Fatty Acid Oxidation and Ketones Flashcards
What are the sources of energy in the body?
Carbohydrates - enough glycogen to sustain energy levels for 12 hours.
Fats - Lipid energy reserves provide energy for up to 12 weeks
Protein - Used when muscle glycogen stores fail.
What are fatty acids?
Carboxylic head group with aliphatic tail.
Hydrophilic head, hydrophobic tail
Can be saturated eg butter and unsaturated eg oil
What are most fatty acids derived from?
Most are derived from triglycerides and phospholipids.
How are lipids absorbed and transported?
- Fats ingested in diet
- Bile salts emulsify fats in small intestine, forming micelles.
- Intestinal lipase degrades triacylglycerols / triglycerides
- Fatty acids and other broken down products are taken up by intestinal mucosa
- Triacylglycerols are incorporated with cholesterol and apoproteins to make chylomicrons.
- Chylomicrons move through lymphatic system and bloodstream to tissues.
- Lipoprotein lipase is activated by apoC-11 in capillary, releases fatty acids and glycerol.
- Fatty acids enter cells and are oxidised as fuel or reesterified for storage.
What is the process of fatty acid activation?
Must be activated in the cytoplasm before they can be oxidised in the mitochondria.
Fatty acids > (ATP) > Acyl Adenylate > (CoA-SH + acyl-CoA synthetase) > Acyl-CoA
How do Acyl CoA diffuse?
If the Acyl-CoA has < 12 carbons – can diffuse through mitochondrial membrane
Most dietary fatty acids have > 14 carbons – Taken through mitochondrial membrane using the carnitine shuttle.
Explain fatty acid beta oxidation: 467689
- Oxidation - Acyl CoA +
How is Acetyl CoA used in normal conditions?
Under normal metabolic conditions most Acetyl-CoA is utilised via the TCA acid cycle to produce glucose.
A small proportion of Acetyl-CoA is converted into ketones.
How is Acetyl CoA used in increased metabolic conditions?
During high rates of fatty acid oxidation, large amounts of acetyl-CoA are generated.
This exceeds the capacity of the krebs cycle which results in ketogenesis.
Where is ketone produced?
Molecules produced by the liver from acetyl-CoA.
What is ketogeneis?
Production of ketones
What does acetoacetate undergo in ketogenesis? 35895
- Spontaneous decarboxylation to acetone
- Enzymatically converted to beta - hydroxybutyrate.
What factors affect ketogensis?
- Release of free fatty acids from adipose tissue.
- High concentration of glycerol-3-phosphate in the liver results in triglyceride production
- High demand for ATP
- Glucagon and insulin levels
What is ketoacidosis? Where does it occur?
Build up of ketones in blood when insulin level is low.
- Occurs in insulin-dependent diabetes when dose is low and demand is high
- Occurs in chronic alcohol abuse
What does patients with ketoacidosis present with?
Hyperventilation and vomiting.
