Pathology Introduction Quiz

Questions and Answers

What is the definition of pathology?

Pathology is the study of disease.

Which of the following are causes of cell injury? (Select all that apply)

Chemical agents (correct)

Hypoxia (correct)

Genetic defects (correct)

Infectious agents (correct)

Pathogenic mechanisms can result in morphologic changes that are visible to the naked eye.

True

__________ deficiency is a common cause of cell injury and death.

Oxygen Signup and view all the answers

What is meant by 'atrophy'?

Decrease in the size of an organ or tissue due to decreased cell size and/or number. Signup and view all the answers

Match the following terms with their definitions:

Metaplasia = Transformation of one mature tissue into another mature tissue Dysplasia = Disordered cell proliferation with abnormal cell arrangement Carcinoma insito = Disordered cell proliferation involving the entire epithelial thickness Signup and view all the answers

What are the three categories of names a drug generally has?

Chemical name, Non-proprietary name, Proprietary name. Signup and view all the answers

What does the term 'Bioavailability' refer to?

The total proportion of the drug that reaches the systemic circulation from the site of administration Signup and view all the answers

Pharmacodynamics is the study of drug effects on the body, including the mechanism of action, pharmacological action, and adverse effects.

mechanism of action, pharmacological action, adverse effects Signup and view all the answers

Agonist is an agent that inactivates a receptor to prevent an effect.

False Signup and view all the answers

What is the definition of an antagonist?

An agent that prevents the action of an agonist on a receptor, but does not have any effect of its own. Signup and view all the answers

Define Competitive antagonism.

The antagonist is chemically similar to the agonist, competes with it and binds to the same site to the exclusion of the agonist molecules. Signup and view all the answers

Explain what Potency means in pharmacology.

Potency is a measure of the amount of drug necessary to produce an effect of a given magnitude. Signup and view all the answers

What is Efficacy in pharmacology?

Efficacy is the ability of a drug to elicit a physiologic response when it interacts with a receptor, measured by Emax. Signup and view all the answers

Which of the following are types of drug effects?

All of the above Signup and view all the answers

Drug dependence is a state in which drugs are used for personal satisfaction.

True Signup and view all the answers

Study Notes

Introduction to Pathology

Pathology is the study of disease, where "patho" means disease and "logy" means study.
Diseases are defined as abnormal variations in structure or function of any part of the body.

Pathology of a Disease

Pathology of a disease is studied under four subdivisions:
- Etiology: the cause of the disease
- Pathogenesis: the mechanism through which the cause operates to produce the pathological and clinical manifestations
- Morphologic changes: the structural changes in cells or tissues that occur following the pathogenetic mechanisms
- Functional changes and clinical symptoms and signs

Causes of Cell Injury

1. Hypoxia: oxygen deficiency, which can be due to inadequate oxygenation of the blood or reduction in oxygen carrying capacity of the blood
1. Chemical agents: any chemical substance can cause cell injury, including poisons, therapeutic drugs, and even glucose or salt if sufficiently concentrated
1. Infectious agents: bacteria, viruses, fungi, and parasites
1. Immunological agents: immune reaction can result in cell or tissue injury, e.g. allergy to drugs or foreign materials, autoimmune disease
1. Genetic defects: may result in pathological changes, e.g. congenital malformation associated with Down syndrome, single amino acid substitution in sickle cell anemia
1. Nutritional imbalance: nutritional deficiency or excess can cause cell injury, e.g. protein-calorie insufficiency, obesity, diet rich in animal fat
1. Physical agents: trauma, temperature, radiation, electric shock

Cellular Response to Injury

Reversible injury: cell adapts to changes in its environment, e.g. mild duration of ischemia leads to reversible injury
Irreversible injury: cell dies due to injury, e.g. long duration of ischemia leads to irreversible injury

Mechanisms of Cell Injury

1. ATP depletion
1. Oxygen deprivation or oxygen free radicals
1. Loss of calcium homeostasis
1. Defects in plasma membrane
1. Mitochondrial damage

Cellular Adaptation

Definition: reversible changes in the size, number, phenotype, metabolic activity, or functions of cells in response to changes in their environment
Types:
- Atrophy: decrease in the size of an organ or tissue due to decrease in the size and/or number of its cells
- Hypertrophy: increase in the size of an organ or tissue due to increase in the size of its cells
- Hyperplasia: increase in the size of an organ or tissue due to increase in the number of its cells
- Metaplasia: transformation of one mature tissue into another mature tissue of the same category

Atrophy

Definition: decrease in the size of an organ or tissue due to decrease in the size and/or number of its cells
Types:
- Physiological atrophy: e.g. thymus gland atrophy after puberty
- Pathological atrophy: e.g. starvation atrophy, cachexia, disuse atrophy, neuropathic atrophy, hormonal atrophy

Hypertrophy

Definition: increase in the size of an organ or tissue due to increase in the size of its cells
Types:
- Physiological hypertrophy: e.g. muscles of athletes
- Pathological hypertrophy: e.g. left ventricular hypertrophy due to aortic stenosis

Hyperplasia

Definition: increase in the size of an organ or tissue due to increase in the number of its cells
Types:
- Physiological hyperplasia: e.g. hormonal hyperplasia of the mammary gland at puberty, pregnancy, and lactation
- Pathological hyperplasia: e.g. hormonal hyperplasia as in ovarian dysfunction that leads to excessive estrogen secretion and leads to mammary and endometrial hyperplasia

Metaplasia

Definition: transformation of one mature tissue into another mature tissue of the same category
Types:
- Epithelial metaplasia: e.g. squamous metaplasia of urinary bladder mucosa in case of bilharziasis, squamous metaplasia of bronchial mucosa in case of smoker
- Connective tissue metaplasia

Epithelial Dysplasia

Definition: disordered cell proliferation characterized by abnormal cell arrangement and appearance involving part of the epithelial thickness
Fate:
- Regression
- Progression into Carcinoma in situ or carcinoma

Carcinoma in Situ

Definition: disordered cell proliferation characterized by abnormal cell arrangement and appearance involving the entire thickness of the epithelial thickness
Fate:
- Regression
- Most cases progress to invasive carcinoma

General Pharmacology

Pharmacology is the study of the effects of drugs on the functioning of living organisms.
A drug is an active chemical used for diagnosis, prevention, or treatment of a disease.

Drug Nomenclature

A drug has three categories of names:
- Chemical name: describes the substance chemically (e.g., N-(4-hydroxyphenyl)ethanamide)
- Non-proprietary name: accepted by scientific authority (e.g., acetaminophene)
- Proprietary (Brand) name: assigned by the manufacturer (e.g., Paracetamol, Panadol, Amol, Adol, and Paramol)

Pharmacokinetics and Pharmacodynamics

Pharmacokinetics: what the body does to the drug (ADME: absorption, distribution, metabolism, and excretion)
Pharmacodynamics: what the drug does to the body (mechanism of action, pharmacological action, and adverse effects)

Pharmacokinetics (ADME)

Absorption: uptake of drug through biological membranes
- Mechanisms: passive diffusion, facilitated diffusion, active transport, endocytosis, and exocytosis
- Factors affecting absorption: area of absorbing surface, vascularity, pH, contact time, and expression of P-glycoprotein
Distribution: how the drug is distributed throughout the body
- Factors affecting distribution: total body water, binding to plasma and tissue proteins, blood flow, and capillary permeability
Metabolism: biotransformation of the drug in the body
- Types: nonsynthetic/phase I/functionalization reactions (oxidation, reduction, hydrolysis) and synthetic/phase II/conjugation reactions (glucuronide conjugation, acetylation, methylation, etc.)
Elimination: removal of the drug from the systemic circulation
- Routes: urine, feces, and hepatic metabolism

Pharmacodynamics

Receptors: macromolecules or binding sites that recognize the drug and initiate the response
- Types: ion channels, G protein, enzymes, and intracellular receptors
Agonists: activate the receptor to produce an effect
- Types: partial agonists and full agonists
Antagonists: prevent the action of an agonist on a receptor
- Types: competitive antagonism and non-competitive antagonism
Dose-Response Relationship: effect of the drug on a receptor depends on the concentration of the drug
Potency: amount of drug necessary to produce an effect of a given magnitude
Efficacy: ability of a drug to illicit a physiologic response when it interacts with a receptor

Adverse Drug Effects

Side effects: unwanted but often-unavoidable pharmacodynamics effects that occur at therapeutic doses
Secondary effects: suppression of bacterial flora by the drug causes growth of opportunistic pathogens
Toxic effects: excessive pharmacological action of the drug due to overdosage or prolonged use
Idiosyncrasy: drug interacts with some unique feature of the individual due to genetic mutation
Drug allergy: immunologically mediated reaction
Drug dependence: state in which the use of drugs is for personal satisfaction
Drug withdrawal reactions: sudden stop of the drug results in adverse effects
Teratogenicity: drug causes fetus abnormalities when administered to the pregnant mother
Carcinogenicity: capacity of a drug to cause genetic defects and cancer