L1. General Toxicology

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Questions and Answers

What distinguishes selective toxicity in antibiotics from other toxic agents?

They enhance human immune response against infections.

They selectively target microorganisms while being nontoxic to humans. (correct)

They are equally toxic to both humans and microorganisms.

They are lethal to all organisms.

Which statement best describes molecular toxicity?

It primarily results in behavioral changes in organisms.

It involves interactions with macromolecules and disrupts gene expression. (correct)

It only occurs in the presence of pollutants.

It exclusively affects the cellular membrane integrity.

What type of toxicity is characterized by its harmful effects on nervous system function?

Immunotoxicity

Teratogenicity

Neurotoxicity (correct)

Carcinogenicity

Which form of toxicity is directly related to uncontrolled cell proliferation?

Carcinogenicity Signup and view all the answers

What is a key factor determining toxicity at the level of organ function?

The frequency of exposure to the toxic agent. Signup and view all the answers

What aspect of drug action is considered when evaluating adverse drug reactions (ADRs)?

Their potential to cause toxicity at therapeutic doses. Signup and view all the answers

Which type of toxicity involves effects on the developmental stages of an embryo or fetus?

Teratogenicity Signup and view all the answers

Which classification of toxic agents is most accurately represented by lead and cadmium?

Industrial chemicals Signup and view all the answers

What does the concept of selective toxicity primarily refer to?

The ability of a substance to target specific cells without harming others Signup and view all the answers

Which mechanism is primarily responsible for the genetic alterations seen in carcinogenicity?

Molecular disruption that leads to DNA damage Signup and view all the answers

Behavioral toxicity primarily concerns the impact of toxic substances on which aspect?

Cognitive functions and psychological well-being Signup and view all the answers

Which of the following is NOT a factor determining toxicity?

The psychological state of the affected individual Signup and view all the answers

Paracelsus' principle emphasizes the importance of what in determining the toxic effects of substances?

The dose of the substance administered Signup and view all the answers

What is the primary target of DDT toxicity in the human body?

Central nervous system and female reproductive system Signup and view all the answers

Which mechanism describes the process where a toxicant interacts with its target leading to potential cellular dysfunction?

Interactions between the toxicant and its target Signup and view all the answers

What describes a synergistic effect in toxicological interactions?

The combined response is much greater than the sum of responses to each chemical alone. Signup and view all the answers

Which scenario best exemplifies potentiation in toxic interactions?

A non-toxic substance enhances the toxicity of a chemical when combined. Signup and view all the answers

Which of the following is NOT considered a type of antagonism in toxicity?

Cellular synergism Signup and view all the answers

In receptor antagonism, what is the main action of an antagonist?

Blocks the receptor, preventing the agonist's effect. Signup and view all the answers

Which type of toxicity would be associated with the presence of a chemical reaction that produces a less toxic product?

Chemical antagonism Signup and view all the answers

Which of these mechanisms is primarily concerned with transporting the toxicant to its target?

Delivery of the toxicant to its target Signup and view all the answers

What is one factor that can influence the toxicity level of a chemical in the body?

Duration of exposure Signup and view all the answers

What factor is primarily associated with individual susceptibility to toxic agents?

Genetic polymorphism Signup and view all the answers

Which type of exposure is defined as occurring repeatedly over several weeks but less than three months?

Subacute exposure Signup and view all the answers

What mode of exposure is likely to result in the fastest onset of toxic effects?

Intravenous administration Signup and view all the answers

Which of the following best describes a characteristic of delayed toxicity?

Observed after a lengthy time post-exposure Signup and view all the answers

In assessing toxicity, which factor has a direct influence on the determination of carcinogenic potential?

Metabolism of toxic agents Signup and view all the answers

What is the outcome of a single episode of acute exposure to benzene?

Central nervous system depression Signup and view all the answers

What defines 'cumulative toxic effect' in the context of exposure?

Accumulation of a substance causing worsening toxicity over time Signup and view all the answers

Which of these routes is NOT considered a major pathway for toxic agents entering the body?

Transdermal patch application Signup and view all the answers

Which demographic factor might influence individual susceptibility to the toxic effects of alcohol?

Gender Signup and view all the answers

What is a key factor in acute toxicity classification based on effect onset?

Amount and rapidity of exposure Signup and view all the answers

Which of the following toxicants is most commonly associated with CNS depression as an acute effect?

Ethanol Signup and view all the answers

Which of these substances is classified as having irreversible toxic effects, specifically related to CNS injury?

Lead Signup and view all the answers

What type of toxic response occurs at the site of initial exposure to a toxic agent?

Local toxicity Signup and view all the answers

Which toxicant is primarily linked to liver cirrhosis as a chronic effect?

Ethanol Signup and view all the answers

In terms of target organ toxicity, which organ is primarily affected by arsenic?

Skin Signup and view all the answers

Which of the following statements about cadmium is true regarding its toxic effects?

Cadmium targets the kidney and causes toxicity. Signup and view all the answers

Asbestos exposure is primarily linked to which type of cancer?

Lung cancer Signup and view all the answers

Which factor is NOT typically considered when assessing the toxicity of a substance?

Color of the substance Signup and view all the answers

Which compound is known for producing carcinogenic effects?

Asbestos Signup and view all the answers

What characterizes systemic toxicity?

It requires absorption and distribution of the toxicant. Signup and view all the answers

Study Notes

General Toxicology

Toxicology is the study of harmful effects of chemicals, physical, and biological agents on living organisms and the ecosystem.
Paracelsus principle: Every substance is a potential poison; the dose makes the poison.
Adverse drug reactions (ADRs) are noxious or unintended responses to a drug at therapeutic doses.
Toxicology is categorized into different subdivisions: analytical, environmental, forensic, occupational, clinical, molecular (toxicogenomics), and regulatory.

Learning Objectives

Understand basic principles, terminology, and subdivisions of toxicology, including selective toxicity.
Know the general classification of adverse drug reactions (ADRs).
Understand the Paracelsus principle.
Outline major mechanisms of toxicity (molecular, biochemical, carcinogenicity, teratogenicity, mutagenicity).
Understand factors influencing toxicity (dose, route, duration of exposure, individual susceptibility).
Know different types of toxic responses (immediate/delayed, reversible/irreversible, local/systemic) and target organ toxicity.
Understand dose-response relationships in toxicology (graded and quantal dose-response curves), important toxicodynamic parameters (TD50, LD50, threshold, NOAEL, LOAEL, ADI, TLV).

Types of Toxicity

Molecular Toxicity: Interaction of xenobiotics with biological macromolecules damaging the gene expression and signaling pathways.
Biochemical Toxicity: Harmful effects on enzymes, reactive intermediates, and ROS-causing damage to normal cellular function and accelerating cell death.
Target Organ Toxicity: Organ-level effects due to xenobiotic interactions.
Behavioral Toxicity: Adverse effects on animal and human behavior involving the PNS, CNS, and other organs.
Carcinogenicity: Uncontrolled cell proliferation leading to cancer.
Teratogenicity: Harmful effects on the developing embryo or fetus.
Mutagenicity: Damaging the genetic material.
Immunotoxicity: Toxic effects on the immune system.

Classification of Toxic Agents

Food additives (e.g., aspartame, sodium nitrite)
Pesticides (e.g., DDT, paraquat)
Industrial chemicals (e.g., lead, cadmium)
Environmental pollutants (e.g., SO2, CO)
Natural toxins (e.g., botulinum toxin, tetanus)
Household poisons (e.g., solvents, benzene)
Drugs and drug abuse

Factors Determining Toxicity

Dose and concentration
Route of exposure (ingestion, inhalation, dermal, parenteral)
Duration of exposure (acute, subacute, chronic)
Physicochemical properties of the toxicant
Metabolism of the toxicant (toxicokinetics)
Individual susceptibility factors (genetics, age, gender, diet, pregnancy, overall health)

Types of Toxic Responses

Acute Toxicity: Rapidly developing toxic effect after single or repeated exposure.
Chronic Toxicity: Toxic event after weeks, months, or years of repeated or long-term exposure.
Reversible Toxicity: Effects that can be reversed.
Irreversible Toxicity: Effects that are not reversed (usually permanent).
Local Toxicity: Effect at the site of first contact with the toxic compound.
Systemic Toxicity: Effects spread beyond the site of initial contact.

Toxicological Interactions

Additive effect: Combined response equals the sum of individual responses
Synergistic effect: Combined response is greater than the sum of individual responses.
Potentiation: One substance enhances the toxicity of another substance.
Antagonism: One substance reduces the toxicity of another substance.

Types of Antagonism

Receptor antagonism: Chemicals bind to the same receptor, preventing the action of another chemical.
Chemical antagonism: Direct chemical reaction between chemicals.
Dispositional antagonism: Disposing of or altering the way the body absorbs, distributes, metabolizes, or excretes the substance reducing its concentration at the target organ.
Functional antagonism: Chemicals acting through opposing pathways to counteract each other's effects.

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Description

This quiz covers the fundamental principles and subdivisions of toxicology. You'll explore the Paracelsus principle, different types of adverse drug reactions, and major mechanisms of toxicity. Enhance your understanding of how various factors influence toxicity and the classification of these reactions.