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332 Cards in this Set
- Front
- Back
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What is the function of the digestive system?
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Turn food we eat into energy that our body needs to survive
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What is food intake regulated by?
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hunger and appetite
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What does hunger determine?
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the amount of food
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What does appetite determine?
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determines the type of food we eat
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Food intake is regulated by?
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- Central nervous system (hypothalamus)
- Endocrine system - GI system |
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What is the GI tract also known as?
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Alimentary or Digestive tract
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What is the GI tract?
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Tube like structure extending from mouth to anus
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How long is the GI tract?
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15 ft long in humans
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Teeth, tongue, salivary glands, liver, gallbladder, exocrine, pancreas are what type of organs?
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Accessory organs
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Which GI organ does food intake, mixing, and size reduction; food propulsion; taste?
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Oral Cavity
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What does the Oral cavity prevent doing?
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prevent pulmonary aspiration
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Which organ does: food bolus propulsion into the stomach?
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Esophagus
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What does the exophagus prevent?
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prevent gastric reflux (upper and lower esophageal spinchters)
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Which GI organ does nutrient storage; mixing; homogenization and propulsion; secretion?
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Stomach
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Which GI organ involves acid, pepsin, gastrin and intrinsic factor?
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Stomach
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What does the stomach regulate?
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regulation of stomach emptying
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Which GI organ is the major site of nutrient digestion and absorption, mixing and propulsion of chyme; secretion?
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Small intestine
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Which GI organ is GI regulatory hormones, mucus, H2O, electrolytes?; ileal emptying control?
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Small intestine
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Which GI organ does mixing, propulsion; final H2O and electrolytes absorption
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Large intestine
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Which GI organ has a function of storage of fecal materal?
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Rectum
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Which GII organ has the control of defecation?
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Anus
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Which Accesssory organ: Exocrine glands has the funciton of Saliva production (lubrication, mechanical trauma & immune protection, limited carbohydrate & lipis digestion)?
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Salivary glands
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Which Acessory Organ has function of Digestive enzymes production, HCO3, & H2O secretion?
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Exocrine Pancreas
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Whis Acessory Organ have the funciton of bile production?
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Liver
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Which Accessory organ has the function of bile storage?
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Gallbladder
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List the four general processes in the GI tract
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Motility
Secretion of digestive juices Digestion of food Absorption |
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Which process of the GI tract does mixing, propulsion of ingested materal along the tract?
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Motility
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Which process of the GI tract does chemical and enzymatic breakdown of complex ingested nutrients into simpler molecules ?
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Digestion of food
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Which general processes in teh GI tract has the function of movement of digested and other nutrients OUT of the GI lumen into blood?
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Absorption
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List the voluntary muscles of the GI tract
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Upper tract
Lower tract |
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Which GI tract controls the mouth, pharynx, and 1/3 of esophagus?
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Upper tract
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Which tract controls the external anal sphincter?
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Lower tract
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Where is the enteric nervous sytem located?
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Entirely within GI tract,
Extended from esophagus to anus |
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What are the two plexus of teh Enteric Nervous system?
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Myenteric plexus
Submucosal plexus |
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What is another name for Myenteric plexus?
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Auerbach's plexus
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Where is the Myenteric plexus located?
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btween longitudinal and circular muscles
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What is another name for Submucosal plexus?
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Meissner's plexus
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Where is the submucosal plexus located?
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submucosa
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Is the Enteric nervous sytem connected to the CNs by sympathetic and parasympathetic nerves?
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TRUE
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Can the Enteric Nervous system function autonomously (intrinsic nervous system)?
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TRUE
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Which enteric plexus innervate the glandular epithelium, intestinal endocrine cells, and submucosal blood vessels?
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Submucosal plexus
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What is the functio fo the submucosal plexus?
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controls GI secretion and local blood flow
Regulates contraction of muscularis mucosae and affects mucosal surface area. |
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Which enteric nervous sytem promotes secretion from mucosal endocrine and other secretory cells?
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Submucosal plexus
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What is the function of the myenteric pleuxs?
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Controls the GI movements
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Which enteric nervous system plexus regulates local and inter-regional motility activity through regulation of contraction/relaxation of contraction/relaxation of circular and longituinal smooth muscle layers?
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Myenteric plexus
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List the neurotransmitters of the enteric nervous system
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Major
Nonpeptides Peptides |
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List the nonpeptides ot the enteric nervous sytem
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ATP, adenosine, serotonin, GABA, histamine, glycine, NO
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Whist the peptides of the enteric nercous sytem
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Vasoactive intestinal peptide (VIP), substance P
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What if the MAJOR neurotransmiiters?
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Excitatory: Acetycholine (Ach)
Inhibitory (norephinephrine (NE) |
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List the Enteric Nervous System neurons
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Sensory neurons
Motor neurons Interneurons |
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Which neuron has the function of recieving information from sensory receptors in the mucosa and muscle?
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Sensory neurons
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Which neuron control gastrointestinal motility and secretory neurons secretion, and possibly absorption?
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Motor neurons
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Which neuron is responsible for integrating information?
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interneurons
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List the layers of the layers of teh smooth muscle from the gut
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longituinfal muscle and Circular muscle
Mucosal muscle |
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Which muscle is responsible for the most of the GI motility activities?
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Longitufinal muscle and Circular muscle.
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Which muscle mainly regulated by neural pathways integrated through teh enteric myenteric plexus?
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Longitudinal muscle and circular muscle
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Which muscle alters the mucosal surface and regulates lymph flow though the central lacteal into the lymphatic system?
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Mucusal muscle
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Does the GI system function as a syncytium?
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True
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How are individual smooth muscle fibers arranged?
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in bundles
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What type of signal initiate muscle contraction?
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Electrical
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List the two types of muscle contractions
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Phasic
Tonic |
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Which muscle contraction is rhymical and function as contraction-relaxation cycles- most of GI contraction?
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Phasic contraction
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Which musle contraction sustain contraction )minutes to hours) - GI sphincters? Latch mechanism (with low ATP consumption)
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Tonic contraction
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What is slow wave potentials (or slow waves, the Basic Electrical Rhythm (BER)?
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Spontanrous cycles of depolarization and repolarization
"fluctuating resting membrane potenial major determinant of teh phasic nature of contraction |
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What determines the frequency of contraction?
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depends on the frequency of the slow wave potentials
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True or False:
The frequency of slow waves varies by the region of teh digestive system |
TRUE
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What is wave frequency in the stomach?
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3 waves/min in stomach
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What is the wave frequency in the duodenum?
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12 wave/minute
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What are spike potentials?
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action potentials
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What is the function of spike potentials?
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cause muscle contraction
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What is known as: spontanrous rhythmic fluctuation of the "resting" membrane potential of smooth muscle?
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Slow wave potentials
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What is he # range for slow wave potentials (or BER)?
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65-45mV
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What is depolarization phase caused by?
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Na influx ( Na going in cell)
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what is repolarization caused by?
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K efflux (K going out)
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What iniates the slow wave potentials?
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interstitial cells of Cajal (smooth muscle like pacemaker cells)
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Which part of the Gi system has NO slow waves? TQ
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esophagus and proximal portion of the stomach
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what influences slow wave potentials?
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body temperature ans metabolic activity
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Does the Slow wave potential (BER) cause muscle contraction?
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NO! it may initate contraction in the stomach
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In Pike action potentials (APs) the depolarization is due to?
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Ca+ influx
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In spike action potentials the repolarization is due to?
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K+ efflux
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True or False: Are action potentials associated with the depolarization phase of teh slow wave?
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TRUE
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What does the Action potentials trigger?
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muscle contraction (tension)
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The force of muscle contraction is directly related to the frequency of what?
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Action potentials
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The duration of contraction is related to the number of what?
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Action Potentials (frequency + duration of firing)
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If there are more spikes (depolarization), what type of contraction will you have?
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stronger contraction (tension)
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What does Ach do to the spike action?
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increase the number of spikes and INCREASES tension of the smooth muscle
muscle cause GI tract to increase active |
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What does epinephrine do to the spike action?
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epinephrine decreases the number of spikes and DECREASES tension of the smooth muscle (b/c it is sympathetic signal, inhibits stomach contraction)
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What are the factors the depolarize the membrane, which stimulate contraction?
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Stretching of the muscle
Stimulation by parasympathetic nerves |
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What are the factors that HYPERPOLARIZE the membrane leading to Decrease contraction?
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Stimulation by sympathetic nerves (norepinephrine)
Ephinephrine |
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What is it called: when smooth mucles sphincters are under continuous contraction?
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TONIC contraction, or Basal tone
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What does tonic contraction maintain?
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continuous contraction (min-hours)
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Is tonic contraction associated with BER?
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NO
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What is Upper Eophageal Spincter (UES) involve?
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Oral Cavity- Esophagus
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What does the Lower Esophageal Sphincter (LES) involve?
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Esophagus-Stomach
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What does Pyloric Sphincter involve?
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Stomach-Duodenum
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What does the Lleocecal Sphincter involve?
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Illeum-Colon
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What does the Colorectal Sphincter involve?
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Colon-Rectum
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What does the internal Anal Sphincter involve?
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Rectum- Anal canal
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What does the External Anal Spincter involve?
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Anal Canal-External
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Will the GI Motility increase or decrease when the GI relax?
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increase GI Motility
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Will the GI Motility increase or decrease when teh GI contracts?
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Decrease GI Motility
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Note: Opposite effect on motility from contraction and relazation of smooth muscle layer within the GI tract
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NOTE
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List the regulation of GI Gunction
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Humoral Control
Nervous Control Myogenic Control |
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What does the humoral control involve?
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Hormones
Paracrine |
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List the two types of Nervous control
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Intrinsic Control
Extrinsic Control |
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Example of Intrinic Control
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Enteric Nervous System
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Example of Extrinsic Control
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Autonomic Nervous Sytem
Central Nervous System (voluntary control) |
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How is teh Humoral control of the GI function classified as?
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Classified according to the mechanism of delivery to target cell
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True or False:
Actions may be integrated with or independent of neural actions |
TRUE
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List the mechanisms of delivery to target cell via humoral control
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Hormones
Paracrine Neurocrine |
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List the hormones of Humoral control
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Gastrin
Chlecystokinin (CCK) Secretin Gastric inhibitory Peptide (GIP) Motlin |
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What is involved in paracrine? of humral control?
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Somatostatin
Histamine |
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What is involved in Neurocrine? of humoral control?
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Vasoactive intestinal peptide (VIP)
Gastrin releasing peptide (GRP) Ekephalins |
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What is the action of Gastrin?
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increase HCI secretion, pepsinogen secretion and stimulates gastric motility
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What is the action of Secretin?
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increase water and bicarb (HCO3) secretion by pancreatic ductal cells and billary tract.
inhibit gastric secretion and motility Stimulate bile duct secretion of H2O and HCO3 |
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Which GI hormone increase enzyme secretion by pancreatic acinar cells, and increase contraction of the gallbladder? and inhibits gastic motility
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Cholescytokinin
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Which GI hormone inhibit gastric secretion and motility, stimulate insulin secretion?
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Gastric Inhibitory peptide (GIP)
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Which GI hormone increase motility and initiate the migrating motor complex MMC
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Motilin
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What is the GI transit time in the esophagus?
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8-10 sec
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What is the transit time in the stomach?
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1-2 hours (depends on type of food)
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What is the transit time in the feces?
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up to 72 hours
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What is the function GI Motility?
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Ingestion and breakdown
Transport Waste Removal |
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What waste is removed?
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undigested, unabsorbed, secreted materal
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List the GI motility movements in the smooth muscle cell
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Contraction
Relaxation |
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What does contraction of the smooth muscle cell do?
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increases GI motility
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What does relaxation of the smooth muscle cell do?
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decreases GI motility
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What muscle is involved in the intestinal smooth muscle?
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Circular and longiudinal
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What are the two basic patterns of muscle contracile activity?
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Segmentation and Perstalsis
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What is the function of segmentation?
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Mixing
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What is the function of Peristalsis?
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Propulsion
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Segmentation and Perstalsis are two major reflexus within which Nervous System?
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Enteric Nervous system
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What does Segmentation do?
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focal contraction of teh circular muscle layer
results in mixing on GI contents Mixing of food on both side of the toothpaste |
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When Segmentation mixes; what does it do?
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reduce food particle size
homogenizes particles with digestive enzymes exposes material to mucosal surface |
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Does Segmentation result in significant net movement of materal along tract?
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DOES not result in significant net movement of material along the tract
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What is the cause of Peristalsis
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Caused by initiation of the circular muscle contraction that spreads unidirectionalyl in the aborad direction
toothpaste to get one end to the other |
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What is the resulting action of Peristalsis?
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rsults in propulsive action on GI contents along the tract.
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What stimulates Peristalsis?
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stimulated by bolus of foodstuff in lumen
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TQ:
What stimulate afferent enteric neurons (Peristalsis)? |
Mecahnical distension and mucosal irritation. These sensory neurons synapse with two sets of cholinergic INTERNEURONS
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What are the interneurons of the enteric system?
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Excitatory motor neurons
Inhibitory motor neurons |
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Which interneuron activates the enteric system?
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Excitatory
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What is the function of the excitatory motor neurons?
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These interneurons activates motor neurons above the bolus
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LIST the excitatory motor neurons of the enteric system?
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acetycholine adn substance P
which stimulate contraction of smooth muscle above the bolus |
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What is the interneuron that inhibit the enteric nervous system?
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interneurons that activates inhibitory motor neurons
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What is the function motor neurons?
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interneurons activates inhibitory motor neurons that stimulate relazation of smooth muscle BELOW the bolus.
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LIST the inhibitory motor neurons of the enteric system
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Nitric Oxide
Vasoactive intestinal peptide ATP |
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List the regulation of GI motility
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Extrinsic Autonomic Control
Enteric Autonomic Control Myogenic Voluntary and GI peptide control |
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What happens in the extrinsic autonomic control when parasympathetic increases?
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increase motility
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What happens in the extrinsic autonomic control when sympathetic increases?
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decrease motility
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What does the enteric autonomic control function as?
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primarily myenteric plexus
integrates with extrinsic controls coordinates local and inter-regional control |
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What is the function of teh Myogenic?
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local control and contratile "Rhythm" (BER)
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What are the voluntary organs?
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tongue
upper pharynx external anal sphincter |
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What does the parasympathetic stimulation involve?
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Excitatory
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The Afferent fibers initially relay sensory information recieved from chemo or mecahno receptors within the GI mucosa or muscle latyers to neurons located in which plexus?
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ENTERIC plexus
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In Parasypathetic: ______________efferent fibers from vagus and pelvis nerves eneter the various organs of the GI tract where they typically synpases with cells of the enteric plexus
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Preganglionic
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In parasympathetic: _______________efferent fibers synapse with target cells.
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Postganglionic
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True or False:
Afferent fibers relay sensory information recieved by mucosal and smooth muscle receptors directly to prevertebral ganglia or to the spinal cord |
TRUe
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In Sympathetic: The _______ efferent fibers synapse outside of the GI tract with prevertebral ganglia
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Preganglionic efferent
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In Sympathetic:
MOST ______________ efferent fibers synapse with neurons located with ENTERIC PLEXUSES |
Postganglionic
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A FEW________ effernt fibers exit ganglia and end directly on target cells
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Postganglionic efferent
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In Parasympathetid, everything increases: GI motility, secretion, vasodilation and blood flow, EXCEPTdecrease in
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tone of GI smooth muscle sphincter
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In Sympathetic, everything decreases: vasoconstriction, blood flow, GI motility and secretion; EXCEPT increase in
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tone of GI smooth muscle sphincter
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TQ on GI reflexes
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NOTE
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What is the function of GI reflexes?
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integrative action of teh intrinsic and extrinsic nervous sytems
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What are the two GI reflexes?
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Short reflexes
Long reflexes |
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Which reflex are integrated entirely within the gut wall enteric nervous system and controls secretion, perstalsis, mixing and contraction?
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Short reflexes
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Which reflex comes from the gut to the prevertebral sympathetic ganglia and then back to the GI tract?
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Long reflexes
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Which organs that long reflex involve?
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gastrocolic reflex (colon, large intestine)
enterogastric reflex (sm. intestine to stomach) colonoileal reflex (colon-ileum) |
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Reflexes from the stomach and duodenum to the CNS by the vagus nerves controls what?
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control gastric motor and secretory activity
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Pain reflexes function
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inhibition of entire GI tract
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Defecation reflexes function
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power contraction
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What is Mastication?
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Chewing
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Name the CN which most of the muscles of chewing are innervated by..
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motor branch of 5th CN
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The chewing process is controlled by what organ?
|
controlled by nuclei in brain stem
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What type of reflex causes: a bolus of food in the mouth at first initates reflex inhibition of teh muscles of mastication, allowing the LOWER JAW to drop?
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A chewing reflex
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What leads to a REBOUND contraction?
|
After the jaw drops during chewing reflex, the drop in turn initiates a stretch reflex of the jaw mucles that leads to REBOUND contraction
Like a rubberband |
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What is Deglutition?
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Swallowing
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List the stages of swallowing
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Voluntary stage
Involuntary Stage |
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What are the two steps of the involuntary stage?
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Pharyngeal stage
Esophageal stage |
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How long does the Pharyngeal stage last for?
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6 sec
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How long does the esophageal stage last for?
|
8-10 sec
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Which involuntary stage involves: upper airway passages are closed, respiration is stopped, and primary esophageal peristalsis is iniated?
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Pharyngeal stage
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Which involuntary stage involves primary and secondary peristalsis, receptive relaxation of the lower esophageal sphincter and receptive relazation of the stomach?
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Esophageal Stage
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The voluntary stage is iniated by what?
|
propulsion of material -- into the oropharync primarily by movements of tongue
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What is the end of voluntary stage?
|
after food bolus is pushed backward against the hard palate, then the food bolus slides toward the pharynx
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What iniates the pharyngeal stage (involuntary stage)?
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stimulation of epithelial receptor in the pharynx
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In th pharngeal stage what are the steps?
|
Food enter esophagus
Nasopharynx closes Trachea closes Respiration INHIBiTED then with UES, bolus move to esophagus |
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Where does the esophageal stage of swallowing starts?
|
Begins as UES opens.
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Where does all the food empty?
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through esophagus into stomach
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What determines the propulsion of ingested foodstuff?
|
determined by peristalsis and gravity
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Esophageal Sphincter Actions during swallowing involves:
|
UES relaxes and food bolus pass to esophagus
Peristalsis at esophagus (below UES) then food move to tomach LES relaxes BEFORE perisaltic wave arrives (RECEPTIVE RELAXATION) and constricts after food pass into fundus.. to prevent acid reflux. |
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List the two different types of Peristalsis
|
Primary Peristalsis
Secondary Peristalsis |
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What is the function of primary peristalsis?
|
propel newly entering boluses ot stomach
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What happens in Primary peristalsis?
|
propulsive aborad contractile wave within the esophagus that is iniated through pharyhgeal receptor contact (swallowing)
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Primary Peristalsis is controlled by what nerve? in connection with the esophageal myenteric plexus
|
Vagus nerve
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SEcondary peristalsis is initiated by what?
|
distention of teh esophagus
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What controls the secondary peristalsis?
|
both intrinsic (myenteric) adn extrinsic nervous system
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What is the function of secondary peristalsis?
|
clear or "sweep" the esophagus of residual food particles remaining after primary peristaltic wave or to remove gastric reflux
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Why is the esophageal sphincter action (bwtn swallowing) important?
|
important barrier function that prevents air and gastric contents (acid) into the esopahgus
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Esophageal Sphincter actions is largely prevented through _____________ contraction of teh smooth muscle UES and LES which produces greater pressure than their adjacent compartments
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TONIC contraction
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What motility disorder of the esophgus causes gastric acid reflex, has LOW LES tone, Weak secondary peristalsis?
|
Pyrosis (Hearburn)
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What are the foods and beverages that decrease LES tone?
|
Chocholate, citrus juices, coffee, cola, tea, fatty meals, garlic, onions, peppermint, spices, tomatos juices, ethanol.
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Is the gastric pressure in Pyrosis increased or decreaed?
|
increased
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Which Motility disorder of the esophagus, causes swallos of teh esophagus which may produce chest pain with radiation through to the back?
|
Diffuse Esophageal Spasm
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List the Motility disorders
|
Pyrosis (Heartburn)
Diffuse Esophageal Spasm Achalasia |
|
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List the characteristics of Achalasia?
|
Dilated, tortuous esophagus
Narrow lower end of esophagus deformity BIRD's BEAK |
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Which motility disorder of the esophagus is caused by degeneration of postganglionic inhibitory (NO/vIP) neurons in the myenteric plexus?
|
Achalasia
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What are the characteristics of Achalasia?
|
Abnormalities in peristalsis and in the tone of LES
Loss of peristalsis of the esophagus Loss of the LES relaxation in response to swallowing Elevated resting LES pressure Functional obstruction and progressive esophageal dilation, stasis of food |
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What is the function fo Gastric motility?
|
Volume accodation
Mixinf Emptying |
|
|
List the motility function of the stomach
|
Volume accomodation
Mixing gastric contents Gastric emptying |
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What is volume accomodation?
|
Storage of food until the food can be processed in the stomach, duodenum, and lower intestinal tract
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|
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What is mixing of gastric contents?
|
Particle size reduction
Homogenization with gastric juice (form CHYME) facilitates digestion and absorption |
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What is gastric emptying?
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Propulsion into duodenum
Empties stomach at a rate suitable for proper digestion and absorption by small intestine. |
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What does gastric emptying control and prevent?
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Control nutrient availability
Prevent enzyme saturation |
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List the anatomical stucture of the stomach
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body
ANTRUM |
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List the Physiological structure of the stomach
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ORAD
CAUDAD |
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Where is the ORAD located?
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2/3 of the body
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What is the function of the ORAD?
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STORAGE OF INGESTED FOOD
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Where is the CAUDAD portion located?
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remainder 1/3 of the body plus antrum
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What is teh function fo teh CAUDAD?
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MIXING AND EMPTYING
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What is teh motor function of the stomach involves?
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Volume accomodation
Mixing of food Emptying |
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In volume accomodation (storage), what type of relaxatio is involved?
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REceptive relaxation
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What is teh purpose of receptive relaxation of vlume accomodation?
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maintain LOW intragastric pressure as the stomach fills during eating *IMPORTANT*
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What regulates the volume accommodation?
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autonomic nervous system
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What appenes during regulation by autonomic nercous system during volume accomodation?
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Vagal reflex is initiated from the lower esophagus in response to swallowing--reflex elicted by mechanically distending the stomach.
Nuerotransmitter: VIP, NO |
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During volume accomodation, as food enters the stomach, it forms concentric circles of teh food in the ______ portion of teh stomach
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ORAD
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In volume accomodation, as food initiates a stretch reflex, it will:
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reduce the tone in the muscular wall of the body of the stomach
The stomach accomoddates greater quantities of food up to a limit |
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During mixing of food, the mixing wave is a weak ________________
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peristaltic constrictor wave (every 15-20 sec)
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As mixing reaches the distal antrum, the pylorus constricts, the ___________ stomach grinds and mizes food.
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CAUDAD
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Emptying of the stomach is promote by_______ contractions in the stomach antrum
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Peristaltic
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In modulation nof gatric motor activity, list the two effects
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Neural effects
Hormonal effects |
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In Neural effects, the parasympathetic stimulation (vagal) typically increase or decrease contractile frequency, force, and duration of contractions.
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INCREASES
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In neural effects, sympathetic stimulation (celiac ganglion) typically increase or decrease contractile frequency, force, duration?
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DECREASES
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In hormonal effects, ________ increases contraction of the caudad stomach (increase motility)
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MOTILIN
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In hormonal effects, ___________ and __________ supress motility
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SOMATOSTATIN and GIP
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List what controls the gastric emptying
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Osmolality and caloric content
pH Particle size Intragastic pressure Pyloric sphincter resistance Duodenal pressure Irritation of the duodenal mucosa Negative feedback |
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True or False:
Emptying of isotonic, non-caloric fluids is proportional to the volume or distension of the stomach |
TRUE
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Which empties slower:
Hypertonic/Hypotenoic fluids or Isotonic fluid? |
Hypertonic/Hypotonic. because neural and hormaonl factors
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What creates a slower emptying: lower or higher pH?
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Lower pH
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Small or large particles decrease teh emptying rate?
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LARGE particles
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Lesser or greater the antral peristalsis and intragastric pressure creates a faster emptying
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GREATER the intragastric pressure
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What does the pyloric sphincter function as?
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pyloric sphincter tone controls gastric emptying
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Greater or Lesser resistance of teh pyloric sphincter will slow emptying
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Greater resistance slows emptying
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Increase or decreased duodenal ressure slows emptying
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Increased duodenal pressure slows emptying
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Irritation of teh duodenal mucosa causes increase or decrease in emptying rate?
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decrease emptying rate
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The negative feedback of gastric emptying is mediated by what factors?
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neural and numoral factors activated by nutrients
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What decrease emptying?
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FATS and proteins
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Normal gastric emptying involves:
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propulsion is balances with capacity of duodenum and accesssory GI organs to adequately buffer acid as well as process chyme for digestion and absorption
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If Gastric emptying is TOO SLOW
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interrupts flow of nutrients to body
stimulate excess gatric acid secretion results in poot digestion adn absorption |
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If Gastric emptying is TOO RAPID
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Overwhelms digestive and absorptive capacity of small intestine and fails to fully buffer acidic chyme
Leads to poor digestion and absorption with inadquate acid neutralization |
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When food is in the intestine, intestinal motility is stimulated by:
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Parasympathetic stimulation
hormones: CCK, gastrin |
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When food is in the intestine, gastric motility is inhibited by:
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enterogastric reflex
hormones Secretin, CCK, GIP glucagon like peptide 1 (GLP-1) fat |
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What are the hormones that stimualtes intestinal motility?
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CCK
gastrin |
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What are the hormones that inhibites intestinal motility?
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Secretin
CCK GIP glugacon-like peptide (GLP-1) fat |
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In the Small Intestine: The BER (slow wave) iniitiatio nand frequency are independent of _____ input
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extrinsic
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In the small intestine, spike potential initiation (i.e. contraction) is influenced by what factors?
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neural and hormonal factors
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In small intestine, what are the extrinsic neural regulation-- involving parasympathetic input?
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stimulate spike potentials, increasing contraction frequency, force and duration
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In small intestine, what are the extrinsic neural regulation-- involving sympathetic input?
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exerts opposite effects
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In the small intestine, what are the humoral control that inhibits action?
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Epinephrine
VIP NO secretin glugacon |
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In the small intestine, what the humoral control that stimulates action?
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Gastrin
CCK insulin motilin serotonin |
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List the small intestine neural reflexes:
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peristalsis and segmentation reflexes
Enterogastric reflex ileocecal reflex gastroileal reflex |
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The peristalsis and segmentation reflexes of small intestine is CONTROLLED by ______ nervous sytem, but the activity is subject to autonomic influences
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enteric
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The enterogastric reflex of the small intestine is ACTIVATED by___________ receptors sensitive to hydrogen ion, distention, and changes in osmolartiy
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intestinal
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The enterogastric reflex_________ decreases motility and slows the rate of gastric emptying, protecting the intestine from excessive acidity
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DECREASE
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The ileocecal reflex of the small intestine is ACTIVATED by what organ?
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distension of teh ileum
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What does the ileocecal reflex do?
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increase motility of teh ileum and relaxes the ileocelcal sphincter, allowing chyme to pass from teh ileum to the cecum
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The gastroileal reflex is ACTIVATED by what organ?
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distended stomach
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What does the gastroileal reflex of small intestine function?
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increases ileal motility and movement through the ileocecal sphincter
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What organs are involved in the regulation of emptying at the ileocecal valve?
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ileocecal valve
ileocecal sphincter |
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What is the function of the ileocecal valve during the regulation of emptying?
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prevents fecal reflux into the ileum
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What is the function of the ileocecal sphincter during the regulation of emptying?
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remains mildly constricted (tonic contraction) and controls ileal emptying rate.
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Note Distention modulates emptying. What are the two organs that is involved in this?
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ileal distention
colon distension |
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Ileal distension
increase or decrease sphincter tone SPEEDS or SLOWS motility rate |
decrease sphincter tone
SPEEDS motility rate |
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Colon distension:
increase or decrease sphincter tone SPEEDS or SLOWS motility rate |
increase sphincter tone
SLOWS motility rate |
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What is the motility disorder of small intestine?
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Vomiting (Emesis)
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What is vomiting?
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protective reflex
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What does vomiting involve?
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Many stimuli (peripheral and central) --> vomiting center: medulla --> nausea and retching --> autonomic discharge (salivation, sweating, pallor, dizziness, hyperventilation, variable heart beat) --> REVERSE PERISTALSIS
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List the complications of vomiting:
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Loss of gatric contents: loss of fluid, H+ and ions (decrease K, increase pH)
loss of intestine content: additional loss of ions, fluid, bicarbonates, bile nutritional deficiency ulceration weakening of UES and LES Tooth decay |
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What is the acid base disorder of Vomiting?
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Metabolic alkalosis and hypokalemia
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What happens to the pH of vomiting?
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increase pH
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What does the colon conserves what?
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colon and electrolytes (LI has large absorptive capacity)
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What is the motility function of Large intestine (colinic)?
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Colonic motility function in the mixing of material for mucosal absorption, propulsion of contents from ileum to rectum to anal canal, storage of feces, and evacuation (defecation) of waste
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List ways of motility action in the large intestine?
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Haustrations
Mass movements |
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What is haustrations in the large intestine?
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segmenting contractions
local constricting contractions act to mix contents with little net propulsion Deeply contrict lumen-- HAUSTRATIONS More force and longer 12-60 sec than SI |
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What is Mass movement?
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propulsive movements (peristaltic type of contractions)
Less frequent but longer (10-30 min) than in SI Propel contents longer distance (20 cm) than in SI |
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What is the most common motility action?
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Haustrations
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List the regulation of Large intestine Motlity?
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Neural control
Myogenic control Humoral control |
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The Neural Control of the large intestine-- of the enteric system
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inhibit motility; relaxation mediated by VIP via NO
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What is Hirschsprungs disease?
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congential absence of the enteric plexus in the distal colon
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The Neural Control of the large intestine-- of the Extrinsic autonomic control, parasympathetic
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increase motlity
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The Neural Control of the large intestine-- of the Extrinsic autonomic control, sympathetic
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decrease motility
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What happens in the extrinsic voluntary control of teh Large intestine?
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external anal sphincter, important control in defecation
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The Myogenic control of Last intestine motility
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Colonic slow waves (BER) similar to Small intestine
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List the neural reflexes in Large intestine
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Gastrocolic reflex
Duodenal Reflex |
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Which Neural Reflexes in the Large intestine concerns stomach distension stimulating gastric emptying which reflexly stimulates a colonic mass movement.
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Gatrocolic reflex
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Which neural reflexes in the large intestine does:
Duodenal distension Augments stimulation of colonic mass movements Responsible for defacation |
Duodenalcolic reflex
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Where is the rectum located?
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proximal to the anal canal
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How is the anal kept closed?
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tonic contraction of the internal sphincter
prevent dribble of feces through the anus |
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What is the function of the rectum?
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Rectum stores fecal materal prior to defecation
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When does defecation occur?
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As colonic material fills rectum, 25% capacity, a sensation or urge to defecate develops.
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When the rectum empties, what happens?
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rectum is relaxed, IAS tonically constricted
EAS relaxed |
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In order for defecation to occur, what is required?
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intrinsic (rectsphincteric reflex)
extrinsic parasympathetic voluntary nervous inputs |
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How is defecation initiated?
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defecation reflexes
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List the defecation reflexes
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intrinsic reflex
Parasympathetic defecation reflex |
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Which reflex is mediated by the enteric nervous system in teh rectal wall (rectosphincteric reflex) and is normall weak?
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Intrinsic reflex
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Which defecation reflex is greatly intensify the peristaltic waves through the distal colon, rectum and anus and facilitates relaxation of IAS?
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Parasympathetic defecation reflex
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Voluntary control of defecation--- the external anal sphincter is controlled by what nervous system?
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Somatic Nervous System (pudenal nerve)
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Which motility disorder of Large intestine is abnormally FAST stool transit and increased volume and liquidity)?
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Diarrhea
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What cause diarrhea?
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Secretory
Osmotic Inflammatory Psychogenic |
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Which motility disorder of large intestine that is abnormally SLOW transit and decreased volume and liquidity?
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Constipation
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What cause constipation?
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Dietary
Obstructive Irregular bowel habits |
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When does FED GI motor activity?
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occur after a meal (food is in the GI tract)
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When does Fasting motor activity occur?
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occur during fasting fasting (>90 min) and are associated the migrating motor complex (MMC)
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What is Migrating Motor Complex?
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Is the pattern of electrical and motor activity in GI smooth muscle during FASTING or interdigestive state
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Where does the Migrating Motor Complex (MMC) originate
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Stomach
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The Migrating Motor Complex is initiated by what?
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MOTILIN
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The Migrating Motor Complex is inhibited by what?
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eating
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The Migrating Motor Complex is dependent on what nervous system?
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Enteric
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What does the The Migrating Motor Complex prevent?
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Prevent bacterial overgrowth in teh gut by sweeping the gastric acid to the ileum
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List the three phases of MMC
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Phase 1
Phase 2 Phase 3 |
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Which phase of Migrating Motor Complex (MMC) has NO SPIKES, no contraction?
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Phase 1
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Which phase of Migrating Motor Complex (MMC) has irregular spokes and contractions (50% of the slow waves are associated with contractions)?
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Phase 2
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Which phase has bursts of regular spikes and contractions (100% of slow waves are assoicated with contractions), and gastric material is MOVEd to longer distances
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Phase3
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How is Migrating Motor Complex (MMC) in the stomach is Characterized?
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Vigorous and prolonged peristaltic wave
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Migrating Motor Complex (MMC) in the stomach is initiated where?
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at the id body of stomach adn moves distally over to vaudad region and through pylorus
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Migrating Motor Complex (MMC) in the stomach is initiated at infrequent but regular intervals of____ minutes of ____ minutes duration
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90, 3-5
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What is the function of Migrating Motor Complex (MMC) in the stomach?
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Clear stomach of debris btween meals
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What happens when the Migrating Motor Complex (MMC) in the stomach approaches?
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Pyloric sphincter relxes
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What is the "growling" noise caused by?
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Migrating Motor Complex (MMC) contractions (hunger contraction, hunger pain)
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What is the function of Migrating Motor Complex (MMC) in the small intestine?
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Keeps the SI clean of indigestiable meal residua, bacteria, desquamated cells only during fasting
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What interrupts and iniates the Migrating Motor Complex (MMC) in the small intestine?
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feeding
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What relaxes the Migrating Motor Complex (MMC) in the small intestine?
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ileocelcal sphincter
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What initiates Migrating Motor Complex (MMC) in the small intestine in response to neural signal?
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MOTILIN
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