Esophagus Anatomy and Pathology

Assessment of Digestive and Gastrointestinal Function

• Bleeding, perforation, obstruction, inflammation, and cancer indicate digestive and gastrointestinal dysfunction.
• The GI tract is susceptible to many organic diseases.
• Extrinsic factors such as stress, anxiety, fatigue, and sudden diet changes can affect digestive and gastrointestinal function.

Anatomic and Physiologic Overview

• The GI tract is a long, folded tube from the mouth to the anus.
• The GI tract includes the mouth, esophagus, stomach, small intestine, cecum, colon (large intestine), rectum, and anal canal.
• Food moves through the tract via peristalsis for digestion and absorption.

Esophagus

• It is a fibromuscular tube, approximately 25cm in length, that transports food from the pharynx to the stomach.
• It originates at the inferior border of the cricoid cartilage (C6) and extends to the cardiac orifice of the stomach (T11).
• Its passes through the diaphragm at an opening called diaphragmatic hiatus.

Important Sphincters in Digestion

• The Upper Esophageal Sphincter (UES) is an anatomical sphincter at the top of the esophagus that connects to the pharynx.
• The UES controls the entry of food and prevents air from entering; it is made of skeletal muscle (cricopharyngeus and pharyngeal constrictor muscles).
• The Lower Esophageal Sphincter (LES) is a functional sphincter comprised of smooth muscle that connects to the stomach.
• The LES prevents backflow of stomach contents and maintains a high-pressure zone.

Barrett's Esophagus

• Metaplasia involves the change of lower esophageal squamous epithelium to gastric columnar epithelium.
• The cause is chronic acid exposure from a malfunctioning lower esophageal sphincter.
• Acid irritates the esophageal epithelium, leading to a metaplastic change.
• A common symptom is a long-term burning sensation of indigestion.
• It can be detected via endoscopy and monitored for cancerous changes.

Esophageal Carcinoma

• Around 2% of malignancies in the UK are esophageal carcinomas.
• Clinical features include dysphagia, which worsens over time as the tumor grows, and weight loss.
• Two major types: squamous cell carcinoma and adenocarcinoma.
• Squamous cell carcinoma is the most common.
• Adenocarcinoma occurs in the inferior third of the esophagus and is associated with Barrett's esophagus.

Esophageal Varices

• Abnormally dilated sub-mucosal veins occur in this anastomosis.
• These are caused by an increased pressure in the portal system (portal hypertension).
• Portal hypertension often results from chronic liver disease (e.g., cirrhosis) or portal vein obstruction.
• Esophageal Varices are prone to bleeding, and patients often present with haematemesis [vomiting blood].
• Alcoholics are particularly at risk of developing esophageal varices.

Esophagus Location

• The esophagus begins at the level of the cricoid cartilage at vertebral level C6.
• The esophagus opens into the cardia of the stomach.

Stomach Divisions

• The stomach, an intraperitoneal digestive organ, sits between the esophagus and the duodenum.
• The cardia surrounds the superior opening of the stomach at the T11 level.
• The Fundus is the rounded, often gas-filled portion superior to and left of the cardia.
• The Body is the large, central portion inferior to the fundus.
• The Pylorus connects the stomach to the duodenum and is divided into the pyloric antrum, pyloric canal, and pyloric sphincter.
• The pyloric sphincter demarcates the transpyloric plane at the level of L1.

Stomach Curvatures and Attachments

• The greater curvature forms the long, convex, lateral border of the stomach.
• The lesser curvature forms the shorter, concave, medial surface of the stomach.
• The hepatogastric ligament attaches to the lesser curvature and is supplied by the left gastric artery and the right gastric branch of the hepatic artery.

Stomach Sphincters

• The pyloric sphincter is between the pylorus and the duodenum.
• This sphincter controls the exit of chyme from the stomach.
• It is an anatomical sphincter with smooth muscle that constricts to regulate stomach content discharge.

Stomach Peritoneum and Omenta

• The peritoneum is a double-layered membrane within the abdominal cavity.
• The peritoneum supports most abdominal viscera and assists with attachment to the abdominal wall.
• Omenta are structures consisting of peritoneum folded over itself (four membrane layers in total).
• Both the greater and lesser omenta attach to the stomach and important anatomical landmarks.

Gastro-Esophageal Reflux Disease (GERD)

• GERD is a digestive disorder affecting the lower esophageal sphincter, leading to the movement of gastric acid and food into the esophagus.
• GERD affects approximately 5-7% of the population and includes symptoms such as dyspepsia, dysphagia, and a sour taste in the mouth.
• The three main causes of reflux disease are dysfunction of the lower esophageal sphincter, delayed gastric emptying, and hiatal hernia.
• Treatment includes lifestyle changes/medication such as a PPI to reduce stomach acid, and as a last resort, surgery.

Hiatal Hernia

• A hiatal hernia occurs when part of the stomach protrudes into the chest through the esophageal hiatus in the diaphragm

Small Intestine

• The Small Intestine is a 6.5m long organ in the gastrointestinal tract; aiding in digestion and absorption.
• It extends from the stomach's pylorus to the ileocecal valve, meeting the large intestine.
• Three parts: duodenum, jejunum, and ileum.
• All major digestive events and most of the absorption takes place in the small intestine

Duodenum

• The duodenum is the most proximal part of the small intestine, forming a 'C' shape around the pancreas.
• It has four parts: superior, descending, transverse and ascending
• Only the beginning of the first part is an intraperitoneal region (connected to the liver by the hepatoduodenal ligament)

Jejunum and Ileum

• They are intraperitoneal and cannot be clearly distinguished from one another.
• The Jejunum is long and leaf-like with villi, more plicae circulares, and an intermediate number of goblet cells and lacks peyer's patches.
• The Ileum has fewer shorter villi.
• The Ileum is abundant, occupies the RLQ and appears pale pink and has is longest in lengh.

Cecum

• It is the most proximal part of the large intestine, located in the right iliac fossa of the abdomen.
• It lies inferiorly to the ileocecal junction.
• It can be palpated if enlarged due to feces, inflammation, or malignancy.
• The name 'Cecum' originates from the Latin word 'caecus', which means 'blind' (referring to its inferior bind-end)

Appendix

• Is a narrow, blind-ended tube attached to the posteromedial end of the cecum (large intestine).
• It contains a large amount of lymphoid tissue but is thought to have no vital functions.

Appendicitis

• Inflammation of the appendix causes acute severe abdominal pain.
• Maximum tenderness occurs at McBurney's point (located one-third of the way from the right anterior superior iliac spine to the umbilicus).
• In young individuals, it is commonly caused by an increase in lymphoid tissue size, occluding the lumen.
• In adults over 30 years, it’s more likely to be caused by a faecolith blockage.
• Pain starts in the umbilical region and then localizes to the right lower quadrant as inflammation increases.
• If untreated, the appendix can necrotize and rupture, leading to peritonitis (inflammation of the peritoneum).

Colon

• It is the distal part of the gastrointestinal tract that receives digested food from the small intestine.
• It's main functions involves absorption of water and electrolytes to form feces.
• The colon averages 150 cm in length.
• The Colon has 4 parts: Ascending, transverse, descending, and sigmoid.
• The colon forms an arch around the small intestine.

Ascending Colon

• The ascending colon is a retroperitoneal structure & begins as the colon.
• It ascends superiorly from the cecum.
• The colon turns 90 degrees horizontally when meeting the right lobe of the liver, and this is known as the right colic flexure (or hepatic flexure).

Transverse Colon

• The transverse colon extends from the right colic flexure to the spleen.
• Other factors for the transverse colon are; it’s left colic flexure (or splenic flexure), phrenicocolic ligament and transverse mesocolon

Descending Colon

• Descending colon has features and is located and is located inferiorly towards the pelvis

Sigmoid Colon

• A 40cm-long sigmoid colon is located in the left lower quadrant
• It is located in an "S" shape and uses sigmoid mesocolon

Rectum

• The rectum is the most distal segment of the large intestine.
• It has an important role as a temporary store of feces
• The rectum begins at the level of the S3 (as a continuation of the sigmoid colon)
• The rectum is macroscopically distinct from the colon with an absence of tenia coli, haustra, and omental appendices.

Characteristic Features of large intestine

• The large intestine has a number of characteristic features that distinguishes it from the small intestine.
• Attached to the surface of the large intestine are omental appendices which - small pouches of peritoneum, filled with fat.
• Running longitudinally along the surface of the large bowel are three strips of muscle; known as the teniae coli; they are called the mesocolic, free, and omental coli.
• The teniae coli contract to shorten the wall of the bowel, producing sacculations known as haustra.
• The large intestine has a much wider diameter compared to the small intestine

Anal Canal

• The anal canal is the final segment of the gastrointestinal tract.
• The anal canal plays an important role in defecation and maintaining faecal continence.
• Except during defecation, the anal canal is collapsed by the internal and external anal sphincters to prevent passage of faecal material.

Anal Sphincters

• The anal canal is surrounded by internal and external anal sphincters.
• The internal anal sphincter surrounds the upper 2/3 of the anal canal and is formed from a thickening of the involuntary circular smooth muscle in the bowel wall.
• The external anal sphincter is a voluntary muscle that surrounds the lower 2/3 of the anal canal (and so overlaps with the internal sphincter).
• The external anal sphincter blends superiorly with the puborectalis muscle of the pelvic floor.

Haemorrhoids

• They are vascular cushions found within the anal canal of healthy individuals; which help with the maintenance of faecal continence .
• They can cause bleeding and itchiness, and can be managed conservatively or surgically depending on the severity.

Abdominal Pain

• Abdominal pain can be broadly classified into three groups: somatic, visceral and referred.
• Somatic pain can arise from the skin, fascia, muscles and parietal peritoneum; lateralizing if the origin is on one side and is severe /precisely localised.
• Visceral pain arises in abdominal organs, visceral peritoneum and mesenteries; it's dull and poorly localized (colic) but the stretching of a viscus or mesentery, distention of a hollow viscus, impaired blood supply (ischemia) to a viscus, and chemical damage can act as causes
• Referred pain is a feeling of pain at a location other than the site of origin of the stimulus, however are supplied by the same/adjacent segments of the spinal cord.

Portacaval Circulation

• Anastomosis between "PORTAL VEIN" and "SYSTEMIC BLOOD"
• the "PORTAL VEIN" supplies bold from GUT liver then the "Systemic Venous system'
• It is able to perform "detoxification" , "Nutrient storage and/ release"

Portal Hypertension

• An increase in pressure in the portal vein due to liver diseases (ascities)
• Portacaval Shunt is caused as esophageal varices , Caput Medusae , Hemorrhoids.
• It bypasses liver , drains to systemic circulation (alternative direction)

Function of the Digestive System

• Digestion processes food to break it down.
• Absorption: is used mainly for nutrient
• Elimination happens after nutrients are extracted.

Saliva Function

• Reflex salivation is triggered through eating, sight, smell, or taste of food.
• Daily saliva production is approximately 1.5 liters of saliva secreted daily.
• Important salivary glands - parotid, submaxillary, and sublingual glands - contribute to secretion.
• Ptyalin (salivary amylase) is an enzyme that begins starch digestion.
• Water and Mucus lubricate food, facilitating chewing and swallowing.

SWALLOWING Reflex

• Swallowing is a voluntary act regulated by medulla
• The epiglottis covers the tracheal opening > peristalsis propels the bolus of food > LES Relaxes> Food enters Stomach> ES closes",

Gastric Function Cells involved in digestion

• Parietal Cells produces "HCL acid " , "intrinsic factor" . They are eosinophilic + ditt mitochondria to produce H+ to power H+ pump(
• Chief cells secrete the enzyme pepsinogen, are basophilic and are largely found body + fundus
• Mucous cells mucus as protective layer on stomach lining
• G cells - Produce GASTRIN (goes to > parietal cells (HCL) + chief cells (pepsinogen).
• ENTEROENDOCRINE CELLS - "SOMATOSTATIN""

Stomach Hormones

• Ghrelin (hunger hormone) regulates appetite, energy balance, and fat storage.
• It aids in stimulating a patient’s release of growth hormone, promotes calorie intake and reduced energy expenditure + hormone produced in Stomach" "Small Intestine" " pancreas" " brain"
• Leptin contributes to the signaling satiety and inhibiting hunger,

Gastric Actions

Peristalsis moves food from pylorus + body, this is mainly due to the pyloric sphincter (mechanical reaction

• It takes 30minutes- several hours before Chyme (partially digested foods) can mix with gastric secretions
• Hormones/ Regulators controls secretions & mobility (speed)

Small Intestine Function

• Duodenum mainly continues + finishes the digestive process
• Enzymes included here are amylase , lipase (from bile duct and "trpsin"
• Digestive secretions enter through pancreatic duct - Common bile duct + enters ampulla van walter (bile acids)

Secretin

• Secreted by s cells in duodenum",Stimulus needed, mainly "PH<",Stimulate increase output HCL fluid", bile and pancreatic enzymes"

Contractions

• 2 Types of intestinal contraction are "Segmentation" " Intestinal Perisatslis" these cause food to stay between 3-6 hours
• Villi "fingerlike" absorb nutrients unchanged, main absorber in Jejunum

Types of Small Intestine cells

• Enterocytes - they line the surface and has microvilli", increase surface"
• Goblet - secretes lubricant and protection (mucus)
• Paneth
• Enteroendocrine

Colonic Functions

• Peristalsis pushes residue (terminal Ileum > cecum after 4 hrs with food
• Gut / Microboes" can breakdown waste and make it smaller

Colic Secretions

• Bicarbonate : counter actions of bacteria
• Mucus protects the colic mucosa and helps fecal mass adherence
• The Slow and weak peristalsis (absorbs water + electrolytes)
• Intermittent and strong (push contents)
• Transit time is 12 hrs as rectum gets expanded.

Waste Products of Digestion

• Undigested foods ,Inorganic material, water + Bacteria
• 75%) Fluid / 25%) solid
• "Bile > bacteria (Sterc obilum
• Odour chemical " Methane " hydrogen sulfide and ammonia "Gas"(150mL within GI")
• flatus

Gut/ micro biome: in digestion and absorption

Colonic Functions

• Colonization short period + starts shortly after birth and is 2yrs / assistin waste ,Vit synthesis"
• Genetics [ "bacteroides"] or Diet [Lactobacillus, Bifidobacterium, Bacteroides"]
• Protection : against pathogens , increase anti inflammatory , prevents pathogens.

Clinical Tests

• Gag Reflex Test: stimulate the back of neck , this checks for symmetry and checks "vagus nerve" function
• Uvula Movement , This checks for nerves when AHHH Swallowing , check muscles that are used with swallowing"

Abdominal Inspection, Auscultation, Percussion, and Palpation

• Inspection:
  • Note skin changes, nodules, lesions, scarring, discolorations, inflammation, bruising, or striae.
  • Lesion (diseases and changes. Observe contour and symmetry of the abdomen.
  • Identify localized bulging, distention, or peristaltic waves

Abdominal contour/structure: for check up.

• structure of abdomen and see if it feels flat, rounded, or scaphoid

Auscultation Before Percussion and Palpation:

• the "Reason",is to see how the" bowel sounds are"
• sounds "Clicks " 5-30 times per minute / hypoactive
• Diaphragm = normal
• bell (Bruits )