Water-Soluble Vitamins Overview Quiz

Vitamins

• Water-soluble vitamins are characterized by being easily excreted in urine, non-toxic, and not stored in the body.
• Vitamin A is a provitamin that can be converted into Vitamin A inside the body.
• Vitamins A, D, E, and K are classified as fat-soluble vitamins.
• The main characteristic of fat-soluble vitamins is that they are stored in the body and can be toxic in high doses.

Ketogenesis

• The main cause of the formation of ketone bodies (KB) in the fasting state is the breakdown of fatty acids in the liver.
• The enzyme HMG-CoA synthase is considered the key enzyme of ketogenesis.
• In extrahepatic tissues, ketone bodies are primarily used as an energy source.

Ketolysis

• During ketolysis, acetoacetate is converted into acetyl-CoA, which is then used in the citric acid cycle.
• The enzyme 3-hydroxybutyrate dehydrogenase is responsible for the oxidation of 3-hydroxybutyrate to acetoacetate in extrahepatic tissues.
• The brain is the tissue that lacks the enzyme necessary for metabolizing ketone bodies.

Ketoacidosis

• Acetone, a minor side product of ketone bodies, is exhaled through the lungs.
• Patients with type 1 insulin-dependent diabetes mellitus (DM) develop ketoacidosis when they have low insulin levels and high glucagon levels, leading to increased glucose production and ketone body formation.
• Patients with type II non–insulin-dependent diabetes mellitus (NIDDM) are much less likely to show ketoacidosis due to their insulin resistance, which leads to higher insulin levels and lower glucagon levels.