Exam 1 - Upper GI Flashcards
What are the five steps of the alimentary canal pathway?
Mouth, Esophagus, Stomach, SI, LI
What is the name of the sphincter between the mouth and esophagus?
Upper Esophageal Sphincter
What is the name of the sphincter between the esophagus and stomach?
Lower esophageal sphincter
What is the name of the sphincter between the stomach and Small Intestine?
Pyloric sphincter
What is the name of the sphincter between the Small Intestine and Large Intestine?
Ileocecal Valve
What is the name of the sphincter between the Large Intestine and the world?
Anal Sphincter
What are the three “Accessory Organs” of the GI tract?
Liver, Gall Bladder, Exocrine Pancreas
Which sphincter for the Liver, Gall Bladder, Exocrine Pancreas?
Sphincter of Oddi
What are the three layers of the GI tract from inner to outer?
Mucosa, Submucosa, Muscularis
Which layer of the GI tract controls peristalsis?
Mucosa. Specifically, the Muscularis Mucosa.
What does the Adventiva (Serosa) layer contain and is like?
Like saran wrap. Contains mesentary allowing blood supply, lymph, innervation
What are the 4 major jobs of the GI tract?
Motility, Secretion, Digestion, Absorption
MSDA
What is the job of the Motility process of the GI tract?
Physically move food/bolus through GI tract to allow secretion/digestion/absorption to occur
Constant tone in the GI tract is called
Tonic Contractions
What maintains Tonic Contractions in the GI tract?
Sphincters
What is Propulsive Peristalsis and where does it occur?
Moving bolus down by contract and relax. In esophagus, distal stomach, small intestine, and rectum.
What sweeps up debris in the Small Intestine?
Migrating Motor Complex (MMC)
What sweeps up debris in the Large Intestine?
Haustrations
What do exocrine glands secrete into the GI tract?
Water, electrolytes, substances necessary for digestion (mucus, enzymes, bile salts)
What are three substances necessary for digestion which are secreted by exocrine glands into GI tract?
Mucus, enzymes, bile salts
What do endocrine hormones do in the GI tract?
Regulate GI system
What is digestion?
Process of breaking down carbohydrates, proteins, and fats into simple absorbable molecules
Carbohydrates are absorbed as what?
Monosaccharides (glucose, sucrose, galactose)
Proteins are absorbed as what?
Amino Acids
Fats are absorbed via what process?
Micelle formation. Bile emulsifies fats into small lipids. Small lipids incorporated into bile salt aggregated called “micelles”, which allows for FFA and glycerol absorption
Fats are absorbed as what two things?
FFA and Glycerol
Where are the pacemaker cells of the GI tract located?
In and around muscular cell layers
What are the pacemaker cells of the GI tract called?
Interstitial Cells of Cajal (ICCs)
What activity do the ICCs maintain? In which muscle type?
Maintain tonal activity in smooth muscles.
APs travel through what?
Gap Junctions
What are the two neural systems of the GI tract?
Intrinsic and Extrinsic
What two nervous systems make up the Extrinsic Neural system of the GI tract?
CNS and PNS (CNs and autonomic NS)
Intrinsic control of the GI tract is by which nervous system?
Enteric Nervous System
Can the Intrinsic and Extrinsic Neural Pathways of the GI track function on their own?
Yes, with minimal adaptive changes
Extrinsic Control to the GI tract comes from what type of inputs?
Sensory to CNS=smell, taste, sight, emotion, feedback loop from GI tract
The CNS stimulates what two type of neural control to the GI tract?
- Autonomic output to GI tract
2. Peripheral/Cranial nerve voluntary actions (eating, swallowing, defecating)
The CNS stimulates cranial nerves/peripheral nerve output for what type of motor actions?
Voluntary motor actions: eating, swallowing, defecating
Which nerves and nervous system are part of the PNS?
Cranial/peripheral nerves, autonomic NS
The cranial/peripheral nerves in the oral cavity and proximal esophagus innervate what type of muscles?
Voluntary skeletal muscle
Which nerves innervate the External Anal Sphincter’s voluntary skeletal muscle?
S4 and Inferior Rectal Nerve (branch of pudendal nerve)
What are the two parts of the Autonomic Nervous System?
Sympathetic NS and Parasympathetic NS
The nerves of the Sympathetic Tract to the GI Tract are located in the ____ and ____ ____ regions
Thoracic and Upper Limb regions
Does the Sympathetic NS excite or inhibit GI Tract?
Inhibits the GI Tract
What two things are inhibited/decreased by Sympathetic NS stimulation of the GI Tract?
Decreased Motility Peristalsis/Secretions, Inhibit/Vasoconstrict blood flow to GI Tract
What are the Parasympathetic NS nerves to the GI Tract?
Vagus Nerve and Pelvic Nerves of Sacral Plexus
The Vagus Nerve is travels from the _____ to the ____ ____.
Esophagus to the Transverse Colon
Does the Parasympathetic NS excite or inhibit the GI Tract?
Excited the GI Tract
What three functions does the Parasympathetic NS have on the GI Tract?
- Increase motility/peristalsis and secretions
- Relax involuntary sphincters of the GI Tract
- Facilitate/vasodilate blood flow to the GI Tract
Intrinsic Neural Control aka ____Nervous System
Enteric Nervous System
The Enteric Nervous System is likened to what “in the gut”?
Brain in the gut
The neural plexuses of the Enteric Nervous System are located where?
Within layers of the intestinal wall
What are the two major plexuses of the Enteric Nervous System?
- Submucosal Plexus
2. Myenteric Plexus
Where is the Submucosal Plexus located and in which layer?
Located in Submucosa Layer in SI and LI
The two major roles of the Submucosal Plexus are controlling what and what?
Controlling secretions and absorption
Which two places is the Submucosal Plexus not found?
Esophagus and Stomach
Which layers are the Myenteric Plexus located in?
Between Circular and Longitudional Layers of muscularis
The Myenteric Plexus is distributed in the GI Tract from where to where?
From Upper Esophagus to Internal Anal Sphincter
The Myenteric Plexus’ major role is in what?
Controlling motility
What is the “third” plexus of the Enteric NS and what does it respond to?
Subserosal Plexus, involved in pain response when distended.
Can the intrinsic system feedback on itself and act autonomously?
Yes
Which neurons communicate in the enteric system of the GI Tract?
Motor and Sensory neurons
Can the intrinsic neural system influence the extrinsic system?
Yes, and vice versa
What are the two functional neurons of the enteric plexus?
Sensory Neurons and Motor Neurons
What two things do the sensory neurons of the enteric plexus monitor?
Distention and chemical status of GI tract
What three things do the motor neurons of the enteric plexus control?
- Motility of gut wall
- Secretions of the mucosa/submucosa
- Smooth muscle of GI vasculature
What does the hormone gastrin stimulate? What needs to be kept closed because of gastrin?
Stimulates acid secretion and motility. Need to keep LES closed.
Where is gastrin secreted and in response to what three things?
Stomach. In response to proteins, stomach distention, and parasympathetic input to stomach.
Where is CCK secreted and in response to what?
Duodenum and Jejunum. In response to fat or protein products in Duodenum.
What does CCK do?
Inhibits gastric secretion and motility, stimulates other secretions, relaxes Sphincter of Oddi
Where is the hormone Secretin released and in response to what?
Duodenum and Jejunum. In response to acid in duodenum.
What does the hormone Secretin do?
Inhibits gastric secretion and motility, stimulates other secretions
Where is GIP secreted and in response to what?
Duodenum and Jejunum. In response to glucose, fats, or acid in duodenum or distention of duodonem
What what the hormone GIP do?
Inhibits gastric secretion and motility, stimulates insulin release
What is appetite?
Hunger
What is Satiety?
Sensation of feeling full/satisfied
What are the two centers/nuclei in the hypothalamus that control appetite and satiety?
Lateral Center (appetite), Medial Center (satiety)
The Lateral Center of the Hypothalamus controls what?
Appetite
The Medial Center of the Hypothalamus controls what?
Satiety
What is the function of the Lateral Center of the Hypothalamus?
To stimulate appetite
What can stimulate the Lateral Center of the Hypothalamus?
Depletion of nutrient stores, smell/vision/taste/hearing, memory, hormone ghrelin
What is the hormone Ghrelin and where is it released from?
Hunger hormone, released from stomach. Goes to hypothalamus and brainstem, stimulates hunger.
What is the function of the Medial Center of the Hypothalamus?
Suppressed appetite
What are four hormones that stimulate the Medial Center of the Hypothalamus?
GI Hormones (CCK, GLP-1, etc), Leptin, PYY, Insulin
Where is Leptin released and what is the duration of it’s effect?
Released by fat and chief cells. Long term in energy balance and suppressing food intake.
Where is PYY released and what is the duration of it’s effect?
From SI after meal. Short term.
Where is Insulin released and what is the duration of it’s effect?
Released by Pancreas and increased in BGL after meal. Short term effect.
Which hormone counteracts ghrelin?
PYY
The motility of the mouth/oral cavity is under what type of control?
Somatic control
What are the three salivary glands?
Submandibular, Sublingual, and Parotid
Which nervous systems stimulate production of saliva?
Both sympathetic and parasympathetic
Is secretion of saliva controlled by hormones?
NO
What are the three main parts of saliva?
Water, Salivary Amylase, and IgA
What are the five components of the water component of saliva?
Contains mucus, sodium, bicarb, chloride, and potassium.
What is the role of the water component in saliva?
Maintain pH in mouth to neutralize bacteria in order to prevent tooth decay
What is the role of Salivary Amylase in the saliva?
Initiates carbohydrate digestion in mouth
What is the role of IgA in the saliva?
Prevent infection. Why dogs lick their wounds.
What are the two parts of digestion?
Mechanical and Chemical
What does the mechanical part of digestion do?
Chews and softens food
What does the chemical part of do?
Breaks down food for absporption.
Which chemical begins the breakdown of carbohydrates?
Amylase
What part of the mouth is used for fast delivery of meds?
Sublingual capillaries
What type of muscle makes up the upper 1/3 and lower 2/3 of the esophagus?
Upper 1/3=Striated (voluntary) muscle
Lower 2/3=Smooth (involuntary) muscle
Which CN innervates the upper 1/3 and lower 2/3 of the esophagus?
Upper 1/3=CN 10 Vagus
Lower 2/3=CN 10 Vagus “double nerve”
What is the name of the muscle of the Upper Esophageal Sphincter?
Cricopharyngeus muscle
The Upper Esophageal Sphincter is at the junction of which two areas?
Pharynx and Esophagus
The Upper Esophageal Sphincter is at the level of which cartilidge?
Cricoid
What are the two functions of the Upper Esophageal Sphincter?
- Prevent air from entering esophagus during ventilation
2. Closes after bolus enter esophagus
Where is the Lower Esophageal Sphincter?
At narrowing of esophagus proximal (above) to junction of esophagus and stomach
What is the function of the Lower Esophageal Sphincter?
Barrier of regurgitation/reflux of stomach’s acidic environment
What maintains the tone of the Lower Esophageal Sphincter?
Increased smooth muscle tone
What is the normal tone range of the Lower Esophageal Sphincter?
10-45mmHg
Belching is when air in the stomach exceeds what?
Exceeds LES pressure
What happens to Lower Esophageal Sphincter smooth muscle tone during swallowing?
Relaxes
The Lower Esophageal Sphincter relaxes during swallowing as what approaches it?
Peristaltic wave
Is the Lower Esophageal Sphincter a true anatomical sphincter?
No
What maintains sphincters in the esophagus?
Tonic contractions
What two things are secreted in esophagus?
Mucus and Bicarb (HCO3-)
What is the job of mucus and bicarb secretion in the esophagus?
Mucus=Lubricant to protect
Bicarb=Alkaline to protect against gastric acids
Does any digestion or absorption happen in the esophagus?
Nope
Which part of the brain is the swallowing center located in?
Brainstem
What is the name of the swallowing center in the brainstem?
Reticular Formation
Which two systems/tracts does swallowing require coordination of?
Digestive tract and Respiratory system
What are the three phases of swallowing?
- Oral phase
- Pharyngeal phase
- Esophageal phase
What happens during the Oral Phase of swallowing?
Food enters and t/p to post-canine region, chewing breaks down food, tongue pushes small food into posterior oropharynx, chewing continues until all food t/p to oropharynx
How long does the Pharyngeal Phase of swallowing occur?
1-2 seconds
Which sphincter does the food bolus pass in the Pharyngeal Phase of swallowing?
Upper Esophageal Sphincter into esophagus
What does the Pharyngeal Phase of swallowing do to the airway?
Protects airway
What are the five steps of the Pharyngeal Phase of swallowing?
- Food enters pharynx causing soft palate to elevate and close nasopharynx, 2. base of tongue pushes bolus against pharyngeal walls, 3. epiglottis and vocal cords close, 4. UES opens, 5. constrictors push bolus into esophagus
The UES opening during Pharyngeal Phase of swallowing happens in what three steps?
- UES relaxes
- Open UES by contraction of suprahyoid and thyrohyoid muscles
- Pressure of bolus pushing through toward esophagus
How long does the Esophageal Phase of swallowing take?
5-10 seconds
What signifies the beginning and end of the Esophageal Phase of swallowing?
Begin: Bolus entering esophagus
End: Bolus enters stomach
Which sphincter closes to prevent bolus from going back up during the Esophageal Phase of swallowing?
UES
How is food bolus moved to stomach during Esophageal Phase of swallowing?
Peristaltic wave
What happens during Peristaltic Wave of Esophageal Phase of swallowing?
Coordinated contraction and relaxation of longitudional and circular muscles in esophagus
What is the range of esophageal muscle pressures of peristaltic contractions during Esophageal Phase of swallowing?
35-80mmHg or higher
What happens if the peristaltic contraction wave pressure during Esophageal Phase of swallowing is less than 30mmHg?
Food residue left in esophagus
What does distention (tension/stretch) of esophagus due to the force of contractions during Esophageal Phase of swallowing?
Increases force of contractions
Intense contractions of the esophageus during Esophageal Phase of swallowing can cause what?
Substernal pain similar to agina/heartburn
What happens to LES as the peristaltic wave nears the end of the esophageus?
LES relaxes allowing food bolus into stomach
What are the two types of peristalsis in the esophagus?
Primary and Secondary
What happens in Primary Peristalsis in Esophagus?
Normal peristaltic wave after food bolus swallowed and enters esophagus, continuation of oral and pharyngeal phases, pressure around 35-80mmHg
What stimulates Secondary Peristalsis in Esophagus?
Stimulates by food residue from ineffective primary peristalsis or bolus that is stuck in esophagus
What type of feedback is triggered by Secondary Peristalsis? What does it do?
Intrinsic Feedback, stimulates constriction above bolus and relaxation below bolus to push along
Which nerve controls peristalsis?
CN 10 Vagus Nerve
What type of parallel signaling come from CN 10 Vagus Nerve during esophageal peristalsis?
Parallel inhibitory and excitatory signaling from vagus nerve
What is the LES resting/basal tone pressure?
10-45mmHg
What three factors contribute to the basal/resting LES pressure?
- Myogenic tone that is independent of any neural input
- Excitatory vagal tone (cholinergic)
- Inhibitory neural tone (nitrergic – nitric oxide)
What two factors increases LES tone/pressure?
- Vagus nerve excitatory pathways via ACh release
2. Gastrin which stimulates acid secretion in stomach requiring LES to close to prevent regurg
What three things can decrease LES tone/pressure?
- Anticholinergic meds
- Hormones (progesterone, secretin, glucagon, CCK)
- Common foods/substances
Elevated Progesterone levels in pregnancy and second half of menstrual cycle can have what sort of effect on the LES?
Reduce LES tone allowing reflex
A single swallow of food initiates a peristaltic wave which lasts for how long and is followed by what?
Lasts 5-10 seconds, followed by short refractory period
What does the 5-10 second long esophageal peristaltic wave inhibit?
Inhibits ability to swallow a second bite for 10-15 seconds
How long does swallowing liquids last?
1-2 seconds
What is Deglutitive Inhibition?
Inhbition of esophagus from contracting during swallowing by quick subsequent swallows
What does Deglutitive Inhibition cause the esophagus to do and allow for liquids?
Causes esophagus to stay relaxed and to allow more liquid to descend
How long does Deglutitive Inhibition last for and what happens after it ends?
Until last swallow. Followed by full peristaltic contraction.
What is a Hiatal Hernia? What can it cause?
Portion of cardia of stomach protrudes above diaphragm causing LES dysfunction. Common cause of GERD.
What is GERD? What causes it?
Gastoesophageal Reflex Disease allowing acid from stomach to enter esophagus. Due to hypotensive LES less than 10mmHg. Causes esophagatits.
What is esophagatits? What does it result in?
Chronic acid reflex into esophagus, results in inflammation/pain and eventual destruction of esophageal wall
What do parasympathetic drugs do to LES tone?
Increase LES tone. Tx for hypotensive LES causing GERD.
What is Achalasia? What is etiology?
Increase in LES tone above 45 causing pain w/eating and drinking. Unknown etiology but possibly dysfunction of intrinsic esophageal plexus causing loss of inhibitory motor neurons in esophagus.
What are the two “mechanical results” of achalasia?
Absent/impaired peristalsis of esophageal muscles, failure of LES to relax
Achalasia aka…?
Cardiospasm
What are four possible treatments of Achalasia?
- Pneumatic dilation of LES to stretch out
- Medications to relax LES (sympathetics?)
- Myotomy
- Botox injections
What is Eosinophilic Esophagatitis? AKA?
“Asthma of the esophagus”, like achalasia pain and difficulty swallowing.
What is etiology and causes Eosinophilic Esophagatitis?
Eosinophils accumulating in esophageal wall causing inflammation. Triggered by food and other allergens.
How is Eosinophilic Esophagatitis diagnosed?
Biopsy of esophageal squamous mucosa showing eosinophils
What are Esophageal Varicies? Most common cause/consequence?
Severely dialated submucosal veins in esophaus. Consequence of portal hypertension.
PTs with Esophageal Varicies have a strong tendency to develop what? What are consequences?
Strong tendency to develop chronic GI bleeding. Major systemic consequences.
What is Barrett’s Esophagus?
Stomach acid in esophagus causing mature cells to be replaced by different mature cells due to exposure to stomach acid. Metaplasia.
What cells are changed in Barrett’s Esophagus?
Normal esophageal squamous epithelium replaced by spectrum of metaplastic columnar mucosa
What is Metaplasia? What condition is it found in?
One mature and physically normal cell type replaced by another type of mature and physically normal cell. Barret’s Esophagus.
What is Metaplasia and Dysplasia?
Metaplasia=Mature and physically normal cell type replaced by another mature and physically normal cell type
Dysplasia=Abnormal development/maturation of cell
What is Dysplasia often an indicator of?
Early neoplastic process
What are the two types of Esophageal Cancer?
- Squamous Cell Carcinoma
2. Adenocarcinoma
How do Squamous Cell Carcinoma and Adenocarcinoma of the Esophagus differ in terms of location?
Squamous Cell Carcinoma from squamous cells of entire esophagus, Adenocarcinoma in lower esophagus
In Adenocarcinoma normal cells are replaced with what type?
Columnar cells, through metaplasia/dysplasia
What is a major risk factor in the development of Adenocarcinoma?
GERD
GERD can lead to what type of cancer?
Adenocarcinoma
Where does the Small Intestine start and finish?
Start at Pyloric Sphincter and end at Ileocecal Valve
What is the length and sections of the SI?
Duodenum 25-35cm, Jejunum 2.5m, Ileum 3.5m. Total 5-6m.
Where does the Duodenum begin and end?
Begin at Duodenal Bulb, end at Ligament of Treitz
What does the Sphincter of Oddi (aka Hepatopancreatic Ampula) allow to enter the duodenum?
Bile and Pancreatic Enzyme secretions
Where are Brunner’s Glands located?
Proximal Duodenum
What do Bunner’s Glands secrete and where to?
To Proximal Duodenum. Secretes Bicarb-rich mucus to protect against chyme entering from stomach.
What SI portion regulates stomach emptying?
Duodenum
What is the triad of hormone messengers released from duodenum that regulate gastric emptying?
Secretin, VIP, CCK
Where is Secretin released from?
Duodenum
What stimulates the release of Secretin from Duodenum?
Acidity, pH less than 4-5
What is Secretin’s action?
Inhibits gastric activity and facilitates digestion
Which hormone does Secretin inhibit?
Gastrin
Gastrin is inhibited by which hormone?
Secretin
What does Secretin do in the pancreas?
Stimulates secretion of watery bicarb solution
What does Secretin to do stomach?
Inhibit gastric motility, inhibits gastrin from producing gastric secretions
What does Secretin do to Brunner’s Glands of Duodenum?
Stimulate secretion of alkaline/bicarb rich mucus
CCK is secreted by which part of the SI?
Duodenum
What is the stimulus of CCK?
Fatty chyme (partially digested proteins) entering duodenum
What two major roles does CCK do?
- Promotes bile and pancreatic enzyme release,
2. Inhibitory to gastric activity
What does CCK do to the liver?
Stimulate bile output for fat digestion
What does CCK do to the Gallbladder?
Stimulates contraction to release stored bile
What two organs is CCK majorly connected to?
Live and Gall Bladder
CCK has a huge role in the digestion of what type of foodstuff?
Fat digestion. Gets bile to duodenum to start.
CCK, GIP, VIP, and Intestinal Gastrin are all stimulated by ___ entering the ___
Chyme entering the Duodenum
What is the major role of GIP?
Tells pancreas to pump out insulin when chyme/food enters duodenum
What is the major role of VIP?
Gets blood to intestines to promote digestion
What is the major role of Intestinal Gastrin?
Stimulate motility
Which hormone is the “housekeeper of the intestinal tract”?
Motilin
What are the stimuli for Motilin?
Fasting or periodic release every few hours
What is the action of Motilin?
Initiates MMC (migrating motor complex). Motilin active when fasting.