Fat soluble vitamins and fat metabolism

Retinol

A form of vitamin A that comes from animal sources and is essential for vision, reproduction, growth, epithelial tissue, and immune functions.

Beta-carotene

A provitamin A found in plants that is inefficiently converted to retinol in the body.

Vision

Dependent on retinal, the aldehyde derivative of retinol, which is crucial for the isomerization process in the visual cycle.

Retinoic acid

A hormone derived from retinal that plays a role in epithelium regeneration by activating gene transcription.

Vitamin A Deficiency

Can lead to night blindness (nyctalopia), loss of visual cells, xerophthalmia, and other serious health issues.

Calciol

A form of vitamin D synthesized in the skin upon exposure to sunlight, essential for calcium absorption and bone health.

Vitamin D Synthesis

Involves several steps including absorption, hydroxylation in the liver and kidney, and activation of the active form of vitamin D.

Vitamin D Functions

Regulates calcium homeostasis, bone health, and is crucial for preventing conditions like rickets and osteomalacia.

Tocopherols

Compounds that act as antioxidants in lipids, protecting cells from oxidative damage.

Vitamin K

Essential for blood coagulation and bone formation, existing in various forms like phylloquinone and menaquinones.

Fatty Acid Breakdown

Involves beta-oxidation, acetyl-CoA decomposition, and oxidation of NADH and FADH2 in the electron transport chain for energy production.

Ketone Body Synthesis

Occurs when excess acetyl-CoA from fatty acid breakdown is converted into ketone bodies in the liver mitochondria for energy utilization in extrahepatic tissues.

Non-essential fatty acids

Saturated fatty acids with an even number of carbon atoms that can be synthesized in humans and are not required in the diet.

Essential fatty acids

Unsaturated fatty acids with double bonds beyond carbon atom 10 that must be obtained through the diet, including linoleic (omega-6) and α-linolenic (omega-3) acids.

Fatty acid synthesis stages

Priming, initiation, condensation, elongation, reduction, and release of palmitic acid from the fatty acid synthase complex.

Characteristics of fatty acid synthase

Large enzyme with two identical subunits, each containing seven catalytic activities and an acyl carrier protein segment with a free sulfhydryl group.

Termination of fatty acid synthesis

The release of palmitic acid from the fatty acid synthase complex by the palmitoyl-thioesterase domain.

Regulation of fatty acid synthesis

Central regulatory point at acetyl-CoA carboxylase, which inhibits CPTI and controls the balance between fatty acid synthesis and oxidation.

Elongation of C-atom chain

Process of adding two-carbon units to fatty acids, primarily catalyzed by the microsomal fatty acid elongation system in the smooth endoplasmic reticulum.

Synthesis of non-essential unsaturated fatty acids

Production of unsaturated fatty acids by desaturases in the smooth endoplasmic reticulum, using NADH as an electron source.

Metabolism of essential fatty acids

Essential fatty acids act as substrates for the synthesis of complex lipids, eicosanoids, and play a crucial role in cellular membrane formation.

Synthesis of eicosanoids

Compounds derived from arachidonic and other polyunsaturated fatty acids, synthesized in various tissue cells to regulate functions like inflammation, blood clotting, and smooth muscle contraction.