GI - pt 2 Hormones etc Flashcards
Zollinger-Ellison Syndrome
- Non [] cell tumors of the pancrease or duodenum
- Continually produce [] gastrin [] of the stomach
- Not controlled by [] regulation
- If left untreated
- Diarrehea –> [] acid causes inactive digestive enzymes
- Steatorrhea –> Excess [] in stool
- Can cause [] which leads to a [] of parietal cells in the [] glands and G cell.
- Non beta cell tumors of the pancrease or duodenum
- Continually produce unregulated gastrin outside of the stomach
- Not controlled by somatostatin regulation
- If left untreated
- Diarrehea –> increased acid causes inactive digestive enzymes
- Steatorrhea –> Excess fat in stool
- Can cause hypergastinemia which leads to a growth of parietal cells in the Oxynitic glands and G cell.
Cholecystokinin (CCK)
- Structure is similar to []
- Released from []-cells in the [] and jejunum
- Released in response to [] from
- peptides, amino acids, fatty acids, acids
- Stimulates:
- Gall bladder []
- [] of Sphincter of Oddi
- potent stimulator of [] [] secretion
- Inhibits [] emptying
- trophic action of [] pancreas, and mucosa of [] []
Cholecystokinin (CCK)
- Structure is similar to gastrin
- Released from I-cells in the duodenum and jejunum
- Released in response to chemoreception from
- peptides, amino acids, fatty acids, acids
- Stimulates:
- Gall bladder contraction
- Relaxation of Sphincter of Oddi
- potent stimulator of pancreatic enzyme secretion
- Inhibits gastric emptying
- trophic action of exocrine pancreas, and mucosa of gall bladder
Secretin
- Chemically homologous to []
- Released from []-cells of the duodenum
- most important stimulus is [] (and [] [] to a lesser extent)
- Stimulates
- intestinal []and [] secretion
- [] secretion from the stomach
- Inhibits
- [] [] secretion by parietal cells
- Chemically homologous to Glucagon
- Released from S-cells of the duodenum
- most important stimulus is acid (and fatty acids to a lesser extent)
- Stimulates
- intestinal HCO3- and H2O secretion
- Pepsinogen secretion from the stomach
- Inhibits
- gastric acid secretion by parietal cells
Secretin serves to [] the acid content of the intestine
reduce
Glucose-Dependent Insulinotropic Peptide (Gastric inhibitory Peptide, GIP)
- Member of the []/[] family
- Released from mucosal []-cells of the duodenum and [] []
- Released in response to [] [] in the [] lumen
- Stimulates pancreatic []-cell relese of [] in response to glucose and is the reaosn [] glucose is cleared form blood faster than [] glucose.
Glucose-Dependent Insulinotropic Peptide (Gastric inhibitory Peptide, GIP)
- Member of the secretin/Glucagon family
- Released from mucosal K-cells of the duodenum and proximal jejunum
- Released in response to oral glucose in the duodenal lumen
- Stimulates pancreatic Beta-cell release of insulin in response to glucose and is the reaosn oral glucose is cleared from blood faster than intravenous glucose.
- Secreted by crypt M-cells found in the duodenum and Jejunum
- Relese mechanism is unknown
- Stimulates:
-
Migrating myoelectric Complex (interdigestive myoelctric complex)
- Clears the small intestine of food in anticipation of the next meal
- Alakalin pH - stimulates gastic motor functions
- Acidic pH - inhibits gastric motor functions
-
Migrating myoelectric Complex (interdigestive myoelctric complex)
Pancreatic Polypeptide
- released from the []-cells of the [] pancreas
- Released in response to [], [], and [] that are delivered through the []
- Acts to inhibit:
- All [] enzyme release
- [] secretion
- released from the PP-cells of the endocrine pancreas
- Released in response to proteins, fats, carbohydrates that are delivered through the blood
- Acts to inhibit:
- All pancreatic enzyme release
- HCO3- secretion
Enteroglucagon
- released from the mucosa of the distal ileum and colon
- released in response to glucose (primarily) and fat (secondarily)
- Stimulates hepatic bile flow
- Inhibits:
- acid secretion and motility
- Decreases flow rate in order to increase the amount of absorption that can take place.
- This is done because glucose should not be this far into the large intestine.
Histamine
- synthesized in [] []-[] (ECLs) of the stomach
- released by [] gland of the mucosa
- Diffuses to []-[] Receptors on the nearby parietal cells.
- Stimulates [] [] secretion
- May be the most potent [] of gastric HCl…but so may gastrin.
- synthesized in enterchromaffin-like cells (ECLs) of the stomach
- released by Oxyntic gland of the mucosa
- Diffuses to H2-Type Receptors on the nearby parietal cells.
- Stimulates gastic acid secretion
- May be the most potent stimulator of gastric HCl…but so may gastrin.
Vasoactive Intestinal Polypeptide
- Chemically similar to []/[] family
- released from nerve [] (half life 2-3 minutes)
- Acts as a []
- Mediates relaxation of:
- [] smooth muscle
- [] smooth muscle
- Stimulates intestinal mucosa to release:
- [] fluid, [] and [].
- Inhibits gastrin-stimulated [] secretion
- Chemically similar to secretin/Glucagon family
- released from nerve varicosities (half life 2-3 minutes)
- Acts as a vasodilator
- Mediates relaxation of:
- GI smooth muscle
- Vascular smooth muscle
- Stimulates intestinal mucosa to release:
- Pancreatic fluid, HCO3- and H2O.
- Inhibits gastrin-stimulated gastric acid secretion
Nitric Oxide
- N-NOS, [] [] [] [], forms NO for release in [] endings
- released in the [] mucosa and [] [] []
- [] visceral smooth muscle and vasuclar smooth muscle
- []would constrict the LES
- N-NOS, or neuronal nitric oxide synthase, forms NO for release in nerve endings
- released in the GI mucosa and Lower esophageal sphincter
-
Relaxes visceral smooth muscle and vasuclar smooth muscle
- Ach would constrict the LES
The muscles that are involved in jaw closing:
Masseter (most important)
Medial Ptergoid
Temporalis Muscles
The muscles that are involved in the jaw opening:
Lateral pterygoid
Digastric Muscles
Mouth mastication is innervated by the []
Trigeminal Nerve (V)
Chewing Reflex:
- Occurs when a bolus of food touches the lining of the []
- Causes [] of the []jaw muscles
- the jaw []
- []stretch reflexes are activated which causes a rebound [].
- Occurs when a bolus of food touches the lining of the mouth
- Causes relaxation of the striated jaw muscles
- the jaw opens
- Monosynaptic stretch reflexes are activated which causes a rebound contraction.
Chewing rhythm is generated by [] stimuli to the [] center from the [] receptors. This caues a cycle of about [] duration.
Chewing rhythm is generated by afferent stimuli to the chewing center from the pressure receptors. This caues a cycle of about 1 second duration.
Deglutition ([])
- May be initiated []
- After the oral phase, exclusively []
- Swallowing is a reflex triggered by [] [] receptors.
- this reflex includes a component to inhibit [] and prevent []
Deglutition (swallowing)
- May be initiated voluntarily
- After the oral phase, exclusively reflexive
- Swallowing is a reflex triggered by pharyngeal pressure receptors.
- this reflex includes a component to inhibit inspiration and prevent aspiration
What are the 3 phases of swallowing?
Buccal Phase
Pharyngeal Phase
Esophageal Phase
Buccal Phase of Swallowing
- initiated by [] receptors in the back of the mouth
- The tongue lifts the bolus against the [] [] and propells it backwards.
- Afferent Pressure Receptors
- V - []
- VII - []
- IX - []
- X - []
- Efferents
- V - []
- VII - []
- IX - []
- X - []
- XII - []
- initiated by tactile receptors in the back of the mouth
- The tongue lifts the bolus against the hard palate and propells it backwards.
- Afferent Pressure Receptors
- V - Trigeminal Nerve
- VII - Facial Nerve
- IX - Glossopharyngeal Nerve
- X - Vagus Nerve
- Efferents
- V - Trigeminal Nerve
- VII - Facial Nerve
- IX - Glossopharyngeal Nerve
- X - Vagus Nerve
- XII - Hypoglossal Nerve
Pharyngeal Phase of Swallowing
- [] palate and [] are pulled up and [] [] close to prevent nasal reflex
- Pharyngeal muscles [] around the bolus
- Vocal cords [] to close the glottis
- [] covers the Trachea and respiration is []
- UES [] and peristaltic wave begins
- UES [] once bolus passes by
- [] [] propels the bolus.
- Soft palate and uvula are pulled up and palatopharyngeal folds close to prevent nasal reflex
- Pharyngeal muscles accomodate around the bolus
- Vocal cords contract to close the glottis
- Epiglottis covers the Trachea and respiration is inhibited
- UES relaxes and peristaltic wave begins
- UES contracts once bolus passes by
- Peristaltic stripping propels the bolus.