Gastrointestinal System

What is the Gastrointestinal System?

Digestion Mechanical and chemical breakdown of foods and the

absorption of nutrientsMechanical digestion breaks large pieces into

smaller ones without altering their chemical composition

Chemical digestion breaks food into simpler chemicals

Alimentary Canal

Includes Mouth, Pharynx, Esophagus, Stomach, Small

Intestine, Large Intestine, Rectum, and Anus Accessory Organs

Salivary Glands, Liver, Gallbladder, and Pancreas

Mouth

Tongue Mixes food particles with saliva Frenulum – connects the tongue to the floor of the

mouthSalivary Glands

Serous Cells Secrete Amylase which breaks down glycogen

Mucous Cells Secrete Mucus which lubricates food while swallowing

Structure of the Mouth

Pharynx and Esophagus

• Passageways whose muscular walls function in swallowing

• Pharynx connects the nasal and oral cavities with the esophagus

• Esophagus connects the pharynx to the stomach– Lower Esophageal Sphincter closes the entrance to the

stomach, preventing stomach contents from regurgitating

• Peristalsis – a wavelike motion that propels food down a tube– A wave of contraction occurs, pushing down tubular

contentsBoth lined with stratified squamos epithelium

Peristalsis

Stomach

• J-Shaped pouch-like organ• Gastric Secretions– Chief Cells – Digestive enzyme pepsinogen– Parietal Cells – Hydrochloric Acid– Together form pepsin

• Begins the digestion of all types of protein

• Pyloric Sphincter– A muscular valve that controls gastric emptying into

the Small Intestine

Structure of the Stomach

Small Intestine

Coiled mass filling most of the abdominal cavity inferior to the stomach and liver – about 6-7 m long

Simple Columnar Receives secretions from the pancreas and

liver, completes digestion of the nutrients in chyme, absorbs the products of digestion, transports the residues to the large intestine Duodenum Jejunum Ileum

Digestion of Nutrients

Proteins and Peptides – Amino Acids

Lipids(fats) – Fatty Acids and Glycerol

Carbohydrates – Simple Sugars (monosaccharides)

Pancreas and Gallbladder

• Pancreas – Secretes pancreatic juice which digests

carbohydrates, fats, nucleic acids, and proteins– Pancreatic Lipase

• Gallbladder– Absorbs/stores bile between meals– Bile

• Yellowish-green liquid which breaks down fat globules into smaller droplets

• Also enhances absorption of fatty acids, cholesterol, vitamins A, D, E, and K

• Cystic Duct

Liver

General functions : Carbohydrate metabolism Lipid metabolism Protein Metabolism Storage Blood filtering Detoxification Secretion

Liver, Gall Bladder, and Pancreas

Large IntestineAbout 1.5 m longLined with simple columnar epitheliumNo longer digests food. Instead, absorbs

vitamins created by bacteriaConsists of the colon, cecum, rectum, and

anal canal(rectum)Secretes mucus, absorbs water and

electrolytes, forms and stores fecesRectum uses peristaltic movement to

remove fecal matter from the body

Large Intestine

Links

http://www.wisc-online.com/objects/ViewObject.aspx?ID=NUR2403

Diseases of Gastrointestinal System

Digestive disease that damages the SIInterferes with absorption of nutrients from

foodCannot tolerate gluten, a protein in:

Wheat Rye Barley Some medicines Some vitamins Some lip balms

Mal-absorption and an abnormal reaction to gluten

What is Celiac Disease?

If foods are eaten, or products are used that contain gluten, the immune system responds by damaging and/or destroying villi

Villi are tiny, fingerlike protrusions lining the SI that allow nutrients from food to be absorbed through the walls of the SI into bloodstream

Without villi, a person will become malnourished

What Happens?

Major Symptoms that occur Abnormal bloating and pain Chronic diarrhea Vomiting Pale, foul-smelling or fatty stool Weight loss Short status Anemia Bone/joint pain, arthritis, bone loss Leads to liver diseases and cancers of the intestine

What are the Symptoms?

GeneticCan be triggered by:

Surgery Pregnancy and childbirth Viral infection Severe emotional stress

People with celiac tend to have other disease: Type 1 Diabetes Autoimmune Thyroid Disease Autoimmune Liver Disease Rheumatoid Arthritis

What Causes it?

More than 2 million people in the US or 1 in 133 people

Has been long misdiagnosed, easily confused with: Irritable Bowel Syndrome Anemia Inflammatory Bowel Disease Diverticulitis Intestinal infections Chronic Fatigue Syndrome

Rate of Occurrence and Misdiagnosis

Blood tests are done for diagnosis Biopsy of SI is performed, to check the damage of

villiCheek swap samples check for DNA containing the

Celiac Disease geneHowever, there is no known cure

The best cure-> eliminate gluten from diet (i.e. read ingredient labels carefully

How its Diagnosed and Treated

Celiac Villi

Comparison of Celiac Villi

Non-Celiac Villi

Inflammation of digestive tract (inflammatory bowel disease)

Any area of the GI tract: mouth to anusUsually affects the lower part of the SI, called

the ileumSwelling extends deep into the lining of the

affected organ Causes pain and makes the intestines empty

diarrhea

What is Crohn’s Disease?

Blockage of the intestine Thickens intestinal wall (swelling and scar tissue,

narrowing the passage)Ulcers in the affected areas and into

surrounding tissues Nutritional complications also common in this

disease Deficiencies of proteins, calories, and vitamins are

caused by the inadequate dietary intake, intestinal loss of protein, or poor absorption

What Happens?

Overall symptoms: Abdominal pain in the lower right area Diarrhea Rectal bleeding Weight loss Arthritis Skin problems Fever

Children Delayed development and stunted growth

What are the Symptoms?

GeneticMore often in:

20-30 years old Jewish heritage

Can be difficult to diagnose because it is similar to other inflammatory bowel diseases, such as IBS

Rate of Occurrence and Misdiagnosis

Can be diagnosed through physical exams and a series of tests Blood test may be done to check for:

Anemia, which could indicate bleeding in the intestines A high white blood cell count, which is a sign of

inflammation somewhere in the body Testing a stool sample->reveal if there is bleeding or

infection in the intestinesFurther testing is required, such as a

colonoscopy

Diagnosis

Differs by how severe: Medications -> help control inflammation, correct

nutritional deficiencies, and relieve symptoms Most require surgery to remove inflamed tissue and

treat complications After surgery, there may be a period of remission but the

disease tends to reappear over a person’s lifetime

However, disease is unpredictable-> no set treatment for the disease, range of medication and surgery depends on the severity

Treatment

Intestinal view of the Inflammation of Crohn’s Disease

Diseases and Disorders (cont.)

Appendicitiswhat it is- an irritation, inflammation, and infection of the appendix. occurs when inside becomes filled with mucus, stool, or parasites (causes swelling)causes- pain, no purpose but if goes untreated it can burst and lead to infectionsymptoms- stomach ache on right sidediagnosis-blood and urine testmost occur between ages 10 and 30treatment: removal