11/9: Upper GI Flashcards
What does the alimentary canal extend from?
Oral cavity to anus
What are the 5 phases of food breakdown?
Ingestion
Fragmentation
Digestion
Absorption
Elimination
What occurs in the oral cavity?
Ingestion
What is ingestion accompanied by?
Fragmentation
What does fragmentation result in?
Bolus formation
What completes fragmentation and initiates digestion?
Stomach
What are contractions of smooth mm called? What control are they under?
Peristalsis; autonomic control
What occurs in the duodenum?
Pancreatic and biliary secretions -> emulsifications of fat
What occurs in the jejunum and ileum?
Primary absorption of nutrienbts
What occurs in the colon?
Resorption of water and elimination of waste
What anchors the tongue to the floor of he mouth?
Lingual frenulum
What is a short frenulum called?
Ankyloglossia or tongue-tied
What is the gastrointestinal (alimentary) tract lined by?
Mucus membrane
What is inside the mucus membrane?
Large #s of glands associated with tract, liver, gallbladder, pancreas and itsetinal glands; emrbyological outgrowths of GI tract
What are diffused lymphoid tissue?
MALT and GALT
What tissue layers make up the wall of the GI tract?
Mucosa
Submucosa
Muscularis externa
Adventita (Serosa)
What are the 3 overall functions of the GI tract?
Protection
Secretion
Absorption
What is the GI tract wall subdivided into?
Epithelium
Lamina propria
Muscularis Mucosae
What surrounds the lumen of the GI tract?
Mucosa
What does the mucosa consist of?
Epithelial cell layer supported by CT tissue (lamina propria)
What is the muscularis mucosa?
Thin layer of smooth muscle that supports the mucosa and provides it with ability to move and fold
What are the 4 distinct types of mucosal variations?
Protective mucosa
Secretory mucosa
Absorptive mucosa
Absorptive/protective mucosa
What is protective mucosa characterized by?
Stratified squamous epithelium
Where is protective mucosa found?
Oral cavity
Pharynx
Esophagus
Anal Canal
What cells do secretory mucosa contain?
Cells that are responsible for the secretion of digestive enzymes
Where is secretory mucosa found?
Stomach
What two structures do absorptive mucosa contain?
Crypts and villi
What is absorptive mucosa responsible for/
Absorbing digested nutrients
Where is absorptive mucosa found?
Along the entirety of the small intestine
What does absorptive/protective mucosa specialize in?
Water absorption and mucus secretion
Where is absorptive/protective mucosa found?
Large intestine
What four points does mucosa undergo abrupt transition from one form to another?
The gastro-esophageal junction, the gastroduodenal junction, the ileocecal junction and the anorectal junction
Describe the lamina propria and what it contains?
Underlying CT; lymphoid nodules, glands, blood vessels and lymphatics
Describe the muscularis mucosae and where it’s located?
Thin layer of smooth mm; boundary between mucosa and submucosa
What does absorptive/protective mucosa specialize in?
Water absorption and mucous secretion
What is the general organization of the GI tract?
What is contained in the submucosa?
Arteries
Veins
Lymphatics
Nerves
What surrounds the submucosa?
Muscularis externaa
What is the muscularis externa composed of?
Two muscle layers, inner circular and outer lonitudinal
How do the two muscle layers of muscularis externa move?
Perpendicularly to one another and form basis of peristalsis
What does the adventitia/serosa consist of?
CT containing blood vessels, nerves, fat
What is adventitia/serosa lined by?
Mesothelium
What layer of the gut are local contractions found?
Segmentation -> mixing of food
Occur proximally and distally
Which way does peristalsis propel food?
Distally only
What is the layer of the gut lined by?
Simple squamous epithelium (= mesothelium)
Smooth muscle of the gut is controlled by what nervous system?
Autonomic
_______ stimulation is excitatory
_______ stimulation is inhibitory
Parasympathetic; sympathetic
Where do parasympathetic motor Nn synapse with?
Ganglia near effector organ
In the GI tract, where are ganglia located?
Within wall of the gut, within submucosa and muscularis externa
What are meissner’s plexus?
Clusters of parasympathetic ganglia within submucosa
What are myenteric or Auerbach’s plexus?
Larger clusters located between inner circular & outer longitudinal Mm layers
What is the key differene between Meissner’s and Auerbach’s plexus?
Meissner’s plexus is in the submucosal tissue of the gut
tube
Auerbach’s plexus is between the circular muscle
layer and longitudinal muscle layers
What is the esophagus and where does it run?
Hollow muscular tube; laryngopharynx to stomach
What does the resting muscle in the circular muscle layer in the superior 3 cm of esophagus prevent?
Air from entering
What does resting muscle tone at inferior end prevent?
Backflow from stomach
What is the esophagus lined with?
Stratified squamous nonkeratinized epithelium
Where is the site of GERD/esophageal cancers?
Distal side of the esophagus
In upper third, muscularis
externa composed of?
voluntary skeletal Mm
What is the middle third of the esophagus composed of?
Skeletal mm and smooth mm
What is the lower third of the esophagus composed of?
Smooth mm only
What is a hiatus hernia?
Protrusion of the upper part of the stomach into the thorax through a tear or weakness in the diaphragm
What does the gastro-esophageal junction between the esophagus and stomach contain?
Gastroesophageal sphincter
What is pyrosis?
(aka “heartburn”)—
due to regurgitation of
stomach acid into distal
esophagus from cardia of stomach
What is Barrett’s esophagus?
Serious complication of GERD
What does Barrett’s esophagus increase the risk of?
Developing esophageal adenocarcinoma
What are esophageal cancer symptoms?
- Difficulty and pain with swallowing, particularly when eating meat, bread, or raw vegetables
- Pressure or burning in the chest.
- Indigestion or heartburn.
- Vomiting.
- Frequent choking on food.
- Unexplained weight loss.
- Coughing or hoarseness.
- Pain behind the breastbone or in the throat.
What are esophageal cancer risks?
Smoking and poorly controlled acid reflux
Is esophageal cancer treatable?
Most cases, but rarely curable
