29 Questions
What is the primary function of the enteric nervous system?
To control the motility of the alimentary canal
What is the primary function of the parasympathetic nerves in the alimentary canal?
To increase GI secretion and motility
What is the primary function of the hepatic portal system?
To transport protein and carbohydrate to the liver
What is the primary function of the parietal peritoneum?
To line the abdominal wall
What is the primary function of the mouth in the digestive process?
To ingest, chew, and mix food, and begin the chemical breakdown of carbohydrates and lipids
What is the primary function of the pharynx in the digestive process?
To propel food to the esophagus
What is the approximate length of the alimentary canal or gastrointestinal tract?
25 feet
What type of epithelium is found in the stomach and intestines?
Columnar
What is the function of the muscularis mucosa layer?
Maintains tension in the mucosa
What is the role of the submucosa layer?
Contains the submucosal plexus of nerves
Which layer of the gastrointestinal tract is responsible for peristalsis?
Muscularis
What is the primary purpose of the digestive process described in the text?
To break down complex food molecules into their building blocks
Which of the following is NOT a type of regulatory mechanism described in the text?
Mechanical control
Where is skeletal muscle found in the gastrointestinal tract?
At both ends (swallowing and defecation)
What is the primary function of the tongue according to the text?
Digestion
What is the purpose of the uvula according to the text?
To stop food from entering the nasal cavity
What is the primary function of the small intestine described in the text?
Absorption of nutrients
Which of the following hormones is NOT mentioned in the text as playing a role in the digestive process?
Insulin
What is the primary function of the stomach in the digestive system?
Break down proteins chemically
Which organ is responsible for releasing bile salts to emulsify lipids for digestion and absorption?
Liver
What is the function of peristalsis in the digestive system?
Propel food through the alimentary canal
Which process exposes a larger surface area of food to digestive juices?
Mechanical digestion
What is the role of the gallbladder in the digestive system?
Store, concentrate, and release bile
Which part of the digestive system absorbs some fat-soluble substances such as alcohol and aspirin?
Small intestine
What is the primary digestive organ responsible for most absorption?
Small Intestine
Which section of the small intestine is the longest and has more vascular and mucosal folds?
Ileum
What initiates peristalsis in the intestine to move chyme through?
Hormone motilin
Which contractions mix chyme with digestive juices and force particles toward the mucosa for absorption?
Segmentation
What part of the small intestine contains circular folds, villi, and microvilli to enhance absorption?
Jejunum
Study Notes
Digestive System Overview
- The digestive system, also known as the alimentary canal or gastrointestinal (GI) tract, is approximately 25 ft long from mouth to anus.
- It has 4 layers: mucosa, submucosa, muscularis, and serosa.
GI Tract Layers
- Mucosa: mucous membrane epithelium in contact with food, with epithelium, lamina propria, and muscularis mucosa.
- Submucosa: dense connective tissue with blood and lymphatic vessels, and has a collection of nerves called the submucosal plexus.
- Muscularis: inner circular layer and outer longitudinal layer in the small intestine, responsible for mechanical digestion and peristalsis.
- Serosa: most superficial layer, only in the region inside the abdominal cavity, made of loose connective tissue.
Small Intestine
- Primary digestive organ and most absorption occurs here.
- Longest part of the canal, with a huge surface area.
- Has 3 regions: duodenum, jejunum, and ileum.
- Contains circular folds, villi, and microvilli to enlarge surface area and enhance absorption.
Mechanical Digestion
- Peristalsis: moving chyme through the intestine, started by hormone motilin, takes 90-120 minutes for chyme to reach the end of the ileum.
- Segmentation: back and forth contractions to mix chyme with digestive juices and force particles toward the mucosa to be absorbed.
Nerve Supply
- Enteric nervous system runs from esophagus to anus and is separated into 2 plexuses: myenteric and submucosal.
- Autonomic nervous system extrinsically innervates the alimentary canal.
- Sympathetic nerves restrict enteric neurons, while parasympathetic nerves increase GI secretion and motility.
Blood Supply
- Hepatic portal system delivers nutrients and oxygen to organs of the alimentary canal.
- While resting and digesting, 25% of blood pumped enters arteries serving the intestines.
The Peritoneum
- Holds digestive organs in place, with 2 different regions: parietal peritoneum and visceral peritoneum.
- Peritoneal cavity: space between parietal and visceral peritoneum.
Digestive System Processes
- Ingestion: entry of food into the alimentary canal through the mouth.
- Mechanical digestion: physical process that does not change the chemical nature of food (mastication, churning, segmentation).
- Chemical digestion: breaking down complex food molecules into their building blocks (water, acid, enzymes, and salts).
- Absorption: primarily in the small intestine, taking nutrients into the bloodstream or lipids into lymphatic system.
- Defecation: undigested materials are removed from the body.
Test your knowledge on the overview of the digestive system including the alimentary canal, layers of the GI tract, and accessory digestive organs. Learn about the process of breaking down food to release and absorb nutrients.
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