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