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MCM Test 3 > B2.041 Metabolism and its Regulation Pt. 1 > Flashcards

B2.041 Metabolism and its Regulation Pt. 1 Flashcards

1
Q

what is caloric homeostasis?

A

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

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2
Q

what are calories?

A

fuel that can be metabolized to do work

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3
Q

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

A

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

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4
Q

what types of fuel does the body utilize?

A

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

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5
Q

where are fuels primarily stored?

A

liver (glycogen)

adipose (triacylglycerol and triglycerides)

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6
Q

what drives the starve-feed cycle?

A

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

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7
Q

define glycolysis

A

conversion of glucose to pyruvate or lactate

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8
Q

define glycogenesis

A

conversion of glucose to glycogen

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9
Q

define lipogenesis

A

conversion of carbon of glucose and amino acids to fat

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10
Q

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

A

pancreatic B cells produce insulin

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11
Q

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

A

liver is glycogenic, glycolytic, and lipogenic

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12
Q

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

A

muscle is glycogenic

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13
Q

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

A

adipose is lipogenic and stores TAG

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14
Q

how do red blood cells derive energy?

A

need constant supply of glucose for anaerobic respiration, no mitochondria

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15
Q

what is the function of the pentose phosphate pathway?

A

produces NADPH

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

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16
Q

list the glucose transporters and their locations in the body

A

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

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17
Q

how do blood glucose and liver glucose compare?

A

very similar bc all blood filtered through liver via portal vein

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18
Q

what do glucuronides do?

A

solubilize insoluble compounds

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19
Q

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

A

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

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20
Q

what state is the body locked in during obesity?

A

fed state

due to overconsumption of high energy fuels

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21
Q

what is the relationship between insulin and glucagon in obesity?

A

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

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22
Q

what is the rate limiting enzyme for fatty acid synthesis?

A

acetyl CoA carboxylase

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23
Q

what is lipogenesis from glucose?

A

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
Q

why does lipogenesis require mitochondria?

A

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

25
Q

for what tissues is glucose a primary fuel?

A

brain, RBCs, white muscle, kidney medulla, macrophages

26
Q

for what tissues are fatty acids an important fuel?

A

heart, skeletal muscle, liver, kidney

27
Q

why are ketone bodies important?

A

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

28
Q

for what tissues are amino acids an important fuel?

A

liver and gut (glutamine)

29
Q

what is the distinction between heavy calories and light calories?

A

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
Q

when does hepatic gluconeogenesis become important during starvation?

A

increases before exhaustion of hepatic glycogen

begins rising at 4 hours and peaks at 2 days

31
Q

why does gluconeogenesis drop after 2 days of starvation?

A

increased production of ketone bodies by the liver and their use by other tissues

32
Q

what is the substrate most important for keeping someone alive during starvation?

A

ketone bodies

33
Q

define glycogenolysis

A

conversion of glycogen to glucose

34
Q

define gluconeogenesis

A

conversion of lactate, glycerol, and amino acids to glucose

35
Q

define ketogenesis

A

conversion of fatty acids to ketone bodies

36
Q

define proteolysis

A

conversion of proteins to amino acids

37
Q

define lipolysis

A

conversion of triacylglycerol to free fatty acids

38
Q

what does the pancreas do in the fasting state?

A

pancreatic a cells produce glucagon

39
Q

what does the liver do in the fasting state?

A

makes ketone bodies but can’t use them

40
Q

what does the anterior pituitary do in the fasted state?

A

produces GH

41
Q

what does the brain do in the fasted state?

A

uses ketone bodies but not fatty acids

42
Q

how does adipose tissue function in the fasted state?

A

adipose is lipolytic

43
Q

how are counter regulatory hormones used in the fasted state?

A

adrenal cortex produces cortisol

medulla produces catecholamines

44
Q

how does muscle function in the fasted state?

A

muscle is proteolytic

45
Q

how does the liver function in the fasted state?

A

liver is glycogenolytic, gluconeogenic, ketogenic, and proteolytic

46
Q

when does ketoacidosis occur?

A

ketoacidosis occurs when the rate of B-hydroxybutyrate + H production by the liver exceed the rate of its uptake by other tissues

47
Q

how is excretion related to ketoacidosis?

A

excretion of B-hydroxybutyrate in urine with Na+ leaves H+ in blood, resulting in ketoacidosis

48
Q

what two reactions are coupled to convert palmitate to neutral compounds?

A

ketogenesis by liver
palmitate to b-hydroxybutyrate and H+
ketolysis by other tissues
b-hydroxybutyrate and H+ to CO2 and H2O

49
Q

what state is a DM1 patient locked in?

A

starved state

50
Q

what compounds accumulate in the starved state?

A

glucose, ketone bodies, fatty acids, triacylglycerols

51
Q

what does a glucose tolerance test demonstrate?

A

slow clearance = lack of insulin and/or insulin resistance

rapid clearance depends on stimulation of GLUT4

52
Q

what are the major differences between the DM1 state and starved state?

A

person w diabetes consumes food
body does not transition to fed state with consumption of food
ability to maintain caloric homeostasis is lost in DM1
in starved state, insulin levels are low but present, in DM1 there is no insulin

53
Q

how do DM1 and DM2 manifest differently in lab tests?

A

both have high blood glucose

DM1 also has a higher pH, HCO3, and urine glucose/ketones when DM2 is usually normal

54
Q

why is high glucose toxic?

A

causes oxidative stress (too much ROS)
glycation increases
increased hexosamine pathway

55
Q

what is glycation?

A

addition of sugar to proteins without an enzyme

produces advance glycation age end products (AGEs)

MCM Test 3 (23 decks)

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