Secretions - Lopez Flashcards
What is the origin of the salivary gland?
Blood supplied to it is from where?
Ectodermal
External carotid a.
What is responsible for ejecting saliva into the mouth?
Myoepithelial cells
In the intercalated duct, what is saliva compared to plasma?
Ionic composition
What is the striated duct lined by?
How does it modify saliva?
Columnar epithelial cells
Makes it hypotonic
What is saliva composed of?
H20
Alpha-amylase
Lingual lipase
Kallikrein
Describe K, Na, HCO3, Cl [ ]s compared to plasma
HIGH K, HCO3
low NaCl
What does Kallikrein do?
Makes bradykinin (vasodilator)
Is there more absorption or secretion of solute?
More absorption (NaCl)
Name the exchangers (3) in the salivary ductal cell
Na/H
Cl/HCO3
H/K
All on apical membrane
What does the CFTR channel secrete or absorb?
How is it activated?
SECRETES HCO3 and Cl-
By cAMP
What is the result in patients with deficient CFTR gene?
Ca, Na, protein INCREASED
What is super special about ductal cells?
ductal cells are IMPERMEABLE to water
Where do PS presynaptic nerves originate?
What do postsynaptic fibers innervate?
CN 7 and 9
Individual glands
Where do Symp preganglionic nerves originate?
Where do the postganglionic extend to?
Cervical ganglion
Periarterial space glands
What does CN 7 innervate?
CN 9?
(Both PS pathways)
Submandibular and sublingual glands
Parotid gland
What nt does PS salivary secretion use?
What receptor?
What 2nd messenger?
ACh
MAChR
IP3 and Ca2+
What nt does Symp pathway use for salivary secretion?
What spinal levels?
What receptor and 2nd messenger?
NE
T1-T3
Beta-andrenergics
cAMP
How does vasopressin and aldosterone modify saliva?
Dec. [Na] and INC [K]
By inserting channels in membrane (reabsorbs sodium)
What branch of the ANS increases salivary secretion?
BOTH
What are the main components of gastric juice?
HCl Pepsinogen Mucus Intrinsic Factor H2O
What is intrinsic factor required for?
Where?
Absorption of Vit B12
Ileum
Where is the oxyntic gland located?
What does it secrete?
Proximal 80% of stomach (body and fundus)
Acid
Where is the pyloric gland located?
Function?
Distal 20% of stomach (antrum)
Release Gastrin
Where are parietal cells located?
What do they secrete?
Oxyntic glands
HCl, Intrinsic factor
Where are G cells located?
Pyloric gland
In the gastric parietal cell, what exchanger is located on the luminal side?
H+/K+
H+ is going into lumen (secreted) as Cl- follows H+
What inhibits the H+ ion exchanger?
Omeprazole
What exchanger is located on the basolateral side?
HCO3-/Cl- exchanger
Cl- going back INTO the cell
What is absorbed via the parietal cell?
HCO3- absorbed into blood
What releases histamine?
What else stimulates histamine release?
What does histamine do?
ECL cells
ACh and Gastrin
Stimulates HCl secretion
Where does histamine bind?
What blocks the receptors?
What does it act through?
H2 receptors
Cimetidine
cAMP
What releases ACh?
What does it stimulate?
Vagus n.
HCl secretion
Where does ACh bind?
What blocks the binding?
What 2nd messenger does it use?
M3 on parietal cells
Atropine
IP3/Ca2+
Where does Gastrin bind CCK?
What 2nd messenger does it work through?
Does Atropine block this pathway?
CCK B receptors on parietal cells
IP3/Ca2+
NO
What releases somatostatin?
What does it do?
Where does it bind?
D cells in antrum
inhibits HCl
SSTR2 on parietal cells
What effects does somatostatin have?
Direct effect - inhibits adenylate cycle -> inhibit H+
Indirect effect - inhibits histamine and Gastrin
What has potentiation effects?
Histamine on ACh and Gastrin
ACh on histamine and Gastrin
What do PGs do in gastric parietal cells?
Inhibits cAMP (Gi)
What nt do G cells use when vagally stimulated?
GRP
What stimulates the cephalic phase?
Smelling, tasting, chewing, swallowing
What is the MOA for the cephalic phase?
Vagus n. -> parietal cell using ACh
Vagus n. -> Gastrin -> parietal cell using GRP
What stimulates the gastric phase?
Distention of stomach, breakdown proteins, a.a., small peptides
What are the MOA for the gastric phase?
2 Vagal reactions
Distention of antrum
A.a. And small peptides
What foreign substance can stimulate gastric HCl secretion?
Coffee (incl. decaf)
What stimulates the intestinal phase?
Distention of s.i. Digested proteins (a.a.) via direct effect
Gastric juice is what kind of solution?
low secretion rates what is high?
High secretion rates?
Isotonic
NaCl
HCl
What is the most important stimulus for pepsinogen secretion?
Vagus nerve stimulation
When is pepsin irreversibly inactivated?
pH > 7-8
What leads to pernicious anemia?
Failure to secrete intrinsic factor
Atrophic gastritis
What damages the gastric mucosa?
acid Pepsin NSAIDs H. Pylori Alcohol Bile Aspirin
How do gastric ulcers primarily form?
What is the major cause?
Via what mechanism?
Mucosal barrier defective
H. Pylori
Urease allows bacteria to colonize the gastric mucosa, converts urea to NH3
How do duodenal ulcers form?
Cause?
H+ secretory rates higher than normal (most common)
indirectly H.pylori inhibits somatostatin
What are the 2 main components of the exocrine pancreas?
Aqueous solution, has HCO3-
Enzymatic secretion
What secretes the HCO3-?
Ductal and centroacinar cells
Where are Symp post-gang nerves from?
Celiac and Superior Mesenteric plexuses
PS nervous system innervation from where?
Where do preganglionics synapse?
Postganglionics?
Vagus n.
ENS
On exocrine pancreas
In the exocrine pancreas what is inhibitory?
Excitatory?
Symp
PS
Where are pancreatic proteases activated?
Lumen of duodenum
What exchanger is present on the luminal side of the pancreatic ductal cell?
HCO3-/Cl-
HCO3- secreted into pancreatic juice
What exchanger is present on the basolateral side of pancreatic ductal cell?
H+/Na+
H+ into the blood, so it becomes ACIDIC
At high flow rate is bicarbonate high or low in pancreatic juice?
HIGH
Which phase of pancreatic secretions accounts for the majority of secretion?
What does this phase have that the others don’t?
Intestinal (80%)
Has enzymatic and aqueous secretions
Whic salivary gland is the largest?
What enzyme does it have a lot of?
Parotid gland
Amylase
