23: integration of metabolism (first part) Flashcards
what’s the most important organ in biochemistry?
the liver duh. it does freakin everything. processes fats, carbohydrates, proteins for diet, synthesizes and distributes lipids, ketone bodies, and glucose and converts nitrogen to urea. has lots of metabolic flexibility and rapid enzyme turnover
review sugar distribution in the liver
glucose-6-phosphate is the key point. from there sugar can go through glycolysis (form acetyl-CoA) in the liver and create energy via CAC or create fatty acids, be stored as liver glycogen, go through PPP to yield NADPH, or leave as blood glucose
23 slide 3
review amino acid distribution in the liver
amino acids are the key point. from there we can do protein synthesis, export to bloodstream, build precursors for other compounds, degrade into pyruvate or CAC intermediates to produce glucose and acetyl-coA, also contributes NH4+ which goes to urea
23 slide 4
what’s the glucose alanine cycle?
if fuel is needed, proteins breakdown in the muscle and builds up NH4+. transamination reactions put NH4 into Ala which can carry it to the liver and be turned into pyruvate and urea
review lipid distribution in the liver
fatty acids are the key point. from there we can make liver lipids, go through B-oxidation to product acetyl-CoA, or transport as lipoproteins or free FA in blood. under most circumstances, FA are the primary source of fuel in the liver
23 side 5
what is the neuroendocrine system
they system that uses hormone signaling (which involves generation of hormone in one tissue then translocation to a distant target). This is home metabolism is coordinated
endocrine vs paracrine vs autocrine
endocrine: released into bloodstream, carried to target cells throughout body
paracrine: released into extracellular space and diffuse to neighboring target
autocrine: released by and affect the same cell
list ways that hormones are diverse
structure: peptides, catecholamines, steroids, NO, Eicosanoids
function: blood volume, blood pressure, embryogenesis, digestion, sexual differentiation, hunger
how is hormone release regulated?
by a hierarchy of neuronal and hormonal signals. each continuation of the signal is amplified until we have large result by the end. each level of the cascade is subject to feedback inhibition. very similar to regulation of a biosynthetic pathway, but on an organism-wide scale
23 slide 7-8
how does the neuroendocrine system maintain carbohydrate needs?
major players are the liver, muscle, adipose tissues and they use 4 hormones: insulin, glucagon, epinephrine, and cortisol
insulin: blood glucose is too high
glucagon: blood glucose is too low
epinephrine: need a burst of activity
cortisol: I’m so stressed
what is the role of the pancreas?
secretes insulin or glucagon in response to blood glucose. a-cell is glucagon, B cell is insulin. when blood glucose is high, insulin secretion increases to promote cell uptake of glucose. when glucose is low, glucagon secretion increases to promote release of stored glucose and fat breakdown
review the effects of insulin in response to high blood glucose
23 slide 11
glucose uptake increases, glycogen synthase increases, glycogen phosphorylase decreases, store the excess as fat
review the effects of glucagon in response to low blood glucose
23 slide 12
stimulates breakdown of stores
how does fuel reserve usage change with time after eating?
immediately after eating: glucose is high, use glucose as fuel and store excess
3-5 hours after: glucose is decreasing, receive glucose from glycogen for fuel and no lipid synthesis
24 hours after: low glucose, low insulin, high glucagon, receive fuel from TAG breakdown
prolonged fasting: degradation of protein for fuel, gluconeogenesis in liver
23 slide 13
effects of epinephrine signaling
signals impending activity, mostly acting on liver, muscle, and adipose tissue. Increases delivery of O2 to tissues, increases glycogen breakdown and gluconeogensis to increase glucose for fuel, increases glycolysis (muscle) and fatty acid mobilization (adipose), increases glucagon and decreases insulin
23 slide 14
