9 28 Metabolism and Glucosogen Insilin-Table 1

Question 1

what if the blood glucose levels drop?

Answer 1

then hypoglycemia and you get a epinepherin response to get jittery and sweaty etc. then goes to nervous system shut-down and coma.

Question 2

what if too much glucose in the blood

Answer 2

Eye, Kidney, Nerve, and heart disease damage (diabetes)

Question 3

what happens to insulin after a meal with sugar?

Answer 3

the level of it spikes

Question 4

what is insulin and its functions?

Answer 4

Comes from the Beta cells it signals growth, glucose uptake; signals anabolic pathways (most potent anabolic hormone); glycogen synthesis; Inhibits release of fatty acids. [[Just eaten build and store potent anabolic hormone!]]

Question 5

what would be expected to happen to someone who makes no insulin?

Answer 5

low muscle mass, low protien synthesis; spiking blood glucose levels;

Question 6

what if you have insulinoma?

Answer 6

over expression of blood insulin – Hypoglycemia: seizures; irritable; sweaty; jittery; weight gain;

Question 7

what pathways in the liver would be inhibitted by insulinoma?

Answer 7

gluconeogenisis is inhibited, glycogen breakdown inhibited

Question 8

the endocrine cells in the pancreus:

Answer 8

the pancreatic islet cells. Beta-cells: Insulin; Alpha-cells: Glucagon

Question 9

When (compared to glucose in the blood) is insulin released?

Answer 9

when blood glucose reaches 80mg/dL and insilin is released within munuties.

Question 10

how does glucose lead to insulin release?

Answer 10

glucose comes in through Glut 2: glycolysis: TCA etc.: ATP conc. up: ATP stops the K+ channels and won’t let K+ out: Increase cell potential (depolariztion): allow Ca2+ channels to open: Ca2+ binds to Insullin vesicles and cause them to bind to the plamsa membrane and be released.

Question 11

what is glucagon and what does it do

Answer 11

comes form the alpha cells in the islets: insulin counter regulatory that increases blood glucose. Signal in the liver to release glucose into the blood.

Question 12

what is the primary target of glucagon?

Answer 12

liver

Question 13

how does muscle and most cells in the body reacte to glucagon

Answer 13

they don’t they don’t have receptors

Question 14

how is the liver targeted by the pancreatic hormones?

Answer 14

the portal vien right to the liver means the liver sees 4X the level of hormone.

Question 15

how does insulin act on the alpha cells

Answer 15

appears to have a paracrine effect and inhibit the release of glucagon

Question 16

how does the flux of glucose affect glucagon

Answer 16

drop in glucose means a rise in glucogon

Question 17

What type of signalling pathway is glucagon?

Answer 17

G-protien coupled receptor that leads to transcription regulators and other effector protien changes

Question 18

What type of signalling pathway is Insulin?

Answer 18

Receptor Tyrosine kinase that leads to effector proteins and transcription regulators.

Question 19

what is glycogen ultimately?

Answer 19

A source of glucose storage

Question 20

What are the main parancymal tissue cells of the liver?

Answer 20

hypatocytes

Question 21

what is the purpose of glycogen in hypatocytes

Answer 21

to store energy for release into the blood stream for use in other organs

Question 22

why would we want to store a highly branched glycogen instead of startch?

Answer 22

because we can add and take off glucose from all of the many branch points in glucose!

Question 23

how do we make glycogen?

Answer 23

we make UDP-glucose; add this to the branch points of glycogen by glycogen synthase; then when the branch is long enough a transferase moves the brach over to a new spot on the chain of glucogen

Question 24

how do we break down glycogen?

Answer 24

phosphorylase trims off the glucose and then debranching enzyme takes the little branches and adds them to the longer branches to allow phosphorylase to continue to pluck off glucose.

Question 25

what is a phosphorylase vs. phosphatase vs. kinase

Answer 25

phosphorylase activates phosphate to do the cleavage of glucose; phosphatase activates water to break off a phosphor group; kinase uses ATP to add phosphor group

Question 26

what effect does insulin signaling have on hepatic glycogen?

Answer 26

synthesize more of it!

Question 27

what effect does insulin signaling have on muscle glycogen

Answer 27

synthesize more of it!

Question 28

what effect does glucagon signaling have on hepatic glygcogen?

Answer 28

break it down!

Question 29

what effect does glucagon signalling have on muscle glycogen

Answer 29

no effect!!! (there are no receptors)

Question 30

what effect does epineprine signaling have on hepatic glycogen?

Answer 30

stimulate breakdown so you get more energy

Question 31

waht effect does epinerprine signaling have on muscle glycogen?

Answer 31

stimulate breakdown so you get more energy!

Question 32

what is special about glucose 6-phosphatase

Answer 32

it allows the removal of phosphase off of glucose 6 phosphatase to get just glucose that can go out the GLUT 2 transporter to the blood stream!

Question 33

what does a phosphatase do?

Answer 33

it removes phosphase

Question 34

what does a dehydrogenase do?

Answer 34

Oxidize a substrate to give NADH or FADH

Question 35

what does a kinase do

Answer 35

add a phosphate

Question 36

what does a cylcase do?

Answer 36

forms a cyclic compound

Question 37

what do the blue arrows on the metabolic pathway?

Answer 37

occurs only in or primarily in hepatocytes

Question 38

how do we maintain blood glucose level?

Answer 38

at about 3 to 4 hours after eating we have a rise in hepatic glycogen, then at about a day that response goes off, and then hepatic gluconeogenesis takes over and goes on until die!

Question 39

what is glucagon’s effect on liver glycogen synthesis and breakdown

Answer 39

glucagon’s G-protien receptor binds and tells us we need more glucose in blood with the goal of activating glycogen phosphorylase and getting glucose out of the cell! therefore we will decrease glycogen synthase activity! this is throuhg: The G-protien receptor doing: 1. Increasing cAMP which increases the activity of Protein kinase A which does two things: 1. phosphorylate glycogen synthase to stop the production of glycogen and 2. phosphorilates phosphorylase kinase, which then phosphorlates glycogen phosphorlase and allows the release of glucose.

Question 40

what is insulin’s effect on liver glycogen synthesis and breakdown?

Answer 40

Insulin binds to the tyrosine kinase receptor that acts on AKT that acts on PP1 that then does two things: 1. removes the phosphor on glycogen synthesis to activate it (phosphorlase activity); and then it removes phosphor off phosphorylase kinase, and the phosphorlase off of glycogen phosphate to turn off the release of glucose to the blood stream. (basically the opposite of what glucogon does!

Question 41

when glucose is low and insulin is low and glucagon is high:

Answer 41

glycogen goes to glucose in the liver and this goes to the RBC and then to the brain etc.!

Question 42

The stores of glycogen in the liver are limited, so how do we get more glycogena to supply the liver to supply body with glucose after the short term response to glucagon wears off?

Answer 42

TG (little piece of glycerol) from adipose goes to the liver; or Protein from muscles and the lactate from RBC are converted to pyruvate and that goes to the liver.

Question 43

how do protiens end up giving us glucose

Answer 43

many go through oxyloacitate then up the glycolysis chain backwards to glucose. (some go through pyruvate as well)

Question 44

what is the one place where insulin inhibits an anabolic pathway

Answer 44

it inhibits gluconeogenisis

Question 45

why can’t we use the fatty acid carbons to make oxyloacitate to make glucose?

Answer 45

becuase the carbons from the fatty acids are used to just produce CO2 in the TCA cycle and you don’t get any net carbons out of the fatty acids to produce more oxyloacitate

Question 46

which steps in gluconeogenisis are not just the reverse of glycolysis?

Answer 46

the irreversible steps: The first step of glycolysis that adds Phos. to glycolysis; the third step that makes bis-p from single phosph. fructose, and the last step: pyruvate kinase.

Question 47

how do we get around the non-reversible steps in glycolysis for gluconeogenisis?

Answer 47

4 enzymes specific to gluconeogenesis: 1. pyruvate carboxylase 2. phosphoenolpyruvate carboxykinase (PEPCK) 3. fructose1,6 bisphoshpatase 4. glucose 6-phoshpatase

Question 48

gluconeogenisis is along time-line process so how is it regulated?

Answer 48

transcriptionally regulates the expression of the 4 enzymes that are needed for gluconeogenisis

Question 49

what if you have been fasting for a while how do you get to gluconeogenisis?

Answer 49

Glugagon binding to the G-protien receptor and increasing cAMP and protien kinase A can activate a transcritption factor CREB that will aid in making PEPCK.\

Question 50

what if you eat a meal now what happens to gluconeogenisis

Answer 50

Insulin binding to TKR activates Akt that activates PP1 that will de-phoshporilate CREB and turn off the transcription of PEPCK. It will also posphorilate the other transcription promoters for gluconeogenesis.

Question 51

where do hepatocytes get the energy for gluconeogenisis?

Answer 51

from oxydating fats!

Question 52

what are the short and long term responses to fasting?

Answer 52

glucagon signals glucose release form glycogenolysis short term and from gluconeogenesis long term. this is of course to prevent hypoglycemia.

Question 53

what level of glucose in the blood is normal?

Answer 53

70-100 mg/dl