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Biochem 2 > Starvation Well fed state > Flashcards

Starvation Well fed state Flashcards

(40 cards)

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1
Q

Mechanisms that Consume Energy at Synapses

A

The brain
2% of total body weight
20% of total oxygen and energy consumption

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2
Q

Compare Km of GLUT3 to that of GLUT1

A

Km GLUT3 < Km GLUT1

(Km is the concentration of substrate which permits the enzyme to achieve half Vmax)

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3
Q

Carbohydrate metabolism with neuron

A

Glycogen synthase
is inactive
(GS is hyperphosphorylated by GSK3 ➔ubiquitin-dependent proteasomal degradation )

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4
Q

LIPID METABOLISM
-> Name the structures in red circles

A
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5
Q

Carbohydrate metabolism with LDH1

A

decreased affinity for pyruvat
➔ enters into the citric acid cycle

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6
Q

Carbohydrate metabolism with PPP

A

pentose phosphate pathway
(➔ NADPH
➔ fatty acid synthesis, free radical protection)

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7
Q

Name of this cycle

A

glutamate-glutamin cycle

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8
Q

astrocyte-neuron network
-> Identify the substances

A
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9
Q

astrocyte-neuron network
-> Name these substances

A
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10
Q

Metabolism of intestinal epithelial cells
-> What is happening in the gut?

A

2 urea cycle enzyme:

  1. Carbamoylphosphate synthetase I (CPS1)
  2. Ornithine transcarbamylase (OTC) ➔ citrulline is produced
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11
Q

Metabolism of intestinal epithelial cells
-> What is happening in the kidney?

A

2 urea cycle enzyme:
1/ Argininosuccinate synthetase (ASS)
2/ Argininosuccinate lyase (ASL) ➔ from citrulline, arginine is produced

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12
Q

Role of glutamin in proliferating cells

A

The rates of utilization of both glucose and glutamine are high in rapidly dividing cells (enterocytes, lymphocytes, tumor cells)

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13
Q

What are “Brite” cells?

A

brown adipocytes surrounded by white fat tissue

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14
Q

Sites of de novo fatty acid synthesis

A

liver, adipose tissue

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15
Q

Schematic drawing of Adipose tissue metabolism in well fed state

A
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16
Q

Schematic drawing of Adipose tissue metabolism in starvation

A
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17
Q

Schematic drawing Triacylglycerol lipolysis

Study These Flashcards
A

1) MAGL: Monoacylglycerol lipase
2) ATGL: Adipose triglyceride lipase
3) HSL: hormone sensitive lipase
4) CGI-58: comparative gene identification 58 (ATGL co-lipase)
5) PKA: protein kinase A

18
Q

Overview of acylglycerol biosynthesis
-> Name this substance

Study These Flashcards
A

Glycerol-3-phosphate

19
Q

Is Glycerol kinase present in liver and adipose tissue?

Study These Flashcards
A

Glycerol kinase present in liver but not in adipose tissue

20
Q

Conversion of glycerol
to the glycolytic intermediate dihydroxyacetone phosphate in liver
-> Name of this enzyme

Study These Flashcards
A

Glycerol kinase

21
Q

Glyceroneogenesis Is Important for which process?

Study These Flashcards
A

Triacylglycerol Biosynthesis

22
Q

The dihydroxyacetone phosphate used to make glycerol-3-phosphate for triacylglycerol synthesis comes ___ (2 sources)

Study These Flashcards
A

1l/ Glucose via the glycolytic pathway
2/ Oxaloacetate via an abbreviated version of gluconeogenesis termed glyceroneogenesis

23
Q

How many phases does glucose homeostasis have?

24
Q

When is Glyceroneogenesis necessary?

Study These Flashcards
A

Glyceroneogenesis
is necessary in times of starvation,
(when glycolysis is inhibited) since approximately
30% of the fatty acids that enter the liver during a
fast are reesterified to triacylglycerol and exported as VLDL.

25
Can Adipocytes carry out glyceroneogenesis or glucogenesis in times of starvation?
Adipocytes also carry out glyceroneogenesis in times of starvation. They do not carry out gluconeogenesis
26
Adipocytes do not carry out gluconeogenesis but contain ___
the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK)
27
Adipocytes do not carry out gluconeogenesis but contain the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) -> What is the role of this enzyme?
This enzyme is upregulated when glucose concentration is low, and participates in the glyceroneogenesis required for triacylglycerol biosynthesis.
28
Glucose homeostasis -> Characteristics of phase I (Origin of blood glucose; tissues using glucose; major fuel of brain)
Origin of blood glucose: Exogenous Tissues using glucose: All Major fuel of brain: Glucose
29
Glucose homeostasis -> Characteristics of phase II (Origin of blood glucose; tissues using glucose; major fuel of brain)
Origin of blood glucose: Glycogen - Hepatic gluconeogenesis Tissues using glucose: All except liver (muscle and adipose tissues at diminished rates) Major fuel of brain: Glucose
30
Glucose homeostasis -> Characteristics of phase III (Origin of blood glucose; tissues using glucose; major fuel of brain)
Origin of blood glucose: Hepatic glucogenesis; Glycogen Tissues using glucose: All except liver (muscle and adipose tissue at rates between II and IV) Major fuel of brain: Glucose
31
Glucose homeostasis -> Characteristics of phase IV (Origin of blood glucose; tissues using glucose; major fuel of brain)
Origin of blood glucose: Gluconeogensis; glycogen Tissues using glucose: Brains, RBCs, renal medulla, small amount by muscle Major fuel of brain: Glucose, ketone bodies
32
Glucose homeostasis -> Characteristics of phase V (Origin of blood glucose; tissues using glucose; major fuel of brain)
Origin of blood glucose: Gluconeogensis, hepatic and renal Tissues using glucose: Brain at diminished rate, RBCs, renal medulla Major fuel of brain: Glucose, ketone bodies
33
What does this slide indicate?
The fasting state: the glucogenic liver
34
What does this slide indicate?
Fuel metabolism in the liver during prolonged fasting or in uncontrolled diabetes mellitus
35
Metabolic characteristics of starvation in hepatocytes -> What are the substance and adrenergic receptors being used?
Glucagon adrenergic receptors: beta2 alpha 1
36
Metabolic characteristics of starvation in hepatocytes -> The role of pyruvate- carboxylase
anaplerotic carboxylation of pyruvate to oxaloacetate during starvation: gluconeogesis
37
Metabolic characteristics of starvation in hepatocytes -> acetyl-CoA carboxylase is inhibited by __?
Inhibited by phosphorylation, high level of palmitil-CoA, low level of citrate
38
Long term starvation➔ glucokinase expression is low or high?
Low
39
Long term starvation ➔ glucokinase expression is low -> what are the 2 consequences?
Refeeding➔glucose will not taken up by liver cells because glucokinase expression is low Consequences 1: ➔ glucose is used by extrahepatic tissue and lactate is produced (pyruvate dehydrogenase is inhibited, the source of acetyl-CoA is fatty acid breakdown during starvation) ➔ lactate enters liver cells * Consequences 2: ➔ sudden elevation of glucose level in blood ➔ Insulin level elevates➔glycogen synthesis
40
Metabolic characteristics of well- fed state in hepatocytes -> Which substance is prominent?
Insulin

Biochem 2 (38 decks)

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