Human Anatomy Digestive System Quiz

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Questions and Answers

Which of the following statements about the lesser omentum is FALSE?

It contains the hepatic portal vein, hepatic artery, and common bile duct.

It serves as a route for blood vessels and other structures entering and leaving the liver.

It suspends the stomach and duodenum from the liver.

It forms a large pouch extending inferiorly between the anterior body wall and the anterior surface of the small intestine. (correct)

What is the primary function of the greater omentum?

To provide padding and protection for the abdominal organs. (correct)

To connect the liver to the anterior body wall.

To serve as a route for blood vessels and other structures entering and leaving the liver.

To suspend the stomach and duodenum from the liver.

Which of the following structures is NOT a component of the lesser omentum?

Hepatic artery

Splenic artery (correct)

Hepatic portal vein

Common bile duct

What is the significance of the falciform ligament?

It connects the liver to the anterior body wall. (A) Signup and view all the answers

Which of the following is NOT a characteristic of the submucosal neural plexus (Meissner's)?

It is located in the muscularis propria layer of the digestive tract. (D) Signup and view all the answers

Which of the following is NOT a characteristic of the esophagus?

It secretes enzymes to aid digestion. (A) Signup and view all the answers

Where in the body does the esophagus enter the abdominopelvic cavity?

Through the diaphragmatic hiatus. (D) Signup and view all the answers

What type of muscle tissue makes up the inferior third of the esophagus?

Smooth muscle only. (C) Signup and view all the answers

What is the role of the upper esophageal sphincter?

To prevent air from entering the esophagus. (B) Signup and view all the answers

The term 'hiatal hernia' refers to what condition?

A protrusion of the stomach into the thoracic cavity. (B) Signup and view all the answers

What type of epithelium lines the mucosa of the esophagus?

Stratified squamous epithelium. (C) Signup and view all the answers

During swallowing, what structure seals off the nasopharynx?

The soft palate. (C) Signup and view all the answers

Which phase of swallowing is a reflex action triggered by the entry of a bolus into the oropharynx?

Pharyngeal phase. (D) Signup and view all the answers

Which process primarily uses water to break down chemical bonds in food?

Hydrolysis (C) Signup and view all the answers

What is the primary function of the large intestine in the digestive system?

Dehydration and compaction of indigestible materials (B) Signup and view all the answers

Which of the following best describes 'peristalsis'?

Muscular contractions that propel food through the GI tract (C) Signup and view all the answers

The gallbladder's primary digestive function is to:

Store and concentrate bile (D) Signup and view all the answers

Which of these organs is primarily responsible for both chemical and mechanical processing in digestion?

Stomach (A) Signup and view all the answers

Which of the following is NOT a typical function of the liver as described in the content?

Storing concentrated bile (A) Signup and view all the answers

What is the main function of the small intestine?

Enzymatic digestion and absorption of nutrients (C) Signup and view all the answers

Which of the following is NOT a component of mechanical digestion?

Hydrolysis (D) Signup and view all the answers

What is the primary function of the serous fluid secreted by the peritoneum?

To allow sliding movements without friction or irritation (C) Signup and view all the answers

Which organs are classified as retroperitoneal?

Kidneys and ureters (D) Signup and view all the answers

What comprises the primary structure termed 'mesentery'?

Double sheets of peritoneal membrane with areolar tissue in between (A) Signup and view all the answers

What is the approximate volume of peritoneal fluid at any given time?

50 mL (A) Signup and view all the answers

Which condition is associated with the accelerated accumulation of peritoneal fluid?

Liver disease and heart failure (A) Signup and view all the answers

What is the primary function of the myenteric plexus?

Coordinate local control of digestive activity (B) Signup and view all the answers

What type of neurons are contained in the submucosal plexus?

Sensory neurons and autonomic nerve fibers (D) Signup and view all the answers

Which type of stimulation from the ANS increases secretion and motility in the GI tract?

Parasympathetic stimulation (B) Signup and view all the answers

What structure helps prevent food from entering the pharynx prematurely?

Uvula (C) Signup and view all the answers

Which layer of the oral cavity is characterized by keratinized stratified squamous epithelium?

Superior tongue surface (D) Signup and view all the answers

Which structure serves as the anterior boundary of the oral cavity?

Labia (lips) (C) Signup and view all the answers

What is the primary component of saliva secreted by salivary glands?

Water (B) Signup and view all the answers

Which part of the tongue is marked by a V-shaped line of vallate papillae?

Root of the tongue (D) Signup and view all the answers

What is the function of the frenulum of the tongue?

Attaches the tongue to the floor of the mouth (B) Signup and view all the answers

What is a key feature of the enteric nervous system (ENS)?

It operates independently with minimal external influence (B) Signup and view all the answers

What is one of the major functions of the palatine arches?

Aid in swallowing (B) Signup and view all the answers

Which glands are responsible for releasing saliva into the oral cavity?

Salivary glands (D) Signup and view all the answers

What is located between the circular and longitudinal muscle layers of the GI tract?

Myenteric plexus (C) Signup and view all the answers

Which area of the oral cavity has a thin, nonkeratinized lining?

Cheeks (D) Signup and view all the answers

What percentage of total saliva secretion is provided by the parotid glands?

25 percent (D) Signup and view all the answers

Which of the following secretes a mucous secretion that acts as a buffer and lubricant?

Sublingual glands (B) Signup and view all the answers

What is the primary function of salivary amylase?

To digest starches (B) Signup and view all the answers

Which component of saliva is responsible for providing protection against pathogens?

Lysozyme (B) Signup and view all the answers

Which of the following structures is found within the root of a tooth?

Pulp cavity (B) Signup and view all the answers

How does sympathetic stimulation affect salivation?

Decreases salivation (C) Signup and view all the answers

What structure connects the root of the tooth and the alveolar bone?

Periodontal ligament (A) Signup and view all the answers

Which part of the tooth is primarily used for chewing or grinding food?

Crown (C) Signup and view all the answers

What type of secretion is produced by the submandibular glands?

Mixed secretion (C) Signup and view all the answers

Which of the following correctly describes the composition of saliva?

99.5% water, 0.5% solutes (D) Signup and view all the answers

What initiates the 'cephalic phase' of digestion related to salivation?

Taste and smell of food (C) Signup and view all the answers

What is the main role of mechanical digestion in the mouth?

Forming a bolus for swallowing (B) Signup and view all the answers

What is the main mineral component of enamel?

Calcium phosphate (B) Signup and view all the answers

Which of the following describes lingual lipase?

Inactivated by stomach acid (C) Signup and view all the answers

Study Notes

Anatomy & Physiology FT 400/PT700

Course focusing on anatomy and physiology.

Chapter 24: Digestive System Part 1

Lecture outline covers functions of the digestive tract, overview of major digestive system organs, layers of the GI tract, the peritoneum, neural innervation of the GI tract, and the GI tract (oral cavity, pharynx, esophagus).

Digestive System Anatomy

Consists of two main parts:
- Gastrointestinal (GI) Tract: A muscular tube (also called the digestive tract or alimentary canal) that moves food from mouth to anus.
- Accessory Organs: Produce or store secretions that flow into the GI tract through ducts. These organs aid in digestion.

Functions of the Digestive Tract

Ingestion: Solid and liquid food enter the oral cavity.
Mechanical Digestion: Crushing and shredding of food (in oral cavity and stomach), mixing and grinding (also involves swallowing and mixing, peristalsis).
Chemical Digestion: Enzymatic breakdown to small organic molecules (digestive epithelium absorbs these).
Secretion: Release of fluids (water, acids, enzymes, buffers, salts) from tract epithelium and accessory organs.
Absorption: Nutrients are moved across digestive epithelium and into the bloodstream.
Defecation: Undigested material is compacted into feces and eliminated from the body.

Functions of the Digestive Tract - Mechanical Digestion

Includes all movements that help digest food
- Mastication (chewing)
- Swallowing
- Mixing
- Peristalsis: muscular contractions in the wall of the GI tract Physically break down food, propel it along the tract, and help dissolve foods by mixing them with fluids secreted into the tract.

Functions of the Digestive Tract - Chemical Digestion

Enzymes secreted by accessory organs/cells that line the tract break down food chemically
Primarily accomplishes this through hydrolysis (using water to break chemical bonds) to achieve the following;
- Breakdown fats into fatty acids and glycerol.
- Breakdown carbohydrates into monosaccharides.
- Breakdown proteins into amino acids.

Digestive Tract Overview

A ten-meter (33-foot) muscular tube beginning at the mouth and ending at the anus.
Major Organs include the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine.
Accessory organs include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Accessory Organs Overview

Include organs that produce or store secretions;
- Salivary glands: Produce saliva with mucins and enzymes.
- Gallbladder: Stores and concentrates bile from the liver.
- Pancreas: Exocrine cells secrete buffers and digestive enzymes; endocrine cells secrete various hormones.
- Liver: Almost 200 known functions (e.g., bile production, metabolism, detoxification).

Layers of the GI Tract

Four primary layers from esophagus to anal canal:
- Mucosa: Inner lining with epithelium, lamina propria (connective tissue), and muscularis mucosae (smooth muscle).
- Submucosa: Layer of connective tissue (dense irregular), blood & lymphatic vessels, and exocrine glands (secrete buffers/enzymes).
- Muscularis Layer: Smooth muscle (inner circular, outer longitudinal) for mechanical digestion.
- Serosa/Adventitia: Outermost layer (serosa is a covering of mesothelium; adventitia is dense irregular connective tissue)

Layers of the GI Tract - Mucosa

Three layers: epithelium, lamina propria, muscularis mucosae.
Epithelium varies throughout tract (e.g., nonkeratinized stratified squamous in the mouth, simple columnar in intestines).
Lamina propria is connective tissue, contains blood/lymphatic vessels and mucosa-associated lymphatic tissue (MALT).
Muscularis mucosae is smooth muscle, creating folds to increase surface area.

Layers of the GI Tract - Submucosa

Dense irregular connective tissue layer with blood vessels, lymphatic vessels, and exocrine glands.
Exocrine glands secrete buffers and enzymes into the digestive tract.
Contains a network of neurons called the submucosal (Meissner's) plexus.

Layers of the GI Tract - Muscularis Layer

Primarily smooth muscle in inner circular and outer longitudinal layers.
Involved in mechanical processing and movement along the tract.
Contains the myenteric (Auerbach's) plexus between smooth muscle layers.

Layers of the GI Tract - Serosa

Outermost layer which is the visceral peritoneum.
A serous membrane.
Lines the abdominal cavity.
Connects the GI tract to adjacent structures via adventitia (dense connective tissue).

Peritoneum

Largest serous membrane in the body.
Divided into parietal and visceral peritoneum.
Parietal lines the inner surface of the peritoneal cavity; visceral covers organs within the cavity (visceral peritoneum is also known as serosa).
Space between layers contains lubricating serous fluid.

Peritoneum - Continued

Serous membrane continuously secreting peritoneal fluid into the peritoneal cavity.
Normal volume is ~50 mL.
Thin layer separates parietal and visceral surfaces and permits smooth sliding movements without friction.
Inflammation in this cavity may lead to abdominal swelling, known as ascites.

Peritoneum (Folds)

Contains three major peritoneal folds: mesentery, omenta, and falciform ligament

Peritoneal Folds - Mesentery

Double sheets of peritoneal membrane with areolar tissue between mesothelial layers, providing access routes for blood vessels, nerves, and lymphatics.
Stabilizes attached organs.
Prevents entanglement of intestines.
Includes the mesocolon (mesentery of the colon)

Peritoneal Folds - Omenta

Continuations of the mesentery; includes the greater omentum and lesser omentum.
The greater omentum is a large pouch extending inferiorly, containing adipose tissue for padding and protection. Also contains blood vessels and lymphatic tissue.
The lesser omentum suspends the stomach and duodenum from the liver and provides a pathway for blood vessels and other structures entering/leaving the liver (the hepatic portal vein, hepatic artery, and common bile duct).

Peritoneal Folds - Falciform Ligament

Connects the liver to the anterior abdominal wall.
Is the only digestive organ attached to the anterior abdominal wall.
Remnant of the umbilical vein.

The Oral Cavity

Space containing the tongue, teeth, and gums.
Lined by stratified squamous epithelium (oral mucosa).
The oral cavity boundaries include a hard palate, formed by the palatine processes of the maxillary bones and the horizontal plates of the palatine bones, and a soft palate, the muscular posterior section.
Anterior and Lateral Boundary involves the cheeks and lips (labia).
The inferior boundary is the body of the tongue.
The posterior boundary comprises the uvula, and palatine tonsils.
The oral cavity also contains salivary glands.

The Oral Cavity - Salivary glands

Parotid glands: Secrete a serous secretion containing large amounts of salivary amylase which starts the chemical digestion of carbohydrates. Accounts for about 25% of total saliva.
Submandibular glands: Secrete aqueous fluids with buffers and mucins. Secrete salivary amylase. Accounts for about 70% of total saliva.
Sublingual glands: Produce a mucous secretion acting as a buffer and lubricant; provide ~5% of total saliva.

The Oral Cavity - Saliva

Mostly water (~99.5%).
Contains ions (Na+, K+, Cl-, HCO3-, PO42-), dissolved gases, urea, uric acid, mucous, immunoglobulins (IgA), lysozyme, and salivary amylase.
Acts on starches and continuously flushes oral surfaces.
Maintains a pH near 7.0 to safeguard against bacterial acid buildup.
Contains antibodies and lysozyme.
Mixes with food to form a bolus. Small glands (Ebner's glands) secrete lingual lipase for lipid digestion.

The Oral Cavity - Salivation

Controlled by the autonomic nervous system.
Parasympathetic stimulation increases saliva secretion.
Sympathetic stimulation decreases saliva secretion, which is also influenced by the taste and smell of food (“cephalic phase” of digestion).

Teeth

Accessory digestive organs.
Dentin forms most of the tooth (harder than bone).
Covered by enamel (even harder).
Deciduous teeth (baby teeth).
Permanent (secondary teeth)
Have different components in different regions of the jaw. These vary in size, shape, and function, including occlusal surface, crown, neck, and root.

Teeth - Components of a tooth

Occlusal surface: Portion of the crown used for crushing, slicing, or chewing.
Enamel: Covers the dentin of the crown (hardest manufactured substance), composed of calcium phosphate, and requires vitamin D for formation and decay resistance.
Pulp Cavity: Inner chamber of the tooth containing a mineralized matrix similar to bone.
Root canal: Narrow tunnel within the root containing passageways for blood vessels and nerves.
Apical foramen: Opening into the root canal.
Periodontal ligament: Creates gomphosis, an articulation between root dentin and alveolar bone.

Teeth - Regions of a Tooth

Crown: Part projecting into oral cavity from gum surfaces.
Neck: Boundary between crown and root.
Root: Part below gum line, residing within the bony socket (alveolus).

Digestion in the Mouth

Mechanical: Chewing (mastication), tongue manipulating food, teeth grinding, mixing with saliva, to form the bolus (soft, flexible mass).
Chemical: Salivary amylase acting on starches, and lingual lipase secreted by lingual glands acting on triglycerides.

Pharynx

Membrane-lined cavity behind the nose and mouth.
Skeletal muscle walls play a crucial role in swallowing (with esophagus). Common pathway for food, liquid, and air.
Three regions: Nasopharynx (respiration only), Oropharynx, and Laryngopharynx.

The Esophagus

Hollow, muscular tube (~25 cm long, 2 cm wide).
Carries food/liquids to stomach.
Narrowest point behind cricoid cartilage.
Descends behind trachea.
Enters abdominal cavity through esophageal hiatus in diaphragm. Hiatal hernia occurs when part of the stomach protrudes into the esophagus.

The Esophagus - Histology

Muscular layers: Superior third is skeletal muscle, middle third is mixed skeletal and smooth muscle, inferior third is smooth muscle.
Mucosa is nonkeratinized stratified squamous epithelium for protection.

The Esophagus - Control of movement

Upper esophageal sphincter: Band of smooth muscle (functions as sphincter). Prevents air entering the esophagus.
Lower esophageal sphincter (cardiac sphincter): At the inferior end of the esophagus; normally contracted to prevent backflow from the stomach.

Swallowing (Deglutition)

Three phases: Buccal phase, Pharyngeal phase, Esophageal phase.
Buccal (voluntary): Compression of bolus against hard palate. Tongue forcing into oropharynx, elevating soft palate to seal nasopharynx.
Pharyngeal (involuntary): Tactile stimulation of uvula, palatine arches triggering swallowing reflex. Larynx elevated; epiglottis folded; uvula and soft palate raised, moving bolus to esophagus.
Esophageal (involuntary): Bolus forced into esophagus; peristalsis pushes it downward toward stomach. Lower esophageal sphincter opens, bolus enters the stomach.

Peristalsis

Wave of smooth muscle contractions in the GI tract wall.
Propels bolus in one direction along the tract.
Circular (behind) and longitudinal (ahead) muscles contract sequentially.

GI Pathology

Discusses periodontal disease (most common cause for tooth loss).
Results in gingival (gum) inflammation when dental plaque forms between teeth and gums.
Potentially linked to cardiovascular diseases (like inflammation and atherosclerosis).

Review Questions

Students are asked to consider and answer review questions related to the components of the GI tract, and accessory digestive organs, and specific layers.

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Description

Test your knowledge of the human digestive system with this comprehensive quiz. Covering important structures like the lesser omentum, esophagus, and their functions, this quiz will challenge your understanding of anatomy and physiology. Perfect for students studying health sciences or anatomy in-depth.