fed and fasted states Flashcards Preview

biochem block 1 > fed and fasted states > Flashcards

Flashcards in fed and fasted states Deck (36):
1

how long does the fed/post-prandial state last?

2-3 hours

2

major storage form of fuel

triacylglycerol

3

major source of energy for overnight fast

fat

4

fates of glucose (3)

1- used for energy
2- stored as glycogen
3- converted to fat and stored

5

where is excess glucose converted to fat?

mainly liver, adipocytes are also able

6

how is fat exported from the liver?

TAG is exported from the liver as VLDL

7

what stimulates protein synthesis in mm?

insulin

8

fates of amino acids (3)

- used for protein synthesis (induced by insulin)
-catabolized for energy
-excess aa are token down- urea excreted and carbon skeletons used to make fat

9

how does the liver "trap" glucose?

glucose is trapped in the liver by phosphorylation- glucokinase phosphorylates

10

what increases the activity of glucokinase? (2)

- increased glucose concentration (bc of high km)
-insulin

11

amount of glucose used by the brain/day in the fed state

150 g/day

12

which tissues do not use insulin for glucose uptake?

CNS, liver, RBCs

13

why do RBCs require glucose for energy?

they lack mitochondria, must use glucose for glycolysis

14

site of amino acid catabolism? exception?

liver is the main site of amino acid catabolism, exception is branched chain aa (isoleucine, leucine and valine) that can be oxidized by muscle

15

how long after a meal does gluconeogenesis begin?

4 hours

16

steps in glycogenolysis (7)

- glucagon causes increase in cAMP
- cAMP stimulates PKA
- PKA phosphorylates/activates glycogen phosphorylase
- glycogen phosphorylase breaks down glycogen into glucose-1-phosphate
- g-1-p is converted to g-6-p
- g-6-p is dephosphorylated by glucose-6-dephosphorylase
- glucose is released into the blood

17

major fuel of the body during fasting

fatty acids

18

what are the breakdown products of TAG?

glycerol- used in glucoeogenesis
fatty acids- feed into TCA cycle for ATP synthesis

19

what transports free fatty acids in the blood?

albumin

20

substrates for gluconeogenesis (3)

amino acids (alanine and glutamine)
lactate- from RBC glycolysis
glycerol - from TAG

21

sites of gluconeogenesis

liver and kidney

22

2 aa used most in gluconeogenesis

alanine and glutamine

23

role of glutamine in kidney gluconeogenesis

buffers ketoacidosis

24

site of ketone body production

liver

25

when during a fast does ketone body levels increase? large increase?

18-24 hrs
large increase at 3-5 days

26

how are ketone bodies made?

partial oxidation of fatty acids in liver

27

which tissues primarily uses ketone bodies for fuel?

1*= muscle
can also be used by brain

28

main fuel during starvation

fatty acids and ketone bodies

29

what happens to glucose use by brain after ketone bodies available?

once ketone bodies available, glucose use by the brain decreases from 150 g/day to 40 g/day

30

what is "adaptation" during starvation?

when use of ketone bodies increases, demand for glucose decreases thus gluconeogenesis decreases and protein breakdown in decreased, ultimately increases survival

31

what factor will increase the use of ketones for fuel?

increased length of fast

32

what can be used as an index for protein catabolism? exception?

urea excretion, exception is GI losses or wounds

33

preferred fuel of mm in fasted, resting state

fatty acids

34

type of exercise that increases use of glucose

high intensity

35

type of exercise that increases use of fatty acids

sustained exercise

36

what will accumulate with very intense exercise?

lactate