Gastrointestinal System

Flashcards covering key vocabulary and concepts from the gastrointestinal digestive system lecture.

Deglutition

Swallowing. The process by which food passes from the mouth to the stomach.

Buccal Phase

The first stage of deglutition, involving the voluntary mastication and movement of food to the pharynx.

Pharyngeal phase

The second stage of deglutition, where food is involuntarily propelled down the pharynx into the oesophagus.

Oesophageal Phase

The phase of swallowing where food is moved through the oesophagus via involuntary peristalsis.

Peristalsis

Wave-like muscle contractions that move food through the digestive tract.

UES (Upper Esophageal Sphincter)

A muscle that controls the entrance of the oesophagus, preventing backflow into the pharynx.

LES (Lower Esophageal Sphincter)

A muscle that relaxes to allow food to enter the stomach from the oesophagus. Also closes off to prevent reflux of stomach contents back into the oesophagus.

Cricopharyngeal muscles

Contract to seal the upper oesphageal sphincter

Oesophagus

A muscular tube connecting the pharynx to the stomach, facilitating the passage of food.

Approx 25cm long

Shares a wall with trachea

Stomach

The muscular organ that stores and digests food, mixing it with gastric juices to break it down before passing it into the small intestine.

3 notable areas of stomach for SaLT

•       Fundus

•       Pylorus

•       Duodenum

Pancreas

A glandular organ that produces digestive enzymes and hormones, such as insulin, playing a crucial role in digestion and glucose regulation.

12-15cm long

Liver and gallbladder

The liver is a large gland that produces bile to aid in digestion, and the gallbladder stores bile until needed for fat digestion.

Small intestine

The small intestine is a long, coiled tube where most digestion and nutrient absorption occurs, consisting of three parts: duodenum (20-25cm), jejunum, and ileum.

6m in length

Large intestine

The large intestine, also known as the colon, absorbs water and electrolytes from indigestible food matter, compacts waste into stool, and facilitates its excretion.

Connects to the ileum of small intestine and terminates at the anus

Neural & hormonal regulation of gastric secretions (3 phases)

Cephalic phase

Gastric phase

Intestinal phase

Cephalic phase

The cephalic phase is the first phase of gastric secretion that begins before food enters the stomach, triggered by the sight, smell, or thought of food, preparing the digestive system to process incoming nutrients e.g. producing saliva

Involves vagus nerve action

Gastric phase

The gastric phase is the second phase of gastric secretion that occurs when food enters the stomach, stimulating the release of gastric juices through neural and hormonal mechanisms to aid in digestion.

Intestinal phase

The intestinal phase is the final phase of gastric secretion that occurs when partially digested food enters the small intestine. It is stimulated by chyme entering the duodenum and regulates/slows gastric emptying

GORD (Gastro-oesophageal Reflux Disease)

A chronic condition where acid from the stomach leaks into the oesophagus.

Chyme

The semi-fluid mass of partially digested food that is formed in the stomach.

Pyloric Sphincter

A muscular valve that controls the movement of chyme from the stomach into the duodenum.

Reflux

When stomach contents leak back into the oesophagus, causing heartburn and discomfort. Usually due to a weakness of the lower oesophageal sphincter

Reflux in infants

Common condition in babies - likely where immature lower oesophageal sphincters allow stomach contents to flow back into the oesophagus

Results in forceful expulsion of feed

Can result in aspiration as vomit/acid leaks back down into trachea and lungs

Colic

Reflux often mistaken for clic

Colic is digestive discomfort, likely caused by build up of gas

Infant reflux treatment - thickening milk

Involves adding a thickening agent to formula or breast milk to reduce reflux incidents by making the feed heavier and less prone to regurgitation.

Infant reflux treatment - pacing and positioning

Refers to techniques such as holding the baby upright during and after feedings and pacing the feeding to allow for burping, reducing the likelihood of reflux.

Infant reflux treatment - early introduction of solids

Solid foods are heavier, denser and less likely to be regurgitated, reducing instances of reflux

Adult reflux treatment - medication

Medications such as Gaviscon can be used to coat contents of stomach and reduce backward movement into oesophagus

Adult reflux treatment - Fundoplication

A surgical procedure that involves wrapping the top of the stomach around the esophagus to prevent acid reflux. Works by tightening the lower esophageal sphincter, thereby reducing the risk of reflux episodes.

Pyloric stenosis

A condition in infants where the pylorus muscle thickens, narrowing the duodenum and blocking food from entering the small intestine. This leads to severe vomiting, dehydration, and requires surgical intervention to remove thickened muscle to allow normal passage of food.

Oesophageal stricture

A narrowing of the oesophagus (from 30-13mm or less)

Causes: GERD (70-80%), oesophagitis (inflammation leading to scarring), cancer, injury, etc.

Symptoms: Difficulty swallowing (especially thicker consistencies), weight loss, pain, choking

Treatment: dilation of the esophagus or surgical interventions.

Oesophageal stricture - webs

Thin membranes that can form in the esophagus, contributing to narrowing and difficulty swallowing.

Can be congenital or acquired

Cause: may be due to reflux, iron deficiency, etc

Symptoms: dysphagia (food ‘stuck’), potential for aspiration

Treatment: treat cause (e.g. anaemia), dilation or surgical removal of webs.

Oesophageal stricture: rings

Circular bands of tissue that form in the lower oesophagus, causing narrowing.

Causes: can be congenital but usually associated with reflux

Symptoms: dysphagia (when lumen gap is less than 12mm)

Treatment: may require dilation or surgical intervention for treatment.

Enteral Feeding

Nutrition delivered directly to the stomach or intestines, bypassing the mouth.

Intravenous Feeding

Dietary nutrients delivered directly into the bloodstream.

Achalasia

A motility disorder where the lower oesophageal sphincter fails to relax and peristalsis is impaired

Symptoms: difficulty in swallowing, chest pain, vomiting and reflux

Treatment: surgery (cut muscle fibres to relax LES, fundoplication)

Stoma

An opening created surgically on the abdomen for inserting feeding tubes.

Gastric Emptying

The process by which the stomach contents are passed into the duodenum.

Orogastric tube

A tube inserted through the mouth into the stomach

Nasogastric (NG) tube

A tube inserted through the nose into the stomach

Nasojejunal tube

A tube inserted through the nose into the jejunum (part of small intestine)

Nasoduodenal tube

A tube inserted through the nose into the duodenum (first part of the small intestine).

Gastronomy (PEG - percutaneous endoscopic gastronomy)

A surgical procedure that involves creating an opening into the stomach through the abdominal wall.

Jejunostomy

A surgical procedure that creates an opening directly into the jejunum

Also known as PEGJ - percutaneous endoscopic gastronomy extending to jejunum

Gravity/Bolus Feed

Delivering a pre-set amount of liquid nutrition into the stomach through an NG tube, often using a large syringe and gravity.

Continuous/Pump Feed

A method of administering liquid nutrition slowly over a long period, typically 24 hours, using a pump to control the flow rate.

Pros and Cons of IV Feeding

Pros - good alternative when there is a problem absorbing nutrition from digestive system

Cons - high risk of infection