7 Sphincters in the GI Tract

Questions and Answers

What is the location of the Upper Esophageal Sphincter?

Between the small and large intestine

Between the stomach and duodenum

Between the esophagus and pharynx (correct)

Between the rectum and anus

Where is the Lower Esophageal Sphincter located?

Between the pharynx and esophagus

Between the stomach and duodenum

Between the low-end of esophagus and stomach (correct)

Between the rectum and anus

Which sphincter is located between the stomach and duodenum?

Upper Esophageal Sphincter

Pyloric Sphincter (correct)

Lower Esophageal Sphincter

Sphincter of Oddi

What is the function of the Sphincter of Oddi?

Control the flow of bile and pancreatic juice Signup and view all the answers

Where is the Ileocecal Sphincter found?

Between small and large intestine Signup and view all the answers

What is ingestion?

Intake of food/drink by lips, teeth, and tongue. Signup and view all the answers

What does digestion involve?

Breaking food into pieces by chemical and mechanical mechanisms with the teeth and saliva. Signup and view all the answers

What is mechanical digestion?

Chewing and segmentation Signup and view all the answers

What role do enzymes play in chemical digestion?

They break bonds and require specific substrates and pH Signup and view all the answers

What is absorption?

Transport of nutrients from GI organs into blood and lymph. Signup and view all the answers

What is the process of defecation?

Expulsion of wastes through anus. Signup and view all the answers

What is peristalsis?

Wavelike contractions of smooth muscle that move substances through body organs. Signup and view all the answers

Define segmentation.

Rhythmic local constrictions of the intestine. Signup and view all the answers

What is the peritoneum?

A serous membrane that lines the abdominal cavity. Signup and view all the answers

What are the two types of peritoneum?

Visceral and Parietal Signup and view all the answers

What layer of peritoneum is touching the abdominal organ?

Visceral peritoneum Signup and view all the answers

What is the role of mesenteries?

Hold blood vessels and fat between intestines Signup and view all the answers

What does the omentum refer to?

Fatty mesentery hanging off the stomach Signup and view all the answers

What is meant by retroperitoneal?

Peritoneum found on anterior side of the body Signup and view all the answers

What are the four layers of the digestive tract?

Mucosa, Submucosa, Muscularis Externa, Serosa Signup and view all the answers

Describe the mucosa of the digestive tract.

Inner layer; epithelium layer; stratified squamous to simple columnar. Signup and view all the answers

What does the submucosa of the digestive tract contain?

Connective tissue; contains major blood and lymph vessels; nervous and serous glands; and elastic fibers. Signup and view all the answers

What is found in the muscularis externa of the digestive tract?

Circular and longitudinal smooth muscle layers. Signup and view all the answers

Define serosa in the context of the digestive tract.

Visceral and parietal layers; simple squamous ET on outside; areolar CT on inside. Signup and view all the answers

What are the main ingredients of saliva?

Enzymes, water, and ions Signup and view all the answers

What are the three salivary glands?

Sublingual, Parotid, Submandibular Signup and view all the answers

Where is the sublingual salivary gland located?

Beneath the tongue Signup and view all the answers

What type of secretion does the parotid salivary gland produce?

Serous only Signup and view all the answers

What is the function of amylase?

To break down starch Signup and view all the answers

Which cranial nerves influence salivary secretions?

Cranial nerves VII (facial) and IX (glossopharyngeal). Signup and view all the answers

How many neurons are part of the enteric nervous system?

Approximately 100 million neurons. Signup and view all the answers

What is the role of the LES (Lower Esophageal Sphincter)?

To allow food to enter stomach and prevent acid reflux Signup and view all the answers

What condition is caused by a hiatal hernia?

Heartburn due to acid entering the esophagus Signup and view all the answers

What does GERD stand for?

Gastroesophageal reflux disease. Signup and view all the answers

What are the main functions of the stomach?

Digestion, absorption, and storage of nutrients Signup and view all the answers

What is the mucosal lining of the stomach made of?

Simple columnar ET with many goblet cells for absorption. Signup and view all the answers

Study Notes

Sphincters in the GI Tract

Upper Esophageal Sphincter: Located between the esophagus and pharynx.
Lower Esophageal Sphincter (Cardiac Sphincter): Situated between the low-end of the esophagus and the stomach.
Pyloric Sphincter: Found between the stomach and duodenum (small intestine).
Sphincter of Oddi: Located between the duodenum and the ducts of the liver and pancreas.
Ileocecal Sphincter: Positioned between the small intestine (ileum) and large intestine (cecum).
Internal Sphincter: Involuntary sphincter within the rectum.
External Sphincter: Voluntary sphincter at the anal opening.

Digestive Processes

Ingestion: Intake of food and drink using lips, teeth, and tongue.
Digestion: Breakdown of food into smaller pieces through chemical and mechanical means (teeth and saliva).
Mechanical Digestion: Involves chewing and segmentation of food.
Chemical Digestion: Enzymatic process that breaks chemical bonds, requiring specific substrates and pH.
Absorption: Transportation of nutrients from GI organs into blood and lymphatic system (lacteals).
Defecation: Expulsion of wastes from the body through the anus.
Peristalsis: Wavelike contractions of smooth muscle that facilitate movement of substances through the GI tract.
Segmentation: Rhythmic contractions of the intestine that mix and slowly move chyme.

Peritoneum: Serous membrane lining the abdominal cavity.
Two Types of Peritoneum: Visceral (touches abdominal organs) and parietal (touches body wall).
Visceral Peritoneum: Inner layer in contact with abdominal organs.
Parietal Peritoneum: Outer layer in contact with the abdominal wall.
Mesenteries: Double peritoneal membranes containing fat and blood vessels found between the intestines.
Omentum: Fatty mesentery that hangs from the stomach, resembling an apron.
Retroperitoneal: Refers to the positioning of organs located on the anterior side of the body (e.g., duodenum, ascending/descending colon).

Digestive Tract Layers

Four Layers of the Digestive Tract: Mucosa, submucosa, muscularis externa, and serosa.
Mucosa: Inner lining of the digestive tract with a transition from stratified squamous to simple columnar epithelium.
Submucosa: Connective tissue layer housing major blood and lymph vessels, neural networks, and serous glands.
Muscularis Externa: Contains circular and longitudinal muscle layers for peristalsis and segmentation.
Serosa: Outer layer of the digestive tract comprised of visceral and parietal layers; features simple squamous epithelium and areolar connective tissue.

Salivary Functions and Glands

Main Ingredients of Saliva: Water, ions, lubricating mucus, digestive enzymes (e.g., amylase), bicarbonate for pH balance, lysozyme, and antibodies for infection defense.
Three Salivary Glands:
- Sublingual: Located beneath the tongue, produces mucus only.
- Parotid: Found covering the masseter, secretes watery serous fluid.
- Submandibular: Situated beneath the mandible, produces both serous and mucous secretions.
Amylase Function: Enzyme that breaks down starch at a pH of 6.8.

Nervous System and GI Tract Interaction

Salivary Secretion Control: Influenced by cranial nerves VII (facial) and IX (glossopharyngeal).
Enteric Nervous System: Comprises approximately 100 million neurons responsible for regulating gastrointestinal functions.

Stomach Functions and Conditions

Lower Esophageal Sphincter: Opens for food entry into the stomach and closes to prevent acid reflux into the esophagus.
Hiatal Hernia: Condition where a stretched hiatus allows gastric acid to enter the esophagus, leading to heartburn.
Gastroesophageal Reflux Disease (GERD): Chronic condition characterized by acid reflux.
Main Functions of the Stomach: Involved in chemical and mechanical digestion, absorption of sugars, drugs, water, and alcohols, along with storage of nutrients during GI tract inactivity.
Mucosal Lining of Stomach: Composed of simple columnar epithelium with abundant goblet cells aiding absorption.

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Description

Test your knowledge on the seven crucial sphincters in the gastrointestinal tract. This quiz covers their locations and functions within the digestive system, essential for understanding digestion. Perfect for students of anatomy and physiology.