80 - Nutritional Value of Fats and Proteins Flashcards
Why can’t fat be converted to glucose?
Can’t convert Acetyl-CoA to pyruvate
Energy reserves of a normal 70kg male
400MJ of fat.
100MJ in protein
6.5MJ of glycogen
Primary fat made by humans
Palmitic acid (saturated) Some unsaturated fats (mostly from plants)
Why do free fatty acids need to be packaged into TAGs?
Detergents, acidic
Protein with which free fatty acids are packaged to form chylomicrons
ApoC-II
How do chylomicrons get into the blood?
Travel through lymphatics into the blood (through thoracic duct)
Appearance of lymph after a fatty meal
Cloudy
Blood vessels into which thoracic duct empties into
Left and right subclavian veins
How is fat mobilised for energy? 1 2 3 4
1) Adrenaline and glucagon released, both stimulate cAMP as a secondary messenger.
2) Fatty acids are carried by serum albumins.
3) Glycerol is used for glucose synthesis
4) Rarely (EG with serious exercise) amount of fatty acid released overwhelms albumin, which might contribute to a heart attack with sustained physical stress
What transports acyl-CoA into mitochondria for oxidation?
Carnitine
Role of carnitine
Transports acyl-CoA into mitochondria for beta oxidation
Amount of ATP generated per molecule of palmitate
106 (from beta oxidation of acetyl CoA)
What generates ketone bodies?
Liver mitochondria, from acetyl-CoA
What are ketone bodies?
Mixture of acetoacetate, beta-hydroxybutyrate, acetone (acetoacetate and beta-hydroxybutyrate predominate).
How can ketones lead to acidosis?
Ketones are strong organic acids.
Once glucose is exhausted, first macromolecule used to generate energy
Amino acids from protein
Why can’t the brain use FFAs, but can use ketone bodies?
FFAs are long-chain fatty acids, and can’t cross the blood brain barrier.
Ketone bodies are short-chain fatty acids, and can cross the BBB.
Use of 100g of protein in the body
1-5
Calculated by looking at nitrogen. 1g of N in faeces 15g of N in urine as urea Neurotransmitters, haem synthesised ~300g of protein made and broken down each day
Disease caused by eating only corn
Pellagra
Pellagra
Niacin, tryptophan deficiency from eating only corn.
Clinically manifests as four D’s:
Photosensitive dermatitis, diarrhoea, dementia, death
Amino acid deficiency in people who only eat corn
Tryptophan
Role of pyradoxyl phosphate
Essential for transamination (link between amino acids and keto acids)
Role of alanine in muscle
Produced by muscle to carry excess nitrogen to the liver or kidneys
Where is urea produced?
In the liver (from NH4+)
Amount of uric acid and urea excreted by a healthy human each day
0.6g of uric acid
30g of urea
Disease from not excreting urea
Gout
Gout treatment
Allopurinol.
