Brainscape's Knowledge GenomeTM

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


See full index

MEH (Milly's) > Lipid Metabolsim > Flashcards

Lipid Metabolsim Flashcards

1
Q

What are the 3 classes of lipids?

A

Fatty acid derivatives
(Fatty acids, triacylglycerols, phospholipids, eicosanoids)
Hydroxyl-methyl-glutaric acid derivatives / HGM compounds (ketone bodies, cholesterol, cholesterol esters, bile acids and salts)
Vitamins (A, D, E, K) - cannot be made in the body

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

What is the main function of triacylglycerols?

A

Fuel storage for prolonged aerobi exercise, stress situations such as starvation, during pregnancy and insulation

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

Storage of triacylglycerols is under normal control. Name the hormone that promotes the storage of fat?

A

Insulin

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

Storage of triacylglycerols is under normal control. Name the hormones that reduced the storage of fat?

A 
Glucagon
Adrenaline
Cortisol
Growth hormone 
Thyroxine

*hormones that are causing processes to happen that require energy

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

What is the first stage of triacylglycerol metabolism?

What are the products? What does this process require?

A

Hydrolyses by pancreatic lipase in the small intestine

Glycerol and fatty acids are produced

Requires bile salts and (protein factor) colipase

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

Where is glycerol metabolised?

A

In the liver

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

*fact

A

Arachidonic acid is an important polyunsaturated fatty acid (essential fatty acid) as it is the starting point for the synthesis of the eicosanoids, which are a family of signaling molecules in the body, including prostaglandins.

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

What is stage 2 of lipid metabolism?

A

Catabolism of fatty acids

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

What is lipolysis and why does it occur?

A

It is when adipose tissue triacylglycerols are hydrolysed by the enzyme hormone-sensitive lipase to release fatty acid and glycerol

It happens when the body is subjected to stress situations ie aerobic exercise, starvation, lactation

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

Why hormones effect lipolysis and how?

A

Activated by; adrenaline, glucagon, growth hormone, cortisol, thyroxine

Inhibited by; insulin

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

What is the enzyme that catalyses the lipolysis reaction?

A

Hormone sensitive lipase

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

How are fatty acids transported around the body?

A

Bound non covalently to albumin - called non esterified fatty acids (NEFA) or free fatty acids (FFA)- in the blood

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

By what process are fatty acids oxidised to release energy and where does it occur?

A

Beta oxidation

In mitochondria

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

Why does beta oxidation of fatty acids not occur in the CNS?

A

Because fatty acids do not readily cross the blood-brain barrier

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

In order to be oxidised, fatty acids need to be activated. How are they activated?

A

By linking to coenzyme A via the S atom forming a high energy of hydrolysis bond

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

How does activated fatty acid get into mitochondria?

A

By using the special transport system that uses carnitine to shuttle the fatty acid

*this system plays an important role in regulation the rate of fatty acid oxidation by controlling their entry into mitochondria

17
Q

What inhibits the transport of activated fatty acid into the mitochondria for metabolism? Why?

Why is this process important?

A

Malonyl CoA

It is an intermediate in the synthesis of fatty acids

It prevents fatty acids newly synthesised in the cytoplasm from being immediately transported into the mitochondria and being oxidised.

18
Q

How would someone who has a defective mitochondrial fatty acid transport system present?

A

With a poor exercise tolerance

Unusually large amounts of triacylglycerols in their muscles cells

19
Q

Is beta oxidation of fatty acids an aerobic or anaerobic process?

A

Aerobic, it cannot occur in the absence of oxygen since this is require for stage 4 of catabolism to re-oxidise the NADH and FAD2H formed.

20
Q

Where is the major site of lipid synthesis in the body and name an important intermediate in lipid biosynthesis?

A

Liver

Acetyl-CoA

21
Q

What are the 3 ketone bodies produced in the body? How are they produced?

A

Acetoacetate -synthesises in the liver from acetyl CoA

Acetone- arises form the spontaneous decarboxylation of acetoacetate

Beta-hydroxybutyrate - synthesised in the liver from acetyl CoA

22
Q

The normal concentration of ketone bodies in circulation is low (<1mmol/L) but this can increase. What two situations would it increase and what are the names given to these types of raised ketone body conc.

A

Starvation - physiological ketosis

Untreated type 1 diabetes- pathological ketosis

23
Q

What do you call it when there are ketone bodies in urine?

A

Ketonuria

24
Q

What causes ketoacidosis?

A

Acetoacetate and beta-hydroxbutyrate - relatively strong organic acids, when present in the plasma they can cause acidosis

25
Q

Where might acetone be excreted? How can this be used to diagnose diabetes (type 1)

A

Via the lungs

The characteristic smell of acetone (nail varnish remover) can often be smelt on the breath of someone with diabetes (untreated)

26
Q

What enzymes are used in the synthesis of ketone bodies and how are these controlled?

A

Lyase and reductase- controlled by insulin/glucagon ratios

27
Q

When the insulin;glucagon ratio falls what is the effect on lyase and reductase (enzymes involved in the synthesis of ketone bodies)? What is result on the overall production of ketone bodies

A

Lyase-activated
Reductase-inhibited

Ketone body formation is activated.

28
Q

When the insulin;glucagon ratio increases, what is the effect on lyase and reductase (enzymes involved in the synthesis of ketone bodies)? What is synthesised?

A

Lyase-inhibited
Reductase- activated

Ketone body formation is inhibited and cholesterol synthesis occurs

29
Q

What two things are needed for the synthesis of ketone bodies to occur?

A
  • fatty acids to be available for oxidation in the liver following excessive lipolysis in adipose tissue -this supplies the substrate
  • the plasma insulin/glucagon ratio to be low, usually due to a fall in plasma insulin- this activates the lyase and inhibits the reductase
30
Q

Why are ketone bodies wanted in the body?

A

They are important fuel molecules that can be used by all tissues containing mitochondria

They provide spare glucose in early starvation/diabetes

They are converted to acetyl- CoA and this is subsequently oxidised via stage 3 of catabolism (TCA cycle)

31
Q

Give an example of an essential polyunsaturated Fatty acid

A

Linolenic acid

31
Q

What are the broad steps involved in beta oxidation?

A

Activation- energisation of molecule in cytoplasm

Moving- conversion to molecule that is capable of being transported into mitochondria (use carnitine shuttle)

Acetyl CoA production- cleaving and oxidising 2 carbons with every cycle

32
Q

How do statin drugs work and when would you use them?

A

They are used to inhibit the action of the HMG-CoA reductase enzyme which converts HMG-CoA into cholesterol.

It is used to treat hypercholesterolemia

33
Q

What is a test for diabetes

A

Checking for ketonuira (ketone bodies in urine)

34
Q

Outline the process by which triacylglycerols would be used to generate energy in the patient during exercise

A

1) broken down by hormone sensitive lipase, hydrolyses TAGs
2) fatty acid transported bound to albumin to tissues
3) released and activated- bound to CoA
4) moved into mitochondria by carnitine shuttle
5) beta-oxidation occurs
6) acetyl CoA produced enter the TCA cycle

MEH (Milly's) (39 decks)

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