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Questions and Answers
What is the definition of pathology?
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)
Which of the following are causes of cell injury? (Select all that apply)
Pathogenic mechanisms can result in morphologic changes that are visible to the naked eye.
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.
__________ deficiency is a common cause of cell injury and death.
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What is meant by 'atrophy'?
What is meant by 'atrophy'?
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What are the three categories of names a drug generally has?
What are the three categories of names a drug generally has?
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What does the term 'Bioavailability' refer to?
What does the term 'Bioavailability' refer to?
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Pharmacodynamics is the study of drug effects on the body, including the mechanism of action, pharmacological action, and adverse effects.
Pharmacodynamics is the study of drug effects on the body, including the mechanism of action, pharmacological action, and adverse effects.
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Agonist is an agent that inactivates a receptor to prevent an effect.
Agonist is an agent that inactivates a receptor to prevent an effect.
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What is the definition of an antagonist?
What is the definition of an antagonist?
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Define Competitive antagonism.
Define Competitive antagonism.
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Explain what Potency means in pharmacology.
Explain what Potency means in pharmacology.
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What is Efficacy in pharmacology?
What is Efficacy in pharmacology?
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Which of the following are types of drug effects?
Which of the following are types of drug effects?
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Drug dependence is a state in which drugs are used for personal satisfaction.
Drug dependence is a state in which drugs are used for personal satisfaction.
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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
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- Hypoxia: oxygen deficiency, which can be due to inadequate oxygenation of the blood or reduction in oxygen carrying capacity of the blood
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- Chemical agents: any chemical substance can cause cell injury, including poisons, therapeutic drugs, and even glucose or salt if sufficiently concentrated
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- Infectious agents: bacteria, viruses, fungi, and parasites
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- Immunological agents: immune reaction can result in cell or tissue injury, e.g. allergy to drugs or foreign materials, autoimmune disease
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- Genetic defects: may result in pathological changes, e.g. congenital malformation associated with Down syndrome, single amino acid substitution in sickle cell anemia
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- Nutritional imbalance: nutritional deficiency or excess can cause cell injury, e.g. protein-calorie insufficiency, obesity, diet rich in animal fat
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- 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
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- ATP depletion
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- Oxygen deprivation or oxygen free radicals
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- Loss of calcium homeostasis
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- Defects in plasma membrane
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- 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
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Test your understanding of the basics of pathology, including the definition and subdivisions of disease study.
