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Questions and Answers
What is the primary function of the epithelium lining the mouth and esophagus?
What is the primary function of the epithelium lining the mouth and esophagus?
Which layer of the GI tract contains the myenteric (Auerbach's) plexus?
Which layer of the GI tract contains the myenteric (Auerbach's) plexus?
What is the function of the muscularis mucosae?
What is the function of the muscularis mucosae?
Where is the submucosal (Meissner's) plexus located?
Where is the submucosal (Meissner's) plexus located?
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What kind of epithelium lines the stomach and intestines?
What kind of epithelium lines the stomach and intestines?
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Which of the following is NOT a component of the mucosa?
Which of the following is NOT a component of the mucosa?
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What is the main difference between serosa and adventitia?
What is the main difference between serosa and adventitia?
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What is the primary function of the outer longitudinal layer of the Muscular layer?
What is the primary function of the outer longitudinal layer of the Muscular layer?
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Which of these is NOT a feature of the greater omentum?
Which of these is NOT a feature of the greater omentum?
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What is the primary function of the lesser omentum?
What is the primary function of the lesser omentum?
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Which of the following is TRUE about the falciform ligament?
Which of the following is TRUE about the falciform ligament?
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What is the primary function of the submucosal neural plexus (Meissner's)?
What is the primary function of the submucosal neural plexus (Meissner's)?
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Which of the following statements accurately reflects the role of the sympathetic nervous system in digestive activity?
Which of the following statements accurately reflects the role of the sympathetic nervous system in digestive activity?
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Which of the following structures is NOT a component of the oral cavity?
Which of the following structures is NOT a component of the oral cavity?
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Which layer of the digestive tract does the myenteric plexus reside within?
Which layer of the digestive tract does the myenteric plexus reside within?
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What is the primary function of the submucosal plexus?
What is the primary function of the submucosal plexus?
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What is the role of the vagus nerve in the digestive system?
What is the role of the vagus nerve in the digestive system?
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Which of the following best describes the effect of sympathetic stimulation on the digestive system?
Which of the following best describes the effect of sympathetic stimulation on the digestive system?
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Which oral structure is involved in chewing and forcing food towards the back of the mouth?
Which oral structure is involved in chewing and forcing food towards the back of the mouth?
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Which of the following oral structures is primarily responsible for preventing food from entering the nasopharynx during swallowing?
Which of the following oral structures is primarily responsible for preventing food from entering the nasopharynx during swallowing?
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Which type of epithelium lines the oral mucosa?
Which type of epithelium lines the oral mucosa?
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What is the primary function of peristalsis?
What is the primary function of peristalsis?
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Where is the keratinized epithelium found in the oral cavity?
Where is the keratinized epithelium found in the oral cavity?
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Which phase of swallowing involves the coordinated action of pharyngeal muscles?
Which phase of swallowing involves the coordinated action of pharyngeal muscles?
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What is the function of the frenulum of the upper lip?
What is the function of the frenulum of the upper lip?
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What is the primary cause of periodontal disease?
What is the primary cause of periodontal disease?
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Which of the following structures is NOT a part of the oral vestibule?
Which of the following structures is NOT a part of the oral vestibule?
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What is the primary function of the esophagus?
What is the primary function of the esophagus?
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What is the function of the upper esophageal sphincter?
What is the function of the upper esophageal sphincter?
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Which accessory digestive organ is responsible for producing bile?
Which accessory digestive organ is responsible for producing bile?
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Which of the following BEST describes the type of muscle found in the tongue?
Which of the following BEST describes the type of muscle found in the tongue?
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Which type of muscle is found primarily in the inferior third of the esophagus?
Which type of muscle is found primarily in the inferior third of the esophagus?
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How does parasympathetic stimulation affect digestion?
How does parasympathetic stimulation affect digestion?
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Which of the following salivary glands is NOT considered a major salivary gland?
Which of the following salivary glands is NOT considered a major salivary gland?
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Which of the following is NOT a component of the digestive tract?
Which of the following is NOT a component of the digestive tract?
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What is the primary function of the lower esophageal sphincter?
What is the primary function of the lower esophageal sphincter?
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Which of the following statements is TRUE regarding the role of saliva in digestion?
Which of the following statements is TRUE regarding the role of saliva in digestion?
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Which of the following structures helps to prevent food from entering the pharynx prematurely?
Which of the following structures helps to prevent food from entering the pharynx prematurely?
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What is the correct sequence of layers in the GI tract from innermost to outermost?
What is the correct sequence of layers in the GI tract from innermost to outermost?
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Which phase of swallowing is involved in moving the bolus of food from the mouth to the oropharynx?
Which phase of swallowing is involved in moving the bolus of food from the mouth to the oropharynx?
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Which of the following statements regarding the formation of a hiatal hernia is CORRECT?
Which of the following statements regarding the formation of a hiatal hernia is CORRECT?
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Which of the following is a potential consequence of periodontal disease?
Which of the following is a potential consequence of periodontal disease?
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Which oral structure is responsible for providing traction for compression of food by the tongue?
Which oral structure is responsible for providing traction for compression of food by the tongue?
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Which of these is NOT a function of saliva and mucus in the swallowing process?
Which of these is NOT a function of saliva and mucus in the swallowing process?
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How does the esophagus connect to the abdominopelvic cavity?
How does the esophagus connect to the abdominopelvic cavity?
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What is the primary function of salivary amylase?
What is the primary function of salivary amylase?
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Which salivary gland is responsible for producing the majority of saliva?
Which salivary gland is responsible for producing the majority of saliva?
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What is the function of the lingual lipase?
What is the function of the lingual lipase?
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Which of the following is NOT a function of saliva?
Which of the following is NOT a function of saliva?
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What is the hardest biologically manufactured substance in the human body?
What is the hardest biologically manufactured substance in the human body?
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What is the function of the periodontal ligament?
What is the function of the periodontal ligament?
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What is the name of the soft tissue that fills the interior chamber of the tooth?
What is the name of the soft tissue that fills the interior chamber of the tooth?
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Which of the following structures forms the boundary between the crown and the root of a tooth?
Which of the following structures forms the boundary between the crown and the root of a tooth?
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What is the process of chewing called?
What is the process of chewing called?
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What is the role of the autonomic nervous system in salivation?
What is the role of the autonomic nervous system in salivation?
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What is the cephalic phase of digestion?
What is the cephalic phase of digestion?
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Which of the following statements about deciduous teeth is true?
Which of the following statements about deciduous teeth is true?
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What is the function of the root canal?
What is the function of the root canal?
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Which of the following is NOT a region of a tooth?
Which of the following is NOT a region of a tooth?
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Which of these regions of the pharynx is the uppermost region?
Which of these regions of the pharynx is the uppermost region?
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Study Notes
Anatomy & Physiology FT 400/PT700
- Digestive System: A system of organs and accessory organs that take in, digest, and absorb food.
Chapter 24: Digestive System, Part 1
-
Lecture Outline:
- Functions of the digestive tract
- Overview of the major organs of the digestive system
- Layers of the GI tract
- The peritoneum
- Neural innervation of the GI tract
- The GI tract: oral cavity, pharynx, and esophagus
Digestive System Anatomy
-
Consists of:
-
1. Gastrointestinal (GI) Tract:
- Muscular tube (also called the digestive tract or alimentary canal)
- Food passes from mouth to anus
-
2. Accessory Organs:
- Produce or store secretions that flow into the GI tract through ducts
-
1. Gastrointestinal (GI) Tract:
Functions of the Digestive Tract
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Ingestion: Occurs when solid food and liquid enter the oral cavity
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Mechanical Digestion and Propulsion: Crushing and shredding of food in the oral cavity and mixing/ churning in the stomach
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Chemical Digestion: Chemical and enzymatic breakdown of food into small organic molecules for absorption by the digestive epithelium.
- Secretion: Release of water, acids, enzymes, buffers, and salts by the digestive tract epithelium and accessory digestive organs.
- Absorption: Movement of nutrients across the digestive epithelium and into the bloodstream
- Defecation: Indigestible food is compacted into feces and eliminated.
Mechanical Digestion
- Includes all movements that help digest food.
- Mastication (chewing)
- Swallowing
- Mixing
- Peristalsis
Chemical Digestion
- Enzymes secreted by accessory organs and cells in the tract chemically break down food.
- Mainly accomplished by using water to break down chemical bonds (hydrolysis)
- Fats broken down into fatty acids and glycerol
- Carbohydrates broken down into monosaccharides
- Proteins broken down into amino acids
Digestive Tract Overview
- Muscular tube ~10 m (33 ft) long, from mouth to anus.
-
Major Organs and their Functions:
- Oral cavity (mouth) - Mechanical processing (teeth and tongue), moistening, and mixing with salivary secretions.
- Pharynx- Muscular propulsion of food into the esophagus.
- Esophagus- Transport of materials to the stomach.
- Stomach- Chemical breakdown and mechanical processing.
- Small intestine - Enzymatic digestion and absorption.
- Large intestine- Dehydration and compaction of indigestible materials.
Accessory Organs Overview
- Salivary glands: Produce saliva (mucins and enzymes).
- Gallbladder: Stores and concentrates bile from the liver.
- Pancreas: Exocrine cells secrete buffers and digestive enzymes. Endocrine cells secrete hormones.
- Liver: Almost 200 known functions (various).
Layers of the GI Tract
- Four major layers from esophagus to anal canal:
- Mucosa
- Submucosa
- Muscular layer
- Serosa or adventitia
Mucosa (inner lining)
- Epithelium
- Lamina propria
- Muscularis mucosae
Submucosa
- Layer of dense irregular connective tissue.
- Contains blood vessels and lymphatic vessels.
- Exocrine glands in some regions.
- Secretes buffers/enzymes into the digestive tract
- Contains a nerve network (Meissner's plexus).
Muscular Layer
- Smooth muscle in two layers (inner circular layer, outer longitudinal layer).
- Involved in mechanical processing and movement along the tract.
- Myenteric plexus (Auerbach's plexus) between muscle layers.
Serosa
- Outermost covering of organs along the digestive tract (in abdominal cavity).
- Called the visceral peritoneum.
- No serosa in oral cavity, pharynx, esophagus, or rectum (Adventitia instead).
Peritoneum
- Largest serous membrane of the body.
- Divided into parietal (lines the inner surface of the peritoneal cavity) and visceral peritoneum (covers organs enclosed by the peritoneal cavity; also called the serosa).
- Space between is the peritoneal cavity and contains lubricating serous fluid.
- Serous membrane continuously secretes peritoneal fluid into peritoneal cavity (~7 liters/day).
- Thin layer separates parietal and visceral surfaces preventing friction and irritation.
- Rate of fluid accelerated by liver disease, kidney disease and heart failure, leading to abdominals swelling (ascites).
- Retroperitoneal: Some organs are retroperitoneal - the peritoneum only covers the anterior surface (kidneys, ascending/descending colon, duodenum, pancreas, ureters).
Peritoneal Folds: Mesentery
- Double sheets of peritoneal membrane.
- Areolar tissue lies between mesothelial layers (provides access route for blood/lymphatic vessels, nerves, and stabilizes the organs; prevents entanglement).
- Includes the mesocolon, mesentery of the colon.
Peritoneal Folds: Omenta
- Continuations of the mesentery, 2 types:
- Greater Omentum: Large pouch attached to the stomach and transverse colon. Contains adipose tissue for padding, protection, blood vessels, and lymph tissue.
- Lesser Omentum: Suspends the stomach and duodenum from the liver. Provides access route for blood vessels, hepatic portal vein, hepatic artery and common bile duct.
Peritoneal Folds: Falciform Ligament
- Connects the liver to the anterior body wall.
- Only digestive organ attached to the anterior abdominal wall.
- Remnant of umbilical vein.
The Oral Cavity
-
Space containing tongue, teeth, gums
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Lined by oral mucosa (stratified squamous epithelium)
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Keratinized (areas exposed to abrasion)
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Thin, non-keratinized (cheeks, inferior tongue)
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Little to no nutrient absorption.
-
Carbohydrate and lipid digestion begins here.
- Boundaries: hard palate, soft palate, anterior and lateral boundaries (cheeks and lips), inferior boundary (tongue/floor of mouth), posterior boundary (uvula, Palatine tonsils, root of tongue, lingual tonsils).
-
Salivary Glands (Parotid, Submandibular, Sublingual): Produce saliva to keep the mouth moist and clean, lubricate, and initiate chemical digestion.
- Produce secretions (Saliva) containing water, mucins, lingual lipase, and salivary amylase.
Tongue
- Accessory digestive organ
- Skeletal muscle covered by mucous membrane.
- Extrinsic (move tongue) and intrinsic (shape tongue) muscles.
- Dorsum and lateral surfaces contain papillae with taste buds, touch receptors.
Swallowing (Deglutition)
- Initiated voluntarily, but proceeds automatically.
- Facilitated by secretions (saliva/mucus).
- Involves mouth, pharynx, and esophagus.
- Three phases:
- Buccal phase
- Pharyngeal phase
- Esophageal phase
Pharynx
- Membrane-lined cavity posterior to the nose and mouth.
- Skeletal muscle.
- Plays a key role in swallowing.
- Continuous passageway for solid food, liquids, and air.
- Three regions: (Nasopharynx, Oropharynx, Laryngopharynx).
Esophagus
-
Hollow, muscular tube, (~25 cm; 10 in long, 2 cm;0.8 in. wide).
-
Transports food and liquids to the stomach.
-
No enzyme production, no absorption.
-
Structures:
- Upper esophageal sphincter.
- Lower esophageal sphincter (cardiac sphincter)
-
Histology:
- Mucosa: Non-keratinized stratified squamous epithelium
- Submucosa: Areolar connective tissue with blood vessels and mucous glands
- Muscularis externa: Superior 1/3 skeletal muscle, middle 1/3 mixed skeletal/smooth, inferior 1/3 smooth muscle only
- No serosa; Adventitia of connective tissue.
-
GI Pathology: This section discusses disorders of the digestive tract, a key topic in anatomy and physiology.
- Periodontal Disease: Inflammation of the gums and surrounding structures from bacterial activity; a common cause of tooth loss.
Review Questions
- Components of the GI tract
- Accessory digestive organs
- Most innermost layer of the GI tract
- Parasympathetic stimulation effect on digestion
- First enzyme acting on carbohydrates and its location.
- Place of lingual lipase origin and function
- Esophagus secretions
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Description
Test your knowledge on the anatomy and functions of the digestive system. This quiz covers the roles of various layers and components, such as the epithelium of the mouth and esophagus, myenteric plexus, and muscularis mucosae. Challenge yourself with questions about the structural differences and functions of elements within the gastrointestinal tract.
