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74 Cards in this Set
- Front
- Back
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What is the primary function of the digestive system?
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transfer of nutrients water and electrolytes from food into the body
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what are the four digestive processes?
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MADS
motility absorption digestion secretion |
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what percentage of ingested food is available for bodys energy use?
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95%
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What does steady tone of the GI tract do?
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this maintains steady pressure on the contents of the GI system, and prevents distention of the walls
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What are the two types of motility?
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propulsive
and mixing |
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What are the two types of propulsive GI motility? found where?
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rapid transit- found in the esophagus
and slow transit, found in the small intestine |
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What does Mixing Motility aid in? two things...
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digestion by mixing food with digestive juices
absorption by exposing contents to surfaces of the GI tract |
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what type of control is used in the smooth muscle in the walls of the GI tract?
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involuntary control
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what type of control is used in the skeletal muscle at either end of the GI? chewing, swallowing, and defecation
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voluntary control, like all skeletal muscle
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what is sucrose made of?
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glucose and fructose
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what is lactose made of?
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glucose and galactose
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how does most carbohydrate come in for digestion?
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as polysaccharides
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what are most dietary fats ingested as?
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TG's a glycerol plus 3 fatty acids
this gets turned into 2 fatty acids and a monoglyceride after digestion |
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what layer of the mucosa of the digestive tract wall is important for defense
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the lamina propria
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what 3 types of cells does the mucus membrane of the digestive tract wall contain?
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excorine cells
endocrine cells epithelial cells |
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what 3 layers are contained in the Mucosa of the GI tract?
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mucous membrane
lamina propria muscularis mucosa |
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what 2 layers are found in the muscularis externa?
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outer longitudinal layer
inner circular layer |
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what is contained in the submucosa of the digestive tract wall? what is its function?
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this has the CT mostly
larger blood and lymph vessels meissner's plexus this provides the distensibility and elasticity of the GI tract wall |
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What is contained in the muscularis externa?
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this has the inner circular layer
the outer longitudinal layer and the myenteric plexus |
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what does the serosa secret?
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this secrets serous fluid, which lubricates and prevents friction between the digestive organs and the surround viscera
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what is the serosa continuous with?
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this is continuous with the mesentery (allows support and relative fixed positioning, while still allowing motility)
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What are the two major factors in regulation of digestive function?
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1) autonomus smooth muscle function
2) intrinsic nerve plexuses |
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What does ACh promote in smooth muscle cells?
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contraction
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what does VIP (vasoactive intestinal peptide) promote in smooth muscle cells?
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this promotes relaxation
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What is the pacesetter cells of autonomous smooth muscle function? where are they located?
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these are called the interstitial cells of cajal
these regulate the RATE of rhythmic contractions located between Longitudinal and circular smooth muscle. in the myenteric plexus |
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What does ACH do to the enteric nervous system?
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contraction of SM
relaxation of sphincters increased secretion of Salivary, Gastic, and Pancreatic stuff |
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What does NE do in the enteric nervous system?
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this causes relation of SM
contraction of sphincters increase in salivary secretion |
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what does VIP (vasoactive intestinal peptide) do?
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relaxation of SM
increase in intestinal secreation, and pancreatic secretion |
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What does GRP (gastrin-releasing peptide) do?
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this increases gastin secretion
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what do Opiates (enkephalins) do?
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these cause contraction of smooth muscle, and a decrease in intestinal secretion
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What does Neuropeptide Y do to the enteric nervous system?
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this causes relaxation of smooth muscle
and a decrease of intestinal secretion |
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what does substance P do to the enteric nervous system? what is it cosecreted with?
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this causes contraction of SM
increase in salivary secretion cosecreted with ACH |
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How does the SNS affect GI secretion and motility? what pathway?
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this will SLOW it.
this travels along preganglionic fibers that synapse in ganglia outside the GI tract |
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How does the PNS affect GI secretion and motility? pathways?
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this tends to increase motility and secretion.
these synapse in the myenteric and submucosal plexuses Vagus nerve to upper GIT (esophagus, stomach, SI, ascending colon) Pelvic nerve to lower GIT (anal canal, tranverse, descending, and sigmoid colon) |
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What do GI peptides do? in general.
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these cause contraction of SM wall, and relaxation of sphincters
secrete digestive enzymes secrete fluid and electrolytes |
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What are the GI peptide hormones?
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CCK
Gastrin Secretin |
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What are the GI peptide paracines?
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somatostatin
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what are the GI peptide neurocines?
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Ach
NE VIP |
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what is the function of the uvula?
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this seals off nasal passages during swallowing
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What are the 3 salivary glands?
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Parotid gland
submandibular gland sublingual gland |
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What is produced in the parotid gland? what cell type?
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the parotid gland produces aqueous fluid, from serous cells
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what is produced in the sublingial and submandibular glands? what types of cells?
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serous cells produce aqueous fluid
mucus cells produce mucin and glycoproteins |
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what does amylase do?
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this breaks polysaccharides into maltose (2 glucose)
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what are the 3 salivary proteins?
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amylase, mucus, lysozyme
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What does Kallikrein do? where is it found?
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this is found in saliva....this cleaves kininogen into bradykinin
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what does bradykinin do?
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this is a vasodilatior, when it is cleaved into its active bradykinin form. (by kallikrein) this increases Blood Flow to the salivary glands when secretion is high
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what are the 4 functions of saliva?
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1) solvent for molecules to stimulate taste buds
2) aids speech 3) keeps teeth and mouth clean 4) contains HCO3- buffers, to prevent tooth decay |
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what contracts to eject saliva?
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myoepithelial cells, which are on the outside of the acinar cells
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what are the net secretions of a salivary duct cell?
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K and HCO3
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what are the net absorptions of a salivary duct cell?
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Na and CL
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are salivary duct cells permeable to H2O?
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no they are not
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what is the tonicity of saliva when its created? when it exits the duct?
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this is isotonic at creation
but due to net absorption of Na/Cl, it comes out hypotonic |
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how does salivary flow rate affect its concentration?
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the higher the flow rate, the less time to modify the saliva, so the more isotonic/similar to plasma it is
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what kind of salivary secretion does the PNS create?
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this creates watery, enzyme rich- which is dominant normally
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what kind of salivary secretion does the SNS create?
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lower volume, mucus rich (active with stress)
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what types of external stimulants cause saliva secretion?
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conditioning
food nausea smell |
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whats the biochemical pathway, transmitter, receptor, end product, of the PNS's action on salivary ducts?
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PNS releases ACH, which acts on musucarinic receptors...which leads to an accumulation of IP3 and Ca2+
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whats the SNS pathway, receptor, transmitter, and what does this lead to an accumulation of in salivary duct cells?
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this uses NE on a Beta adrenergic receptor, which causes a rise in cAMP in the cell
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What is Xerostomia?
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this is a decrease in saliva production, due to salivary gland infections, mumps, stones, lots of medications
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what is Achalasia?
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this is a failure of the lower esophageal sphincter to relax during swallowing
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how long does swallowing take?
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less than 10 seconds
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What happens during the Oral Phase of the Swallowing reflex? after food is pushed two the rear of the mouth
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This sitmulates tactile receptors- somoatosensory ones
these input to the medullary swallowing center. this information travels to the medulla via the Vagus and Glossopharyngeal nerves |
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What 4 things happen in the Pharyngeal phase of swallowing?
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soft palate pulled upwards
epiglottis moves to cover opening to larynx upper esophagal sphincter relaxes peristalsis |
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why does the soft palate move upwards during the pharyngeal phase of swallowing?
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prevents reflux of food into nasopharynx
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why does the epiglottis move to conver the opening to the larynx? what way does it move? (during the pharyngeal phase of swallowing)
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this occurs to prevent food from entering the trachea.
the larynx will move forward and upward against the epiglottis |
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what is inhibited during the pharyngeal phase of swallowing reflex?
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respiration
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what causes GERD?
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an incompetent lower esophageal sphincter
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what conditions can cause GERD?
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obesity and pregnancy, both cause increased intraabdominal pressure
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what is Cineradiography?
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this is a barium swallow and videotaped X-ray
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what is Manometry?
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this is the measuring of timing and strength of esophageal and valve contractions
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what type of muscle is found at the beginning and end of the GI tract?
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voluntary skeletal muscle
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what kinds of things can stimulate GI secretions?
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neural and hormonal input
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what types of things are formed during digestion of fat?
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monoglycerides and two free fatty acids
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What is sucrose comprised of?
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glucose and fructose
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