Fat metabolism Flashcards
What are the functions of nonessential lipids?
- act as energy source
- isolate against cold
- protect vital organs against damage
What is the function of essential lipids?
must be eaten to serve as precursors of essential chemical messengers
Which fatty acids have a straight carbon chain without double bonds?
Saturated fatty acids
Which double bond makes a bend in unsaturated FA? (cis or trans)
Cis FA
What kind of FA is easily oxidized?
- Unsaturated
- Gives an unpleasant taste and odor
Which FA has the lowest melting point? (saturated or unsaturated)
- Unsaturated
- Oil
Hvilke slags fedtsyrer indeholder hhv. animalsk og plantefedt mest?
Animalsk: mættede/saturated
Plante: Umættede/unsaturated
Which are the most important essential fatty acids, and which ratio of them is best to have in the diet?
- linoleic acid = omega 6
- alfa-linoleic acid = omega 3
- 4:1 ratio of omega 6 to omega 3
Where can PUFAs be found in the body? (PUFA = poly unsaturated fatty acid)
- In blood as unesterified FA
- Esterified to more complex lipids such as cholesteryl esters and phospholipids
- Converted into oxylipin
What effect does oxylipin have in the body?
Regulate inflammation, pain response, cell adhesion, migration and proliferation, apoptosis, angiogenesis, blood coagulation
What does high and low levels of leptin secretion signal?
- High levels signal sufficient energy and gives a feeling of satiety (mæthed)
- Low levels stimulate food intake
When is adiponectin secreted from the adipocytes and what does it signal?
- When in caloric restriction
- Increases breakdown of fatty acids
- decreases gluconeogenesis
How are phospholipids composed?
- one glycerol
- two fatty acids
- one phosphate
- one amino alcohol
What are the four principal phospholipids in animal tissue?
- phosphatidylinositol
- phosphatidylserine
-Phosphatidylethanolamine - phosphatidylcholine
Adioocytes in (VAT or SAT?) are more metabolically active, has a greater capacity to generate free fatty acids and are more insulin resistent
VAT = visceral adipose tissue
Cholesterol changes the membrane in fluidity in what way?
- Decreases fluidity at high temperature
- Increases fluidity at low temperature
(VAT or SAT?) is the most active in absorption of circulating free FA and TAG
SAT = subcutaneous adipose tissue
When and why does blood plasma appear cloudy/turbid?
After a meal with high fat content, due to the insoluble chylomicrons containing high levels of TAG
Hvilken slags molekyler fragter fedtsyrer fra leveren til væv? Hvilken pathway er det en del af?
VLDL. Den endogene pathway
Fat is stored as __ in adipose tissue and can be mobilized by the reaction __, which liberate __ and glycerol.
Insert: ( Beta-oxidation, FFA, TAG)
TAG, Beta-oxidation, Free fatty acids
Which hormones are key regulators in FFA oxidation and TAG synthesis?
Insulin stimulate TAG synthesis.
Glucagon stimulates FFA oxidation
(Insert glucose og fatty acid)
__ is the preferred energy source and __ is
saved when whenever possible.
Fatty acids, glucose
When and where are ketone bodies produced?
In the liver in times of caloric restriction, or lack of carbohydrates in the diet
How are ketone bodies used as energy source?
Brain or muscle tissue convert ketone bodies to acetyl CoA, which take part in the citric acid cycle
What decreases the melting point of lipids the most?
Polyunsaturated fatty acids with cis bonds
Which lipoproteins transports fat from the intestine to the liver?
Chylomicron remnants and chylomicron
How is atherosclerosis developed? (åreforkalkning)
Accumulated oxidized LDL is taken up by macrophages and over time the macrophages will develop into foam cell
β‐oxidation refers to the sequential removal of two‐carbon units from acyl chains, what is the end product?
Acetyl‐CoA
What kind (cis/trans) of fatty acids are found in the human body?
Mostly cis ‐fatty acids, however some trans are found in the eyes
Where does β‐oxidation take place in the cell?
In mitochondria and peroxisome
How do fats play a role in cell signaling?
Membrane inositol phospholipids are mediators of hormone and neurotransmitter action
(se f.eks. insulin signallering, PIP2 og PIP3)
How do chylomicrons in entereocytes within the small intestine enter the exogenous lipoprotein pathway?
Via the lymph system
TAG is hydrolysed by lipoprotein lipase, found on the surface of endothelial cells lining capillaries.
Where is VLDL synthesised?
In the liver.
Metabolised to LDL
What are the carriers of TAG?
Chylomicrons and VLDL
What transports cholesterol?
LDL and HDL
Which two fatty acids are essentiel and why?
Linoleic acid and alpha-linolenic acid cannot be synthesised by animal cells and are therefore essentiel.
They give rise to the n-6 and n-3 polyunsatturated fatty acids through desaturases and elongases
Mention the type of sterols in animals and plants
Animal sterol: Cholesterol
Plant sterol: Phytosterol
What is the function of the citrate shuttle?
The citrate shuttle transports acetyl-CoA via Citrate across the inner mitochondrial membrane (both ways)
Important for the fatty acid synthesis in the cytosol
