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Questions and Answers
Which structure is predominantly composed of proliferating B lymphocytes and provides protection against pathogenic bacteria?
Which structure is predominantly composed of proliferating B lymphocytes and provides protection against pathogenic bacteria?
- Peyer’s patches (correct)
- Celiac plexus
- Hepatic portal vein
- Superior mesenteric artery
What type of innervation is associated with the vagus nerve in the gastrointestinal system?
What type of innervation is associated with the vagus nerve in the gastrointestinal system?
- Sympathetic innervation
- Motor innervation
- Parasympathetic innervation (correct)
- Sensory innervation
Which blood vessel is responsible for draining blood from the small intestine into the liver?
Which blood vessel is responsible for draining blood from the small intestine into the liver?
- Hepatic portal vein (correct)
- Inferior mesenteric artery
- Thoracic splanchnic nerve
- Superior mesenteric artery
What type of enzyme is found on the brush border of microvilli and is essential for completing food digestion?
What type of enzyme is found on the brush border of microvilli and is essential for completing food digestion?
Which of the following is NOT a function of the sympathetic innervation in the gastrointestinal system?
Which of the following is NOT a function of the sympathetic innervation in the gastrointestinal system?
Where in the gastrointestinal tract are Peyer’s patches predominantly located?
Where in the gastrointestinal tract are Peyer’s patches predominantly located?
What is the primary function of the peritoneum?
What is the primary function of the peritoneum?
Which layer of the gastrointestinal tract is responsible for secreting slippery fluid to prevent friction?
Which layer of the gastrointestinal tract is responsible for secreting slippery fluid to prevent friction?
What does the greater omentum arise from?
What does the greater omentum arise from?
Which peritoneum layer lines the abdominal and pelvic cavities?
Which peritoneum layer lines the abdominal and pelvic cavities?
Which organs are referred to as retroperitoneal organs?
Which organs are referred to as retroperitoneal organs?
What are intraperitoneal organs mainly characterized by?
What are intraperitoneal organs mainly characterized by?
Which layer is not typically found in the esophagus's structure?
Which layer is not typically found in the esophagus's structure?
What type of tissue primarily forms the serosa layer of the gastrointestinal tract?
What type of tissue primarily forms the serosa layer of the gastrointestinal tract?
What initiates the motility in the gastrointestinal tract?
What initiates the motility in the gastrointestinal tract?
How often do slow waves occur in the duodenum?
How often do slow waves occur in the duodenum?
What happens to the frequency of slow waves from the duodenum to the colon?
What happens to the frequency of slow waves from the duodenum to the colon?
Which of the following substances acts as an excitatory stimulant in gastrointestinal motility?
Which of the following substances acts as an excitatory stimulant in gastrointestinal motility?
Peristaltic contractions in the stomach primarily originate from which region?
Peristaltic contractions in the stomach primarily originate from which region?
Which type of stimulants inhibit gastrointestinal motility?
Which type of stimulants inhibit gastrointestinal motility?
What is the primary function of the cardiac sphincter?
What is the primary function of the cardiac sphincter?
Which cells in the stomach produce hydrochloric acid (HCl)?
Which cells in the stomach produce hydrochloric acid (HCl)?
What initiates the chemical breakdown of carbohydrates in the oral cavity?
What initiates the chemical breakdown of carbohydrates in the oral cavity?
Which structure allows for the transfer of food from the esophagus to the stomach?
Which structure allows for the transfer of food from the esophagus to the stomach?
What type of epithelium changes at the Z-line of the gastroesophageal junction?
What type of epithelium changes at the Z-line of the gastroesophageal junction?
Which layer in the muscularis externa of the stomach is unique and allows for vigorous contractions?
Which layer in the muscularis externa of the stomach is unique and allows for vigorous contractions?
What physiological process primarily occurs within the small intestine?
What physiological process primarily occurs within the small intestine?
What type of secretion is primarily produced by the pyloric glands?
What type of secretion is primarily produced by the pyloric glands?
What is the primary role of saliva in the oral cavity?
What is the primary role of saliva in the oral cavity?
Which structure regulates gastric emptying into the duodenum?
Which structure regulates gastric emptying into the duodenum?
What is the primary function of mechanical digestion?
What is the primary function of mechanical digestion?
What initiates the muscle contractions in a syncytium?
What initiates the muscle contractions in a syncytium?
What is the normal resting membrane potential of GI smooth muscles?
What is the normal resting membrane potential of GI smooth muscles?
Which type of waves are responsible for generating the slow wave potential in the GI tract?
Which type of waves are responsible for generating the slow wave potential in the GI tract?
What role do exocrine glands play in digestion?
What role do exocrine glands play in digestion?
What is the primary purpose of absorption in the GI tract?
What is the primary purpose of absorption in the GI tract?
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Study Notes
Anatomy Overview
- The alimentary or gastrointestinal (GI) tract is a continuous muscular tube extending from the mouth to the anus.
- Major digestive organs are located in the abdominal and pelvic cavity and are supported by a structure called mesentery.
Peritoneum
- A thin connective tissue featuring mesothelium, supports abdominal organs, and contains blood vessels, lymphatics, and nerves.
- Two layers: parietal peritoneum (covers the cavity) and visceral peritoneum (covers organs).
- The peritoneal cavity is the space between the parietal and visceral layers.
- Intraperitoneal organs remain in the peritoneal cavity during embryonic development.
GI Tract Layers
- Four basic tissue layers from esophagus to anus:
- Serosa/Adventitia: Outermost layer, prevents friction.
- Muscularis Propria: Contains smooth muscle layers for peristalsis.
- Submucosa: Layer with mucus-secreting glands and blood vessels.
- Mucosa: Innermost layer responsible for secretion and absorption.
Oral Cavity
- Functions in ingestion, mechanical and chemical digestion, and propulsion of food.
- Saliva contains enzymes like salivary amylase and antibacterial properties.
- There is mechanical digestion through mastication, and chemical digestion begins in the oral cavity.
Esophagus
- A muscular tube connecting the laryngopharynx to the stomach.
- Contains upper and lower esophageal sphincters that regulate the movement of food and prevent acid reflux.
- Muscular contractions (peristalsis) propel food into the stomach.
Stomach
- Located in the upper left abdominal quadrant, responsible for churning, digestion, and storage of food.
- Contains regions: cardia (entry point), fundus (storage), body (largest area), and pylorus (connected to the duodenum).
- Produces gastric juices:
- Mucus cells protect the lining.
- Parietal cells produce HCl.
- Chief cells secrete pepsinogen, initiating protein digestion.
Small Intestine
- Main site for digestion and nutrient absorption, featuring circular folds, villi, and microvilli to maximize surface area.
- Blood supply from the superior mesenteric artery; absorbs nutrients into the hepatic portal circulation.
- Peyer’s patches in ileum act as protective lymphatic tissue.
GI Motility
- Peristalsis moves food through the GI tract, initiated by swallowing and regulated by electrical signals.
- Normal resting membrane potential of GI smooth muscle is between -50mV to -60mV.
- Two types of electrical waves:
- Slow Waves: Generated by pacemaker cells, setting the rhythm of contractions.
- Action Potentials: Triggered when slow-wave threshold is reached, activating muscle contractions.
Key Concepts
- Digestion involves complex food breakdown, secretion of digestive juices, absorption of nutrients, and elimination of waste.
- Each organ in the GI tract has specialized functions and cellular structures catering to its role in the digestive process.
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