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

Terms Definitions
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.
Dental caries
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
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.
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.
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.
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.
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.
Where is emetic center located?
Controls vomiting - in medulla
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