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BIO202 - Ch 23 - Digestive System - Stomach - Marieb/Hoehn - RioSalado - AZ

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Question
Answer
deciduous teeth   milk or baby teeth  
The outer surface of the tooth root is covered by __.   cementum - calcified CT  
What anchors tooth in bony alveolus of jaw?   Peridontal ligament  
Bonelike material underlying enamel cap & makes up bulk of tooth.   Dentin  
Dental caries   cavities  
Calculus   tartar  
Histology of pharyngeal wall   Stratified squamous w/mucus-producing glands  
There are 2 __ layers in pharyngeal wall.   skeletal muscle  
How long is esophagus?   25 cm (10 inches) long  
How does epithelium change abruptly at esophagus-stomach junction.   Esophageal mucosa change from nonkeratinized stratified squamous to simple columnar epithelum which is specialized for secretion.  
Submucosa's esophageal glands secrete?   Mucus to grease the esophageal walls to aid food passage.  
The outermost layer of esophagus.   Adventitia (Fibrous CT)  
Name 2 digestive system structures whose only role is food propulsion.   Pharynx & esophagus  
deglutition   Swallowing - involves 22 separate muscle groups - buccal phase & pharyngeal-esophageal phase.  
Which phase of deglutition is voluntary?   buccal phase  
The pharyngeal-esophageal phase of deflutition is controlled by __.   Swallowing center in brainstem - medulla & lower pons - transmitted through vagus nerves.  
What structural modification of stomach tunic allows mechanical digestion?   Muscularis externa has 3rd layer of smooth muscle to churn food - runs obliquely.  
Size of adult stomach   15-25 cm (6-10 inches) 50 ml empty - 1 gallon full  
What part of stomach is continuous with duodenum.   Pylerus  
Lining of stomach   Simple columnar epithelium w/goblet cells that produce alkaline mucus - makes a bicarbonate-rich fluid layer.  
Mucous neck cells of stomach   Produce thin mucus - acidic  
Parietal cells of stomach   Secrete HCl & intrinsic factor - have microvilli  
Intrinsic factor is?   Glycoprotein for B12 absorption in small intestine, but produced in stomach.  
Ph of stomach   1.5 - 3.5  
Chief cells of stomach   Produce pepsinogen (inactive) - activated by HCl & becomes pepsin - positive feedback process.  
Enteroendocrine cells of stomach   Release chemical messengers - histamine, gastrin, serotonin, somatostatin  
What barrier protects stomach from self-digestion?   Gel-like mucosal barrier - (1) bicarbonate-rich mucus, (2) tight junctions, (3) stem cells that divide & replace quickly.  
gastritis   inflammation of stomach wall due to anything that breaches mucosal barrier  
Name some H2-receptor blocker drugs   Tagmet & Zantac  
Vagus nerve does what what with stomach.   Stimulates secretory activity of virtually all of its glands.  
Which hormone controls gastric secretion?   Gastrin - enzymes, HCL  
3 phases of gastric secretion   Cephalic (reflex), gastric, & intestinal - all may be occuring at same time.  
Cephalic reflex (Phase 1)   Conditioned reflex - occurs before food enters stomach - triggered by senses, prepares stomach - suppressed when emotinally depressed.  
Gastric Phase (Phase 2)   In stomach - 3-4 hours long - distension & gastrin are stimulus.  
G cells   Gastrin - secreting enteroendocrine cells.  
Highly acidic gastric contents __ gastrin secretion.   Inhibit  
Protein __ pH in stomach   raises - stimulates gastrin & HCl release  
HCl secretion is stimulated by which 3 chemicals?   ACh, gastrin, & histamine (by enterochromaffin-like cells) - all 3 combined causes HCl to pour forth.  
Blood draining from stomach is more __ than blood serving it.   alkaline - phenomenon called alkaline tide.  
Intestinal Phase (3)   2 components - excitatory & inhibitory - excitatory - gastric gland in duodendum produce intestinal gastrin: inhibitory - enterogastric reflex that puts on "breaks" to protect small intestine from acidity.  
Enterogastric reflex   release is inhibited.  
Plasticity   Smooth muscle's ability to stretch without greatly increasing tension & contracts expulsively.  
What sets rate of stomach's peristalic waves?   Pacemaker cells in longitudinal small muscle layers called interstitial cells of Cajal - don't initiate beat, neural does.  
Basic electrical rhythm (BER)   Cyclic slow waves of stomach due to pacemaker interstitial cells of Cajal.  
Stomach usually empties completely within __ hours.   4  
emesis   vomiting  
Where is emetic center located?   Controls vomiting - in medulla  


   


 
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