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Aduonum 12-17-07 GI Motility

Aduonum 12-17-07 Gi Motility

by leelara, Dec. 2007

Subjects: losboludosazules m2t2gitest1

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44 Cards in this Set

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	Characterize and describe the types of muscles and contraction in the GI tract Describe the stages of swallowing and how they are regulated Describe and contrast digestive (fed) and interdigestive (fasting) phase motility patterns (esophageal, stomach, small and large intestine) and the mechanisms of their regulation Characterize reflexes that coordinate GI activity Describe various clinical considerations associated with GI motility	-
	Control of Chewing - Innervation - ___ cranial nerve innervates muscles of ____________ Controlled by nuclei in brain stem	Control of Chewing - Innervation - 5th cranial nerve innervates muscles of mastication Controlled by nuclei in brain stem
	2 major salival enzymes for fat and carbs	lingual lipase alpha-amylase
	Three stages of deglutination V_______ (buccal)- initiates swallowing process P_________ - passage of food through pharynx into esophagus E_________ - passage of food from pharynx to stomach	Three stages of deglutination Voluntary (buccal)- initiates swallowing process Pharyngeal - passage of food through pharynx into esophagus Esophageal - passage of food from pharynx to stomach
	Pharyngeal Stage of Swallowing Reflex controlled by brain stem - 1. Food in pharynx - tactile stimulation 2. Soft palate pulled upward 3. P________________ folds (“sizer”) pulled together 4. T______ is closed (respiration inhibited) - Vocal cords approximated - Larynx raises and e__________ covers larynx 5. Relaxation of U________ e_________ s__________ 6. Peristaltic contraction of pharynx	Pharyngeal Stage of Swallowing Reflex controlled by brain stem - 1. Food in pharynx - tactile stimulation 2. Soft palate pulled upward 3. Palatopharyngeal folds (“sizer”) pulled together 4. Trachea is closed (respiration inhibited) - Vocal cords approximated - Larynx raises and epiglottis covers larynx 5. Relaxation of Upper esophageal sphincter 6. Peristaltic contraction of pharynx
	Nervous Control of Swallowing Swallowing Center - m_____ Sensory input from pharynx and esophagus Coordinates activity from _____ nuclei with other centers (e.g., inhibits respiratory center) Pharyngeal Phase - Food in pharynx --> afferent sensory input via vagus / g______________ N. --> swallowing center --> brain stem nuclei --> efferent input to pharynx.	Nervous Control of Swallowing Swallowing Center - medulla Sensory input from pharynx and esophagus Coordinates activity from vagal nuclei with other centers (e.g., inhibits respiratory center) Pharyngeal Phase - Food in pharynx --> afferent sensory input via vagus / glossopharyngeal N. --> swallowing center --> brain stem nuclei --> efferent input to pharynx.
	Esophageal Stage of Swallowing Primary peristalsis - continuation of p_________ peristalsis Secondary peristalsis Induced by d__________ Repeats until bolus is cleared Upper esophagus - upper 1/3 is s_______ muscle Lower esophagus - lower 2/3 is __	Esophageal Stage of Swallowing Primary peristalsis - continuation of pharyngeal peristalsis Secondary peristalsis Induced by distention Repeats until bolus is cleared Upper esophagus - upper 1/3 is striated muscle Lower esophagus - lower 2/3 is SM
	Nervous Control of Esophageal Phase Primary peristalsis - Continuation of p________ peristalsis Coordinated by swallowing center Cannot occur after _____otomy (striated muscle) Secondary peristalsis - Stretch related afferent sensory input to ENS and swallowing center are both involved Can occur after _____otomy (SM)	Nervous Control of Esophageal Phase Primary peristalsis - Continuation of pharyngeal peristalsis Coordinated by swallowing center Cannot occur after vagotomy (striated muscle) Secondary peristalsis - Stretch related afferent sensory input to ENS and swallowing center are both involved Can occur after vagotomy (SM)
	Esophageal Pressures Between Swallows High pressure at sphincters Pressure in esophageal body ~= intra_______ pressure During Swallowing UES relaxes - (low pressure) Peristaltic wave - (high pressure) LES and fundus relax - receptive relaxation (low pressure). V____ input is inhibitory. ___ is transmitter for receptive relaxation.	Esophageal Pressures Between Swallows High pressure at sphincters Pressure in esophageal body ~= intrapleural pressure During Swallowing UES relaxes - (low pressure) Peristaltic wave - (high pressure) LES and fundus relax - receptive relaxation (low pressure). Vagal input is inhibitory. VIP is transmitter for receptive relaxation.
	Esophageal Sphincters - Purpose Purpose of high resting pressures in UES and LES UES - _____ ________ _____ _____ _ LES - _______ ______ ________ ____ ______	Esophageal Sphincters - Purpose Purpose of high resting pressures in UES and LES UES - keeps air from entering esophagus LES - prevents acid reflux into esophagus
	Disorders of Swallowing (Dysphagia) CVA (stroke) / cranial nerves damage Aspiration - UES and pharyngeal contractions are not coordinated Secondary peristalsis is still functional Muscular diseases - m_______ g_____, p_____, b________ Anesthesia - aspiration of stomach contents	Disorders of Swallowing (Dysphagia) CVA (stroke) / cranial nerves damage Aspiration - UES and pharyngeal contractions are not coordinated Secondary peristalsis is still functional Muscular diseases - myasthenia gravis, polio, botulism Anesthesia - aspiration of stomach contents
	Gastroesophageal Reflux Disease (GERD) Heartburn / acid indigestion (_/10 people) Backwash of a___, p____, and b___ into esophagus Can lead to – stricture of esophagus (scar tissue) asthma (aspiration) chronic sinus infection (reflux into throat) _________ esophagus An abnormal change (metaplasia) in the cells of the lower end of the esophagus. In about 10% of patients Considered to be a premalignant condition and is associated with an increased risk of _________ cancer	Gastroesophageal Reflux Disease (GERD) Heartburn / acid indigestion (1/10 people) Backwash of acid, pepsin, and bile into esophagus Can lead to – stricture of esophagus (scar tissue) asthma (aspiration) chronic sinus infection (reflux into throat) Barrett’s esophagus An abnormal change (metaplasia) in the cells of the lower end of the esophagus. In about 10% of patients Considered to be a premalignant condition and is associated with an increased risk of esophageal cancer
	Achalasia and Megaesophagus What is the cause / characteristics? Motility disorder affecting _____ 2/3 of esophagus ___ fails to relax - ___ pressure is high Organized peristaltic contractions are absent Neurological problem with ENS (________ plexus) After months/years ____esophagus develops can hold > 1 liter of food Esophageal ulceration, rupture, and death can occur	Achalasia and Megaesophagus What is the cause / characteristics? Motility disorder affecting lower 2/3 of esophagus LES fails to relax - LES pressure is high Organized peristaltic contractions are absent Neurological problem with ENS (myenteric plexus) After months/years megaesophagus develops can hold > 1 liter of food Esophageal ulceration, rupture, and death can occur
	Achalasia and Megaesophagus What are the symptoms? Difficulty swallowing liquids and solids Regurgitation of undigested food Weight loss, h_______, excessive b______, heartburn What is the treatment? Anti-________ drugs that relax smooth muscle Pneumatic d______ (stiff balloon) Surgical m______	What are the symptoms? Difficulty swallowing liquids and solids Regurgitation of undigested food Weight loss, halitosis, excessive belching, heartburn What is the treatment? Anti-spasmotic drugs that relax smooth muscle Pneumatic dilator (stiff balloon) Surgical myotomy
	Functions of gastric smooth muscle - Relaxes to accommodate food - ____ area (receptive relaxation) Mixes food with gastric juice - caudad area (_____pulsion) Propels chyme into duodenum - caudad area (_____ pump)	Functions of gastric smooth muscle - Relaxes to accommodate food - orad area (receptive relaxation) Mixes food with gastric juice - caudad area (retropulsion) Propels chyme into duodenum - caudad area (antral pump)
	Motility of the Orad Area Contractile activity - Low amplitude contractions occur as meal empties Receptive relaxation - (___ is neurotransmitter) V_______ reflex - vagal aff. carry impulses to CNS - vagal eff. carry impulses from CNS to stomach ___otomy abolishes reflex Gastric distensibility - CCK increases (______ gastric emptying) Gastrin effect not physiologic	Motility of the Orad Area Contractile activity - Low amplitude contractions occur as meal empties Receptive relaxation - (VIP is neurotransmitter) Vagovagal reflex - vagal aff. carry impulses to CNS - vagal eff. carry impulses from CNS to stomach Vagotomy abolishes reflex Gastric distensibility - CCK increases (decreases gastric emptying) Gastrin effect not physiologic
	Motility of the Caudad Area P__________ is the primary contractile event Pressure tracings show - Increased magnitude of contraction on approach to antrum Decreased phase l__ on approach to antrum Decreased phase lag causes increased velocity of p______ wave	Motility of the Caudad Area Peristalsis is the primary contractile event Pressure tracings show - Increased magnitude of contraction on approach to antrum Decreased phase lag on approach to antrum Decreased phase lag causes increased velocity of peristaltic wave
	Electrical and Mechanical Events Relationship between slow wave and muscle tension in caudad area - Slow wave depolarization can elicit c_________ of SM (without spikes) - stomach only Slow wave plateau must reach threshold to cause SM contraction Larger slow waves that have s_____ potentials cause increased strength of SM contraction	Electrical and Mechanical Events Relationship between slow wave and muscle tension in caudad area - Slow wave depolarization can elicit contraction of SM (without spikes) - stomach only Slow wave plateau must reach threshold to cause SM contraction Larger slow waves that have spike potentials cause increased strength of SM contraction
	Regulation of Gastric Emptying Chyme must enter duodenum at proper rate pH must be optimal (____) for enzyme function Slow enough for nutrient absorption Immediately after meal - emptying does not occur before onset of gastric contractions Conditions favor emptying - Increased tone of ____ stomach Forceful peristaltic contractions Decreased tone of pylorus Absence of segmental contractions in intestine	Regulation of Gastric Emptying Chyme must enter duodenum at proper rate pH must be optimal (high) for enzyme function Slow enough for nutrient absorption Immediately after meal - emptying does not occur before onset of gastric contractions Conditions favor emptying - Increased tone of orad stomach Forceful peristaltic contractions Decreased tone of pylorus Absence of segmental contractions in intestine
	Regulation of Gastric Emptying Activation of receptors in intestinal mucosa initiates e_________ reflexes. This decreases gastric emptying by - Relaxation of orad stomach Decreased force of peristaltic contractions Segmentation contractions in intestine	Regulation of Gastric Emptying Activation of receptors in intestinal mucosa initiates enterogastric reflexes. This decreases gastric emptying by - Relaxation of orad stomach Decreased force of peristaltic contractions Segmentation contractions in intestine
	Intestinal Receptors - Gastric Emptying Intestinal mucosa receptors - stimulated by high or low osmolarity, acid, fat, and protein Receptors trigger enterogastric reflexes Fat/proteins - CCK release _________ gastric distensibility which ________ gastric emptying Acid - _________ gastric emptying (in 20-40s) via intrinsic neural reflex Involvement of other hormones - probably not physiologic	Intestinal Receptors - Gastric Emptying Intestinal mucosa receptors - stimulated by high or low osmolarity, acid, fat, and protein Receptors trigger enterogastric reflexes Fat/proteins - CCK release increases gastric distensibility which decreases gastric emptying Acid - decreases gastric emptying (in 20-40s) via intrinsic neural reflex Involvement of other hormones - probably not physiologic
	Disorders of Gastric Motility ____ Gastric Emptying is most common problem - Symptoms: fullness, loss of appetite, nausea, sometimes vomiting Causes: gastric _____ (scar tissue), cancer (physical obstruction), scleroderma, eating disorders (______ nervosa, ______ nervosa, obesity), ___otomy (used to reduce acid secretion). Treatment - _____oplasty, balloon dilation	Disorders of Gastric Motility Slow Gastric Emptying is most common problem - Symptoms: fullness, loss of appetite, nausea, sometimes vomiting Causes: gastric ulcer (scar tissue), cancer (physical obstruction), scleroderma, eating disorders (anorexia nervosa, bulimia nervosa, obesity), vagotomy (used to reduce acid secretion). Treatment - pyloroplasty, balloon dilation
	Gastroparesis What is it? Slow emptying of stomach/paralysis of stomach. Who gets it? 20% ____ ___ ___ ____ ____ _____ _____ Cause: High blood _____ damages ____ nerve Symptoms: nausea, vomiting, an early feeling of fullness when eating, weight loss, abdominal bloating, abdominal discomfort Treatment: Goal is to lower blood _______	Gastroparesis What is it? Slow emptying of stomach/paralysis of stomach. Who gets it? 20% Type I diabetics (some type II) Cause: High blood glucose damages vagus nerve Symptoms: nausea, vomiting, an early feeling of fullness when eating, weight loss, abdominal bloating, abdominal discomfort Treatment: Goal is to lower blood glucose
	Disorders of Gastric Motility Rapid Gastric Emptying (D_______ Syndrome) Symptoms diarrhea (_______ osmotic load) hypotension (decreased ECF) reactive hypoglycemia (______ surge from rapid sugar load) duodenal ulcer (acid erodes mucosa) Causes Resective gastric operations (dumping syndrome) ______oplasty	Disorders of Gastric Motility Rapid Gastric Emptying (Dumping Syndrome) Symptoms diarrhea (increased osmotic load) hypotension (decreased ECF) reactive hypoglycemia (insulin surge from rapid sugar load) duodenal ulcer (acid erodes mucosa) Causes Resective gastric operations (dumping syndrome) pyloroplasty
	Small Intestinal Motility Small intestinal motility contributes to digestion and absorption by - Mixing chyme - with digestive enzymes and other secretions Circulation of chyme - to achieve optimal exposure to mucosa Propulsion of chyme - in an aboral direction Two types of movements in small intestine following a meal - P_________ - a propulsive movement recall “Law of Gut.” A____________ - a mixing movement	Small Intestinal Motility Small intestinal motility contributes to digestion and absorption by - Mixing chyme - with digestive enzymes and other secretions Circulation of chyme - to achieve optimal exposure to mucosa Propulsion of chyme - in an aboral direction Two types of movements in small intestine following a meal - Peristalsis - a propulsive movement recall “Law of Gut.” Segmentation - a mixing movement
	Role of Slow Waves: Contraction is controlled by ____ wave activity - Slow wave frequency- __/min duodenum, __ jejunum, _ ileum Contraction frequency - limited by slow wave frequency Spike potentials necessary - Unlike stomach, contractions do not occur in ______ of spike potentials Slow waves measured at ___ points along small intestine - Slow wave phase ___ - promotes propagation of contractions (peristalsis) Slow wave frequency - decreases at ______ portions of small intestine (5 and 6 are distal)	Role of Slow Waves: Contraction is controlled by slow wave activity - Slow wave frequency- 12/min duodenum, 10 jejunum, 8 ileum Contraction frequency - limited by slow wave frequency Spike potentials necessary - Unlike stomach, contractions do not occur in absence of spike potentials Slow waves measured at six points along small intestine - Slow wave phase lag - promotes propagation of contractions (peristalsis) Slow wave frequency - decreases at distal portions of small intestine (5 and 6 are distal)
	Migrating Motility Complexes (MMC) Purpose - (h________ function). Sweeps undigested residue toward colon to maintain low bacterial counts in ____ intestine. Most coordinated, rapid peristalsis. Occurs between meals. Characteristics - Periods of intense peristaltic contractions Takes ~__ min to go from stomach to colon Mediated by m_______ and ENS	Migrating Motility Complexes (MMC) Purpose - (housekeeping function). Sweeps undigested residue toward colon to maintain low bacterial counts in upper intestine. Most coordinated, rapid peristalsis. Occurs between meals. Characteristics - Periods of intense peristaltic contractions Takes ~90 min to go from stomach to colon Mediated by motilin and ENS
	Control of Small Intestinal Motility Whether spike potentials and hence contractions occur depends upon ______ and hormonal input - Nervous factors - (PNS - stimulates / SNS - Inhibits) Peristaltic reflex - (Law of the Gut) - Mediated by ENS. Intestino-intestinal reflex - severe distention inhibits bowel. Extrinsic nerves. Gastroileal reflex - ____ stimulates. Ileocecal sphincter _______, ileal peristalsis _________.	Control of Small Intestinal Motility Whether spike potentials and hence contractions occur depends upon neural and hormonal input - Nervous factors - (PNS - stimulates / SNS - Inhibits) Peristaltic reflex - (Law of the Gut) - Mediated by ENS. Intestino-intestinal reflex - severe distention inhibits bowel. Extrinsic nerves. Gastroileal reflex - Meal stimulates. Ileocecal sphincter relaxes, ileal peristalsis increases.
	Control of Small Intestinal Motility Whether spike potentials and hence contractions occur depends upon neural and _______ input - Hormonal factors - Epinephrine - released from adrenals - _______ motility Motilin - mediates migratory motor complexes Serotonin and prostaglandins - there are large quantities in small intestine that can stimulate motility Other hormones. G______, CCK, and i_______ stimulate contractions. S_______ and g_______ inhibit contraction. The roles of these are uncertain.	Control of Small Intestinal Motility Whether spike potentials and hence contractions occur depends upon neural and hormonal input - Hormonal factors - Epinephrine - released from adrenals - inhibits motility Motilin - mediates migratory motor complexes Serotonin and prostaglandins - there are large quantities in small intestine that can stimulate motility Other hormones. Gastrin, CCK, and insulin stimulate contractions. Secretin and glucagon inhibit contraction. The roles of these are uncertain.
	Ileocecal Junction Functions as a valve and a sphincter - Valvular function – prevents backflow into ______ intestine mechanically Sphincter function – regulates movement of ileal contents into _____ intestine. ENS and extrinsic nerves.	Ileocecal Junction Functions as a valve and a sphincter - Valvular function – prevents backflow into small intestine mechanically Sphincter function – regulates movement of ileal contents into large intestine. ENS and extrinsic nerves.
	Musculature of Large Intestine Longitudinal SM - 3 groups (_____ coli) Circular SM - continuous to anus Internal anal sphincter - a __________ of circular SM External anal sphincter - _______ muscle, surrounds internal anal sphincter H_____ (h______tions) - not fixed, appear and disappear	Musculature of Large Intestine Longitudinal SM - 3 groups (teneae coli) Circular SM - continuous to anus Internal anal sphincter - a thickening of circular SM External anal sphincter - striated muscle, surrounds internal anal sphincter Haustra (haustrations) - not fixed, appear and disappear
	Innervation of Large Intestine Myenteric plexus - concentrated beneath t______ Parasympathetic input - Vagus innervates ________ colon Pelvic nerves (__-S4 ) - distal colon, rectum / anus Sympathetic input - T10-L2 Celiac ganglion and superior mesenteric ganglion - ______ colon Inferior mesenteric ganglion - ______ colon Hypogastric plexus - ______ and ______ canal External anal sphincter - _______ nerves	Innervation of Large Intestine Myenteric plexus - concentrated beneath teneae Parasympathetic input - Vagus innervates proximal colon Pelvic nerves (S2-S4 ) - distal colon, rectum / anus Sympathetic input - T10-L2 Celiac ganglion and superior mesenteric ganglion - proximal colon Inferior mesenteric ganglion - distal colon Hypogastric plexus - rectum and anal canal External anal sphincter - pudendal nerves
	Haustral Contractions Purpose-mixing movement facilitate fluid and electrolyte absorption (minimal propulsion) Structural and functional basis – They appear and disappear every __-__ sec Require contraction of longitudinal and circular SM Circular SM is concentrated in some areas	Haustral Contractions Purpose-mixing movement facilitate fluid and electrolyte absorption (minimal propulsion) Structural and functional basis – They appear and disappear every 30-60 sec Require contraction of longitudinal and circular SM Circular SM is concentrated in some areas
	Mass Movements Propulsive movements (modified peristalsis) Purpose - move feces to rectum / stimulate defecation reflex Distance - __________ colon to sigmoid colon or rectum Occurrence - After meals, series lasting 10-30 min. (1-2 min each) Reflexes - _________ reflex (distention of stomach) - duodenocolic reflex (distention of duodenum)	Mass Movements Propulsive movements (modified peristalsis) Purpose - move feces to rectum / stimulate defecation reflex Distance - transverse colon to sigmoid colon or rectum Occurrence - After meals, series lasting 10-30 min. (1-2 min each) Reflexes - gastrocolic reflex (distention of stomach) - duodenocolic reflex (distention of duodenum)
	Control of Defecation There are three levels of control – I________ reflex Spinal cord reflex Involvement of higher centers	Control of Defecation There are three levels of control – Intrinsic reflex Spinal cord reflex Involvement of higher centers
	Intrinsic Defecation Reflex Intrinsic reflex mediated entirely by ENS is initiated when feces enters ________ via mass movements Rectal distention initiates afferent signals that spread through myenteric plexus to descending and sigmoid colon, and rectum. This causes contractions that force feces toward anus. Internal anal sphincter relaxes and if external anal sphincter is _________ relaxed, defecation occurs.	Intrinsic Defecation Reflex Intrinsic reflex mediated entirely by ENS is initiated when feces enters rectum via mass movements Rectal distention initiates afferent signals that spread through myenteric plexus to descending and sigmoid colon, and rectum. This causes contractions that force feces toward anus. Internal anal sphincter relaxes and if external anal sphincter is voluntarily relaxed, defecation occurs.
	Defecation Reflex - Spinal Cord P_____________ cord reflex greatly intensifies intrinsic reflex (but is not different qualitatively) _______ distention also initiates cord reflex. Afferent signals go to sacral cord and then back to descending and sigmoid colon, and rectum by way of parasympathetic fibers in pelvic nerves. The lower neurons __-S4 provide sensory and motor fibers for defecation reflex. They are i_____ when spinal cord is injured at higher levels.	Defecation Reflex - Spinal Cord Parasympathetic cord reflex greatly intensifies intrinsic reflex (but is not different qualitatively) Rectal distention also initiates cord reflex. Afferent signals go to sacral cord and then back to descending and sigmoid colon, and rectum by way of parasympathetic fibers in pelvic nerves. The lower neurons S2-S4 provide sensory and motor fibers for defecation reflex. They are intact when spinal cord is injured at higher levels.
	Defecation Reflex - Higher Centers ________ signals entering spinal cord initiate other effects that require intact spinal cord. deep breath, closure of glottis, and increased abdominal pressure all work to move fecal contents downward Spinal transection or injury can make defecation a difficult process cord _________ reflex can be excited (either digitally or with enema)	Defecation Reflex - Higher Centers Afferent signals entering spinal cord initiate other effects that require intact spinal cord. deep breath, closure of glottis, and increased abdominal pressure all work to move fecal contents downward Spinal transection or injury can make defecation a difficult process cord defecation reflex can be excited (either digitally or with enema)
	Colon Motility Disorders Paralysis of defecation reflexes in spinal cord injuries – Destruction of conus medularis (only _______ reflex is functional) Destruction between conus medularis and brain (_______ reflex and ______ ____ reflex are functional) Function of external anal sphincter?	Colon Motility Disorders Paralysis of defecation reflexes in spinal cord injuries – Destruction of conus medularis (only intrinsic reflex is functional) Destruction between conus medularis and brain (intrinsic reflex and local cord reflex are functional) Function of external anal sphincter?
	Encopresis What is it? Frequent bowel movement accidents in ____ older than ____. Incidence? 1-3% of children, mostly ____ Cause? Chronic constipation causes hard, dry feces to build up in colon (80-95% of cases). __________ colon eliminates normal defecation sensations leading to accidents. Semi-liquid fecal matter exits around hard mass; however, feces may appear normal.	Encopresis What is it? Frequent bowel movement accidents in child older than four. Incidence? 1-3% of children, mostly boys Cause? Chronic constipation causes hard, dry feces to build up in colon (80-95% of cases). Distended colon eliminates normal defecation sensations leading to accidents. Semi-liquid fecal matter exits around hard mass; however, feces may appear normal.

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