Term
| what is the process of moving the food in a wave-like contractions toward the esophagus called? |
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Definition
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Term
| can you describe the difference between peristalsis and segmentation? where along the alimentary canal do these processes occur? |
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Definition
| peristalsis is a one way smooth muscle contraction for propultion of food from the esophagus to the anus. segmentation is back and forth smooth muscle contraction in the small intest. only for mechanical digestion |
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Term
| where is the gastroesophageal sphincter is and what does it do? |
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Definition
| its at the junction of the esophagus and the stomach. it opens to allow the passage of bolus into the stomach from the esophagus but also remains shut in between to keep stuff in the stomach from getting into the esophagus |
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Term
| what mechanical process does the stomach perform |
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Definition
| churning. which is twisting, shortening and constricting motion of the stomach |
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Term
| in what ways is the stomach stimulated when a bolus enters it |
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Definition
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Term
| what is the average pH in the stomach |
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Definition
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Term
| how does pH change when the bolus enters the stomach? which cells does this change in ph stimulate? what is the response of these cells |
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Definition
| the bolus causes a rise in the pH (more alkaline). -it stimulates the G cells, which will secrete gastrin to activate parietal cells |
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Term
| list the various functions of the digestive system |
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Definition
| ingestion, digestion, propulsion, absorption, elimination. |
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Term
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Definition
| introduction of food into the mouth |
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Term
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Definition
breaking large food particle into absorbable molecules by chemical or mechanical digestion.
chemical- uses chemicals like acid and enzymes
mechanical- physical process of breaking food down (chewing and stuff) |
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Term
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Definition
| movement of food stuff through the alimentary canal by muscular contractions |
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Term
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Definition
| nutrient molecules crossing the mucosal cells and entering the blood circulation |
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Term
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Definition
| the removal of indigestable foods by defication |
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Term
| what is the difference between elimination and excretion |
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Definition
| elimination rids the alimentary canal of matter that was never part of the body. excretion is the act of removing waste that was produced in the body |
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Term
| can you list the two mechanisms of digestion and the three phases |
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Definition
mechanisms- chemical and mechanical
phases 3- 1.cephalic phase: everything that happens from mouth to stomach including CNS activity. 2 gastric phase: actions preformed in the stomach. 3 intestinal phase: small and large intestines |
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Term
| can you list and describe the various stimuli that can cause a response by the alimentary canal |
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Definition
-change in ph due to acidity change
-change in osmolarity, incoming food brings increased concentration of solute
-stretch to accommodate the size of the food
-CNS the brain can stimulate parts of the canal like churning and secretion HCl by Ach of the vegas nerve |
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Term
| when sensory information regarding food/eating reaches the brain, what responses will occur under parasympathetic direction? |
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Definition
| salivation, stomach motility and secretion of gastric juices. cephalic phase, since these activities are directed by the brain via Parasympathetic nervous system |
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Term
| can you describe which mechanical process occur in the cephalic phase |
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Definition
| chewing (mastication) performed by the teeth to grind the food and the tongue to mix the food with saliva |
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Term
| can you describe the function of saliva in the mouth |
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Definition
| cleanses the mouth, moisten the food to form a bolus, chemical digestion of starches by salivary armylase, dissolves tastants to bind to their receptors and provides immunity in the mouth |
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Term
| do you know the composition of saliva and which cells secrete these components |
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Definition
| serous cells secrete the majority of the slightley acidic saliva, which is mostly water with ions, antibody, lysozymes and mucin. mucous cells secrete additional mucus to help ease the passage of food through the tract |
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Term
| what is a bolus and how is it formed |
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Definition
| it is masticated foodstuff mixed with saliva by the tongue |
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Term
| can you describe the general process of swallowing. what is the scientific name of this process |
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Definition
| it is a voluntary action performed by the skeletal muscle of the teeth, soft palate, pharynx and upper esophagus to propel the bolus into the esophagus from the mouth, called-deglutition |
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Term
| can you describe the make up of the muscular layer of the esophagus and how the make up changes from top to bottom. how does this make up allow the esophagus to function. |
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Definition
| the first third of the esophagus is skeletal muscle and plays a role in the voluntary action of swallowing. the second third is half skeletal and half smooth so voluntary action is completed and involuntary paristolsis begins. the 3rd is smooth continues paristolsis waves |
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Term
| how are G cells turned off |
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Definition
| the HCl production causes the pH to decrease again (more acidic) which stimulates D cells. these ceslls secrete somatostatin, a hormone that enters the blood and inhibits G cells |
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Term
| what is the function of parietal cells |
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Definition
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Term
| can you list the three things that stimulate the parietal cells? and where do these three stimulants come from |
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Definition
Gastric (from G cells)
Ach (from vagus nerve)
histamine (from ECL cells) |
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Term
| what kind of acid is stomach acid? what is this acid good for as far as digestion is concerned |
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Definition
| HCl, it denatures protien and CT digestion |
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