Lecture 19+20 Flashcards
Zellweger syndrome
defective peroxisomal biogenesis in the liver and brain
increased 26-C fatty acids (very long FA)
lead to delayed development and extensive demyelination
hepatomegaly
usually fatal in infancy
Refsum disease
Peroxisomal phytanyl CoA alpha- hydroxylase deficiency (alpha-oxidation defect)
phytanate accumulates (found in dairy)
visual defects, ataxia, polyneuropathy, skeletal manifestations
restrict branched chain fatty acids (Phytanic acid)
omega oxidation
minor pathway for FA oxidation in ER
fatty acids are converted to dicarboxylic acid
dicarboxylic acid is found in the urine when beta oxidation does not work properly (MCAD deficiency)
what are the ketone bodies?
Acetoacetate and 3-hydroxybutyrate and acetone
can be converted to acetyl coA and used for the TCA cycle
ketogenesis in liver
fatty acids go through beta oxidation to be converted to acetyl CoA
acetyl CoA is converted to acetoacetyl CoA by thiolase
acetoacetyl CoA is converted to HMG CoA by mitochondrial HMG CoA synthase
HMG CoA lyase converts HMG CoA to acetoacetate
can be spontaneously converted to acetone
or
converted to 3-hydroxy butyrate by 3-hydroxybutyrate dehydrogenase (uses NADH)
using ketone bodies in peripheral tissues?
acetoacetate is converted to acetoacetyl CoA by the enzyme succinyl CoA: acetoacetate CoA transferase or thiophorase
NOT found in liver
ketoacidosis and DM (type I)
have excessive tissue lipolysis (low insulin levels) and hormone sensitive lipase is very active
high ketone body levels
ketone bodies lost in urine
metabolic acidosis (high anion gap )
elevated 3-hydroxybutyrate
more acetone production (fruit odor)
hypoketonemia and FA oxidation disorders
low rates of beta oxidation
impaired gluconeogenesis, thus hypoglycemia
low beta oxidation = low acetyl coA
meaning ketone body synthesis is impaired
extrinsic innervation of the GI
para vs sympathetic
parasympathetic: excitatory upper GI will be vagus N and lower GI will be pelvic N preganglionics synapse on plexi postganglionics synapse on SM / cells
sympathetic: inhibitory thoracolumbar fibers (T8-L2) preganglionics = prevertebral ganglia postganglionics = plexi
intrinic innervation of the GI
uses local reflexes
myenteric plexus = control enteric motility
submucosal = regulates secretions and blood flow
gastrin
stimuli? inhibit? effects?
endocrine regulator
secreted from gastric antrum after a meal
stimuli:
small peptides and AA’s
stomach distension
vagal stimulation mediated by GrP
inhibition:
increasing acidity of the stomach
effects:
increases H secretion by the parietal cells
stimulates growth of gastric mucosa
CCK
endocrine regulator
effects: gallbladder constriction and relaxation of the sphincter of oddi stimulates pancreatic enzyme secretion stimulation of HCO3 secretion inhibits gastric emptying
stimuli:
small peptides and AA’s
fatty acids and monoglycerides
secretin
endocrine regulator
effects:
reduce acidity in the small intestine
stimulates HCO3 release
inhibit H release from parietal cells
stimuli:
H+ in the lumen of the SI
fatty acids in the lumen of the SI (D)
The incretins: GIP and GLP
endocrine function
both enhance insulin secretion in response to oral glucose intake
GIP inhibits H secretion by the parietal cells
somatostatin
paracrine regulator
short distance
secreted throughout the GI in response to H+
secretion is inhibited by vagus N
inhibits release of all GI hormones
inhibits gastric H+ release
