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Pathology - Cellular death
Necrosis is an inadequately regulated kind of cell death characterized by the loss of membrane integrity, resulting in the spilling of cellular contents and an inflammatory reaction.
• Coagulative necrosis is the predominant type, marked by the absence of cell nuclei while maintaining the overall structural integrity. The necrotic tissue appears macroscopically pale and firm.
Liquefactive necrosis results in the total destruction of cellular architecture, transforming it into a mushy, semi-solid mass. This is commonly observed in the brain subsequent to cerebral infarction.
Caseous necrosis is a form of necrosis characterized by dead tissue that macroscopically resembles cream cheese. It can manifest in several diseases, but is predominantly linked to tuberculosis.
• Gangrene denotes necrotic tissues altered by air exposure, leading to desiccation (dry gangrene) or infection (wet gangrene). In cases of critical limb ischaemia, toes that experience blood deprivation typically exhibit dry gangrene.
Apoptosis is a regulated process of cellular demise when no intracellular components are expelled from the dying cell, hence preventing any inflammatory response. Apoptosis can occur naturally, such as in the elimination of cells during embryogenesis and those with DNA damage, or pathologically. Apoptosis can be initiated via two primary mechanisms: the activation of surface death receptors, such as Fas or TNF-α (extrinsic pathway), or through cellular damage (intrinsic pathway). The final outcome is the activation of protease enzymes known as caspases, which deconstruct the cell's cytoplasm and nucleus.
Apoptotic cells undergo shrinkage and fragmentation into apoptotic bodies, each maintaining an unbroken cell membrane. • Apoptotic entities are promptly eliminated by neighboring cells. • Dysregulated apoptosis is believed to play a crucial role in various significant disease mechanisms, especially carcinogenesis.
Necrosis is an inadequately regulated kind of cell death characterized by the loss of membrane integrity, resulting in the spilling of cellular contents and an inflammatory reaction.
• Coagulative necrosis is the predominant type, marked by the absence of cell nuclei while maintaining the overall structural integrity. The necrotic tissue appears macroscopically pale and firm.
Liquefactive necrosis results in the total destruction of cellular architecture, transforming it into a mushy, semi-solid mass. This is commonly observed in the brain subsequent to cerebral infarction.
Caseous necrosis is a form of necrosis characterized by dead tissue that macroscopically resembles cream cheese. It can manifest in several diseases, but is predominantly linked to tuberculosis.
• Gangrene denotes necrotic tissues altered by air exposure, leading to desiccation (dry gangrene) or infection (wet gangrene). In cases of critical limb ischaemia, toes that experience blood deprivation typically exhibit dry gangrene.
Apoptosis is a regulated process of cellular demise when no intracellular components are expelled from the dying cell, hence preventing any inflammatory response. Apoptosis can occur naturally, such as in the elimination of cells during embryogenesis and those with DNA damage, or pathologically. Apoptosis can be initiated via two primary mechanisms: the activation of surface death receptors, such as Fas or TNF-α (extrinsic pathway), or through cellular damage (intrinsic pathway). The final outcome is the activation of protease enzymes known as caspases, which deconstruct the cell's cytoplasm and nucleus.
Apoptotic cells undergo shrinkage and fragmentation into apoptotic bodies, each maintaining an unbroken cell membrane. • Apoptotic entities are promptly eliminated by neighboring cells. • Dysregulated apoptosis is believed to play a crucial role in various significant disease mechanisms, especially carcinogenesis.
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Pathology - Cellular modifications
Atrophy
• A decrease in the dimensions of a tissue or organ.
• Can result from a decrease in cell quantity by death or a loss in cell volume through shrinkage.
• Atrophy can manifest as a natural physiological phenomenon, such as thymic atrophy throughout puberty and ovarian atrophy during menopause. Pathological atrophy examples encompass muscle atrophy resulting from denervation and cerebral atrophy caused by cerebrovascular illness.
Hypertrophy
An augmentation in the dimensions of individual cells.
• As a result of an augmentation of cellular proteins and organelles.
• Observed in organs with terminally differentiated cells that are incapable of proliferation, such as cardiac and skeletal muscle. Examples of physiological hypertrophy encompass the myometrium of the uterus during pregnancy and the musculature of a bodybuilder. Pathological hypertrophy examples encompass left ventricular hypertrophy resulting from hypertension or aortic stenosis.
Hyperplasia
• An augmentation in cellular quantity. Examples of physiological hyperplasia encompass the endometrium and breast lobules in reaction to cyclical estrogen stimulation. Pathological hyperplasia examples include benign prostatic hyperplasia and parathyroid hyperplasia.
Metaplasia
A transformation in which one cellular type is replaced by another. • Considered to arise from progenitor cells differentiating into a novel cell type rather than through direct morphogenesis from one cell type to another. • Predominantly observed in epithelial cells, frequently as a reaction to chronic injury. • Metaplasia is designated based on the newly formed cell type; for instance, a transition from non-squamous to squamous epithelium is referred to as squamous metaplasia. Common locations of squamous metaplasia encompass the endocervix, forming the transformation zone associated with cervical neoplasia, and the bronchi of smokers. Common locations of glandular metaplasia encompass the lower esophagus in certain individuals with reflux illness, resulting in a discernible Barrett's esophagus.
Metaplasia serves as an indicator of chronic epithelial injury that may, in certain instances, progress to epithelial dysplasia and ultimately cancer.
Atrophy
• A decrease in the dimensions of a tissue or organ.
• Can result from a decrease in cell quantity by death or a loss in cell volume through shrinkage.
• Atrophy can manifest as a natural physiological phenomenon, such as thymic atrophy throughout puberty and ovarian atrophy during menopause. Pathological atrophy examples encompass muscle atrophy resulting from denervation and cerebral atrophy caused by cerebrovascular illness.
Hypertrophy
An augmentation in the dimensions of individual cells.
• As a result of an augmentation of cellular proteins and organelles.
• Observed in organs with terminally differentiated cells that are incapable of proliferation, such as cardiac and skeletal muscle. Examples of physiological hypertrophy encompass the myometrium of the uterus during pregnancy and the musculature of a bodybuilder. Pathological hypertrophy examples encompass left ventricular hypertrophy resulting from hypertension or aortic stenosis.
Hyperplasia
• An augmentation in cellular quantity. Examples of physiological hyperplasia encompass the endometrium and breast lobules in reaction to cyclical estrogen stimulation. Pathological hyperplasia examples include benign prostatic hyperplasia and parathyroid hyperplasia.
Metaplasia
A transformation in which one cellular type is replaced by another. • Considered to arise from progenitor cells differentiating into a novel cell type rather than through direct morphogenesis from one cell type to another. • Predominantly observed in epithelial cells, frequently as a reaction to chronic injury. • Metaplasia is designated based on the newly formed cell type; for instance, a transition from non-squamous to squamous epithelium is referred to as squamous metaplasia. Common locations of squamous metaplasia encompass the endocervix, forming the transformation zone associated with cervical neoplasia, and the bronchi of smokers. Common locations of glandular metaplasia encompass the lower esophagus in certain individuals with reflux illness, resulting in a discernible Barrett's esophagus.
Metaplasia serves as an indicator of chronic epithelial injury that may, in certain instances, progress to epithelial dysplasia and ultimately cancer.
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Terminology of pathology
Nomenclature of diseases
Aetiology denotes the fundamental cause of an illness. Diseases with an unclear aetiology are termed idiopathic, cryptogenic, or essential.
Pathogenesis denotes the mechanism via which the etiological agent induces the signs of a disease.
Incidence denotes the quantity of newly diagnosed instances of an illness within a specified timeframe.
Prevalence denotes the aggregate number of disease cases within a community at a specific point in time.
Prognosis refers to the anticipated progression of an illness.
Morbidity refers to the degree to which a patient's overall health is impacted by a condition. •
Mortality indicates the probability of mortality due to a specific disease
.Acute and chronic denote the temporal progression of a disease occurrence. Acute diseases manifest abruptly.
Chronic illnesses typically exhibit a gradual onset and are more prone to a protracted duration.
A syndrome denotes a collection of symptoms and clinical indications that, when present concurrently, indicate a certain underlying cause(s).
Classification of diseases
Genetic disorders are hereditary conditions resulting from a faulty gene, such as cystic fibrosis.
Infectious disorders arise from the invasion of the body by pathogenic microorganisms, such as malaria.
Inflammatory disorders result from excessive activity of inflammatory cells in an organ, such as rheumatoid arthritis.
Neoplastic illness arises from the unregulated proliferation of cells, such as breast cancer.
• Vascular diseases occur as a result of blood vessel disorders, such as ischemic heart disease.
• Metabolic disorders stem from abnormalities in metabolic processes, such as diabetes mellitus.
Degenerative diseases arise from the destruction and/or loss of specialized cells, such as the loss of neurons from the cerebral cortex in Alzheimer's disease. Iatrogenic disease arises from the consequences of medical treatment, such as osteoporosis resulting from prolonged glucocorticoid therapy
. • Congenital disorders are present at birth, while those that arise postnatally are termed acquired diseases.
Nomenclature of diseases
Aetiology denotes the fundamental cause of an illness. Diseases with an unclear aetiology are termed idiopathic, cryptogenic, or essential.
Pathogenesis denotes the mechanism via which the etiological agent induces the signs of a disease.
Incidence denotes the quantity of newly diagnosed instances of an illness within a specified timeframe.
Prevalence denotes the aggregate number of disease cases within a community at a specific point in time.
Prognosis refers to the anticipated progression of an illness.
Morbidity refers to the degree to which a patient's overall health is impacted by a condition. •
Mortality indicates the probability of mortality due to a specific disease
.Acute and chronic denote the temporal progression of a disease occurrence. Acute diseases manifest abruptly.
Chronic illnesses typically exhibit a gradual onset and are more prone to a protracted duration.
A syndrome denotes a collection of symptoms and clinical indications that, when present concurrently, indicate a certain underlying cause(s).
Classification of diseases
Genetic disorders are hereditary conditions resulting from a faulty gene, such as cystic fibrosis.
Infectious disorders arise from the invasion of the body by pathogenic microorganisms, such as malaria.
Inflammatory disorders result from excessive activity of inflammatory cells in an organ, such as rheumatoid arthritis.
Neoplastic illness arises from the unregulated proliferation of cells, such as breast cancer.
• Vascular diseases occur as a result of blood vessel disorders, such as ischemic heart disease.
• Metabolic disorders stem from abnormalities in metabolic processes, such as diabetes mellitus.
Degenerative diseases arise from the destruction and/or loss of specialized cells, such as the loss of neurons from the cerebral cortex in Alzheimer's disease. Iatrogenic disease arises from the consequences of medical treatment, such as osteoporosis resulting from prolonged glucocorticoid therapy
. • Congenital disorders are present at birth, while those that arise postnatally are termed acquired diseases.
