NURS 245- Chapter 37 (Gastrointestinal Disorders)

What starts the digestive process?

Mastication

What enzymes in saliva help break down complex molecules?

Amylase, lipase, protease

What are the 3 phases of deglutition?

1. Buccal Phase

2. Pharyngeal phase

3. Esophageal phase

Deglutition

Swallowing

Buccal phase

Food/drink is pushed upwards and backwards into the pharynx by the tongue

Pharyngeal phase

The epiglottis closes the entrance to the larynx, and the upper esophageal sphincter relaxes to let food/drink into the esophagus

Esophageal phase

Food/drink moves downwards through the esophagus into the stomach

Dysphagia

Difficulty in swallowing

Clinical manifestations for dysphagia

• Sensation of food getting “stuck” in the throat

• Coughing or gagging when trying to eat/drink

Causes of dysphagia

• Xerostomia (due to reduced salivary secretions with age, dehydration, or poorly controlled diabetes)

• Esophageal narrowing (due to scar tissue formation after chronic acid reflux/radiation therapy)

• Brainstem injury (due to trauma, infections, or tumors)

What test is done to diagnosis dysphagia?

Barium swallow

Barium swallow

Patient is asked to swallow a thick liquid containing barium

• A series of x-rays are taken to obtain sequential images that show the process of swallowing to identify issues

Treatment for dysphagia

• Swallowing exercises

• Dietary modifications (softening foods)

• Feeding with nasogastric tube (in severe cases)

Esophagus

Fibromuscular tube that connects the lower part of the pharynx to the stomach (8-10 inches)

What structure lies posterior to the larynx and trachea as it descends through the mediastinum between the lungs?

Esophagus

Esophagus intersects the diaphragm at T11/T12 vertebra and passes through the ___

Esophageal hiatus

Peristalsis

Involuntary, “wave-like” muscle contractions propelling contents downwards

The upper 1/3 of the esophagus has ___ muscle fibers and is innervated by what 2 nerves?

Skeletal muscle fiber

Glossopharyngeal (CN IX) and vagus (CN X)

The lower 2/3 of the esophagus has ___ muscle fibers and is innervated by what nerve?

Smooth muscle fiber

Vagus (CN X)

What are the two sphincters at either end of the esophagus?

Upper esophageal (pharyngoesophageal) sphincter

Lower esophageal (gastroesophageal) sphincter

Upper esophageal (pharyngoesophageal) sphincter

Prevents reflux from esophagus into the pharynx

Lower esophageal (gastroesophageal) sphincter

Prevents reflux from the stomach into the esophagus

Both sphincters of the esophagus remain closed except during…

Swallowing

What are the layers of the esophagus, from the lumen to the external surface?

Mucosa, submucosal, muscularis externa, adventitia

Mucosa (esophagus)

Lined by stratified squamous epithelium (~3 layers)

Submucosa (esophagus)

Contains mucus secreting cells, blood vessels, and submucosal plexus (network of neurons from the enteric nervous system)

Muscularis externa (esophagus)

Comprised of an inner circular and outer longitudinal layer of muscle separated by the myenteric plexus (network of neurons from the enteric nervous system)

Adventitia (esophagus)

Comprised of fibrous tissue that connects the esophagus to surrounding structures

Achalasia

Incomplete relaxation of the lower esophageal sphincter, producing a functional obstruction

Clinical manifestations & causes of achalasia

• Regurgitation of food

• Coughing and intermittent chest pain

• Loss of appetite and unintentional weight loss

Causes are unknown- possibly from autoimmune damage to the myenteric plexus after viral infection

Diagnosis for achalasia- what characteristic do you see in the x-ray?

Barium swallowing

X-rays reveal conical narrowing at the lower end of the esophagus: “Bird’s beak” or “Rat’s tail” appearance

Bird’s beak/Rat’s tail

Conical narrowing at the lower end of the esophagus; achalasia

Treatment for achalasia

Pneumatic dilation or Heller myotomy

Pneumatic dilation

Cylindrical balloon can be used to expand the lower esophageal sphincter

Heller myotomy

Muscles of the lower esophageal sphincter can be cut to the widen the lumen

Esophagitis

Inflammation of the mucosal lining of the esophagus

Clinical manifestations & causes of esophagitis

• Dysphagia

• Chest pain during eating/drinking

• Pyrosis (heartburn)

Causes…

• Bacterial, viral, or fungal infection

• Acid reflux from the stomach into the esophagus

• Drugs

Diagnosis of esophagitis

Endoscopic examination- to visualize affected areas (by inserting a thin tube equipped with a camera down the throat into the esophagus)

Esophageal diverticula- how does it form?

Sacs or pouches along the esophagus

• Mucosa and submucosa are pushed outwards through the muscularis externa (possible increased pressure and weak walls)

Clinical manifestations of esophageal diverticula

• Halitosis (bad breath)

• Regurgitation of undigested food

What age groups does esophageal diverticula impact? Is it congenital or acquired later in life?

Can affect all age groups, although most cases occur during middle age

Can be congenital or acquired later in life

What are the 3 types of esophageal diverticula, categorized by anatomical location?

Zenker’s diverticulum

Midthoracic diverticulum

Epiphrenic diverticulum

Zenker’s diverticulum

Develops in the upper part of the esophagus (back of the throat near the upper esophageal sphincter)

Midthoracic diverticulum

Develops in the middle part of the esophagus (middle chest)

Epiphrenic diverticulum

Develops in the lower part of the esophagus (just above the diaphragm)

Diagnosis & treatment for esophageal diverticula

Barium swallow- X-rays reveal sacs or pouches along the esophagus

Treatment- surgery

Mallory-Weiss Syndrome

Longitudinal tears or lacerations of the mucous membrane lining the gastroesophageal junction

Clinical manifestations of Mallory-Weiss Syndrome

• Abdominal pain

• Hematemesis

• Melena 

Hematemesis

Vomiting of blood

Melena

Black, tar-like, sticky stools containing partially digested blood (following internal bleeding)

When do most cases of Mallory-Weiss Syndrome occur?

Most cases occur during middle age

Causes of Mallory-Weiss Syndrome

Increased intra-abdominal pressure that forces the stomach contents into the esophagus, leading to tears

• Retching/vomiting

• Intense coughing

• Severe, prolonged hiccupping

• Heavy lifting

• Physical trauma to the abdomen/chest

Diagnosis of Mallory-Weiss Syndrome

How long does this last?

Endoscopic examination to visualize tears

Self-limited disorder- tears usually heal on their own within 7-10 days

Hiatal hernia

Protrusion of a portion of the stomach through the esophageal hiatus in the diaphragm

What are the two types of hiatal hernias?

Sliding hiatal hernia and paraesophageal hiatal hernia

Sliding hiatal hernia

Axial hernia; the esophagus and stomach move up into the thoracic region

Paraesophageal hiatal hernia

Nonaxial hernia; the esophagus stays in place and a portion of the stomach moves up into the thoracic region next to the esophagus

Clinical manifestations of a hiatal hernia

• Small hiatal hernias usually do not cause signs/symptoms

• Large hiatal hernias may cause chest pain, abdominal pain, or pyrosis 

Causes of hiatal hernias

• Increased intra-abdominal pressure (due to intense coughing, straining during bowel movements, heavy lifting, pregnancy)

• Gradual widening of the esophageal hiatus in the diaphragm with age

Treatment for hiatal hernias

Drugs (antacids, protein pump inhibitors, histamine-2 receptor antagonists) to reduce stomach acidity

• Surgery for large hernias (stomach is pulled down into the abdomen, esophageal hiatus is sutured, repair is enforced with mesh)

Gastroesophageal reflux disease (GERD)

Chronic reflux of acidic gastric contents into the esophagus (>2 times a week for >4 weeks); erosive esophagitis (esophageal mucosa gets inflamed/eroded over time)

Erosive esophagitis

Esophageal mucosa gets inflamed and eroded over time

Clinical manifestations of GERD

• Regurgitation of sour/bitter liquid

• Pyrosis- occurs 30-60 minutes after eating, aggravated by lying down, relieved by sitting upright

• Epigastric pain- radiates to the throat, shoulders, or back (may be confused with angina)

What are the causes of GERD?

• Increased intra-abdominal pressure

• Excessive consumption of alcohol, fatty foods, or chocolate (which can increase the relaxation frequency of the lower esophageal sphincter)

What are two complications of GERD?

Esophageal stricture

Barrett’s metaplasia

Esophageal stricture

Esophageal narrowing due to scar tissue formation after chronic acid reflux

Barrett’s metaplasia

Precancerous change in the mucosal epithelium from stratified squamous → simple columnar interspersed with mucus-producing cells

Treatments for GERD

• Drugs (antacids, protein pump inhibitors, histamine-2 receptor antagonists)

• Lifestyle changes (eating small meals, avoid laying down immediately, sleeping with an elevated head)

Esophageal cancer usually impacts what populations (age and gender)?

More common in people >65 y/o

More frequent in men than women

Risk factors for esophageal cancer

• Excessive alcohol consumption

• Smoking

• Barrett’s metaplasia (mucosal epithelium of esophagus changes from stratified squamous → simple columnar)

Clinical manifestations of esophageal cancer

• Odynophagia

• Persistent pyrosis that doesn’t improve with drugs

• Loss of appetite and unintentional weight loss

Odynophagia

Pain with swallowing

Diagnosis and treatment for esophageal cancer

Endoscopic examination- to visualize tumors and take a biopsy specimen (grading the cell’s level of differentiation)

Treatment- chemotherapy, radiation therapy, surgery

Stomach

Pouch-like organ serving as a food reservoir during the early stages of digestion

What are the 4 stomach regions?

Cardiac region, fundus, body, pyloric region

Cardiac region

Portion surrounding the esophageal opening into the stomach

Fundus

Dome-shaped portion that bulges above the cardiac region

Body (stomach)

Middle portion of the stomach

Pyloric region

Funnel-shaped portion (wider antrum & narrower canal) that connects with the duodenum at the pyloric sphincter

What are the two types of stomach glands?

Gastric glands and pyloric glands

Gastric glands are located in which area of the stomach and have what 3 types of cells?

Located in the fundus and body of the stomach

• Mucous cells: secrete mucus

• Parietal (oxyntic) cells: secrete HCl and intrinsic factor (which is needed for Vit B12 absorption)

• Chief (peptic) cells: secrete pepsinogen (which is a proenzyme that turns into the protease pepsin when mixed with HCl)

Pyloric glands are located in which area of the stomach and have what 2 types of cells?

Located in the antrum (wide part) of the pyloric region

• Mucous cells: secrete mucus

• Enteroendocrine cells: secrete histamine, gastrin, and ACh (stimulates parietal cells to secrete HCl)

Mucous cells

Secrete mucus

Parietal (oxyntic) cells

Secrete HCl and intrinsic factor (which is needed for Vit B12 absorption)

Chief (peptic) cells

Secrete pepsinogen- a proenzyme that gets converted to the protease pepsin when mixed with HCl)

Enteroendocrine cells

Secrete histamine, gastrin, and ACh (which stimulate the parietal cells to secrete HCl)

Gastric mucosal barrier

Collective term for the mechanisms that allow the stomach to contain HCl and pepsin without damaging its own walls

What are some characteristics of the gastric mucosal barrier?

• Thick mucus coat rich in bicarbonate

• Tight junctions (proteins) between epithelial cells

• Prostaglandins (produced by the mucosa)- inhibit HCl production and stimulate mucus production

What are some potential disruptors to the gastric mucosal barrier?

• Infectious agents

• Excessive alcohol or spicy food consumption

• Drugs that inhibit prostaglandin synthesis (aspirin/other NSAIDs)

Acute gastritis

Acute inflammation of the gastric mucosa characterized by the presence of grossly visible erosions

Clinical manifestations & causes of acute gastritis

• Pyrosis

• Abdominal pain

• Nausea and vomiting

Causes…

• Excessive alcohol/spicy food consumption

• Drugs (aspirin/NSAIDs)

Diagnosis and treatment of acute gastritis

Endoscopic examination- to visualize inflammation

Treatment…

• Drugs to control excessive gastric acid production

• Elimination of the underlying cause (excessive alcohol, spicy food)

Chronic gastritis

Chronic inflammation of the gastric mucosa characterized by the absence of grossly visible erosions

Clinical manifestations of chronic gastritis

• Early satiety

• Abdominal pain

• Nausea, vomiting, unintentional weight loss

What are the 3 types of chronic gastritis?

Helicobacter pylori gastritis

Autoimmune atrophic gastritis

Reactive (chemical) gastropathy

Helicobacter pylori gastritis

Chronic infection with a flagellated, S-shaped, Gram-negative bacterium that spreads person-to-person through direct contact with saliva, vomit, or fecal matter

H. pylori is present in ___ of the world’s population, but only causes chronic gastritis in about __% of people

Present in 2/3 of the world’s population

Causes chronic gastritis in 20% of people

Pathogenesis of Helicobacter pylori gastritis

1. H. pylori colonizes the gastric mucous cells and can withstand the acidic environment of the stomach by producing/secreting urease

2. Urease converts stomach urea → CO2 (exhaled) and ammonia (buffers environmental acidity)

3. H. pylori releases toxins and enzymes that disrupt the gastric mucosal barrier, resulting in intense inflammation

• Chronic inflammation may lead to development of ulcers in the stomach and duodenum

Diagnosis and treatment for H. pylori gastritis

Urea breath test

Treatment…

• Combination therapy (antibiotics and proton pump inhibitors)

Urea breath test

Patient doesn’t eat for 4-6 hours and then consumes a urea tablet which contains radioactive carbon

• If there’s the presence of lots of bacteria with urease, that means the patient will breathe out a lot of CO2