Final Exam Flashcards
Name the 4 walls of the GI tract from innermost to outermost
- Mucosal layer
- Submucosal Layer
- Muscularis layer
- Serosal layer
What are the 3 subcomponents of the mucosal layer of the GI tract
- epithelium
- lamina propria (CT that contains capillaries and lacteals)
- muscularis mucosae (not important for motility, increases SA)
Describe the Submucosal layer
- connective tissue
- blood vessels, secretory glands and neurons
- submucosal plexus of Meissner’s plexus (post-ganglionic parasympathetic neurons)
Muscular layer
-inner muscle layer is circular and wraps tube
contractions narrow the tube
-outer layer contractions shorten and increase diameter of tube
Where is the myenteric plexus / Auerbachs plexus found
- muscluaris layer
- post ganglionic parasympathetic neurons
Parasymp and Symp in GI
- parasymp is stimulatory
- symp is inhibitory
What are the functions of saliva
- chemical digestion of CHO and some lipids
- lubrication of GI tract, aids in bolus formation
- enhances taste
- keeps mouth and teeth clean
How is saliva production stimulated
-parasymp, produces copious watery saliva
-smell
sour foods
local reflexes
Sjogren’s syndrome
- lymphocyte and plasma cells invade salivary and lacrimal glands
- dry mouth and eyes
- rheumatoid arthritis, lupus, scleroderma
What does the esophagus do?
moves bolus of food from mouth to stomach via peristalsis
Describe the cells in the esophagus
- proximal 1/3 is skeletal muscle, remainder is smooth muscle
- stratified squamous epithelium
- secretes mucus
Gastroesophageal Junction
abrupt transition from stratified epithelium to pseudo columnar epithelium (in stomach)
-lower esophageal sphincter is here
Lower Esophageal Sphincter
- anatomically distinct form surrounding smooth muscle
- allows ingested food into stomach and prevents stomach contents into esophagus
Gastroesophageal Reflux Disease (GERD)
- heartburn that occurs twice per week
- pain in upper/mid abdomen can radiate to chest, throat, shoulder, back
- made worse after eating large meals
- worse at night
- respiratory symptoms
GERD treatment
- stop smoking
- stop drinkin
- lose weight
- wear looser clothing
Barretts esophagus
- conversion of esophageal mucosa to intestinal mucosa after repeated exposure to gastric contents
- occurs in 10-15% ppl w/ GERD
- risk factor for esophageal cancer (adenocarcinoma)
Esophageal Cancer (adenocarcinoma)
- dysphagia and weight loss
- white males
- distal 1/3 of esophagus
Esophageal Cancer (squamous cell carcinoma)
-alcohol and smoking
-blacks
better prognosis
What makes pepsinogen
-chief or zymogenic cells
What do parietal cells do in the stomach
- make HCl
- make intrinsic factor
What does intrinsic factor do
-necessary for vitamin B12 absorption
Pernicious anemia
-lack of vitamin B12 from diet or intrinsic factor
Basic electrical rhythm of stomach
- generates peristaltic contractions
- pacemaker cells in longitudinal muscle layer generate contractions
- 3-5 contractions/minute
What is the role of the pyloric sphincter
- regulates outflow from stomach into duodenum
- only a small amount with each contraction 2-3mLs