DIGESTIVE SYSTEMBy GERALDINE SABATE RIDAD, RN

LEAH MAY P. MADJUS, RN, MN

Functions of DIGESTIVE SYSTEM TAKE IN FOOD

BREAK DOWN THE FOOD

ABSORB DIGESTED MOLECULES

PROVIDE NUTRIENTS

ELIMINATE WASTES

DIGESTIVE SYSTEMconsists of the DIGESTIVE TRACT, SALIVARY GLANDS, and ACCESSORY ORGANS (LIVER, PANCREAS, and GALLBLADDER)

DIGESTIVE TRACT is called the ________.

oral cavitypharynxesophagus

Stomachsmall intestinelargeintestineanus

4 Layers Of Digestive Tract1. MUCOSA – consists of mucous epithelium,

lamina propria and muscularis mucosa

2. SUBMUCOSA- thick layer of connective tissue containing NERVES, BLOOD VESSELS, and SMALL GLANDS.

3. MUSCULARIS- consists of an inner layer of CIRCULAR SMOOTH MUSCLE and an outer layer of LONGITUDINAL SMOOTH MUSCLE

4. SEROSA or ADVENTITIA>SEROSA- peritoneum and underlying connective tissue>ADVENTITIA- not covered by peritoneum

PERITONEUM VISCERAL peritoneum-

PARIETAL peritoneum-

PERITONITIS-

MESENTERIES- hold many of the organs in place within the abdominal cavity.

RETROPERITONEAL ORGANS- other abdominal organs lie against the abdominal wall, have no mesenteries.

ORAL CAVITY

MOUTH, is the FIRST PART of the digestive tract, bounded by lips and cheeks and contains the teeth and tongue.

MASTICATION- chewing; begins the process of MECHANICAL DIGESTION

TONGUE- moves food in mouth, holds food in place during mastication, facilitates SWALLOWING , major sensory organ for TASTE and SPEECH

TEETH

There are 32 teeth in normal adult mouth located in the mandible or maxillary.

Teeth of adults are PERMANENT or SECONDARY TEETH replacement of the 20 DECIDUOUS/ PRIMARY TEETH

Facilitates in MECHANICAL DIGESTION of food

PALATE ROOF of oral cavity

2 parts:

1.HARD PALATE

2.SOFT PALATE

>>separates the oral cavity from the nasal cavity and prevents food from passing into it during chewing and swallowing!!!

TONSILS

TONSILS- are located in the lateral posterior wall of the oral cavity, in the nasopharynxand posterior surface of tongue

SALIVARY GLANDS

Produce SALIVA which is a mixture of SEROUS and MUCUS FLUIDS

Saliva helps keep the oral cavity MOIST and contains enzymes that begin the process of CHEMICAL DIGESTION

1. PAROTID- largest; just anterior to the ear;

(***mumps)

2. SUBMANDIBULAR- produce more serous than mucous secretions

3. SUBLINGUAL- smallest; produce primarily mucus secretions

SECRETIONS of ORAL CAVITY

1. SALIVARY AMYLASE- digestive enzyme in saliva, DIGESTS STARCH (to glucose or isomaltose or maltose)

2. MUCIN – PROTEOGLYCAN that gives a lubricating quality to saliva

Regulated by AUTONOMIC NERVOUS SYSTEM

P

S

FLUID OR ENZYME

FUNCTION

SALIVA Moistens and lubricates food

SALIVARY AMYLASE

Starch digestion (conversion to maltose and isomaltose)

LIPASE Begins LIPID DIGESTION

LYSOZYME Weak antibacterial action

MASTICATION

Breaks LARGE food particles into many small ones; since digestive enzymes act on molecules only at the surface of the food particles, mastication increases EFFICIENCY OF DIGESTION

PHARYNX

THROAT, which connects MOUTH with ESOPHAGUS

3 PARTS

1.NASOPHARYNX

2.OROHARYNX

3.LARYNGOPHARYNX

PHARYNGEAL LIPASE- facilitates lipid digestion

ESOPHAGUS

lined with STRATIFIED SQUAMOUS EPITHELIUM, that extends from pharynx to the stomach

Passes through the DIAPHRAGM

UPPER ESOPHAGEAL SPHINCTER

LOWER ESOPHAGEAL SPHINCTER-CARDIAC SPHINCTER; regulate the movement of food into and out of esophagus.

peristalsis

DEGLUTITION swallowing

3 separate phases:

1. VOLUNTARY PHASE- BOLUS is formed, pushed by tongue against the hard palate into the oropharynx

2. PHARYNGEAL PHASE- begins with the elevation of soft palate, which closes the passage between the nasopharynxand oropharynx

- EPIGLOTTIS is tipped posteriorly covering the LARYNX

3. ESOPHAGEAL PHASE- moving food from pharynx to stomach

>>peristaltic contractions associated w/ swallowing cause relaxation of lower esophageal sphincter as peristaltic waves approach the stomach.

STOMACH Located in the LEFTSUPERIOR part of

the abdomen( )

RUGAE- large folds that allow the STOMACH to stretch when stomach is filled

lined with SIMPLE COLUMNAR EPITHELIUM

gastric pits are openings for GASTRIC GLANDS

5 types of EPITHELIAL CELLS:

1. SURFACE MUCOUS CELLS- produce MUCUS which coats and protects the stomach lining and gastric pits

2. MUCOUS NECK CELLS

3. PARIETAL CELLS-produce HCL acid and intrinsic factor

4. ENDOCRINE CELLS-produce regulatory hormones

5.CHIEF CELLS-produce pepsinogen

SECRETIONS of the STOMACH Functions primarily as a storage and mixing

chamber for ingested food

_________ CHYME

HYDROCHLORIC ACID

INTRINSIC FACTOR

PEPSINOGEN

GASTRIN

REGULATION of STOMACH SECRETIONS CEPHALIC PHASE

GASTRIC

INTESTINAL PHASE

-when CHYME (W/ ph 2.0) enters the DUODENUM SECRETIN and CHOLECYSTOKININ is released

HEARTBURN-

>>painful or burning sensation in the chest usually associated w/ an increase in gastric secretion and /or backflush of acidic chyme into the esophagus

SMALL INTESTINEAbout 6m long; the site at which

greatest amount of digestion and absorption occur.

Duodenum

Jejunum

Ileum

DUODENUM-

common bile duct+pancreatic duct

VILLI- covered by SIMPLE COLUMNAR EPITHELIUM

>> contains blood capillary network and LACTEAL

MAJOR CELL TYPES:

1. ABSORPTIVE CELLS

2. GOBLET CELLS

3. GRANULAR CELLS(PANETH’S CELLS)

4. ENDOCRINE CELLS

PEYER’S PATCHES- found in ILEUM

VIT B12 ABSORPTION???

ILEOCECAL JUNCTION

ILEOCECAL SPHINCTER and VALVE

SECRETIONS of SMALL INTESTINE Peptidases

Sucrases

Maltase

Lipase

Cholecystikinin

Secretin

Acidic chyme enters SMALL INTESTINEsignals the release of hormones:

CHOLECYSTOKININ inhibits GASTRIC SECRETION

contracts GALLBLADDER to release digestive enzymes

contracts PANCREAS to release digestive enzymes

SECRETIN inihbits G.S

and LIVER to release BILE

contracts PANCREAS to release BICARBONATE

MOVEMENTS of SMALL INTESTINE PERISTALTIC CONTRACTIONS- proceed

along the length of the intestine for variable distances and cause chyme to move along the small intestine

SEGMENTAL CONTRACTIONS- propagated for only short distances and function to mix intestinal contents

LIVER located in the

__________________.

2 MAJOR lobes:

1.

2.

CIRCULATION

1. HEPATIC ARTERY-

2. HEPATIC PORTAL VEIN-

3. HEPATIC VEIN-

LIVER1. The hepatic ducts from the

liver lobes combine to formthe common hepatic duct.

2. The common hepatic ductcombines with the cysticduct from the gallbladder toform the common bile duct.

3. The common bile duct andthe

pancreatic duct combine to formthe hepatopancreaticampulla.

4. The hepatopancreatic ampullaempties into the duodenumat the major duodenalpapilla.

5. Pancreatic secretions alsoenter the duodenum throughthe

hepatopancreatic ampulla. The

accessory pancreatic duct alsoempties into the duodenum.

FUNCTIONS OF THE LIVER

DIGESTION

EXCRETION Excretion of CHOLESTEROL, FATS, and BILIRUBIN

NUTRIENTSTORAGE

Store glucose (as GLYCOGEN in liver), fats, VITAMINS (ADEK, B12), and MINERALS (copper and IRON)

NUTRIENT CONVERSION

1.GLYCOGENOLYSIS

2.

DETOXIFICATION 1.AMMONIA 2.DRUG-FIRST PASS

SYNTHESIS of NEW

MOLECULES

Blood proteins: ALBUMIN, FIBRINOGEN, GLOBULINS, and CLOTTING FACTORS

GALLBLADDER holds 30-50 ml of bile, lies

below the liver

CONCENTRATES BILE from liver 5-10 times by absorbing its water and electrolyte content

Inflammation of GALLBLADDER?

GALLSTONE FORMATION?

CHOLECYSTECTOMY?

PANCREAS located RETROPERITONEAL, posterior

to stomach

A complex organ composed of both endocrine and exocrine tissues

The endocrine part consists of the pancreatic islets (islets of Langerhans)

The exocrine part is the acinar gland

ACINI- produce digestive enzymes

FUNCTIONS of PANCREAS PROTEOLYTIC ENZYMES:

1.Chymotrypsin

2.Trypsin

3.Carboxypeptidase

4.Peptidase

PANCREATIC AMYLASE – continues the polysaccharide digestion that was initiated in the oral cavity

PANCREATIC LIPASES – break down lipids

FUNCTIONS of PANCREAS• CCKCHOLECYSTOKININ inhibits

GASTRIC SECRETION/ contracts GALLBLADDER to release digestive enzymes

• SECRETIN inihbits G.S/ contracts GALLBLADDER to release BICARBONATE and LIVER to release BILE

LARGE INTESTINECECUM- RLQ; where APPENDIX is

attached

APPENDICITIS

McBurney’s Point

PERITONITIS

APPENDECTOMY

LARGE INTESTINE COLON:

1. ASCENDING COLON

2. TRANSVERSE COLON

3. DESCENDING COLON

4. SIGMOID COLON

RECTUM

ANAL CANAL

1. INTERNAL ANAL SPHINCTER

2. EXTERNAL ANAL SPHINCTER

FUNCTIONS of LARGE INTESTINE chyme is converted into FECES

absorbs WATER and SALTS

DEFECATION

some bacteria in the colon synthesize VITAMIN K, which is passively absorb in the intestine.

MASS MOVEMENTS- propel the colon contents a considerable distance toward the anus

HEMORRHOIDS

CONSTIPATION

DIARRHEA