Chapter 17

Digestion:Breaking down food into the smallest end products

End Products:Small particles, small enough to pass through cell membrane

Absorption:Getting products into the circulation for cells to use

Eliminate Waste: Bowel Movement

Alimentary Canal (Gastrointestinal Tract)

Open tube from the mouth to the anus,all lines with mucous membrane, in total about 30 ft long.

Accessory Organs

Add secretions to the canals.LiverGall BladderPancreas

Layers of the Digestive System

Mucosa

Submucosa

Muscular

Mucus membrane lining. Specialized

call to secrete mucus and

digestive enzymes

Connective tissue, blood & lymph tissue. Have parasympathetic & Sympathetic nerve ending•Parasympathetic~ increase digestive secretion•Sympathetic~ Decrease digestive secretions

(2) Layers of smooth muscle run in different directions when the contract causes a wave like motion to push food through digestive system called peristalsis

1.2.

3.

Layers of the Digestive System

Peritoneum: Sirius membrane lining of abdominal cavity and covers digestive organs allows for movement

A. Parietal: Lines entire cavity

B. Visceral: Internal layer cover over organs in the cavity

1.) Omentum: Towards front fold of membrane start at stomach to the intestine, like an apron covers & helps support.

2.) Mesentery: Covers and attaches to intestine and attaches to posterior abdominal wall supports and holds loops of bowl in place

4.

Mouth-Oral Cavity

Roof: Roof of the mouth or oral cavity is made of the HARD (anterior) and SOFT (posterior) Palates

Uvula: Hangs down from the soft palate is a V-shaped structure, which assist with swallowing

Tongue:Frenulum:Papillae:

Located on the floor of the mouth. The tongue has Three functions 1. Swallowing- Deglutition 2. Taste 3. Production of sound

Fold of mucous membrane under the tongue

Rough elevations on the tongue which contain the taste buds.

Teeth: Allows us to perform MASTICATION or chewing. Calcium is the most important mineral for tooth growth.

Definitions

Pulp Cavity:

Enamel:

Root:

Inner area of a tooth which contains nerves and blood supply

Covers the part of the tooth above the Gingiva (gum) is the hardest substance in the body.

Entire tooth under the gum line

Crown: Tooth above the gum line

Deciduous: Baby teeth we develop 20 starting at 6 month of and begin to shed at 6 years old. They are replaced by 32 permanent (adult) teeth.

1. Parotid:

2. Submandibular:

3. Sublingual:

Produce saliva which is made of and a digestive enzyme called Amylase.

Back of mandible in front of ear

Under mandible

Under the tongue, floor of mouth

The Pharnyx or throat transports food after deglutition or swallowing. The epiglottis closes off

the trachea during swallowing

Esophagus :10 inch long tube carrying food away from the

pharynx to the stomach. It is lined with mucous membrane and has a muscular wall which performs “peristalsis” (wave like motion to

propel food)

Stomach

•Collapsible pouch, muscular wall is capable of great distention.•Located in LUQ, below the diaphragm•Lined with mucous membrane that lays in the fold or Rugae when empty.

Fundus:

Body:

P ylorus :

Upper section

Central Portion

Lower narrow end

SphinctersCardiac/Lower

Esophageal Sphincter:

Pyloric Sphincter:

Between the esophagus and stomach.

Between the stomach and small intestines.

Chyme:When liquid food

mixture enters the small intestine

1.Reservoir: Stores food2.Secretion: Mucus, HCL, Pepsin(and enzyme that digests

protein) and intrinsic factor for absorption of Vit B12 for RBC production.

3. Churns Food- Breaks down food into smaller pieces

4. Absorption- small amounts of water, alcohol(much faster absorption) and some

medications.

• 20 foot long tube with a diameter of 1inch. Coiled loops fill most

abdominal cavity.1st Section about one

foot long, joins the stomach and is called

the duodenum. The next section is the jejunum, about 8 ft long. Finals section, the ileum, is

11ft long. All lined with mucous membrane

Villi

Small projections or villi extends into the lumen. Single cell thick wall. !st function of small intestine- absorption of nutrients from the food we eat. Some end products of digestion pass into the

capillaries where they join the venous system. End products of fats are absorbed by lacteals and enter the lymph system for transport to the bloodstream. Glands in the mucous lining of the small

intestine secrete mucus and enzyme which help food digestion. (the 2nd function of small intestine) its smooth muscle wall performs peristalsis, pushing digested food to the next structure.

LARGE INTESTINE

AKA COLON• 5-6FT LONG

•2 ½ INCH DIAMETER

CECUM- 1ST SECTION 3 INCHES LONG. SMALL POUCH OFF THE BOTTOM OF THE CECUM IS THE APPENDIX. (NO DIGESTIVE FUNCTION BUT CONTAINS LYMPHATIC TISSUE AND PLAYS A SMALL ROLE IN THE BODY’S IMMUNE SYSTEM.) ILEOCECAL VALVE PREVENTS BACKFLOW FROM THE CECUM OF THE

LARGE INTESTINES INTO THE ILEUM OF THE SMALL INTESTINES. ASCENDING COLON: RUNS UPWARD ALONG THE RIGHT SIDE OF THE ABDOMEN TRANSVERSE COLON: RUNS ACROSS THE ABDOMEN

DESCENDING COLON: RUNS DOWN THE LEFT SIDE INTO THE PELVIS SIGMOID COLON: IS AN S-SHAPED PORTION OF THE COLON.

RECTUM: FINAL 6-8 INCH SECTION SERVES AS A TEMPORARY STORAGE AREA FOR UNDIGESTIBLE OR UNABSORBABLE FOOD .

ANUS: EXTERNAL OPENING IT IS COMPOSED OF THE ANAL SPHINCTER (INVOLUNTARY) AND AN EXTERNAL ANAL SPHINCTER (VOLUNTARY)

FUNCTIONS: NO DIGESTION •ABSORBTION OF WATER , SOME MINERALS AND SOME VITAMINS (VIT K IS PRODUCED BY NORMAL FLORA IN THE INTESTINES)

• SECRETION OF MUCUS• ELIMINATION OF WASTE (FECES)

Accessory Organs of Digestion

LiverGallbladder

Pancreas

Liver-HepatoLocation: RUQ

Function: •Produce bile(1 qt/day)•Stores glucose as glycogen and released prn•Stores fat-solube vitamins-A,D,E,K (Carried around on fat particles)•Makes plasma protein-albumin for water balance globulins for immunity (antibodies) fibrinogen & prothrombin for clotting•Filters blood-filter out toxins•Hemolysis-break down of old blood cells

Bile contains: bile salts, bile rouben(break down of RBC) cholesterolFunction of bile: Emulsification fatsFlow: Out of liver through hepatic ducts and common bile duct. Backs up at sphincter and drains empties into gallbladder.

Gallbladder-CholecystLocation: RUQ under(behind) liver

Functions:1. Stores and concentrates bile after produced in liver

2. When chyme enters the small intestines, the gallbladder contracts to eject bile

through the cystic duct, into the common bile and then into the duodenum

Pancreas-most important organ for digestive enzyme

Location: LUQ posterior to stomach

Functions:1. Endocrine

Beta cells in the illets of langerhauns secrete insulin to decrease blood glucose. Alpha cells secrete

glucagon to increase blood glucose.2. Exocrine

Digestive secretions empty into the pancreatic duct then into the duodenum.

a. HCO3- alkaline substanceb. Enzymes – breakdown all three major nutrients

Digestive processBreaking down food into end products

1. Mechanical-physically breaking down moving fooda. chewing- mastication decrease size of food. Swallowing- deglutition- physically propel food

toward stomachb. Churning –turning in stomach mix food up with enzyme & HCLc. Peristalsis- wave like motion to churn food around in stomach

2. Chemical – changing chemical composition of the food. Breaking down large molecules into small molecules that make up end products.

d. Bile – emulsify fats• 3 nutrients that do not require chem digestion > vitamin, minerals, water, already in the

smallest form.b. Enzyme < need to break down other major nutrients carbs, proteins, fats > secreted in mouth,

stomach, small intestine, pancreas c. End products: smallest particles from major nutrients

CHO-carbohydrates>glucoseProteins>amino acids

Fats>fatty acids glycerol

Digestive processB. Absorption: most takes place in small intestine

1.)stomach- alcohol some medications2.)small intestine- absorption mostly takes place here

a. villi-Blood capillaries through circulation< carbs, proteinsb. Fats- lacteals- lymp- blood

3.) large intestines water is reabsorbed, absorbs vitamins and minerals

c. Elimination- eliminate feces1. Bulk – fiber indigestible substance a. cellulose-(seeds, shells, skins off fruits)

2. Also in fecesa. Bacteriab. Waterc. Mucus

d. Bile pigments – cause stool to have a dark color

THE END!