06/14/2023 Notes Flashcards
What is the entrance to the GI tract?
Oral cavity (mouth)
What is the initial site of mechanical digestion through mastication and chemical digestion?
mouth
What are the 2 distinct regions found within the oral cavity?
Vestibule and oral cavity proper
What is the vestibule in the mouth?
Space between the cheeks/lips and gums
What is the oral cavity proper found?
Central to the alveolar processes of the mandible and maxillae
What forms the lateral walls of the oral cavity?
Cheeks
What does the buccinator muscles do?
Compress the cheeks against the cheeks to hold solid materials in place while chewing
What are the lips?
Area where the cheeks terminate and are formed by the orbicularis oris muscle and are covered by a thin layer of keratinized stratified epithelium
Why do lips have a reddish hue?
Abundant supply of superficial blood vessels and reduced amount of keratin within the outer skin
What are gingivae?
Gingivae are the gums; they are composed of dense regular connective tissue with an overlying stratified epithelium covering the alveolar processes of the upper and lower jaws
What is the labial frenulum?
A thin mucosal fold that attaches the superior and inferior lips to the gingivae at the midline
What does the palate separate the oral cavity from?
Nasal cavity
What is the hard palate?
Anterior 2/3 of the palate formed by the palatine processes of the maxillae and palatine bones
What do the transverse palatine folds (friction ridges) perform?
Assist the tongue in manipulating ingested materials prior to swallowing
What does the soft palate and uvula do during swallowing?
Soft palate and uvula elevate to close off the posterior entrance to the nasopharynx and prevent ingested materials from entering the nasal region
What are palatine tonsils?
Early line of defense that monitors ingested food/drink for antigens and can initiate an immune response if necessary
What is the tongue?
An accessory digestive organ formed by skeletal muscle that participates in sound production
What does the tongue do in digestion?
Manipulate and mix ingested materials during shewing and helps compress the partially digested materials against the hard palate to turn materials in bolus
What is a bolus?
Globular mass of partially digested materials
What is the lingual frenulum?
A thin, vertical mucous membrane that attaches the inferior surface of the tongue to the floor of the oral cavity
What do salivary glands do?
Produce and secrete saliva
How much saliva is secreted daily?
1-1.5 L a day
What are the functions of saliva?
Moisten ingested food, moisten and clean oral cavity structures, aid in chemical digestion, inhibit bacterial growth, and dissolves food to stimulate taste
What is amylase?
A salivary enzyme that begins chemical digestion by breaking down starch
What are lysolyzes?
an antibacterial substance that inhibits bacterial growth in the oral cavity
What are the 3 pairs of salivary glands?
Parotid salivary glands, submandibular glands, and sublingual salivary glands
What are the largest salivary glands?
Parotid salivary glands
When infected with mumps, what happens to the parotid salivary glands?
Become swollen
Which salivary gland is used in “gleeking”?
Submandibular salivary glands
What division of the ANS innervates salivary glands?
Parasympathetic
CN VII innervates what salivary glands?
Facial nerve innervates submandibular and sublingual glands
Glossopharyngeal nerve innervates which salivary gland?
Parotid
What do parasympathetic and sympathic innervation do to salivary glands?
Parasympathetic stimulates salivary gland secretion while sympathetic innervations inhibit secretion and cause dry mouth in frightened people
What are teeth responsible for in mechanical digestion?
Mastication
What are the 3 components of a tooth?
Crown, Neck, and Roots
Where do the root of teeth fit into?
Dental alveoli
What form the gomphosis joint?
Root of teeth, dental alveoli, and periodontal ligaments
What are deciduous teeth?
Milk teeth that erupt 6-30 months after births
What are permanent teeth?
32 teeth that replace deciduous teeth starting with the anterior teeth and moving to the posterior teeth
what are the last teeth to appear?
3rd molars (wisdom teeth)
What are incisors?
Anteriorly placed teeth designed for slicing/cutting into food that are shaped like a chisel
What are canines?
Posterolateral teeth to the incisors with a pointed tip responsible for puncturing and tearing food; “eye teeth”
What are the premolars (bicuspids)?
Teeth with flat crowns that have ridges (cusps) that crush and grind ingested materials
What are molars?
thickest teeth with large, broad, flat crowns also designed for crushing and grinding ingested materials
How many of each teeth are found in 1 quadrant?
2 incisors, 1 canine, 2 premolars, and 3 molars
How may teeth be lost?
trauma, disease, age
What is a common space used by both the respiratory and digestive system?
Pharynx
What 3 skeletal muscle pairs form the pharynx?
Superior, middle, and inferior pharyngeal constrictors
What nerve innervates most pharyngeal muscles?
CN X (vagus)
What does the parietal peritoneum cover?
Inside surface of the body wall
What part of the peritoneum covers the surface of internal organs?
Visceral peritoneum
What are organs covered by the visceral peritoneum called? Which organs are these?
Intraperitoneal organs are the stomach, jejunum, ileum, cecum, appendix, and the majority of the large intestines
What are the organs covered by the parietal peritoneum called? Which organs are these?
Retroperitoneal organs are the kidneys, pancreas, duodenum, ascending colon, descending colon, and rectum
What are mesenteries?
Double-layered folds of peritoneum that support and stabilize the intraperitoneal GI tract organs with blood vessels, lymphatic vessels, and nerves
What are 5 types of mesenteries?
Greater omentum, lesser omentum, mesentery proper, mesocolon, and peritoneal ligament
What is the greater omentum?
Mesentery that extends like an apron from the greater curvature of the stomach and covers most abdominal organs
What is the lesser omentum?
Mesentery that connects the lesser curvature of the stomach to the proximal end of the duodenum to the liver
What is the mesentery proper?
fan-shaped mesentery of peritoneum that suspends most of the small intestines from the internal surface of the posterior abdominal wall
What is the mesocolon?
Fold in the peritoneum that attaches part of the large intestines to the internal surface of the posterior abdominal wall
What is the peritoneal ligament?
Type of mesentery that attaches one organ to another organ, and an organ to the abdominal wall
What does the falciform ligament do?
Attaches the liver to the anterior abdominal wall
What are the 4 tunics that compose the GI tract from the esophagus to the large intestines?
Mucosa (mucous membrane), submucosa, muscularis, adventitia/serosa
What is the mucosa membrane of the tunics?
Innermost layer with absorptive and secretory functions and contains epithelium, connective tissue, and smooth muscle
What is the submucosa tunic?
Dense irregular connective tissue that contains accumulatons of lymphatic tissue, mucin-secreting glands, large blood vessels, lymphatic vessels, and nerve plexus
What is responsible for peristaltic movements through the GI tract?
Muscularis
What do sphincters do?
Close off the lumen at some points in the GI tract and controls the movement of materials along the GI tract
What is adventitia?
Loose connective tissue with dispersed collagen and connective tissue with dispersed collagen and elastic fibers
What makes serosa different from adventita?
Serosa is also covered by a visceral peritoneum
How does parasympathetic innervation promote digestive activity?
Stimulates GI gland secretions, peristalsis, and relaxation of GI sphincters
What is the esophagus?
A tubular passageway for swallowing materials bring conducted from the pharynx to the stomach
What is the esophageal hiatus?
Inferior region of the esophagus that connects to the stomach trough the diaphragm
Where is most of the length of the esophagus found?
Within the thorax anterior to the vertebral bodies
The esophageal has thick walls composed of concentric tunics that are continuous with what other body structures?
Pharynx and stomach
When there is no bolus passing through the esophagus, what happens to it?
Esophagus becomes flat
What can a bolus do to the trachealis muscle?
Causes the trachealis to bulge into the trachea
What two sphincters are associated with the esophagus?
Superior esophageal sphincter and inferior esophageal sphincter
What does the superior esophageal sphincter do?
Closes during inhalation of air so it wont enter the esophagus, but instead travel to the trachea and larynx
What does the inferior esophageal sphincter do since its too weak to prevent materials from refluxing back into the esophagus?
Inferior esophageal sphincter acts as a support to prevent materials from regurgitating from the stomach not the stomach
What is degluttion?
Swallowing; process of moving ingested material from the oral cavity to the stomach
What is the stomach?
J-shaped sac that occupies the upper left quadrant of the abdomen inferior to the diaphragm
What is the function of the stomach?
Chemically and mechanically digest a food bolus
What is chyme?
Bolus after it has been processed within the stomach and becomes a paste-like soup
How is mechanical digestion facilitated within the stomach?
Contractions of the muscularis layer churns and mixes the bolus and gastric secretions
What are the 4 regions of the stomach?
Cardia, fundus, body, and pyloris
What is the cardia?
A small, narrow, superior entryway into the stomach lumen from esophagus
What is the cardiac orifice?
Internal opening where the cardia meets the esophagus
What is the fundus?
dome-shaped region that is lateral and superior to esophageal connection with the stomach with the superior surface touching the diaphragm
What is the body of the stomach?
Largest region of the stomach inferior to cardiac orifice and fundus
What is the pyloris?
Narrow, medially-directed, funnel-shaped pouch that forms the terminal region of the stomach
What is the pyloric orifice?
Opening to the duodenum from the stomach
What is the pyloric sphincter?
Sphincter that regulates material form entering the small intestine by closing during sympathetic innervation and opening during parasympathetic innervation
The inferior, convex border of the stomach is the _____ while the superio, concave border is the _____
Greater curvature; lesser curvature
Where does the greater omentum attach?
Greater curvature of the stomach
Where does the lesser omentum extend from?
Lesser curvature of the stomach to the liver
What are gastric rugae (gastric folds)?
Found on the internal stomach lining that allows the stomach to expand when full, and return to its normal shape when empty
What are small intestines responsible for?
Finishing chemical digestion and absorbing nutrients
Why do ingested materials spend at least 12 hours within the small intestines?
Complete chemical digestion and maximize amount of nutrients absorbed
How long are the small intestines in a dead who recently died?
20 feet long
What artery supplies blood to the small intestines?
Superior mesenteric artery
Where does venous drainage of the small intestine travel to?
Hepatic portal vein
What are the 3 regions of the small intestines?
Duodenum, jejunum, and ileum
What is the duodenum?
10 inch long formation of the small intestines originating from pyloric sphincter
Where does the duodenum become continuous with the jejunum?
Duodenojejunal flexure
What is the major duodenal papilla?
Entryway for bile from the liver and pancreatic juice from the pancreas into the duodenum
What is the jejunum?
2/5 of the small intestine’s entire length (roughly 7.5 ft) that is the primary region for chemical digestion and nutrient absorbtion
What is the ileum?
Final 3/5 of the small intestines that terminates at the ileocecal valve
What is the ileocecal valve?
A sphincter that controls entry of material into large intestines
What are Peyer Patches?
Numerous aggregates of lymph nodes found on the walls of ileum
