Week 3 - Lipids Part 2 Flashcards
(101 cards)
What does MCAD cause ?
Liver damage at an early age due to the inability to metabolise fats during fasting leading to hypoglycemia.
What process does MCAD limit?
Gluconeogenesis
What is the treatment for MCAD?
Frequent feeding, avoidance of fasting and carnitine supplementation
What are the main characteristics of Zellweger Syndrome?
Defects in the import of enzymes into peroxisomes.
Accumulation of very long chain fatty acids in neuronal tissue.
What is the treatment for Zellweger Syndrome?
Fibrates - a class of hypolipidemic drugs that act by inducing peroxisomal proliferation in the liver.
An increased peroxisome number leads to an increased?
VLCFA turnover
What are the two types of fatty acid?
- double bonds 3 carbons from methyl end (w-3 fatty acids)
- 6 carbon from the methyl end (w - 6 FA) - are required for the synthesis of eicosanoids
What are eicosanoids a derivative of?
Arachidonic and eicosapentaenoic acids which are generally taken in from the diet and incorporated into membranes.
What are eicosanoids?
They are poly unsaturated FAs
The precursor PUFA of eicosanoids is released from what and by the action of what?
membrane phosphatidylcholine by the action of phospholipase A2
Eicosapentaenoic acids competitively inhibit the oxygenation of arachidonic acid by enzymes?
Cyclooxygenase and lipoxygenase
What responses do the eicosanoids alter in the body?
Inflammatory, hypersensitivity and allergenic responses
How do eicosanoids act through?
They act through GPCR - have tissue specificity.
Do eicosanoids act on close cells?
Yes, those in close proximity
What are the 3 families of eicosanoids?
Prostaglandins, thromboxanes and leukotrienes
Are eicosanoids stored in cells?
They are not stored within cells, but are synthesized as required in response to hormonal stimuli.
What is the role of Cyclooxygenase I?
in healthy tissue, it is expressed in all tissues and in particular blood cells - responsible for the synthesis of prostaglandins and thromboxane’s including A2
What is the role of Cyclooxygenase II?
Activates the immune system
Activation induces pain, heat, fever, swelling, inflammation through the overproduction of prostaglandin H2
What enzymes are targetted by aspirin?
Cyclooxygenase I (low dose aspirin used to prevent stroke + heart attack) and II
What are some of the roles of sterols?
- structural lipids that are present in all cell membranes
- serve as precursors to steroid hormones, bile acids and vitamin D.
- amphipathic lipids
What is the major sterol in human tissues?
Cholesterol
What are the two ways in which cholesterol enters the body?
- diet
- de novo biosynthesis
What are the 2 cholesterol transporters in the intestine?
- NPC1L1 (treats hypercholesteremia) suppressed by drug ezetimbe
- Reverse cholesterol transport
Where do most catabolic pathways exist?
In the mitochondria