Term
| What is the function of the small intestine? |
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Definition
| Digestion and absorption of food nutrients. |
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Term
| The small intestine is divided into what sections? |
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Definition
| Duodenum and Jejunum (major site of digestion and absorption), and Ileum |
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Term
| How long does it take Chyme to travel through the small intestine? How far must it travel? |
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Definition
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Term
| What are the two main ways the small intestine acts on chyme? |
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Definition
| Mixing with digestive enzymes and propelling chyme forward. |
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Term
| What are are the major divisions of the Large Intestine? |
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Definition
| Cecum, Ascending Colon, Transverse Colon, Descending Colon, Sigmoid Colon, Rectum, and Anal Canal |
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Term
| What system innervates the skeletal muscle in the esophagus and anal sphincter? |
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Definition
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Term
| What extrinsic innervations affect GI motility? |
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Definition
Parasympathetic increases Sympathetic decreases |
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Term
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Definition
Located between the circular and longitudinal muscle layers and provides most innervations for these layers. Controls the motility of the GI smooth muscle. |
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Term
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Definition
| Located between the circular muscle layer and the submucosa and innervates the mucosa. Primarily controls secretion and blood flow |
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Term
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Definition
| Waves of membrane potential of smooth muscle in GI system. Contraction happens if threshold is broken, strength of contraction dependent on number of action potentials. |
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Term
| What controls salivary secretion? |
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Definition
Autonomic Nervous System Parasympathetic causes glands to secrete large volumes of watery fluid high in electrolytes but low in proteins. Sympathetic causes low volume with high concentration of mucus. |
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Term
| What prevents air from entering the upper esophagus and gastric acid from the lower esophagus? |
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Definition
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Term
| Describe structure of esophagus |
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Definition
Upper third, both the inner circular and outer longitudinal muscle layers are striated. Middle third, striated and smooth muscles coexist, with a gradient from all striated above to all smooth muscle below Lower third, muscle layers are composed all smooth muscle cells. |
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Term
| Describe three phases of swallowing |
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Definition
Oral Phase (voluntary): tongue presses food against the hard palate forcing it toward the pharynx Pharyngeal Phase (involuntary): peristalic propels food into the esophagus, airway covered Esophageal phase (involuntary): relaxation of the upper esophageal sphinter allows peristalis to move bolus down the esophagus |
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Term
| Three processes of the stomach |
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Definition
Motility: controlled agitation and movement of material Secretion: adding enzymes and cofactors necessary for digestion Absoprtion: taking up the products of digestion |
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Term
| What part of the stomach acts as a reservoir for the ingested meal? |
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Definition
| The fundus and body (corpus) |
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Term
| What seperates food in the stomach and what is the order of emptying? |
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Definition
| While the food sits in the fundus/body liquids flow around solid food to the bottom while fats rise to the top. Liquids exit first, then solids, then lipids. |
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Term
| Describe peristalic contractions in the stomach. |
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Definition
| Occur near the fundal-body border and proceed downward propelling food towards the pylorus. Mixes chyme with gastric secretions to initiate digestion. |
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Term
| What determines the rate of liquid emptying of the stomach. |
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Definition
| Proportional to volume of liquid. |
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Term
| What is the average/maximum size of food particals exiting the stomach. |
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Definition
| Average size of 0.25 mm diameter (90%), maximum around 2 mm diameter. |
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Term
| What can affect the rate of gastric emptying? |
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Definition
| Decrease in duodenal pH inhibits gastric motility and slows rate of emptying. Hypotonic or hypertonic fluids slow it, and CCK release from fatty foods inhibits as well. |
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Term
| Three phases of Gastric Acid Secretion |
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Definition
Cephalic Phase Secretion Gastric Phase Secretion Intestinal Phase Secretion |
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Term
| Comopunds that increase/decrease gastric acid secretion? |
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Definition
Acetycholine, Histamine, Gastrin agonists of HCl secretion Somatostatin inhibits secretion. |
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Term
| Describe process of vomitting |
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Definition
Begins with deep inspiration followed by the closing of the glottis Pressure wave originating in the intestine propels chyme into the upper part of stomach Increase in abdominal pressure force the chyme into the esophagus and out of the mouth Entry of vomitus into the trachea is prevented by closure of the golttis and inhibition of respiration. |
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Term
| Major sections of the colon |
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Definition
| Cecum, Ascending Colon, Transverse Colon, Descending Colon, Sigmoid Colon, Rectum, Anal Canal |
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Term
| Describe the innervations of the large intestine |
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Definition
Parasympathetic of cecum, ascending and transverse colon promote colonic contraction Sympathetic innervations on both the proximal and distal parts of the colon inhibit colonic contractions. |
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Term
| How is Peristalis in the Large Intestine different from other areas? |
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Definition
| Much slower due to bidirectional movement. Up to 48 hours for material to traverse the colon. |
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Term
| What neurotransmitters affect Digestive Tract Motility? |
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Definition
Excitatory: Acetylcholine, Serotonin, Cholecystokinin, Enkephalins, Gastrin-releasing peptide, Substance P, Neuropeptide Y Inhibitory: ATP, Dopamine, Nitric Oxide, Somatostatin, Vasoactive Intestinal Peptide |
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Term
| What do changes in digestive motility cause? |
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Definition
Enhanced motility decreases time of water absorption causing diarrhea. Impaired motility allows too much water reabsorption causing constipation. |
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Term
| How does the nervous system affect water secretion in the digestive tract? |
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Definition
Parasympathetic promotes net secretion of water and electrolytes. Sympathetic enhances net absorption of water and electrolytes. |
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