Introduction and Basic Concepts of Toxicology   Introduction to toxicology 1. Three major fields of modern toxicology research:  Descriptive toxicology Mechanism toxicology Management toxicology The core is toxicological safety evaluation and health risk assessment.   2. Modern Toxicology The science that studies the damaging effects and biological mechanisms of all exogenous harmful factors (xenobiotics) on biological systems, and conducts safety evaluation and risk assessment.   3. Hygiene Toxicology The branch of toxicology directly related to preventive medicine.   4. Descriptive toxicology Through toxicology tests (toxicity identification) and population observation studies, the toxicity and toxicity characteristics of exogenous chemicals are found, and toxic and harmful substances are identified. (Provide information for safety evaluation and risk management, and provide clues for the toxic mechanism of chemicals)   5. Mechanistic toxicology Clarify th

  Types, Causes and Mechanisms of Hypoxia Hypoxia refers to a pathological process in which the metabolism, function and morphological structure of tissues are abnormally changed due to insufficient oxygen supply or oxygen use disorders in tissues. Hypoxia is a very common pathological process in various clinical diseases. Hypoxia in vital organs such as brain and heart is also an important cause of death. In addition, due to the significant decrease in arterial blood oxygen content, the tissue oxygen supply is insufficient, also known as hypoxemia (hypoxemia). Table of Contents   1 1. Commonly used blood oxygen indicators and their significance 2 2. Types, causes and mechanisms of hypoxia 2.1 2.1 Hypotonic hypoxia 2.2 2.2 Blood hypoxia 2.3 2.3 Cyclic hypoxia 2.4 2.4 Tissue hypoxia 3 3. Metabolic and functional changes of cells during hypoxia 3.1 3.1 Compensatory changes 3.2 3.2 Cell damage 4 4. Organ function and metab