Digestive System

function of GI tract

• starts in the mouth

• motility - movement of food

  • peristalsis

• secretion - secretion of acids, mucus, hydroclous pumps breaking down the food

• digestion - breaking down of the actual food

• absorption - absorption in the small intestines

parasympathetic nervous system (PNS)

• primarily is the vagus nerve

  • when stimulated it triggers an increase in peristalsis

  • things that stimulate it

    • food stretching stomach (NOT OVERSTRETCHING)

    • increase in Ph

    • pleasent smells and hunger

• PNS: rest and digest

sympathetic nervous system (SNS)

• conversely inhibits gastrointestinal activity (ex: overstretching of the stomach)

  • cause vasoconstriction

  • reduces secretions

  • reduces regeneration of epithelial cells

    • cells that sit in the GI tract and as food moves through it takes some of these cells with it

      • these cells are important cause without them you will get irritation and breakdown of the stomach

• SNS: fight or flight

nausea and vomiting

• initiated when vagus nerve is triggered and sent to the medulla and the medulla tells us to throw up

• nausea and vomiting are initiated by the medulla

  • distention or irritation of the digestive tract

  • smells or sights

  • pain or stress (anxiety)

  • inner ear imbalance

  • medications

    • some meds on an empty stomach can cause you to throw it back up

    • chemotherapy

  • noxious (poision) substances or stimuli

  • IICP

    • increased inercranial pressure

      • ex: brain bleed

hematemesis

“coffee grounds” partially digested food mixed with old blood

significance in vomitus

• hematemesis: “coffee grounds” partially digested food mixed with old blood

• deeper brown color may be content from lower instestine (stool) - obstruction

• recurrent projectile vomiting may be pyloric stenosis - usually seen in children

  • pyloric sphincter: the gate from the stomach to the small intestine

    • with pyloric stenosis that gate becomes inflammed and is now narrow and tight so whenever they eat anything, all of it puts pressure on that sphincter and will shoot back out

• dehydration - can lead to metabolic acidosis

  • first with throwing up it will lead to alkalosis because they are throwing up the acid but after severe long vomiting, the body will become dehydrated making the body hypovolemic. due to the small amounts of blood, there is not enough blood with nutrients getting to the tissues with oxygen so the body has to revert to anerobic metabolism to make energy which builds up lactic acid therefore making us acidodic in the end

vomitus

the actual throw up

emesis

the action of throwing up vomitus

diarrhea

excessive frequenncy of loose stools

• to be considered for having diarrhea you have to have 3-4 loose stools within 24hrs

diarrhea - large volume (osmotic)

• short transit time, excess fluid volume flooding intestine, lactose intolerance, leads to hypovolemia and metabolic acidosis

  • ex: eating something that has bacteria in it or cdiff causes inflammation to bowels causing their to be excess flow to the intestine and for poop to flow out in large amounts with out being filtered

diarrhea - small volume

• bowel disease, may contain blood, pus or mucous

  • ex: ulcerative colitus

diarrhea- steatorrhea

• “fatty diarrhea” greasy, loose and foul odor

  • malabsorption syndromes

  • occurs if fats arent getting absorbed in the small intestine bc the food is moving so fast through the gi tract

diarrhea - blood diarrhea

• occult: small hidden amounts of blood

  • fecal occult system

• melena: dark colored (tarry stools)

  • old blood in stool

  • tells us there is high bleeding up in the GI tract so its further from the rectum making it take a minute to get to the end making it rust making it look darker

• hematochezia: passing fresh (frank) red blood

  • this tells us there is bleeding lower in the GI tract because it is more red

  • ex: hemmorides - these are closer to the rectum so when they break open it looks more red

constipation

• can lead to an impaction

• can be acute or chronic

  • acute: holding you poop in during the day and ignoring signals that you need to go because your in public or like constipation for a couple days

• causes

  • increased age

  • inadequate fiber

  • inadequate fluid intake

  • ignore urge

  • muscle weakness and inactivity

  • neuro disorders (MS, spinal cord injuries, etc)

  • drugs (opiates, drugs that block PNS, etc)

  • obstruction

upper GI disorders - Mouth

• cleft lip and/or palate - neural tube disorder

• aphthous ulcers - canker sores or stomatitis

• candidiasis - thrush

• herpes - HSV-1 - transmitted through kissing or close contact - reactivates with stress

• dental issues

  • ex : having dentures and you forgot to bring them so now you can eat

• leukoplakia - precancerous lesions

upper GI disorders - dysphagia

• difficulty in swallowing

  • causes

    • neurological deficit (MS, stroke, infection in brain, brain damage)

      • achalasia - failure in esophageal sphincter to relax

    • congenital atresia - blind pouch

    • fibrosis - stenosis or stricture

    • compression

    • diverticulum

upper GI disorders - hiatal hernia

• a part of the stomach protrudes through the opening (hiatus) in the diaphragm

  • sliding - slides up and back down with positiion changes (esp. laying down)

  • paresophageal - part of the fundus of stomach moves above diaphragm (leads to mechanical constriction of blood vessels in stomach)

    • medical emergency

    • loosing blood flow and its going to become necrotic

Upper GI disorders - Gastroesophageal reflux disease (GERD)

• this is chronic heart burn/chronic reflux of food

• stomach contents chronically regurgitate into esophagus

• causes

  • weak esophageal sphincter

  • obesity

  • hiatal hernia

  • pressure causes gerd - aka pregnancy

Upper GI disorders - esophageal cancer

• usually squamous cell carcinoma

  • mostly found in distal esophagus

  • causes

    • chronic irritation

      • reflux (gerd)

      • esophagitis

      • achlasia

      • hiatal hernia

      • alcohol abuse

      • smoking

    • poor prognosis

Upper GI disorders - acute gastritis

• gastric mucosa inflamed, red, edematous and ulcerated. could bleed in the mucosal barrier is damages

• causes:

  • infection

  • allergies to food or drugs

  • ingesting irritants frequently (ex:spicy foods)

  • excessive alc intake

  • ingestion of aspirin or other ulcerogenic drugs esp. on an empty stomach

  • radiation and chemotherapy

• usually self limiting

Upper GI disorders - chronic gastritis

• atrophy of mucosa of stomach and loss of secretory glands

• causes

  • same causes as with acute, but continued insult

  • infection - helicobacter pylori (bacteria that may times lead to ulcers)

Upper GI disorders - peptic ulcers

• gastric and duodenal ulcers

• patho

  • most commonly found in the proximal duodenum (duodenal ulcers)

  • also found in antrum of the stomach or lower esophagus (gastic ulcers)

  • usually small cavity develops in mucousa that continues to erode into further layers below mucosa

  • eventually invades blood vessels (which causes bleeding)

  • may perforate stomach or intestinal wall and spill gastric contents into peritoneal cavity

peptic ulcers causes

• helicobacter pylori bacteria (most common)

• inadequate blood supply (vasoconstriction caused by stress, smoking, shock, elederly, severe anemia)

• ulcerogenic substances

• atrophy of gastric mucosa (chronic gastritis)

• increased number of acid-pepsin secretory cells in the stomach (a genetic anomaly)

• increased stimulation of acid-pepin secretion (alcohol, caffine, or certian foods)

this ultimately can lead to gastric cancer

peptic ulcer symptoms

• epigastric aching, burning pain 2-3 hours after meals or at night relieved by ingestion of food or antiacids

• heartburn

• nausea

• intake of spicy food exacterbates symptoms

stress ulcers

• result from severe trauma

  • burns: curlings ulcers

  • head injury: cushings ulcers

  • can quickly progess to hemorrhage

  • sepsis

• medications usually given to prevent

upper GI disorders - dumpting syndrome

• control of gastric emptying is lost (many times seen after gastric resection or partial gastrectomy)

  • appropriate dilution of chyme is lost

  • hyperosmolar chyme leaves the stomach and draws too much water into the intestine

  • distention hyper-activates PNS increasing peristalsis and gastric dumpting

    • dizziness and weakness

    • rapid pulse and sweating

    • hypoglycemia

Upper GI disorders - pyloric stenosis

• narrowing and obstruction of the pyloric sphincter

  • can be seen in infants and adults

  • infant form (congenital)

    • sphincter hypertrophied

    • projectile vomiting

  • adult form (acquired)

    • acquired due to surgical adhesions/scars

    • decreased gastric emptying

    • persistent feeling of fullness

    • eventually vomiting as sphincter becomes more constricted

disorders of liver and pancreas - gall bladder disorders

• cholelithiasis

• cholecystitis

• cholangititis

• choledocholithiasis

cholelithiasis

formation of gallstones (calculi) that form in bile in the gallbladder

cholecystitis

stones obstruct duct and leads to inflammation of gallbladder and bile duct

cholangitis

inflammation and infection of bile ducts

choledocholithiasis

obstruction by gallstones of the biliary tract

gallbladder disorder symptoms

• severe upper right quadrant discomfort (biliary colic) that leads to waves of deferred pain

• epigastric pain

• nausea and vomiting

• later stages

  • jaundice

  • fever

  • leukocytosis

hepatitis

• inflammation of the liver

• causes

  • idiopathic (fatty liver)

  • viral hepatitis

  • infectious mononucleosis

  • chemical or drug toxicity

  • chronic inflammation that begins to cause irreparable liver cell damage

viral hepatitis

• virus that specifically attacks the liver

  • acute forms

    • hep a and e

    • transmitted by oral/fecal route

    • self limiting

  • chronic forms

    • hep b, c, and d

    • transmitted by blood and body fluids

    • life-long liver damage

    • produces a chronic or carrier state

hepatitis - preicteric (or prodromal) stage

• insidious onset

• fatigue, anorexia and muscle aching

• fever, headache, and distaste for cigarettes

• mild upper right quadrant discomfort

• AST and ALT begin to become elevated

hepatitis - icteric stage

• onset of jaundice and increase in serum bilirubin levels

• stools become light colored and urine dark

• pruitis

• liver tender and hepatomegaly

• clotting ability decreases

• stage lasts longest with hep b

hepatitis - posticteric or recovery stage

• reduction in symptoms

• extends over weeks

  • acute (esp. hep a) 8-10 weeks

  • prolonged (esp.hep b) over 16 weeks

cirrhosis

• progressive destruction of liver tissue leading to liver failure

• categories

  • alcoholic liver disease (largest group)

  • biliary cirrhosis (stones or cystic fibrosis)

  • postnecrotic cirrhosis (chronic hepatitis or long term exposure to toxic materials)

  • metabolic (storage disorders such as hemochromatosis)

cirrhosis complications - functional losses

• decreased removal and conjugation of bilirubin

• Decreased production of bile

• Impaired digestion and absorption of nutrients

• Decreased production of blood clotting factors and plasma proteins

• Impaired glucose/glycogen metabolism

• Inadequate storage of iron and vit B12

• Decreased inactivation of hormones (aldosterone and estrogen)

• Decreased removal of toxic substances, such as ammonia and drugs

cirrhosis complications - R/T obstruction of bile ducts and blood flow by fibrosus tissue

• Reduction of the amt. of bile entering the intestine

• Back-up of bile in liver – obstructive jaundice

• Blockage of blood flow through liver – leads to increased pressure in portal veins – portal hypertension

• Congestion in the spleen -Splenomegaly – due to increasing hemolysis

• Congestion in intestinal walls and stomach, impairing digestion and absorption

• Development of esophageal varices

• Development of ascites in the peritoneal cavity

cirrhosis symptoms

• Fatigue

• Anorexia

• Weight loss

• Anemia

• Diarrhea

• Dull aching pain in URQ

• Ascites

• Esophageal varices

• Encephalopathy

• Edema

• Increased bruising

• Jaundice

acute pancreatitis

• Inflammation of the pancreas resulting from autodigestion of the tissues.

  • Premature activation of proenzymes in pancreas

  • Activation of proenzyme trypsinogen into trypsin

  • Trypsin converts other proenzymes and chemicals into active forms of amylase and lipase

  • These enzymes digest pancreatic tissue

  • Leads to massive inflammation, bleeding and necrosis

acute pancreatitis - etiology and symptoms

• Gallstones and excessive alcohol intake

• Symptoms:

  • Severe epigastric or abdominal pain

  • Signs of shock – low B/P, pallor, sweating

  • Low-grade fever

    • Abdominal distention and decreased bowel sounds

  • Leukocytosis

upper GI disorders - celiac disease

• malabsorption syndrome that prevents the breakdown of gluten - leads to malnutrition and intestinal inflammation

  • Genetic link – defect in intestinal enzyme

  • Steatorrhea

  • Muscle wasting

  • Failure to thrive

  • Must be on a gluten free diet

  • Higher risk for intestinal cancers

upper GI disorders - chrons disease

• chronic inflammatory bowel disease – most frequently in small intestine

  • Occurs in the mucosal layer

  • Develops shallow ulcerations

  • Leads to thickened walls that can lead to obstruction

  • Destructive masses form (Granulomas) in the intestine walls and regional lymph nodes

  • Decreased ability of small intestine to metabolize and absorb nutrients

  • Increased intestinal motility

crohns symptoms

• Diarrhea

• Cramping

• Melena

• Pain and tenderness RLQ

• Anorexia

• Weight loss

• Fatigue

ulcerative colitis

• Inflammation begins in the rectum and then progresses through the colon

  • Mucosa and submucosa inflamed

  • Tissue becomes edematous and fragile and ulcerations develop

  • Granulation tissue forms but is fragile, vascular and bleeds easily

  • Tissue destruction interferes with absorption of fluid and electrolytes

  • Inflammation impairs peristalsis, leading to swelling and possible obstruction

  • High risk for colon cancer

ulcerative colitis symptoms

• Severe abdominal cramping

• Tenesmus (rectal spasms)

• Bleeding with diarrhea

• Could lead to medical emergency

• Relentless extension of the disease can lead to intestinal paralysis and necrosis of entire colon (toxic megacolon)

• During severe episodes of diarrhea electrolyte disturbances may take place

Diverticulum

herniation or outpouching of the mucosa through the muscle layer of the colon wall, frequently the sigmoid colon

Diverticulosis

asymptomatic diverticular disease – ususally multiple diverticula are present

Diverticulitis

refers to inflammation of the diverticula

diverticular disease - causes and comps

• Causes:

  • Low-residue diets

  • Irregular bowel habits

  • Aging

• Complications

  • Intestinal obstruction

  • Perforation with peritonitis

  • Abscess formation

diverticular disease - symptoms

• Mild lower abdomen pain

• Diarrhea or constipation

• Flatulence

• When there is stasis of feces in pouches forming diverticula there is:

  • LLQ pain and tenderness

  • Nausea & vomiting

  • Fever

  • Leukocytosis

intestinal obstruction - Functional obstruction

• Abdominal surgery - effects of anesthetic combined with inflammation

• Spinal cord injuries

• Inflammation with severe ischemia

• Infection in the abdominal cavity

intestinal obstruction - mechanical obstruction

• Adhesions

• Hernias

• Strictures

• Masses

• Intussusception

• Volvulus

• Hirschsprung’s disease

• Gradual obstruction from chronic inflammation

colicky abdomen

pain develops as peristalsis increases

borborygmi

extreme rumbling bowl sounds caused by building and movement of gas

intestinal rushes

heard before the obstruction in an attempt to propel intestinal contents forward

intestinal obstruction - symptoms

• Colicky abdomen – pain develops as peristalsis increases

• Borborygmi (extreme rumbling bowel sounds caused by building and movement of gas)

• Intestinal rushes heard before the obstruction in an attempt to propel intestinal contents forward.