Term
| Enzymatic Hyrolysis def and 5 eq. |
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Definition
Enzymatic hydrolysis is the breakdown of polyerms (fat, startch, polypeptides) into their building blocks
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Term
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Definition
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Term
| where are the tube of GI tract and anus derived from? |
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Definition
tube - produced by gastrulation during embyoyneogenesis
anus - derived from blastopore |
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Term
| Tissue layers of the GI tract which surround the lumen |
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Definition
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Term
| intermost linning of lumen composed of what type of cells? |
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Definition
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Term
| Describe structure and functions of epithelial cells in GI tract |
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Definition
- epithelial cells attatched to basement membrane
- surface of epithelial cell (faces lumen) called apical surface and contains microvilli
- tight junctions seperate apical surface from rest of cell (thus seperating body fluids from extracellular enviro)
- epitheal cells responsible for most secretory activity in GI tract
[image]
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Term
| contrast longitudinal layer and circular layer of smooth muscle of GI tract. |
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Definition
| longitudinal layer runs lengthwise while circular layer of smooth muscle encircles it. |
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Term
| GI motility def and 5 contributing factors |
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Definition
GI motility is the rhythmic contraction of GI smooth muscle
- automaticity - contracts periodically with out external stimulation due to spontanious depolarization
- functional syncytium - when one cell has action potential and contracts, impulse sent to neighbouring cells
- contains specalized enteric nervous system
- motility increased or decreased by hormonal imput
- parasympathetic nervous system stimulates motility and causes sphincter to relax (allowing food to pass) and sympathetic stim does opposite.
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Term
| contrast mixing of food and passage of food down GI tract in terms of smooth muscle action. |
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Definition
mixing - disordered contractions of GI smooth muscle results in churning motions
movement down GI tract - done through peristalsis, the orderly form of contraction
[image] |
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Term
| GI secretion stimulated and inhibited by? |
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Definition
stimulated by food in gut and parasympathetic system
inhibited by sympathetic nervous system |
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Term
| contrast exocrine and endocrine gland |
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Definition
- exocrine- secrete into ducts that drain into GI lumen
- endocrine- ductless that has secrted hormones picked up by cappillaries that enter blood stream
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Term
| structure of GI tract exocrine gland |
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Definition
composed of speciliazed epithelial cells, organized into sacs called acini (singular: acinus)
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Term
| Digestive organs primarily involved in exocrine secretion |
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Definition
| liver, gallbladder, pancrease |
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Term
| compare/contrast gastric glands and goblet cells |
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Definition
both miniature exocrine glands
- gastric glands - epithelial cells in stomach that secrete acid and pepsinogen
- goblet cells - epithelial cells along entire GI tract that secrete mucus
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Term
| 2 principle cell types in pancrease |
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Definition
- exocrine cells called pancreatic acinar cells, organized into acni that drain into ducts
- edocrine cells in groups called islets of Langerhans that are supplied with capillaries
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Term
Role of mouth in digestion
- 3 roles
- *detailed description of role of saliva
- mouth creates food particle reffered to as?
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Definition
3 roles:
- fragmentation - done by mastication (chewing) creates food bolus
- lubrication - done by saliva
- some enzymatic digestion - by salivia
saliva detail:
- salivary amylase (ptyalin) hydrolyzes startch into fragments (smallest fragment being disacchardie)
- lingual lipase for fat digestion
- lysozyme attacks bacterial cell wall (therfore mouth part of innate immunity)
- not able to digest proteins
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Term
role of pharynx and esophagus in digestion
- opening to trachea and esphagus contained in the?
- name of flap of skin that stops liq and solids from entering trachea during swallowing?
- name of the two muscular rings that regulate movement of food through esophagus?
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Definition
- opening in the pharynx
- epiglottis stops liq and solids
- two rings are the upper esophageal spincter and lower esophageal sphincter (aka cardiac sphincter)
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Term
| 3 purposes of stomach in digestion |
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Definition
- particle digestion of food
- regulated release of food into small intestine
- destruction of microorganisms
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Term
acidity in stomach
gastric pH?- role in digestion
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Definition
- gastric pH =2
- destroys microorganisms
- acid hyrolysis of many dietary proteins
- conversion of pepsinogen to pepsin
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Term
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Definition
- secreted by cheif cells in stomach wall as pepsinogen, a zymogen (inactive form). converted to pepsin by acid in stomach
- catalyzes proteolysis (protein breakdown)
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Term
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Definition
- churns food continuously
- creates chyme - when food mixed with gastric secretions
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Term
sphincters for stomach
- role of two main sphincters
- how one is controlled
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Definition
- lower esophageal sphincter - prevents reflux of chyme into esophagus
- pyloric sphincter - prevents passage of food from stomach into duodenum
- controlled by hormone called cholecystokinin
- opening prevented when small intestine has large load of chyme
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Term
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Definition
- secreted by cells in stomach wall known as G cells
- stimulated by food in stomach or parasympathetic nervous system
- stimulates acid and pepsin secretion and gastric motility
- causes histame secretion
- histame binds to parietal cells to stimulate acid release
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Term
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Definition
- secreted in response to stomach stretching and gastrin
- binds to parietal cells to stimulate acid release
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