Digestive and Gastrointestinal System

• The digestive and gastrointestinal system are the primary organs of digestion in the body.

Anatomy and Physiology

• The functions of the digestive system are:

  • Taking food into the mouth (ingestion)
  • The release of water, acid, and buffers into the lumen (secretion)
  • Churning and propulsion to mix food (mixing and propulsion)
  • Mechanical and chemical breakdown of food matter (digestion)
  • Pass digested products from the GI tract into blood and lymph (absorption)
  • Elimination of feces from the body (defecation)

• The abdominal area can be split into nine regions:

  • Right hypochondriac region
  • Epigastric region
  • Left hypochondriac region
  • Right lumbar region
  • Umbilical region
  • Left lumbar region
  • Right iliac region
  • Hypogastric region
  • Left iliac region

Groups of Organs

• The GI Tract comprises the mouth, pharynx, esophagus, stomach, small and large intestines.
• Accessory digestive organs comprise the teeth, tongue, salivary glands, liver, gallbladder, and pancreas.
• The total length of the digestive system is 7-7.9 meters (23-26ft)
• The mechanical digestion process uses chewing or mastication
• Salivary amylase is secreted by salivary glands and is used to break down starch
• Lingual lipase is secreted by lingual glands in the tongue to break down triglycerides into fatty acids and diglycerides
• Parts of the GI Tract include:

  • The esophagus is a collapsible muscular tube that sits in the mediastinum, anterior to the spine and posterior to the trachea

  • The esophagus is hollow and 10 inches long and connects to the stomach through the diaphragmatic hiatus (opening through the diaphragm)

  • The pharynx is a funnel-shaped organ from the internal nares, that is a skeletal muscle lined by mucous membrane.

  • The pharynx is comprised of the Naso, Oro, and Laryngo

  • Deglutition is the act of swallowing and has three stages:

  • Voluntary stage is the movement of bolus into the oropharynx

  • Pharyngeal stage is involuntary, moving the bolus from the pharynx to the esophagus with the help of the medulla oblongata

  • Esophageal stage is involuntary, moving the bolus from the esophagus to the stomach

  • The stomach has a 1500ml capacity that stores food, secretes digestive fluid, and propels partially digested food.

  • The anatomic regions of the stomach are the cardia (entrance), fundus, body, and pylorus (outlet)

  • The small intestine is the longest segment of the GI tract (2/3 of its total length) Its entire surface area is for absorption and comprise the duodenum (proximal), jejunum (middle), ileum (distal). Its flow of digested material from the ileum to the cecal is controlled by the ileocecal valve (sphincter)

  • The ampulla of Vater is the connection of the common bile duct to the duodenum, allowing the passage of bile (for fats) and pancreatic secretions

  • The large intestine comprises the ascending (R), transverse (R-L), and Descending (L) as well as the sigmoid colon, rectum, and anus in the terminal portion. E. coli help turn protein into amino acids.

Blood Supply

• 20% of the total cardiac output is needed for GI functions and this increases after eating.
• Normal cardiac output is 4-6 Liters.
• Blood is supplied to the GI tract by the thoracic and abdominal vein and artery.
• The superior and inferior mesenteric arteries supply the intestine. The gastric artery supplies the stomach, the splenic artery supplies the spleen, and the cystic artery supplies the gallbladder.
• Blood flows to the liver, then the hepatic vein, then the inferior vena cava.
• The sympathetic nerves have an inhibitory effect that decreases gastric secretion, while motility sphincters and blood vessels constrict.
• Parasympathetic nerves cause stimulation by increasing peristalsis and secretory activities, where sphincters relax except for those in the upper esophagus and the external anal sphincter.

Functions of the Digestive System

• Chewing is the process of breaking down the food into small particles that can be swallowed.
• Swallowing starts under voluntary control but becomes involuntary, with the esophagus contracting in a rhythmic sequence.
• The body secretes 1.5 L of saliva per day which contains Ptyalin (amylase to breakdown starch)

Gastric Function

• The stomach stores and mixes food with secretions, secreting highly acidic fluid at 2.4L/day with a pH as low as 1.
• The stomach has two functions:
  • Break down food into more absorbable contents
  • Aid destruction of most bacteria
• Pepsin helps protein digestion and is the end product of conversion of pepsinogen from chief cells.
• The intrinsic factor combines with Vit B12 for absorption in the ileum.
• Food remains in the stomach for 30 minutes to hours.
• Chyme is digested food plus gastric secretion.

Small Intestine Secretion

• Digestion begins in the duodenum, where secretions come from the pancreas, liver, and gallbladder.
• The body secretes alkaline pancreatic secretions, which contain bicarbonates to neutralize stomach acid, trypsin for protein breakdown, amylase for starch breakdown and lipase for fat breakdown
• These secretions drain into the pancreatic duct and bile duct of the ampulla of Vater
• Bile is stored in the gallbladder to emulsify fats

Function

• The Sphincter of Oddi controls the flow of bile.

• Intestinal secretions are:

  • 1L/ day of pancreatic juice
  • 0.5 L/day of bile
  • 3 L/day of secretions from the glands of the small intestine

• Contractions occur via:

  • Segmentation which is mixing waves that move back and forth in churning motion
  • Intestinal peristalsis which propels contents to the colon, stimulated by chyme (stays in the SI for 3-6 hours)

• Digestion

  • Carbohydrates becomes disaccharides and monosaccharides
  • Protein becomes amino acids and peptides
  • Fats become monoglycerides and fatty acids.

• The Villi are small fingerlike projections that absorb nutrients.

Absorption

• Nutrients are absorbed in the duodenum
• Fats, proteins, carbohydrates, sodium, and chloride are absorbed in the jejunum
• Vit B12 and bile salts are absorbed in the ileum
• With each peristaltic wave of SI, the ileocecal valve opens briefly and permits some content to pass on
• Gut microbes are major components for the breakdown of undigested proteins and bile salts.
• Electrolyte secretions contain bicarbonate solution that neutralize end products and mucus which protects the mucosa from the intraluminal contents and provides adherence for fecal masses.
• After another meal, intestine-stimulating hormones are released.
• Waste reaches the real rectum in about 12 hours although taste may remain in the rectum 3 days after.

Waste Products of Digestion

• Feces contains foodstuff, inorganic materials, water, and bacteria at 75% fluid and 25% solid.
• Odor is created by chemicals from intestinal bacteria like hydrogen sulfide and ammonia.
• Color is caused by the breakdown of bile by bacteria.

Gut Microbiome

• Its purpose is to protect the host against invasion by pathogenic organisms, produce anti-inflammatory metabolites, destroy toxins, prevent colonization of pathogens, and provoke an immune response.
• Intestinal Epithelium is the first line of defense.

Assessment

• Health history
• Pain
• Assess the character, duration, pattern, frequency, location, and distribution.
• Dyspepsia
• Indigestion
• Intestinal Gas
  • Accumulation of gas in GI that may result in belching or flatulence
• Nausea and Vomiting
  • Nausea is an uncomfortable sensation of sickness or queasiness
  • Commonly caused by distention of the duodenum or upper GI
• Vomiting is forceful emptying of the stomach and can cause a Mallory-Weiss Tear evidenced by bright red blood or coffee grounds

Bowel Movements

• Signal colonic dysfunction through changes in:
  • Increased frequency and liquidity of stool (diarrhea)
  • Contents move so rapidly.
  • Decreased frequency of stool (constipation)
  • Normally light to dark brown stool (stool)
  • Melena or black, tarry stool indicates upper GI bleed
  • Bright or dark red stool indicates lower GI bleed
  • Light gray stool indicates decreased conjugated bilirubin.

Physical Assessment

• Oral Cavity Inspection and Palpation

  • Remove dentures
  • Check lips for moisture, hydration, color, and texture
  • Check gums for inflammation, bleeding, retraction, and odor
  • Check tongue dorsum for color, texture, and lesions and check for oral cancer for white or red plaque, lesions, ulcers, and nodules.

• Abdominal IAPP

  • Examination while supine with knees flexed
  • Inspect for skin changes, nodules, lesions, and scarring
  • Use diaphragm of stethoscope for auscultation, counting for 30secs to assess bowel sounds each quadrant. 5-6 bowel sounds indicates hyperactive, 1-2 indicates hypoactive, normal id 5 in 20 seconds.
  • Minimum 5 mins needed per quandrant to confidently assess
  • Using the bell one can hear bruits in aortic, renal, iliac, and femoral arteries or friction rubs over the liver and spleen during respiration
  • Borborygmus indicated by long, prolonged gurgles

• Stomach growling

  • Percussion assesses size and density of various organs and structures
  • Tympani indicates air in the stomach and small intestines
  • Normal solid masses
  • Dullness indicates over solid masses or fluid
  • Palpation assesses for areas of tenderness (light) and identify masses (deep)
  • Rectal Inspection and Palpation assesses fistulas, fissures, rectal prolapse, and polyps.

Diagnostic Evaluation

• Serum Laboratory Studies
  • CBC, Complete Metabolic Panel, PTT, Triglycerides, Liver function test, amylase, and lipase
  • CEA (Carcinoemryonic antigen)
  • CA 19-9 (Cancer antigen)
  • AFP
• Stool Test
  • Determine the consistency, color, and occult content
  • Fecal Urobilinogen, Fecal Fat, Nitrogen, Clostridium Difficile, Feal Leukocytes
  • Obtain samples on random bases or 24-72 refrigerated samples and store them at appropriate temperatures.
  • Guaiac-Based fecal Occult Blood Testing is done for initial screening and is contraindicated for hemorrhoidal bleeding. Avoid meat, aspirin, anti-inflammatories, and vit C for 72 hours prior.
• Breath Test

  • Hydrogen breath test is used to evaluate Carbohydrate absorption

  • Urea Breath est for H. pylori (causes peptic ulcer)

  • Avoid: antibiotics or bismuth subsalicylate for 1 month, PPI for 2 wks, and Cimetidine and Famotidine for 24 hrs

Diagnostic Testing

• The Abdominal Ultrasonography uses high frequency sound waves to detect: Enlargement of gallbladder or pancreatic, gallstones, enlarged ovary, or appendicitis. It can't be used on organs behind bony tissue, gas, and fluid.
  • Fast for 8-12 hrs (decrease gas); Fat free meal (Gallbladder) before the scan
  • If with barium studies, should be after ultrasonography Genetic Testing
  • Lynch Syndrom AImaging Studies
  • Autosomal dominant related to colonic and extracolonic cancers
  • Delineates the GI Tracts using barium sulfate to detect anatomic or functional disorders as well as ulcers, varices, tumors, regional enteritis A double contrast is thick barium suspension for the stomach and esophageal wall, then CO2 tablet (detect water) A Enteroclysis encompasses the entire intestine (continues infusion) and involves - 500ml-1000ml of thin barium for obstruction A The Upper GI Fluoroscopy tests includes:
  • The nursing aspect involves a low residue, with clear liquid, and NPO status with no gum or smoking.
  • Oral meds withheld in the morning and increased fluids. A The Lower Gl Study test. It begins with barium and then moves enema with polyps tumors, lesions in the colon. With double contrast or air contrast, Thicker barium then air nursing aspect involves emptying and cleaning lower bowel with a low rest due for 1-2 days before.

Lower Digestive Studies

• A clear liquid and laxative evening before, NPO after midnight.
• Contraindicated with perforation or obstruction
• Computer Tomography includes:
  • Ct scan
  • Volume CT scanner (more accurate)
  • Appendicitis, diverticulitis, regional enteritis, ulcerative colitis -Nursing is to avoid allergic reaction from contrast to creatinine level
• MRI supplement ultrasonography and CT aids in abdominal soft tissues and bloodvessels. Nurse care involves:
  • NPO 6-8 hours before radiation emitted from radioactive substances (injected A Postiron Emission Tomography- the body)

Procedure of the the Digestive Test

Asses the Gastric intestical: Radionuclide testing assesses gastric emptying and colonic transit time. A. Scintigraphy: helps reveal displaced anatomic structures and changes in the size, neoplasms, and lesions. and measures uptake of RBS and WBC. A Endoscopic Procedures: a) Esophagogastroduodenoscopy + Electronic Video Endoscopes; Larger continuous viewing capabilities + PillCam ESO; Shallow capsule with camera + Endoscopic Retrograde Cholangiopancreatography View bile duct- Endoscop with: → X-ray → Pancreatic duct, gallbladder Nursing ♦NPO 8 hours and Midazolam Moderate sedation with loss of gag reflex b) Fiberoptic Colonoscopy by: larger diameter and EGD → Nursing ; cleansing (laxative and saline enema, or PEG electrolyte lavage solutions) → Sodium Phosphate tablet (Colon cleansing) Precautions precautions → For Implantable defibrillators and pacemakers c) Anoscopy, Proctoscopy, and Sigmoidoscopy Evaluate chronic diarrhea, fecal incontinence, ischemic colitis, and lower GI hemorrhage and observe for ulceration. Position → Left side with the right leg bent and placed anteriorly Nursing → Warm tap water or Fleet enema A Manometry and Electrophysiologic Studies a) Manometry Tests : measures changes in intraluminal pressures and coordination of muscle - Esophageal manometryDetect motility disorders of the esophagus and of the upper and lower esophageal sphincter - Gastroduodenal, Small Intestine, and Colonic Manometry; Evaluate delayed gastric emptying and gastric and intestinal motility disorders - Anorectal Manometrymeasures the resting toner to the internal sphincter and the contractility of external and Rectal Sensory Function studies - Electrogastrography; Assess gastric motility disturbances and can be useful in detecting motor or nerf dysfunction - Defacography is where; Thick barium paste instilled into the rectum. A Gastric Analysis: Gastric and Stimulation Tests, and ph Monitoring i) NPO for 8-12 hours before ii) and ability to secreted → HCI be affected by No acid, severe chronic atrophied gastritis- little or no, acid- Gastric ulcer secrete some acid and Duodenal ulcers Excess amount of Acid and Pemicious Anemia

Upper GI Disorders

• Gastroesophageal Reflux Disease- Backflow of gastric or duodenal contents into the esophagus a) Causes-
  • Pyloric Sten-osis
  • Incompetent lower esophageal sphincter
  • Hiatal Hernia and Motility disorder b) Manifestations:
  • Hallmark: Pyrosis (heartburn) and regurgitation
• Dyspepsia dysphagia or odynophagia, hypersalivation, and esophagitis Dental erosion, ulcerations in the pharynx and the esophagus c) Diagnostic standard: Ambulatory ph monitoring or PPI trialand Endoscopy or barium shallow Evaluate
• Management- Avoid situations that decrease lower esophageal sphincter pressure or cause esophageal irritationand Lifestyle Changes
  • Tobacco cessation and Weight Loss
  • Surgical- Nissen fundoplication ;Wrap gastric funds around the sphincter area of the esophagus Gastritis- inflammation of the gastric mucosa a) Type- acute
    • Causes- by local irritants as such aspirin
    • Nonerosive; Caused by infection to spiral Shape(Helicobacter pylori )
    • Ingestion of strong acid or alkali
    • Chronic and Underlying causative mechanisms. b) Pathophysiology and Disrupting the mural Barrier
    • Disruption of mucosal barrier - HCL contact with mucosa -infammation-edematous and hyperonic -> chronic leads to auto atrophy Manifestation- Epigastria Anorexia Nausea vomiting Diagnostics are- Endoscopy and detection of biopsy

Managing Diets

• One that repairs itself in 1 day refrain from food maintains the irritable parts,
• Maintain with- Medications Antacids and Reduce Anxiety; Promote Optimal Nutritiori
• Peptic Ulcer Disease- Gastric- - duodenal or esophageal ulcer= or in duodenum area a) Causes-From Helicobacter pylori and NSAIDS b) Pathophysiology (Increased concentration of acid and depressed resistance of mural barrier) Manifestations -Gastric- paint occurs immediately after meal or gnawin or burning pain
• diagnostic: upper endoscopy

More Peptic Management

Management-Antibiotics of H.pylari

• NURSING Pain, Anxiety:
• acute Pains are- impair to a nutritinal.

Lower GI dISORDERS

A Celiac Disease- is a autoimmune response product contain protein of gluter Risk Factors Pathologyy types

• Manifestations- diarrhea, malnutrition, abdominal pain, abdominal distention, flatulence, and weight loss diagnostic. nursing

Appendictis

A Management- a) Immediate Surgery (Appendectomy) b) Append- Laparotomy or laparoscopy c) A nursing point d) goals to relieve Volume

Diverticular

• Low Fiber
• Slow Colon Transit time

A manifestations are a= Rectum+ colostomy B= management is on out-patient

• Nursing for a Pain (prevent infection) A Diterficulitis- in ammationmore.

Intestional Structures

a:

• Nurisnig - 2L/day, Soft fluid and fiber B) Intestional obstructions : Most are Signoid(colons) types: Mechananl obstructions and function parts a:
• Small bowl structure. a, increase 3 pressure in verous area. b, decrease dehydration
• Large bowl obstruction a)- undramatic.

IN ammation

A Managenment:

• Maintain function an NG
• 2L/day- soft fluid and fiber

Liver Diseases

Liver- (alters, excreted store of substances with melubalim

• Regulates glucoser and proteins metabolism

A manufactures

• Remobes_ waste products of- streams

• Cannels with Biles

• Liver Disorders : a) bile- and from hepatocytes 1: Bile and Jaundice 2: functions of the livers

Jaundice

• Bilirubin concentration level, serum bilirubin level
• Obustrure- the gallstonrs
• Portal and hypersterim
• Ensosphapeal
• Varices, pathohysiblohy.

Viral Hepatitis

• phases: viral hep C.
• diagnostic- DNA .
• Managment .and prevention
• Non -vinal hepsotox

Cirrhos

• Repaid -ment
• Types
• pathoology A MANIFESTATION
• Asides is low- (Albumin and venous

Gallbladder Disorders/ Bile

a) Acute a) manifestayions s (sever abdomical- high in epigasium a) management (Oral intake withdraw. A.I,)

Chronic pancreas

• manifestations: _ Recurring , opioid (weightless)

B:) cholectotitis- inflammation- right a_gallstiner obstruction of bile out flow_.