Pancreatic Secretions and Spleen Flashcards
What does the pancreas develop from?
Dorsal and ventral bud from small intestine
Dorsal appears first, opposite hepatic duct
Ventral appears later at junction
Name the parts of the dorsal pancreas.
Body, tail, isthmus, accessory pamcreatic duct
Name the parts of the ventral pancreas.
Pancreatic head, uncinate process and main pancreatic duct
Which pancreas becomes dominant after fusion?
The ducts of the ventral pancreas becomes dominant
What happens in pancreas divisum?
Ductal systems of the 2 buds do not fuse and dorsal duct system remains well developed
What is the main pancreatic called?
Duct of Wirsung (ventral pancreas)
What is the accessory pancreatic duct called?
Duct of Santorini (dorsal)
What can lead to acute pancreatitis?
Obstruction of pancreatic ducts
What are the endocrine parts of the pancreas?
islets of Langerhans, insulin, glucagon
What are the exocrine parts of the pancreas?
Pancreatic acini, pancreatic juice
What two components make up pancreatic juice?
Aqueous and enzymatic
What are the exocrine pancreas stimulated and inhibited by?
Stimulated by vagus
Inhibited by sympathetic nerves
What produces the enzymatic component of the pancreatic juice?
Acinar cells
What produces the aqueous component of pancreatic juice?
Duct cells
What makes up the aqueous component?
High levels of bicarbonate ions - neutralize gastric acid in chyme
What stimulates the secretion of the aqueous component?
Secretin
Where is the bicarbonate for secretion by the Centro acinar duct cells sourced?
- Intracellularly by the activity of Carbonic Anyhydrase
- Basolaterally through import via HCO3-/Na+ symporter
What allows the exchange of HCO3- with Cl- in the lumen?
Apical CFTR Cl- channel
What happens in cystic fibrosis regarding the CFTR channel?
Conductance is reduced leading to decreased pancreatic secretion
How is energy consumed in the Centro-acinar duct cell?
When the basolateral sodium potassium ATPase moves sodium out and potassium in
What is ionic composition dependent on?
Flow rate of pancreatic juice
What makes up the enzymatic component of Acinar cells?
Amylase, DNAase, RNAase, elastase and 3 lipases
Name the 3 lipases.
Triacylglycerol hydrolase, cholesterol ester hydrolase and phospholipase
What are the 3 proteolytic enzymes?
Trypsin (activated by enterokinase)
Chympotrypsinogen andprocarboxypeptidase (activated by trypsin)
Where is trypsin inhibitor produced?
Pancreatic tissue
What is Orlistat?
A lipase inhibitor
Treats obesity by preventing hydrolysation of triglycerides into fatty acids
What is Olestra?
Synthetic ‘fat’ composed 7-8 fatty acids attached to a sugar backbone
Dissolves fat soluble vitamins
Passes through GIT unabsorbed
What inhibits secretin secretion?
Neutralization of intestinal acid
What controls the intestinal phase of pancreatic secretion?
Hormone CCK and vago-vagal signalling
What is the cephalic phase mediated by?
Vagus
Direct: ACh and VIP release from vagal pancreatic branches and ganglia
Indirect: gastrin
What is the gastric phase mediated by?
Gastro-pancreatic vago0vagal reflex
Gastrin
What is the intestinal phase mediated by?
CCK
Vago-vagal reflex
What does CCK from I cells activate?
Vagal sensory fibres
What does CCK from fat and protein stimulate?
Acinar cells (enzymes)
What is pancreatitis?
Inflammation of the pancreas caused by activation of trypsin
How can you diagnose pancreatitis?
Transient rise in serum amylase and serum lipases
What is the spleen?
Largest single accumulation of lymphoid tissue
What are the functions of the spleen?
Filters blood. protection against blood-borne antigens, produces antibodies and activated lymphocytes
What is the white pulp of the spleen made up of?
Lymphoid cells
What is the red pulp of the spleen made up of?
Splenic sinusoids
Splenic cords
Removes RBCs and recycles iron
