Gastrointestinal Anatomy, Physiology, and Disorders: Key Concepts for Students

What is the duration for a bolus to pass through the oesophagus in adults?

10-20 seconds

What is intravenous feeding?

A method of delivering nutrition directly into the bloodstream through a vein.

Why might an NJ (Naso-jejunal) tube by used instead of an NG tube?

To deliver nutrients directly to the small intestine; bypasses the stomach so good choice for people with gastro issues.

What muscles contract to seal the upper oesophageal sphincter?

Cricopharyngeal muscles

At what level of spine does the oesophagus pass through?

T10

Which nerve innervates the voluntary muscles fibres in top 1/3 of oesophagus

Vagus nerve (X)

What is the primary function of the lower oesophageal sphincter?

To allow the bolus to enter the stomach and prevent reflux

What are the main functions of the stomach?

Storage organ, secretes gastric juices, and mixes food into chyme

What is the Oesophagus lined with?

connective tissue, smooth muscle and epithelial cells

What is the Pylorus?

Part of the stomach that connect to duodenum. Contains an atrium, canal, and sphincter.

What is the function of the gallbladder?

Stores and concentrates bile

What are some functions of the liver?

Creates bile, supports digestion, metabolism, vitamin d production (requires sunlight), storage of vitamin, fats and minerals

What are the parts of the small intestine?

1. Duodenum

2. Jejunum

3. Ileum

What is the function of the duodenum?

Bile and enzymes are delivered here (from gallbladder, liver and pancreas) to aid food digestion

Where is the Fundus?

Top of stomach

What is the length of the small intestine?

Approximately 6 meters

What is the function of the pyloric sphincter?

Controls the entry of chyme into the duodenum

What is the primary role of the large intestine?

Absorbs water and salts and eliminates waste.

Note: 90% of water already absorbed by small intestine

What are the three phases of gastric secretion regulation?

Cephalic phase, gastric phase, and intestinal phase

What triggers the cephalic phase of gastric secretion?

Thought, sight, and smell of food

What nerve is related to the cephalic phase?

Vagus nerve

What is the cephalic phase?

Earliest phase of digestion when the brain prepares the body in anticipation of food

What is Gastro-oesophageal reflux disease (GORD)?

A chronic condition where stomach acid leaks into the oesophagus (chronic reflux)

What is Gastro-oesophageal reflex disease due to?

Weakness of the lower oesophageal sphincter

What are some symptoms of GORD?

• Discomfort and feelings of heartburn

• Taste in mouth

• Oesophagitis

• Pain when swallowing

• Dental decay

What is pyloric stenosis?

Narrowing of the entrance to the duodenum due to thickened lining of pyloric sphincter muscle, which prevents milk from passing through.

Symptoms of pyloric stenosis

Curdled, yellow vomit, and small hard lump on right side of stomach.

What is Fundoplication?

Surgery that wraps the fundus section of stomach around oesophagus; used to treat GORD.

What should you consider as a cause of acid reflux in infants/children?

CMPA (cow's milk protein allergy) and lactose intolerance

What are symptoms of reflux in infants?

Projectile vomiting, silent reflux, back arching, coughing during feeds.

Reflux treatment in infants

Thicker milk/formula

Feeding modifications

Early introduction of solids (around 16 weeks of age)

Maternal exclusionary diet

Tests for reflux in infants

• Doesn’t always require test but sometimes:

  • pH impedance study

  • Barium swallow

  • Oesophageal manometry

What is achalasia?

A motility disorder where the lower oesophageal sphincter fails to relax

What is enteral feeding?

Nutrition delivered directly to the stomach or intestine

What is the purpose of a Percutaneous Endoscopic Gastrostomy (PEG)?

To create an artificial opening for feeding directly into the stomach.

What is the main risk associated with intravenous feeding?

High risk for infection

What are types of feeds which can be delivered by enteral feeding?

Gravity bolus feed, or continuous pump feed

Why might someone get PEG tube feeding instead of an NG tube?

More long term solution

When is intravenous feeding used?

When there is a problem with absorption, as nutrition is delivered directly to vein.

What is the function of the pancreas in digestion?

Secretes digestive enzymes into the small intestine

What is an Oesophageal stricture?

Narrowing of the oesophagus; can be localised or throughout.

What are two types of oesophageal stricture?

Webs and rings.

What are oesophageal webs?

Type of stricture; Thin, membranous shelves of mucous, usually in the top of oesophagus

What are rings in the oesophagus?

Type of stricture; narrowing of the lower oesophagus usually associated with reflux.

What is the treatment for achalasia?

Surgery to cut muscle fibers to enable LES relaxation

Which pathology affects peristalsis?

Achalasia