Lecture 11 GI Secretion & Absorption Flashcards
what are the 3 types of complex glands
salivary, pancreas, liver
What are the 4 gland types
unicellular mucous, crypts of L, tubular, complex
what are the mechanisms of stimulation
food contact
autonomic stimulation
higher brain centers
hormones
what are some functions of mucous
adhere to food
coat gut wall to prevent actual contact of food
resistant to digestion by GI enzymes
cause fecal adherence
what are the 2 types of salivary gland secretions and what do they consist of?
parotid - serous
sublingual/mandibular - mixed
Where does the 1st stage of salivary secretion of ions occur?
acini
what do salivary secretions contain and what are they typical of
ptyalin (alpha amylase)
ECF
where does the 2nd stage of salivary secretion occur?
salivary duct
give the reabsorption / secretion of ions and whether it is passive or Active transport
Na - active reabsorption
Cl - passive reabsorption
K - active secretion
HCO3- (bicarb) - active/passive secretion
TRUE or FALSE
nervous regulation of salivary secretion is normally parasympathetic system?
TRUE
The facial nerve supplies what ganglion and gland?
submandibular ganglion
submandibular and sublingual glands
the glossopharyngeal nerve supplies what ganglion and gland?
Otic ganglion
parotid gland
what chief cells secrete?
how is their release stimulated?
pepsinogen and intrinsic factor
Ach from Vagus nerve or gastric enteric nervous plexus or acid in stomach
what do parietal cells secrete?
HCl
What ion leaks outside the cell but is transported back in by the ______ pump?
K+
by H-K ATPase pump
what ion is reabsorbed into the cell due to the _______ pump?
Na+
Na-K basolateral pump
How are chloride ions secreted?
through chloride channels into the canaliculi
what are the 2 forms of gastrin and which is more abundant?
G-34 and G-17 (more abundant)
What is gastrin released by?
in response to proteins in the pyloris
what does gastrin cause?
enterochromaffin-like cells to release histamine
what does histamine do?
cause secretion of HCl
what are the 3 phases of gastric secretions?
cephalic
gastric
intestinal
what are the digestive enzymes for proteins?
what are they secreted by?
trypsin, chymotrypsin, and carboxypolypeptidase
trypsin inhibitor
glandular cells
what is the digestive enzyme for carbs?
pancreatic amylase
what is the digestive enzyme for fat?
pancreatic lipase, cholesterol esterase, phospholipase
where is Ach from?
PS nerves and enteric nervous system
what stimulates CCK release?
what is the result of the release?
presence of food in upper intestine
increase in secretion of pancreatic enzymes
what stimulates secretin’s release?
what does it release?
presence of acidic foods in upper intestine
large amounts of sodium bicarbonate
what stimulates release of bile from the gall bladder?
presence of fatty food in the duodenum
how is bile concentrated in the gall bladder?
by active transport of sodium ions, secondary absorption of chloride ions and water
outline the synthesis of bile salts in the liver
cholesterol converted to cholic acid or chenodeoxycholic acid, then conjugated with glycine or taurine
what are the functions of bile?
emulsify fat
complex with lipids to form micelles for absorption
what are the causes of gallstones?
too much absorption of water from bile
too much absorption of bile acids from bile
too much cholesterol in bile
inflammation of the epithelium
what do Paneth cells secrete?
alpha defensins
what do goblet cells secrete?
mucous
what do enterocytes secrete?
water and electrolytes, also reabsorb it
Describe the absorption of glucose in the small intestine
Sodium secondary Active co-transport mech
what does the absorption of peptides/aa in small intestine use?
sodium co-transport mech
how are fats in the small intestine absorbed
by micelles and chylomicrons
