L3: Swallowing and Stomach Histology Flashcards
Peristalsis initiated by the swallow
Primary Peristalsis
Peristalsis initiated by distention of the esophagus
Secondary Peristalsis
During a swallow an initial _______ component leads to _______
Initial Voluntary component leads to involuntary swallow
During a swallow upper oesophageal sphincter opens rapidly and then shuts quickly to prevent ________________ => ___________________ then kicks-in
Upper oesophageal sphincter opens rapidly and then shuts quickly to prevent reflux => Secondary peristalsis then kicks-in
________________ can still occur after vagotomy
Peristalsis can still occur after vagotomy
Vagus nerve is important for physciological peristalsis, however lower esophagus can persist without vagal intervention. The Enteric Plexus is capable of coordinating persistalsis independently of autonomic innervation
Normal swallowing involves the coordinated action of both the ____________ and ____________
Normal swallowing involves the coordinated action of both the ANS and the ENS
During Peristalsis contraction behind the bolus is facilitated by release of _________ while relaxation in front of the bolus is facilitated by release of ________
Contraction behind the bolus (ACh)
Relaxation in front of the bolus (NO)
The ________________________ co-ordinates peristaltic contractions
The Enteric Nervous System co-ordinates peristaltic contractions
What happens during multiple rapid swallows?
What is this known as?
Peristalsis is inhibited until the last swallow
Known as Deglutitive Inhibition
What is used to analyse Esophagus via X-Ray?
Normal Barium Swallow
Esophageal Motility disorder associated with impaired or absent peristalsis
Apearance of Esophagus?
Esophageal Achalasia
Esophgeal Disorder associated w/ Diffuse spasms, Impaired motility, and Uncoordinated contractions
Apearance of Esophagus?
Corkscrew Esophagus
Esophageal condition in which tone of lower esophageal sphincter impaired => acid leaks up damaging the mucosa of lower esophagus=> dysplasia (Barrett’s Esophagus)
Gastro Oesophageal Reflux Disease ( GORD)
Anatomomical Regions (4)
Histological Regions (3)
Part of the stomach primarily responsible for secretion of mucous and relaxation to accomodate a meal?
Function?
Fundus
Secretion of mucous rather than acid. Helps protect esophagus/small intestine
Part of stomach that produces majority of Gastric Acid and Facilitates mixing of stomach contents?
Body/Corpus
Part of stomach which is mainly mucus and highly muscular?
Pylorus
Stomach cell that secretes mucus and bicarbonate?
Location/Role of this cell?
Surface Mucous Cell
Protects Stomach from Acid in Lumen
Stomach cell present in neck or isthmus with an acidic secretion containing Mucin
Location/Characterisitics of this cell?
Mucous Neck Cell
Less columnar - rounded nuclei
Stomach cell present in neck and deeper parts of gland that Secretes HCl and Intrinsic Factor?
Parietal cell
Strong eosinophilic staining
Where are Chief Cells located and what do they Produce?
Lower region of the gastric gland
Produces Pepsinogens, Gastric lipase, Rennin
Pepsinogen: precursor of pepsin => converted by meeting of acid in lumen=> able to digest protein
What is Pepsinogen
From where is it secreted?
Pepsinogen: precursor of pepsin => converted by meeting of acid in lumen=> Pepsin: Active protease that breaks down proteins into peptidesand amino acids
Released from Chief Cells (Response to ACh, Gastrin Secretin)
Gastrin/5HT producing cells in pylous?
Enteroendocrine cells (G-Cells)
What Pathogen exploit’s stomach’s protection from autodigestion?
H. Pylori embeds flagella into mucous layer, enabling it to avoid the stomach’s acid
Process of Gastric Mucous Production?
Mucous secretion is ____________ by prostaglandins
Mucous secretion is stimulated by prostaglandins
NSAIDS can inhibit prostaglandins and thus limit surface mucous production
What Macromolecule begins to be digested in stomach by Gastic Acid?
Proteins
Carbohydrates/Lipids primiarily digested later on
How is protein Digested in stomach?
Denaturing of proteins by gastric acid ->Exposure of peptide bonds
Acid converts Pepsinogen -> Pepsin protease that breaks down proteins into peptides + amino acids
Fundus/ Corpus Histology
What are the folds called?
What are the pright pink cells in middle of the glands?
What are the purple tubular cells at bottom of gland?
Folds/Ruggae of stomach -> when it is empty
Bright pink midle of glands=Pareital cells
Chief cells near bottom of gland: produce pepsinogen/gastic lipase
Describe the process of HCl excretion from Parietal Cells
- CO2 Produced via normal activity encounters H2O and is converted via carbonic anhydrase to ______ and an ____ ion
- ______transported to the intraluminal cell surface
- _____ actively pumping hydrogen ion out into lumen in exchange for potassium
- Loss of H+ on lumenal surface is compensated by exchanging Bicarbonate on the basal side in for____
- _____then participates on the lumenal surface in exchanged for potassium that is co-transported out with Cl- (H+ + CL- => HCl Acid)
- ____ is exchanged for K+ on the basal surface
- CO2 Produced via normal activity encounters H2O and is converted via carbonic anhydrase to Bicarbonate (HCO3-) and an H+ ion
- Hydrogen ions transported to intraluminal cell surface
- Potassium Hydrogen ATPase actively pumping hydrogen ion out into lumen in exchange for potassium
- Loss of H+ on lumenal surface is compensated by exchanging Bicarbonate on the basal side in for Cl- ions
- Cl- then participates on the lumenal surface in exchanged for potassium that is co-transported out with Cl- (H+ + CL- => HCl Acid)
- Na+ is exchanged for K+ on the basal surface
Why do Parietal Cells have an abundance of mitochondira?
Huge number of mitochondria needed to push out H+ into lumen against a massive concentration gradient
What is Intrinsic Factor Required for?
Where is it produced? Optimum pH?
Intrinsic Factor: Protein required for takeup of vitamin B12
Parietal Cells - pH 7
Process of Vitamin B12 Digestion:
- Vitamin B12 (___________) initially binds _________________ in the stomach
- ______________ is then broken down by pancreatic enzymes in duodenum releasing B12 which then binds __________________ in more pH appropriate environment
- This complex is Endocytosed by cells in the _________________
- B12 then released and complexes with ___________________ in the cells before traveling to the liver
What is B12’s Importance?
- Vitamin B12 (Cobalamin) initially binds Haptocorrin (Transcobalamin I) in the stomach
- Haptocorrin is broken down by pancreatic enzymes in the duodenum releasing B12 which then binds Intrinsic Factor in more pH appropriate environment
- This complex is endocytosed by cells in the Terminal Ileum
- B12 then released and complexes with Transcobalamin II in the cells before traveling to the liver
B12 is required for erythropoiesis
Clinical condiiton associated with loss of parietal cells?
Pernicious Anaemia
autoimmune disease
Loss of Parietal Cells => Amount of intrinsic factor is compromised => cant absorb B12 as effectively in small intestine => deficiency of B12 => erythropoiesis is compromised
What hormones trigger Chief Cells?
What do they then release?
Triggerrs: ACh, Gastrin Secretin
Releases: Pepsinogen, Gastric Lipase, Rennin
Pepsinogen is a pro-enzyme released by Chief cells -> pepsin in stomach
Enzyme Producing Cell of Stomach?
Chief Cells (Pepsinogen/ Gastric Lipase)
Hormone Producing Cells of Stomach?
Role of each?
Enteroendocrine Cells
G- cells: Secrete gastrin into blood => Promote gastric acid secretion
D-cells: Secrete Somatostatin => Inhibition of other G cells
Enterochromaffin (EC) Cells: Secrete Serotonin and Substance P => Promotion of gut motility
What do G-Cells do?
What Type of Cell are they?
Secretion of GASTRIN into the blood
Gastrin is a hormone that promotes gastric acid secretion
Enteroendocrine cell
What do D-Cells do?
What Type of Cell are they?
Secretion of Somatostatin
Inhibition of other G cells
Enteroendocrine cell
What do Enterochromaffin (EC) Cells do?
Secretion of Serotonin and Substance P
Promotion of gut motility
Oxyntic Glands vs. Pyloric Glands?
Region and cell types of each
Oxyntic glands have a prevalence of Pareital/Chief Cell
Pyloric Glands have a greater presentation of Mucous Producing (Surface Mucous/ Mucous Neck Cells) and Endocrine cells (Enterochromaffin Cells, D cell, G cells) associated with regulation of acid production in the other acid producing regions
Oxyntic Gland- Fundus/Corpus Pyloric: Near small intestine
