The GI System Flashcards
Functions of the GI system
Digest and absorb ingested nutrients
Excrete waste products
GI system and Nutrients
Most nutrients are too complex for absorption or completely insoluble so the GI system degrades them enzymatically in the simple molecules sufficiently small in size and in a form that permits absorption across the mucosa epithelia
Upper GI Tract
Includes the mouth, esophagus, stomach and duodenum
Aids in the ingestion and digestion of food
Lower GI Tract
Includes small and large intestines
Small intestine
Accomplishes digestion and absorption of nutrients
Large intestines
Absorbs water and electrolytes, storing waste products of digestion until elimination
Integrity of the GI tract immune function and host defense
The gut immune system has 70% to 80% of the body’s immune cells, and the protective blocking action of the secretory response in the gut is crucial to the integrity of the GI tract immune function and host defense
What happens with a reduction of normal bacteria in the gut after antibiotic treatment or in the presence of infection?
May interfere with the nutrients available for immune functions in the GI system
The GI sytem
Harvest the largest micro bio load in the human body
Maintaining balance between immunity against invading pathogens and tolerance to commensal
Commensals
Types of micros that reside on either the surface of the body or the mucosa
These micros don’t harm human health, live in harmony with humans mostly consist of bacteria
x10 more of these bacteria than actual cells in the body
Intestinal homeostasis
Conducted by a tight regulation by cooperation of different branches of the immunity system that includes the innate and adaptive
If there is any source of disruption in this delicate balance, it is going to lead to GI disorders
Signs and Symptoms of GI Disease
Nausea
Vomiting
Diarrhea
Constipation
Dysphagia-difficulty w/swallowing
Achalasia-esophagus muscles don’t contract properly = don’t help propel food down the stomach
Heartburn
Abdominal Pain
GI Bleeding
Fecal incontinence
Most common GI problems in older adults
Constipation
Incontinence
Diverticular disease
Each of these disorders has many different underlying causes
What happens to the alimentary organs (esophagus, stomach, small intestine, and colon) with age?
Like all muscular structures, lose some tone with age but still manage to perform almost as well in age as in youth
Changes within the alimentary tract include decreases in gastric motility, blood flow, nutrient absorption, and volume and acid content of gastric juice
The Esophagus - Hiatal hernia
Upper part of the stomach bulges through the diaphragm
Hernias are either congenital, resulting from a failure of formation or fusion of the multiple developmental components of the diaphragm, or acquired. Acquired hernias can also be categorized as either sliding or paraesophageal
The Esophagus - Hiatal hernia
Incidence
Estimated as 5 per 1000 people, increases with age and may be as high as 60% in people older than 60 years of age. Women>men; children may have the sliding type but do not usually exhibit symptoms until they reach middle age.
Age, common on ppl over 50, obesity, smoke
The Esophagus - Hiatal hernia
Risk factors
Weakening of the diaphragm muscle or anything that alters the hiatus (the opening in the diaphragm for the passage of the esophagus) and increases intraabdominal pressure can predispose a person to hiatal hernia.
Muscle weakness can be congenital or caused by aging, trauma, surgery, or anything that increases intraabdominal pressure
The Esophagus - Hiatal hernia
Symptoms
Heartburn or reflux
Causes of Increased Intraabdominal Pressure:
* Lifting
* Straining
* Bending over
* Prolonged sitting or standing
* Chronic or forceful cough
* Pregnancy
* Ascites
* Obesity
* Congestive heart failure
* Low-fiber diet
* Constipation
* Delayed bowel movement
* Vigorous exercise
Gastroesophageal Reflux Disease (GERD)
Backward flow
Common condition in which the stomach contents move up into the esophagus
Reflux becomes a disease when it causes frequent or severe symptoms or injury, may damage the esophagus, pharynx, or respiratory tract
Primary symptom is heartburn
GERD - Incidence
Most common disorders seen in clinics
Approximately 10% to 20% of American adults have this disorder, seen equally in men and women
Older people are more likely to develop severe disease
GERD - Risk Factors
Low pressure of the lower esophageal sphincter (LES)
Hiatal hernias
Medications, cigarette smoking, esophageal dysmotility disorders, and xerostomia (dry mouth) all can lead to increased acid exposure
What are the 3 factors involved in aiding the esophagus to remain healthy?
- anatomic barriers between the stomach and the esophagus,
- mechanisms to clear the esophagus of stomach acid,
- and maintaining stomach acidity and acid volume
GERD - Symptoms
Heartburn is the main; burning sensation at he stomach and raising to up the chest
chest pain, acid regurgitation, belching, dysphagia, nausea, vomiting, early satiety, and painful swallowing
Esophageal Cancer
2 types of esophageal cancer exist: squamous cell carcinoma and adenocarcinoma
Squamous cell carcinoma
Typically develops in the middle of the esophagus,
90% of all esophageal cancer
Adenocarcinoma
More often located in the distal portion of the esophagus
Rise in frequency, 80% in the US
Esophageal Cancer - Incidence
Relatively uncommon, only 1% of all cancers diagnosed in the US
Cure rate is poor
6th leading cause of cancer deaths worldwide
Men>Woman
Esophageal Cancer - Risk Factors
Geographic region, ethnic background, and gender
Adenocarci. middle-aged white men and often develops from Barrett esophagus
Squamous more common in blacks and is associated with alcohol and tobacco use
Exposure to nitrosamine, corrosive injury to the esophagus (burning from chemicals), achalasia, vitamin deficiencies (selenium and zinc), and human papillomavirus infection
Barret esophagus
Complication of GERD, can lead to adenocarcinoma
Occurs when the normal epithelial cells of the lower esophagus are replaced with columnar cells, typically seen in the intestine = Metaplasia
30- to 40-fold increased risk for cancer
Pts placed in surveillance program
Esophageal Cancer - Symptoms
Dysphagia, initially with solids and progressing to involve liquids
Weight loss
odynophagia (pain with swallowing), cough, hoarseness, chest pain, anemia, and regurgitation
Symptoms associated with progressive disease
Esophageal varices
Most serious consequences in people with cirrhosis ~50%
Fragile, dilated veins in the lower third of the esophagus immediately beneath the mucosa that occur in the presence of portal hypertension
Portal Hypertension
an increase in pressure in the portal veins that return blood to the heart via the liver from the intestines, stomach, spleen, and pancreas
Esophageal varices - Incidence
Most common cause of portal hypertension is cirrhosis (90%). This is due to scar tissue and nodule formation in liver tissue (changing the anatomy and making it difficult for blood to pass through the liver), increased blood flow from dilated splanchnic vessels (secondary to an overproduction of nitrous oxide), and an imbalance between intrahepatic vasodilators and vasoconstrictors
Esophageal veins - Symptoms
Variceal bleeding (painless but significant hematemesis w/or no melena
Mild postural tachycardia to profound shock, depending on the extent of blood loss and degree of hypovolemia
Esophageal veins - Management
All clients with cirrhosis should be evaluated by EGD or transnasal endoscopy for the presence of esophageal varices
Prophylaxis consists of nonselective β-blockers
Vasoactive medications
A stent may be placed between the hepatic vein and the intrahepatic portion of the portal vein
Liver transplantation
Stomach - Peptic Ulcer Disease (PUD)
A break in the lining of the stomach or duodenum of 5 mm or more owing to a number of different causes.
Gastric ulcer - affects the lining of the stomach
Duodenal ulcer - occurs in the duodenum
Stomach - Peptic Ulcer Disease (PUD)
Incidence
6 million ppl per year in US
Men and women equally
Decrease in incidence due to Tx of H. pylori
Stomach - Peptic Ulcer Disease (PUD)
Risk factors
Psychologic stress, diet, caffeine, tobacco use, and alcohol consumption
Corticosteroids along with NSAIDs increase risk
How does PUD happen?
Ulcers develop if there is change in the balance between mucosal insults and mucosal defenses.
Stomach - Peptic Ulcer Disease (PUD)
Symptoms
No specific
Epigastric pain described as burning, gnawing, or cramping near the xiphoid or radiating to the back
Gastric Cancer
Definition and Incidence
Malignant neoplasm arising from the gastric mucosa
90% of the malignant tumors of the stomach
5th most common cancer and 3rd most common cause of cancer death in the world
Gastric Cancer Tx
The only potentially curative Tx approach for pt w/ gastric cancer is surgical resection with adequate lymphadenectomy
Gastric Cancer Risk Factors
Poor diet
GERD
H. pylori infection
Epstein-Barr virus infection
Smoking
Contaminated water
Refrigerated food
Intestines - Malabsorption disorders
Celiac Disease- an immune mediated disorder triggered by the exposure of the digestive tract tom gluten in people who are susceptible
Damage to the villi inhibits nutrient absorption
Symptoms: diarrhea (can be severe), bloating, indigestion, flatulence, weight loss, and abdominal pain/cramping
Tx: Strict gluten-free diet
Inflammatory Bowel Disease (IBD)
Collectively refers to two inflammatory conditions:
Crohn’s disease
Ulcerative colitis
Crohn’s disease
Inflammation of the digestive tract
Chronic, lifelong inflammatory disorder that can affect any segment of the intestinal tract, although most commonly it affects the ileum and/or colon
Ulcerative colitis
Chronic disease of the large intestine, in which the lining of the colon becomes inflamed and develops ulcers
Chronic inflammatory disorder of the mucosa of the colon, typically involving the rectum, which can then advance proximally in a continuous manner to involve the entire colon
Complication: Cancer common
Irritable Bowel Syndrome (IBS)
IBS is a group of symptoms that represent one of the most common disorders of the GI system, with a worldwide prevalence of 11%
Recurrent abdominal pain or discomfort (abdominal sensation not described as pain) at least 3 days a month in past 3 months
IBS Symptoms
Symptoms include chronically reoccurring abdominal pain associated with altered bowel habits in the absence of structural, inflammatory, or biochemical abnormalities
Other: nausea and vomiting, anorexia, sour stomach, bloating, abdominal distention, and flatus
IBS Risk Factors
Woman>man
Ages 20-40
Other pain syndromes including migraine headaches, fibromyalgia, interstitial cystitis, chronic fatigue syndrome, and chronic pelvic pain
Diverticular disease
Diverticulosis:
presence of outpouchings (diverticula) in the wall of the colon or small intestine
Diverticular disease
Diverticulitis:
Inflammation/infection of the diverticula with possible complications such as perforation, abscess formation, obstruction, fistula formation, and bleeding
Diverticular disease - Incidence and Risk factors
Western countries
Constipation, physical inactivity, eating red meat, obesity, smoking, and NSAID use
Ehlers-Danlos syndrome, Marfan syndrome, and scleroderma
Genetics
Chronic steroids and immunosuppressants
Diverticular disease - Manifestation
Symptoms overlap with those of IBS
Blocked diverticula, bacteria that are trapped inside begin to proliferate, causing infection and inflammation
fever, change in bowel habits (usually diarrhea), nausea, vomiting, and anorexia
Neoplasms - Intestinal polyps
A growth or mass protruding into the intestinal lumen from any area of mucous membrane can be termed a polyp
Polyps are either neoplastic or nonneoplastic
Neoplasms - Benign Tumors
The most common benign tumors of the small intestine are adenomas, leiomyomas, and lipomas. Benign tumors of the small intestine rarely become malignant and may be symptomatic or may be incidental findings at operation or autopsy.
Neoplasms - Malignant Tumors
The most common malignant tumors of the small intestine are metastatic through direct extension from adjacent organs (e.g., stomach, pancreas, colon).
Adenocarcinoma and primary lymphoma account for the majority of bowel malignancies
Colorectal Cancer - Malignant tumor
The fourth leading cause of cancer among American men and women,
2nd leading cause of cancer death in both men and women in the US
Colorectal Cancer - Malignant tumor
Risk Factors
Increasing age, male gender, a personal history of adenomatous polyps, IBD (UC, CD), family history of colon cancer or FAP, and obesity.
Cigarette smoking and excessive alcohol consumption may possibly increase risk
Obstructive Disease - Hernia
Abnormal exit of a tissue or an organ, such as the bowel, through the wall of the cavity in which it normally resides
Muscular weakness (congenital or acquired)
~Obesity, pregnancy, heavy lifting, coughing, surgical incision, or traumatic injuries from blunt pressure, increase the risk of developing a hernia
Indirect Inguinal
Location: Sac herniates through internal inguinal ring; can remain in canal or pass into scrotum (men), can extend to the labia (woman)
Symptoms: Pain with straining; soft bulge that increases with increased intraabdominal pressure; may decrease when lying down
Frequency: Most common, 60%, infant<1yr and males 16-20yr
Cause: Congenital or acquired
Direct Inguinal
Location: Directly behind and through external inguinal ring, above inguinal ligament; rarely enters scrotum
Symptoms: Usually painless; round bulge close to the pubis in area of internal inguinal ring; easily reduced when supine
Frequency: 2nd most common, more in men >40yr
Cause: Acquired weakness; deficient posterior inguinal wall brought on by heavy lifting, muscle atrophy, obesity, chronic cough, or ascites
The Appendix - Appendicitis
Inflammation of the vermiform appendix
Appendicitis initially presents with generalized or periumbilical abdominal pain that later localizes to the right lower quadrant
Treatment for Appendicitis
The gold-standard treatment for acute appendicitis is an appendectomy
~Laparoscopic appendectomy is preferred over the open approach
~In cases where there is an abscess or advanced infection, the open approach may be needed
Appendicitis Risk Factors
Any age
Peak btw 15-19 yrs
Males>Females
Infections causing enlarged lymph nodes
CD and UC
The Rectum - Rectal Fissure
A rectal or anal fissure is an ulceration or tear of the lining of the anal canal, usually on the posterior wall
Acute fissure
Occurs as a result of excessive tissue stretching or tearing, such as childbirth or passage of a large, hard bowel movement through the area
Anal fissures
Frequently heal within a month or two when treated with a combination of bran and bulk laxatives or stool softeners, sitz baths, and emollient suppositories
Hemorrhoids, or Piles
Varicose veins of a pillow-like cluster of veins that lie just beneath the mucous membranes lining the lowest part of the rectum and anus
What are hemorrhoids associated with?
With anything that increases intraabdominal pressure
Internal hemorrhoids
Occur in the lower rectum and usually are noticed first when a small amount of bleeding occurs during passage of stool, especially if straining occurs during a bowel movement
External hemorrhoids
Located under the skin around the anus bleed (bright red blood) if the hemorrhoid is injured or ulcerated and are very painful because they form in nerve-rich tissue outside the anal canal
How are external hemorrhoids treated?
With a local application of topical medications, sitz baths, high-fiber diet, and avoidance of constipation and other causes of increased intraabdominal pressure
