Digestive System Upper Tract Overview

<p>Dorsal Surface (C)</p> Signup and view all the answers

<p>To regulate motility in the GI tract. (B)</p> Signup and view all the answers

<p>Lingual Gland (D)</p> Signup and view all the answers

<p>Biting and chewing with teeth (C)</p> Signup and view all the answers

<p>Salivary amylase (C)</p> Signup and view all the answers

<p>Fauces (C)</p> Signup and view all the answers

<p>Alveolar connective tissue and simple squamous epithelium (D)</p> Signup and view all the answers

<p>Mucosa (C)</p> Signup and view all the answers

<p>Nonkeratinized stratified squamous epithelium (A)</p> Signup and view all the answers

<p>Pasaging food into the trachea (C)</p> Signup and view all the answers

<p>Molars (C)</p> Signup and view all the answers

<p>Mixing food with saliva and pushing it towards the pharynx (A)</p> Signup and view all the answers

<p>Smooth muscle (C)</p> Signup and view all the answers

<p>Lamina propria (C)</p> Signup and view all the answers

<p>The creation of folds in the mucosa (A)</p> Signup and view all the answers

<p>Chemical digestion through enzyme secretion (C)</p> Signup and view all the answers

<p>Transporting food from the mouth to the stomach (A)</p> Signup and view all the answers

<p>To initiate the peristaltic wave (D)</p> Signup and view all the answers

<p>Canines (B)</p> Signup and view all the answers

<p>Pharyngeal stage (C)</p> Signup and view all the answers

<p>Hypopharynx (C)</p> Signup and view all the answers

<p>Dentin (D)</p> Signup and view all the answers

<p>Elevation of the larynx (A)</p> Signup and view all the answers

<p>Transporting food to the stomach (A)</p> Signup and view all the answers

<p>Superior and inferior esophageal sphincters (D)</p> Signup and view all the answers

<p>Molars (B)</p> Signup and view all the answers

<p>To push the bolus into the hypopharynx (B)</p> Signup and view all the answers

<p>Bolus (C)</p> Signup and view all the answers

<p>Cardia (B)</p> Signup and view all the answers

<p>Parietal cells (A)</p> Signup and view all the answers

<p>Regulates emptying of the esophagus and passage to the stomach (A), Prevents reflux of gastric contents into the esophagus (B)</p> Signup and view all the answers

<p>Muscularis (D)</p> Signup and view all the answers

<p>Pyloric sphincter (D)</p> Signup and view all the answers

<p>Laryngopharynx (A)</p> Signup and view all the answers

<p>Upper esophageal sphincter (B)</p> Signup and view all the answers

<p>Rugae (C)</p> Signup and view all the answers

<p>G cells (B)</p> Signup and view all the answers

Tube connecting pharynx to stomach, passes through thorax, pierces diaphragm, and enters abdominal cavity.

Muscles regulating bolus flow: upper for entry from pharynx, lower for stomach entry.

Bolus: food from mouth to pharynx; Chyme: stomach contents released to small intestine.

Digestion begins in the oral cavity with mechanical processing and saliva mixing.

The stomach can hold 1.5-2 liters of food.

The stomach wall has three layers of muscles.

Cardia, fundus, body, and pylorus (antrum, canal, sphincter).

Folds in stomach lining allowing for expansion.

Stomach cells producing HCl acid and intrinsic factor.

Stomach cells producing pepsinogen and gastric lipase.

A tooth consists of three parts: the crown (visible part), the neck (connecting crown to root), and the root (embedded in jawbone).

Dentin is the hard, yellowish tissue that makes up most of the tooth, providing its shape and strength.

Enamel is the hardest substance in the body, covering the crown and protecting it from wear and tear.

The pharynx is divided into three sections: the epipharynx (nasopharynx), oropharynx (midpharynx), and hypopharynx (laryngopharynx).

The pharynx plays a key role in swallowing, initiating the peristaltic wave that propels food down the esophagus.

Swallowing (deglutition) occurs in three stages: voluntary (oral cavity to oropharynx), pharyngeal (oropharynx to esophagus), and esophageal (esophagus to stomach).

The initial stage of swallowing, where the tongue pushes the bolus (food mass) towards the back of the mouth, is voluntary.

Once the bolus enters the oropharynx, swallowing becomes involuntary, with muscles coordinating to move the bolus down.

The esophageal stage of swallowing involves peristalsis, rhythmic muscular contractions that propel the bolus through the esophagus.

The digestive system performs six vital functions:

1. Ingestion: Taking in food
2. Secretion: Releasing fluids (about 7 liters) to aid digestion
3. Mixing and Propulsion: Moving food along the digestive tract.
4. Digestion: Breaking down food mechanically and chemically.
5. Absorption: Taking in nutrients from digested food
6. Elimination: Removing waste (defecation).

From innermost to outermost, the digestive tube has four layers:

1. Mucosa: The inner lining, responsible for absorption and secretion.
2. Submucosa: Connective tissue with blood vessels, lymphatics, and nerves.
3. Muscularis: Muscle layers responsible for movement of food through the digestive tract.
4. Serosa: The outermost layer that protects the digestive tract and reduces friction.

The mucosa, the innermost layer of the digestive tube, has three sublayers:

1. Epithelium: The lining of the digestive tract, which varies depending on location.
2. Lamina propria: Connective tissue containing blood vessels, lymph vessels, and immune cells.
3. Muscularis mucosae: A thin muscle layer that creates folds in the mucosa to increase surface area for absorption.

The submucosal plexus of Meissner is a network of nerves located in the submucosa. It controls the movement of the mucosa, regulates blood flow in the digestive tract, and stimulates the secretion of digestive juices.

The muscularis layer, responsible for movement of food, differs in the mouth/pharynx and the rest of the digestive tract:

• Mouth/Pharynx: Composed of voluntary skeletal muscle, allowing for conscious control.
• Rest of the digestive tract: Composed of involuntary smooth muscle, controlled by the autonomic nervous system.

The muscularis layer in the majority of the digestive tract is made of two layers: an inner circular layer and an outer longitudinal layer. These layers work together to propel food through the digestive tract.

The stomach has three layers of muscle: inner circular, outer longitudinal, and a third oblique layer. This unique arrangement allows the stomach to churn and mix food more effectively.

MALT stands for Mucosa-Associated Lymphoid Tissue. It's a type of immune tissue found in the digestive system. It plays a critical role in defending against pathogens that enter the body through the mouth.

Peyer's patches are clumps of lymphatic tissue found in the small intestine, specifically in the ileum. They are part of the MALT and help defend against harmful bacteria entering the digestive system.

The appendix is a small, finger-like projection that extends from the colon. It contains lymphatic tissue and is thought to play a role in immune function and gut bacteria balance.

The tongue is divided into the root, body, and apex.

The serosa is the outermost protective layer of the GI tract, composed of connective tissue and simple squamous epithelium.

The plexus of Auerbach is a network of nerves located between the muscle layers of the GI tract, controlling food movement.

The three major salivary glands are the parotid, submandibular, and sublingual glands.

Salivary amylase is an enzyme in saliva that starts breaking down starch molecules into simpler sugars.

Saliva helps form a bolus, cleanses the oral cavity after meals, and contains enzymes like lysozyme and salivary amylase.

The buccinator muscle helps with chewing by keeping food between the teeth and preventing cheeks from bulging.

The hard and soft palate form the roof of the mouth, assisting with chewing and speech.

Lingual lipase is an enzyme secreted by glands on the tongue, breaking down fats in the mouth.

Humans have two sets of teeth: deciduous (primary) and permanent.