONMECHANICAL

• Physical change• Breaking food into smaller

parts by ripping, churning

• TEETH tear & crush• STOMACH churns

CHEMICAL

• Chemical change• Enzymes break bonds of

food molecules

• Enzymes are made and used by organs– Not always the same

• Each enzyme is specific to a type of macromolecule– Carb, fat or protein

Where does Digestion occur?What Nutrient is Digested?ORGAN TYPE OF DIGESTION NUTRIENT DIGESTED

MouthMechanical

Chemical

All

Carbohydrates

StomachMechanical

Chemical

All

Protein

Small Intestine Chemical All

ENZYMES OF DIGESTION

ENZYME SITE OF ACTION SITE of PRODUCTION NUTRIENT DIGESTED

Amylase

Pepsin

Lipase

Amylase

Trypsin

Peptidase

Maltase

Sucrase

Lactase

Mouth

Stomach

Small intestine

Small intestine

Small intestine

Small intestine

Small intestine

Small intestine

Small intestine

Salivary glands

Lining of stomach

Pancreas

Pancreas

Pancreas

Lining of small intestine

Lining of small intestine

Lining of small intestine

Lining of small intestine

Carbohydrate

Protein

Fat

Carbohydrate

Protein

Carbohydrate

Carbohydrate

Protein

Carbohydrate

OTHER SUBSTANCES INVOVLED IN DIGESTIONSUBSTANCE SITE OF ACTION ACTION

Saliva Mouth Moistens Food

MucusEsophagus, Stomach

Sm. & Lg. Intestines

Helps food move easily

Protects organs

Hydrochloric Acid (HCl) Stomach Helps breakdown food

Kills bacteria

Sodium bicarbonateSmall Intestine

(made in pancreas)

Neutralizes acid so

enzymes can function

BileSmall intestine

(made in liver,

stored in gall bladder)

Separates fat droplets,

making them easier to

break down.

Bacteria Large IntestineHelp breakdown food

Produce vitamin K

ABSORPTION

• After Polymers are broken into Monomers, they must “enter” the body & be circulated.

• Absorbed across the cell membranes of each cell lining the small intestine

• Surface area of S.I. is increased by folds– Villi and microvilli

ABSORPTION cont.

• Water is also absorbed• Occurs across the wall of the Large Intestine

• All that is left is concentrated waste– Undigested material– Cellulose, fiber

ELIMINATION

• Undigested moves through large intestine and is held in rectum until it is eliminated

DISORDERS• Heartburn stomach acid enters esophagus

because of weak cardiac sphincter• Peptic Ulcer Hole in stomach wall caused by

Helicobacter pylori. The pain is caused by the acid.

• Diarrhea Not enough water is absorbed• Constipation Too much water is absorbed• Diabetes Glucose cannot enter cells of body

very well, therefore glucose cannot get turned into energy!!

Diabetes• 6th killer in America (and rising)• Pancreas cannot produce insulin or the body

does not use it properly• Insulin is a hormone that decreases the

amount of sugar in the blood by helping it enter the cells of the body.– Glucose does not enter cells easily, insulin must

“act like a butler” and bind to a cell membrane protein to help it in.

SUMMARY QUESTIONS

• What are the 2 types of digestion?• Where does digestion begin?• Where does MOST digestion happen?• Where do nutrients enter the rest the of the

body? (i.e. leave the GI tract)