14 topics with concise breakdowns: definitions, key facts, and class questions.
Vitamins are not just "useful supplements," but crucial enzyme cofactors and metabolic regulators. In this chapter, we analyze the pathophysiology of vitamin metabolism disorders: from general concepts of hypovitaminosis, hypervitaminosis, and the action of antivitamins to specific clinical and pathophysiological syndromes.
The section details the mechanisms of imbalance of fat-soluble (hypovitaminosis A and D, hypervitaminosis D and K) and water-soluble vitamins (B1, B5, B12, C, PP). We will examine why the toxicity of hypervitaminosis D or K is sometimes more dangerous than their deficiency, and how structural analogues (antivitamins) can shut down entire biochemical cascades.
Seminars and colloquia most frequently require a clear understanding of the pathogenesis of classic deficiencies: scurvy (vitamin C), beriberi (B1), pellagra (PP), and pernicious anemia (B12). Pay special attention to the mechanisms of tissue calcification in vitamin D excess and the principles of competitive inhibition by antivitamins—these are favorite questions of examiners.
How does hypovitaminosis differ from avitaminosis?
Hypovitaminosis is a significant depletion of vitamin stores, whereas avitaminosis represents the extreme degree of deficiency where stores are completely exhausted.
What is the main cause of hypervitaminosis development?
The main etiological cause is the increased intake of vitamins into the body. Unlike hypovitaminosis, where reduced intake or impaired absorption plays a role, here the problem lies in excess. Most often this occurs with self-administration of high doses or erroneous medical prescriptions.
In whose body can antivitamins be detected?
These chemical substances are present in the human body at absolutely any age. Their presence is part of complex biochemical processes.
Why do signs of vitamin A hypovitaminosis develop in biliary tract pathology?
Vitamin A is fat-soluble. For its emulsification and successful intestinal absorption, bile acids are mandatory; their deficiency leads to impaired absorption (malabsorption).
What reduction does vitamin D deficiency lead to at the initial stage of pathogenesis?
The primary key link is a drop in the synthesis of the active metabolite—calcitriol (D-hormone), which subsequently leads to a decrease in intestinal calcium absorption.
Why is hyperphosphatemia replaced by hypophosphatemia in the late stages of hypervitaminosis D?
Initially, vitamin D enhances the reabsorption of phosphorus in the proximal renal tubules. However, due to progressive calcinosis, the tubules are irreversibly damaged, their function drops, and phosphorus begins to be massively lost in the urine.
Master the entire topic in the "Pathophysiology" course
This is a summary. The course covers everything tested in classes and exams.
4,913 pages of study guides on all topics
Assignments and quizzes after every topic — just like in a colloquium