Digestive System AdultEd0

7/28/2019 Digestive System AdultEd0

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Anatomy and Physiology

The Digestive System

Community Education

Mr. Kestner


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Digestive System

The digestive system, also known as the

gastrointestinal system, is responsible for the

physical and chemical breakdown of food

Breakdown is necessary so food can be taken into

bloodstream and used by body cells and tissues

System consists of alimentary canal and

accessory organs


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Food Breakdown

Ingestion

Taking of food into the body

Peristalsis

Physical movement along the tract

Digestion

Mechanical and chemical breakdown of food

Absorption Passage of food from digestive tract into body

Defecation

Elimination of indigestible substances from body


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Alimentary Canal

A long, muscular tube that begins at the

mouth and includes the mouth (oral cavity),

pharynx, esophagus, stomach, small intestine,

large intestine, and anus

Accessory Organs

Accessory organs are the salivary glands,

tongue, teeth, liver, gallbladder, and pancreas


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Parts of the Alimentary Canal

The mouth, also called the buccal cavity,

receives food as it enters body

While food is in mouth, it is

Tasted

Broken down physically by teeth

Lubricated and partially digested by saliva

And swallowed


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The teeth are special structures in mouth thatphysically break down food by chewing andgrinding

Process is called mastication

The tongue is a muscular organ that containsspecial receptors, called taste buds

Taste buds allow a person to taste sweet, salt,sour, and bitter sensations

The tongue also aids in chewing and swallowingfoods


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The hard palate is the bony structure that forms the

roof of the mouth and separates the mouth from the

nasal cavities

Behind the hard palate is the soft palate, whichseparates the mouth from the nasopharynx

The uvula, a cone-shaped muscular structure, hangs

from the middle of the soft palate and prevents food

from entering the nasopharynx during swallowing


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Three pairs of salivary glands Parotid (cheek/jaw)

Sublingual (beneath tongue)

Submandibular (chin/neck)

They produce a liquid called saliva Saliva lubricates mouth during speech and chewing and

moistens food so it can be swallowed easily

Also contains enzyme called salivary amylase

Salivary amylase begins chemical breakdown ofcomplex carbohydrates, or starches, into sugars thatcan be taken into the body


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After food is chewed and mixed with saliva, it is

called a bolus

When bolus is swallowed, it enters the pharynx

(throat)

Pharynx is a tube that carries both air (to

trachea) and food (to esophagus)

When a bolus is being swallowed, muscle actioncauses epiglottis to close over larynx


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The esophagus is the muscular tube dorsal to thetrachea

It receives bolus form pharynx and carries it to

stomach Esophagus, and remaining part of alimentary

canal, relies on rhythmic, wavelike, involuntarymovement of its muscles

Called peristalsis, it moves food in forwarddirection


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The stomach is an enlarged part of alimentary

canal and receives food from esophagus

Mucous membrane lining stomach contains folds

called rugae

Folds disappear as stomach fills with food

Two sphincters at stomach ends called

Cardiac sphincter

Pyloric sphincter


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Cardiac sphincter

Circular muscle between esophagus and stomach

Closes after food enters stomach

Prevents food from going back into esophagus

Pyloric sphincter

Circular muscle between stomach and small intestine

Keeps food in stomach until food is ready to enter intestine

Food usually remains in stomach approx. 1-4 hours


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During time food is in stomach, it is converted

into a semifluid material, called chyme

Chyme is from gastric juices produced by glands

in stomach mixed with bolus

Gastric juices contain HCL and Pepsinogen

HCL kills bacteria, facilitates Fe absorption, and

activates the enzyme pepsin (which starts proteindigestion)


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When food, in form of chyme, leaves stomach, itenters the small intestine

The small intestine is a coiled section ofalimentary canal

Approximately 20 feet in length and one inch indiameter

Divided into three sections

Duodenum Jejunum

Ileum


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The duodenum is the first nine to ten inches of the

small intestine

Bile (from gallbladder and liver) and pancreatic juice

(from pancreas) enter this section through ducts, ortubes

The jejunum is approximately eight feet in length and

forms middle section

The ileum is the final 12 feet of small intestine, and

connects with large intestine at the cecum


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Process of digestion is completed while food is

in small intestine

Products of digestion are absorbed into

bloodstream for use by body cells

Intestinal juices produced by small intestine

contain enzymes maltase, sucrase, and

lactase, which break down sugars into simpler

forms


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Intestinal juices contain enzymes known as

peptidases, which complete the digestion of proteins

Juices also contain steapsin, which aids in the

digestion of fat Bile from liver and gallbladder emulsifies (physically

breaks down) fats

Enzymes from pancrease, like amylase (for sugars)and lipase (for fats) also aid in breakdown


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After food has been digested, it is absorbed

into bloodstream

Walls of small intestine are lined with

fingerlike projections called villi

The villi contain blood capillaries and lacteals


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Capillaries absorb digested nutrients and carrythem to liver, where they are either stored orreleased into circulation for use by body cells

Lacteals absorb most of digested fats and carrythem to thoracic duct in lymphatic system, whichreleases them into circulation

When food has completed its passage through

small intestine, only wastes, indigestible materials,and excess water remain


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The large intestine is the final section of thealimentary canal

It is approximately five feet in length and two-and-a-half inches in diameter

Functions include

Absorption of H2O and any remaining nutrients

Storage of indigestible materials before eliminated

Synthesis (formation) and absorption of some B-complexvitamins and vitamin K by bacteria present

Transportation of waste products out of body


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The large intestine is divided into a series ofconnected sections

The cecum is the first section, attached to smallintestine contains a small projection called thevermiform appendix

Next section is the colon with several divisions

Ascending colon

Transverse colon

Descending colon

Sigmoid colon


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The rectum is the final six to eight inches of the

large intestine and is a storage area for

indigestibles and wastes

It has a narrow canal, called the anal canal,

which opens at a hole, called the anus

Fecal material, or stool, the final waste product

of the digestive process, is expelled through thisopening


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Accessory Organs

The liver Largest gland in the body

Located under diaphragm; in RUQ of abdomen

Secretes bile Used to emulsify fats and

Makes fats water soluble necessary for absorption

Stores sugar in form of glycogen Glycogen converts to glucose and released into bloodstream when additional

blood sugar is needed

Stores Fe and certain vitamins

Produces heparin, which prevents clotting of blood

Produces proteins such as fibrinogen and prothrombin Produces cholesterol

Detoxifies substances such as alcohol and pesticides, and destroysbacteria taken into blood from intestine


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Accessory Organs

The pancreas A glandular organ located behind stomach

Produces pancreatic juices containing enzymes to digestfood

Juices enter duodenum through pancreatic duct

Enzymes in juices break down sugars, proteins, and fats

Produces insulin, secreted into bloodstream

Regulates metabolism (or burning) of carbohydrates toconvert glucose (blood sugar) into energy


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Diseases/Abnormal Conditions

Appendicitis Acute inflammation of appendix

Usually resulting from obstruction and infection

Symptoms include

Generalized abd pain, later localizes at RLQ Nausea and vomiting

Mild fever

Elevated white blood count

Treatment Appendectomy

If appendix ruptures, infectious material will spill intoperitoneal cavity causing peritonitis, a serious condition


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Cholecystitis Inflammation of the gallbladder

When gallstones form from crystallized cholesterol, bile salts, and bilepigments, the condition is known as cholelithiasis

Symptoms (frequently occur after eating fatty foods) include

Indigestion Nausea and vomiting

Pain that starts under the rib cage and radiates to the right shoulder

Treatment Low-fat diet

Lithotripsy (low shock waves used to shatter gallstones)

Cholecystectomy

If gallstone blocks bile ducts, gallbladder can rupture and causeperitonitis


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Cirrhosis Chronic destruction of liver cells accompanied by formation of fibrous

connective and scar tissue

Causes include Hepatitis, bile duct disease, chemical toxins, and malnutrition associated with

alcoholism

Symptoms (vary and become more severe as disease progresses) include Hepatomegaly (enlarged liver), Anemia, Indigestion, Nausea and vomiting,

Nosebleeds, Jaundice, and Ascites (accumulation of fluid in peritoneal cavity)

When liver fails, disorientation, hallucinations, hepatic coma, and death occur

Treatment Directed toward preventing further damage to liver

Alcohol avoidance, proper nutrition, vitamin supplements, rest, infectionprevention, and appropriate exercise are encouraged


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Constipation When fecal material remains in colon too long, causing excessive

reabsorption of water

Feces, or stool, becomes hard, dry, and difficult to eliminate

Causes include

Poor bowel habits, chronic laxative use leading to a lazy bowel, dietlow in fiber, and certain digestive diseases

Treatment

Usually corrected by a high fiber diet

Adequate fluids

Exercise Although laxatives are sometimes used to stimulate defecation,

frequent laxative use may be habit froming and lead to chronicconstipation


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Diarrhea Condition characterized by frequent watery stools

Can be extremely dangerous in infants and childrenbecause of the excessive fluid loss

Causes include Infection, stress, diet, irritated colon, toxic substances

Treatment

Directed toward eliminating cause Providing adequate fluid intake

Modifying diet


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Diverticulitis Inflammation of the diverticula, pouches (or sacs) that form in the

intestine as the mucosal lining pushes through the surrounding muscle

Causes include

Fecal matter and bacteria becoming trapped in the diverticula

Can result in abscess or rupture leading to peritonitis Symptoms (vary depending on amount of inflammation) include

Abd pain, irregular bowel movements, flatus, constipation or diarrhea,abd distention, low-grade fever, and nausea and vomiting

Treatment

Antibiotics, stool-softening medications, pain medications, andsurgery to remove the affected section of the colon (in severe cases)


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Gastroenteritis An inflammation of the mucous membrane that lines

the stomach and intestinal tract

Causes include Food poisoning, infection, and toxins

Symptoms include Abd cramping, nausea, vomiting, fever and diarrhea

Treatment Usual methods are rest and increased fluid intake

Severe cases: antibiotics, IV fluids, and medications to slowperistalsis may be used


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Hemorrhoids Painful, dilated or varicose veins of the rectum and/or anus

Causes include Straining to defecate, constipation, pressure during

pregnancy, insufficient fluid intake, laxative abuse, andprolonged sitting or standing

Symptoms include Pain, itching, and bleeding

Treatment High-fiber diet; increased fluid intake; stool softeners; sitz

baths or warm, moist compresses; and, in some cases, ahemorrhoidectomy


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Hepatitis A viral inflammation of the liver

Type A, HAV, or infectious hepatitis highly contagious

transmitted in food or water contaminated by feces of infected person

Vaccine is available to prevent HAV Type B, HBV, or serum hepatitis

transmitted by blood and serum

more serious than HAV and can lead to chronic hepatitis or cirrhosis ofthe liver

Vaccine developed to prevent HBV is recommended for all health careworkers

Other strains of hepatitis virus identified include types C, D, and E


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Symptoms of hepatitis include

Fever, Anorexia (lack of appetite), Nausea,

Vomiting, Fatigue, Dark-colored urine, Clay-

colored stool, Enlarged liver, and Jaundice

Treatment methods include

Rest and a diet high in protein and calories and

low in fat A liver transplant may be necessary if the liver is

severely damaged


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Hernia Or rupture, occurs when an internal organ pushes through a weakened area or

natural opening in a body wall

Hiatal Hernia When the stomach protrudes through the diaphragm and into the chest cavity

through the opening for the esophagus

Inguinal Hernia When a section of the small intestine protrudes through the inguinal rings of

the lower abdominal wall

Symptoms include Heartburn, stomach distention, chest pain, and difficult swallowing

Treatment A bland diet, small frequent meals, staying upright after eating, and surgical

repair

If hernia cannot be reduced (pushed back in place) a herniorrhaphy isperformed


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Pancreatitis Inflammation of the pancreas

Pancreatic enzymes begin to digest pancreas itself becomes necrotic,inflamed, and edematous; If damage extends to blood vessels in pancreas,hemorrhage and shock occur

Causes May be caused by excessive alcohol consumption or blockage of pancreatic

ducts by gallstones

Many cases are idiopathic, or of unknown cause

Symptoms include Severe abd pain that radiates to back, nausea, vomiting, diaphoresis, and

jaundice if swelling blocks the common bile duct

Treatment depends on cause Cholecystectomy is performed if gallstones are cause

Analgesics for pain and nutritional support are used if cause is alcoholism oridiopathic

This type of pancreatitis has a poor prognosis and often results in death


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Peritonitis Inflammation of the abdominal peritoneal cavity

Usually occurs when a rupture in the intestine allows theintestine contents to enter the peritoneal cavity

A ruptured appendix or gallbladder can cause thiscondition

Symptoms include Abd pain and distention, fever, nausea and vomiting

Treatment includes Antibiotics

Surgical repair of damaged intestine (if necessary)


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Ulcer An open sore on the lining of the digestive tract

Peptic ulcers include gastric ulcers and duodenal ulcers

Causes

Major cause is bacterium Helicobacter pylori (H. pylori), that burrows

into stomach membranes, allowing stomach acids and digestive juicesto create an ulcer

Symptoms include

Burning pain, indigestion, hematemesis, and melena (dark, tarry stool)

Usual treatment methods are

Antacids, a bland diet, decreased stress, and avoidance of irritants

such as alcohol, fried foods, tobacco and caffeine IfH. pyloribacteria are present, treatment with antibiotics and Pepto-

Bismol usually cures the condition

Severe cases, surgery is performed to remove the affected area


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Ulcerative colitis Severe inflammation of colon accompanied by formation of ulcers &

abscesses

Thought to be caused by stress, food allergy, or autoimmune reaction

Main symptom is diarrhea containing blood, pus, and mucous

Other symptoms include wt. loss, weakness, abd pain, anemia, andanorexia

Periods of remission and exacerbation are common

Treatment

Directed toward controlling inflammation, reducing stress, maintainingproper nutrition, and avoiding substances that aggravate condition

In some cases, surgical removal of the affected colon and creation of acolostomy is necessary

Artificial open in colon allows fecal material to be excreted through abd

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Digestive System AdultEd0