B2.041 Metabolism and its Regulation Pt. 1 Flashcards Preview

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Flashcards in B2.041 Metabolism and its Regulation Pt. 1 Deck (55)
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1

what is caloric homeostasis?

in both the fed state and fasting, a healthy body keeps the same amount of "calories" available in the blood

2

what are calories?

fuel that can be metabolized to do work

3

what are the negative consequences of having too much fuel in the blood?

generation of too many electrons via oxidation that react with oxygen to produce ROS

4

what types of fuel does the body utilize?

carbs (glucose, fructose, galactose)
fat (triacylglycerols, free fatty acids, ketone bodies)
protein (20 amino acids)

5

where are fuels primarily stored?

liver (glycogen)
adipose (triacylglycerol and triglycerides)

6

what drives the starve-feed cycle?

increase in ADP concentrations drives fuel oxidation and oxygen consumption (respiration)

7

define glycolysis

conversion of glucose to pyruvate or lactate

8

define glycogenesis

conversion of glucose to glycogen

9

define lipogenesis

conversion of carbon of glucose and amino acids to fat

10

what is the function of the pancreas in the well fed state?

pancreatic B cells produce insulin

11

how does the liver process fuel in the well fed state?

liver is glycogenic, glycolytic, and lipogenic

12

how does the muscle process fuel in a well fed state?

muscle is glycogenic

13

how does adipose tissue process fuel in a well fed state?

adipose is lipogenic and stores TAG

14

how do red blood cells derive energy?

need constant supply of glucose for anaerobic respiration, no mitochondria

15

what is the function of the pentose phosphate pathway?

produces NADPH
NADPH is a reducing agent that keeps glutathione reduced and fights oxidative stress

16

list the glucose transporters and their locations in the body

GLUT1- RBC
GLUT2- liver
GLUT3- brain tissue
GLUT4- adipose, muscle, heart

17

how do blood glucose and liver glucose compare?

very similar bc all blood filtered through liver via portal vein

18

what do glucuronides do?

solubilize insoluble compounds

19

how does the body lower the amount of fuel in the blood during the well fed state?

synthesis and storage of glycogen in the muscle and liver
synthesis of fat in the liver, release of fat into the blood, uptake and storage of fat in the adipose tissue

20

what state is the body locked in during obesity?

fed state
due to overconsumption of high energy fuels

21

what is the relationship between insulin and glucagon in obesity?

insulin is very high
glucagon is very low
high I/G ratio
drives fat synthesis

22

what is the rate limiting enzyme for fatty acid synthesis?

acetyl CoA carboxylase

23

what is lipogenesis from glucose?

occurs in liver in well fed state
requires lots of glucose for glycolysis to produce pyruvate and for the pentose phosphate pathway to produce NADPH

24

why does lipogenesis require mitochondria?

formation of citrate which carries acetyl groups from the mitochondrial matrix space to the cytosol for fatty acid synthesis

25

for what tissues is glucose a primary fuel?

brain, RBCs, white muscle, kidney medulla, macrophages

26

for what tissues are fatty acids an important fuel?

heart, skeletal muscle, liver, kidney

27

why are ketone bodies important?

4 carbon compounds made from fatty acids
water soluble fat calories
important in heart, skeletal muscle, and kidney

28

for what tissues are amino acids an important fuel?

liver and gut (glutamine)

29

what is the distinction between heavy calories and light calories?

heavy calories: 1 lb of glycogen = 4 lbs total due to water uptake
light calories: 1 lb of fat = 1 lb due to fat being dry and not taking up water

30

when does hepatic gluconeogenesis become important during starvation?

increases before exhaustion of hepatic glycogen
begins rising at 4 hours and peaks at 2 days