Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Molecular Medicine > Feast And Famine > Flashcards

Feast And Famine Flashcards

1
Q

To list the major nutrient stores
To list the major tissues involved
To describe what occurs during feast period
To describe what happens during fasting
To describe the general function of the liver,
adrenal gland and pancreas
To explain the significance of the key hormonal controllers

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the major nutrients storage for

  1. Carbohydrates
  2. Fats
  3. Proteins
A
  1. Glycogen in liver and muscle
  2. Triacylglycerol in adipose tissue and liver (packaged into lipoproteins for export)
  3. Proteins in skeletal muscle and liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Glycogen supply glucose continuously to which organ and cell? Why?

A

Brain - Only can use ketone body and glucose due to blood-brain barrier (Lipid cannot pass)

RBC - Only can use glucose due to absent of mitochondria( Kreb’s cycle and oxidative phosphorylation in ETC) as glycolysis takes place in cytosol only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Glycogen occupies how many percent of the total weight of the following organ?

  1. Liver
  2. Skeletal muscle
A
  1. 6-8% in a well-fed adult liver
    - To maintain blood glucose levels at 5mM
  2. 1-2% in a fresh weight of muscle
    - Energy for muscle contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How to identify a well-fed or fasted/famine hepatocyte (liver cell) using an electron micrograph?

A

Well-fed hepatocyte has black spot on it while fasting hepatocyte only has minimal black dot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the process of glycogenesis in term of the involvement of molecules?
State the enzyme involved and in which state does it occur

A

Addition of glucose unit

Step 1:
UTP (Uridine Triphosphate) + Glucose-1-P ——> UDP-glucose + PPi

Step 2: (Enzyme involved - glycogen synthase)
UDP-glucose + [Glucose]n-1 ——> [Glucose]n + UDP

Occur in well-fed stage when excess glucose not used for energy generation are channeled to glycogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the process of glycogenolysis in term of the involvement of molecules?
State the enzyme involved and in which state does it occur

A

Glucose units released from glycogen to maintain blood glucose level

Step 1: (Enzyme involved - Glycogen phosphorylase)
[Glucose]n ——> [Glucose]n-1 + Glucose-1-phosphate

Occurs in the fasting state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the process involved in glycogen metabolism

A

Glucose—> Glucose-6-phosphate —>Glucose-1-phosphate—>Glycogen

Forward movement (From Glucose to Glycogen)

  1. Hexokinase
  2. Phosphoglucomutase
  3. Glycogen synthase

Backward movement ( From Glycogen to Glucose)

  1. Glycogen phosphorylase
  2. No enzyme
  3. Glucose-6-phosphatase

Synthesis and degradation occur in separate pathway and cannot occur simultaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the method of regulation of glycogen metabolism?

A
  1. Allosteric regulation

2. Covalent modification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is allosteric regulation in glycogen metabolism?

A

Positive or negative allosteric effector

Positive will induce while negative will inhibit enzyme activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the positive and negative allosteric effectors involved in glycogen metabolism?

A

Positive allosteric effectors
Glucose-6-phosphate, induce activity of Glycogen synthase to synthesise more glycogen from Glucose-1-phosphate

Negative allosteric effectors
Glucose-6-phosphate, ATP, Glucose, inhibit activity of Glycogen phosphorylase to reduce synthesis of glucose-1-phosphate from glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens in covalent modification in glycogen metabolism?

A

Enzyme is phosphorylated or dephosphorylated to activate or deactivate which is regulated by insulin, glucagon and epinephrine

Hormones involved can be divided into glycogen synthesis promoters and glycogen breakdown promoters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the glycogen synthesis promoters and glycogen breakdown promoters?

A

Glycogen synthesis promoters
Insulin - stimulate glycogen phosphorylase to convert Glucose-1-phosphate to glycogen

Glycogen breakdown promoters (counter-regulatory to insulin, induce glycogen phosphorylase)
Glucagon
Adrenaline
Cortisol (in starvation, stress)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does glucagon control glycogen phosphorylase activity?

A

Glucagon (liver) or epinephrine (muscle) bind to G-protein coupled receptor, which induce release of cAMP (2nd messenger.

PkA is phosphorylated and activated, which phosphorylate and activates phosphorylase kinase to form phosphorylase kinase-P

Next phosphorylase beta (glycogen phosphorylase) is phosphorylated and activated to form phosphorylase alpha (glycogen phosphorylase-P)

Glycogen is phosphorylated and inactivated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does insulin control glycogen synthase activity?

A

Insulin bind to insulin receptor to induce a series of signalling pathway to activate protein kinase B (PkB)

Activated PkB phosphorylate and deactivate glycogen phosphorylase which forms glycogen phosphorylase-P

Glycogen synthase is then dephosphorylated and activated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the promoter for protein synthesis and proteolysis?

A

Protein synthesis

  • Amino acid
  • Growth factors, eg IGF-1 (insulin like growth factor-1, insulin
  • Exercise

Proteolysis

  • Low amino acid
  • Low energy intake
  • Reduced growth factors, eg insulin
  • Reduced exercise
  • Stress response: glucocorticoids, eg cortisol
17
Q

What happen to the muscle during first few days of fasting?

A
  1. Rapid muscle proteolysis
  2. Liver uptake of amino acid
  3. Gluconeogenesis, amino acid conversion to glucose

Initiated by low insulin

18
Q

What happen to the muscle after prolonged fasting/ starvation?

A

Rate of muscle proteolysis decreases, parallel with the decline in glucose requirement by the brain

19
Q 
What is gluconeogenesis?
Describe in term of
Importance
Location
Substrate
Enzymes
A
  1. Maintain blood glucose levels during fasting (for brain and RBC)
  2. Liver and kidney
  3. -Amino acids (converted to intermediates of TCA cycle)
    -Glycerol
    -Lactate
    4.
    i Pyruvate carboxylase
    ii PEP carboxykinase
    iii Fructose-1,6-bisphosphatase
    iv Glucose-6-phosphatase

Gluconeogenesis is production of glucose from non-carbohydrate source

20
Q

Describe triglyceride synthesis during well-fed state

A

Glucose is converted to pyruvate through glycolysis and then to Acetyl CoA, which is the substrate for fatty acid synthesis, which eventually form triglyceride

Acetyl-CoA carboxylase converts Acetyl-CoA to Malonyl-CoA, which is the precursor for fatty acid synthesis

21
Q

State the pathway of gluconeogenesis starting from pyruvate

A

Pyruvate is converted to oxaloacetate by pyruvate carboxylase

Oxaloacetate is converted to phosphoenolpyruvate by PEP carboxlase

Phosphoenolpyruvate is converted to 2-phosphoglycerol by Enolase

2-phosphoglycerol is converted to 3-phosphoglycerol by phosphopyruvate mutase

3-phosphoglycerol is converted to 1,3 bisphosphoglycerate by phosphoglycerate kinase

1,3-bisphosphoglycerate is converted to glyceraldehyde 3-phosphate by glyceraldehyde 3-phosphate dehydrogenase

Glyceraldehyde 3-phosphate is converted to Fructose 1,6-bisphosphate by fructose bisphosphate aldolase

Fructose 1,6-bisphosphate is converted to fructose 6-phosphate by fructose 1,6-bisphosphatase

Fructose 6-phosphate is converted to Glucose 6-phosphate by phosphoglucose isomerase

Glucose 6-phosphate is converted to glucose by glucose 6-phosphatase

22
Q

Where can amino acid enters the Kreb cycle for gluconeogenesis?

A

a-ketoglutarate
Succinyl CoA
Fumarate

23
Q

When is lipolysis promoted?

A
  1. Low energy intake
  2. Low plasma glucose
  3. Low insulin
  4. High epinephrine
24
Q

How is triglyceride broken down to fatty acid?

A

Hormone-sensitive lipase is inhibited by insulin but activated by epinephrine, which converts triglyceride to glycerol and fatty acid

25
Q

What happens to fatty acid released by adipose tissue?

A
  1. Released into blood
  2. Used as energy source by muscle
  3. Oxidised to acetyl CoA in Liver to be converted to ketone bodies
26
Q

What are the examples of ketone bodies?

A

Acetoacetone
Acetone
D-3-hydroxybutyrate
B-hydroxybutyrate

27
Q

Where and when does ketogenesis take place?

A

Where: Liver, to be exported

When: During fasting to be used as energy sources of peripheral tissue

It uses excess Acetyl CoA from fatty acid oxidation

28
Q

Can brain use ketone bodies?

A

Yes, little

29
Q

What does alpha, beta and delta cells of islets of Langerhans in pancreas produce?

A

a: Glucagon
B: Insulin
D: Somatostatin (no need to know)

30
Q

When is insulin produced?

A
  1. Well-fed state
  2. High glucose level
  3. High level of amino acid and fatty acid
  4. Release of gut peptide (GLP-1, GIP)
31
Q

What are the metabolic effect of insulin?

A

Synthesis of glycogen, fatty acid and triglyceride, protein

32
Q

When is glucagon produced?

A
  1. Fasting and starvation
  2. Low blood glucose
  3. Low amino acid and catecholamines
33
Q

What are the metabolic effect of glucagon?

A

Breakdown of glycogen, protein and triglyceride

34
Q

Describe cortisol in term of

  1. Location of synthesis
  2. Function
A
  1. Zona Fasciculata of Adrenal Cortex

2. Promote glycogen backdown and proteolysis

Molecular Medicine (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions