Chr. 24 - The Digestive System Flashcards
[24.1] What is the digestive system?
A system consisting of a group of organs breaking down food into smaller molecules than can be used by body cells.
[24.1] What are the two groups of organs of the digestive system?
The gastrointestinal tract and the accessory digestive organs.
[24.1] What are the six basic processes of the digestive system?
- Ingestion
- Secretion
- Motility
- Digestion
- Absorption
- Defecation
[24.1] What are the types of digestion?
Mechanical and chemical
[24.1] Describe mechanical digestion.
Physical breakdown of food such as mastication and churning of the small intestine.
[24.1] Describe chemical digestion.
Chemical reactions to split food into smaller molecules using hydrolysis.
[24.2] List the layers of the GI tract from deep to superficial.
- Mucosa
- Submucosa
- Muscularis
- Serosa (adventitia)
[24.2] What is the mucosa of the GI tract?
A mucous membrane composed of three layers.
[24.2] List the layers of the mucosa of the GI tract.
- Epithelial tissue layer
- Connective tissue layer
- Smooth muscle layer
[24.2] Describe the epithelial tissue layer of the GI tract.
Epithelial tissue varying in composition throughout the tract.
Nonkeratinized stratified squamous epithelium is found in the mouth, pharynx, esophagus, and anal canal
Simple columnar epithelium with tight junctions line the stomach and intestines.
[24.2] What are enteroendocrine cells?
Cells embedded in the epithelial tissue secreting hormones into the lumen of the tract.
[24.2] Describe the connective tissue layer of mucosa of the GI tract.
Known as the lamina propria, it is a layer of areolar connective tissue containing blood and lymph vessels as well as mucosa-associated lymphatic tissue. Supports epithelial tissue and binds it to the muscularis mucosae.
[24.2] Describe the smooth muscle layer of mucosa of the GI tract.
Known as the muscularis mucosae. Organizes the mucous membrane of stomach and small intestine into folds to increase surface area and produces movement to maximize conact of absorptive cells.
[24.2] Describe the submucosa of the GI tract.
A layer of areolar connective tissue binding the mucosa to the muscularis and containing blood and lymph vessels as well as an extensive network of neurons.
[24.2] What is the muscularis of the GI tract?
Comprised of skeletal muscle in the mouth, pharynx, and esophagus and smooth muscle throughout the rest of the tract. Typically present as two sheets: inner circular fibers and outer longitudinal fibers.
[24.2] Describe the serosa.
Found on portions of the GI tract suspended in the abdominal cavity, composed of areolar connective tissue and simple squamous epithelium and is known as the visceral peritoneum. A single layer of areolar in the esophagus is known as adventitia.
[24.3] What is the enteric nervous system?
A very large network of sensory, inter, and motor neurons innervating the GI tract and comprised of two main plexuses.
[24.3] List the plexuses of the enteric nervous system and where they are found.
- Myenteric plexus, found in both layers of the muscularis
- Submucosal plexus, found within the submucosa.
[24.3] What are the major types of sensory receptors within the enteric nervous system?
Chemoreceptors and mechanoreceptors.
[24.3] How does the autonomic nervous system interact with the enteric nervous system?
The autonomic nervous system regulates the enteric nervous system and can innervate the GI tract without involvement of the enteric system. The vagus X nerve, parasympathetic nerves, and sympathetic nerves all interact.
[24.3] What are gastrointestinal reflex pathways?
Reflex pathways regulating GI secretion and motility in response to stimuli.
[24.4] What is the peritoneum?
The largest serous membrane of the body composed of simple squamous epithelium and an underlying supporting layer of areolar connective tissue.
[24.4] List the divisions of the peritoneum.
- Parietal peritoneum
- Visceral peritoneum
[24.4] What is the peritoneal cavity?
The space between the visceral and parietal peritoneum, containing serous fluid.
[24.4] What is ascites?
The distension of the peritoneal cavity through accumulation of fluid.
[24.4] What does “retroperitoneal” mean?
A description for organs existing outside the peritoneum on the posterior abdominal wall. Covered by the peritoneum on the anterior surfaces that come in contact.
[24.4] List the major folds of the peritoneum.
- Greater omentum
- Falciform ligament
- Lesser omentum
- Mesentery
- Mesocolon
[24.4] Describe the greater omentum.
Longest peritoneal fold consisting of large amounts of adipose tissue. Covers the transverse colon and small intestine in a double fold similar in shape to an apron.
[24.4] Describe the falciform ligament.
A ligament attaching the liver to the anterior abdominal wall and diaphragm.
[24.4] Describe the lesser omentum.
An anterior fold in the serosa of stomach and duodenum connecting these structures to the liver. Contains hepatic portal vein and common hepatic artery.
[24.4] Describe the mesentery.
A double layered fold of the peritoneum binding the jejunum and ileum of the small intestine to the posterior abdominal wall by wrapping around these structures.
[24.4] Describe the mesocolon.
Two separate folds of peritoneum binding the transverse colon and sigmoid colon to the posterior abdominal wall.
[24.5] What is the mouth?
The oral cavity formed by the cheeks, hard and soft palates, and the tongue.
[24.5] What are the cheeks?
Lateral walls of oral cavity composed of nonkeratinized stratified squamous mucous membrane.
[24.5] What are the lips?
Fleshy folds surrounding the opening of the mouth.
[24.5] What is the labial frenulum?
A mucous membrane attaching lips to their corresponding gum.
[24.5] What is the oral vestibule?
The space between the cheeks/lips and gums.
[24.5] What is the oral cavity proper?
The space extending from the gums and teeth to the opening between oral cavity and oropharynx.
[24.5] What are the fauces?
The opening between the oral cavity and the oropharynx.
[24.5] What is the palate?
The septum separating the oral cavity from the nasal cavity; roof of mouth.
[24.5] What is the hard palate?
The anterior portion of the palate formed by maxillae and palatine bones.
[24.5] What is the soft palate?
The posterior portion of the roof of the mouth formed by an arch-shaped muscle lined with mucous membrane.
[24.5] What is the uvula?
A finger-like muscular structure hanging from the free border of the soft palate.
[24.5] What is the palatoglossal arch?
The anterior lateral-running muscular folds on the soft palate
[24.5] What is the palatopharyngeal arch?
Posterior lateral-running muscular folds of the soft palate.
[24.5] What is a salivary gland?
A gland secreting saliva into the oral cavity.
[24.5] List the major salivary glands.
- The parotid glands
- Submandibular glands
- Sublingual glands
[24.5] Describe the parotid glands.
Salivary glands located anteroinferior of ears between skin and masseter muscle. Secrete saliva through the parotid duct.
[24.5] Describe the submandibular glands.
Salivary glands located medioinferior of the mandible and secrete saliva thru submandibular ducts.
[24.5] Describe the sublingual saliva glands.
Saliva glands located beneath the tongue and superior of submandibular glands. Secrete saliva via lesser sublingual ducts.
[24.5] What is the general composition of saliva?
99.5% water and 0.5% solutes.
[24.5] What is salivary amylase?
An enzyme within saliva initiating breakdown of starch.
[24.5] Describe salivation.
Secretion of saliva controlled by autonomic nerves.
[24.5] Describe the tongue.
An accessory digestive organ composed of skeletal muscle and covered with a mucous membrane.
[24.5] What are extrinsic muscles of the tongue?
Muscles originating outside the tongue inserting into the connective tissue of the tongue.
[24.5] what are intrinsic muscles of the tongue?
Muscles originating in the tongue and inserting into the connective tissue of the tongue.
[24.5] What is the lingual frenulum?
A fold of mucous membrane in the midline of the undersurface of the tongue attaching it to the mouth.
[24.5] What are papillae of the tonuge?
Projections of the lamina propria covered with stratified squamous epithelium.
[24.5] What are lingual glands of the tongue?
Glands within the lamina propria of the tongue secreting mucus and serous fluid containing lingual lipase.
[24.5] What is lingual lipase?
An enzyme converting dietary triglycerides into simpler fatty acids and diglycerides.
[24.5] What are the teeth?
Accessory digestive organs within the alveolar processes of the mandible and maxillae.
[24.5] What is the gingivae?
Gums covering the teeth.
[24.5] What is the periodontal ligament?
A fibrous connective tissue ligament anchoring teeth to the socket walls.
[24.5] List the main regions of a tooth.
- Crown
- Roots
- Neck
[24.5] What is the crown of a tooth?
The visible portion of the tooth above the gums.
[24.5] What are the roots of a tooth?
The portion of the tooth covered by gum.
[24.5] What is the neck of the tooth?
The constricted junction of the crown and root.
[24.5] What is dentin?
Calcified connective tissue composing the majority of a tooth.
[24.5] What is enamel?
A layer composed of a compound of calcium phosphate and calcium carbonate covering the dentin of the crown.
[24.5] What is the pulp cavity?
The enlarged space within a tooth containing pulp.
[24.5] What is the pulp of the tooth?
Connective tissue containing blood and lymph vessels, and nerves.
[24.5] What are root canals?
Extensions of the pulp cavity running through the root of the tooth to the alveolar tissue.
[24.5] What is the apical foramen of the tooth?
The opening at the base of each root allowing passage of vessels and nerves.
[24.5] What is endodontics?
Branch of dentistry concerning treatment and disease of the tooth.
[24.5] What is orthodontics?
A branch of dentistry concerned with prevention and correction of abnormal alignment of teeth.
[24.5] What is periodontics?
A branch of dentistry concerned with treatment of abnormal conditions of tissues surrounding the teeth.
[24.5] What are dentitions?
Sets of teeth, deciduous and permanent.
[24.5] What is mastication?
Chewing, mechanical digestion.
[24.6] What is the pharynx?
A funnel-shaped tube extending from the internal nares to the esophagus and larynx.
[24.7] what is the esophagus?
A collapsible muscular tube lying posterior of the trachea.
[24.7] What is the esophageal hiatus?
An opening through the diaphragm where the esophagus passes thru.
[24.7] What is the upper esophageal sphincter?
A sphincter consisting of skeletal muscle regulating movement of food from pharynx into esophagus.
[24.7] What is the lower esophageal sphincter?
A smooth muscle sphincter at the lower end of esophagus regulating movement of food from the esophagus into the stomach.
[24.8] What is deglutition?
The movement of food from the mouth to the stomach.
[24.8] List the three stages of swallowing.
- Voluntary stage
- Pharyngeal stage
- Esophageal stage.
[24.8] Describe the voluntary stage of swallowing.
Begins when food is forced to the back of the oral cavity and into the oropharynx by movement of the tongue.
[24.8] Describe the pharyngeal stage of swallowing.
Food bolus stimulates receptors in oropharynx, sending impulses to the deglutition center of medulla which cause movement of soft palate and uvula to block off the nasopharynx. Epiglottis closes off the larynx.
[24.8] Describe the esophageal stage of swallowing,
This stage begins when the food bolus enters the esophagus and consists of peristalsis.
[24.8] What is peristalsis?
A progression of coordinated contractions and relaxation of circular and longitudinal layers of the muscularis pushing food bolus to stomach.
[24.9] What is the stomach?
A J-shaped enlargement of the GI tract inferior of the diaphragm. Connects esophagus to the duodenum and functions as a mixing chamber and holding reservoir.
[24.9] List the regions of the stomach.
- Cardia
- Fundus
- Body
- Pyloric part.
[24.9] Describe the cardia of the stomach.
Portion of the stomach surrounding the opening of the esophagus.
[24.9] Describe the fundus of the stomach.
The rounded superior portion of the fundus laying left of the cardia.
[24.9] Describe the body of the stomach.
The large central portion of the stomach.
[24.9] Describe the pyloric part.
A region of the stomach separated into three subdivisions.