Health Science Quiz: Disease Concepts

Pathology First Exam Material 2024

• This material covers the concepts of health and disease, including etiology, pathogenesis, morphology and histology, clinical manifestations, diagnosis, clinical course, cellular adaptation, injury, and death, neoplasia, and perspectives on health and disease in populations.

Concepts of Health and Disease

• Health: A "state of complete physical, mental, and social well-being and not merely the absence of disease and infirmity."
• Disease: An interruption, cessation, or disorder in the function of the body organ or system (physiological dysfunction). Characterized by recognized etiologic agents, identifiable signs and symptoms, or consistent anatomic alteration.
• Etiology: The causes of disease, known as etiologic factors, including biological agents (bacteria, viruses), physical forces (trauma, burn, radiation), chemical agents (poisons, alcohol), genetic inheritance, and nutritional excesses or deficits. Most diseases are multifactorial with multiple causes.
• Risk factors: Multiple factors that predispose to a particular disease or increase susceptibility, such as obesity increasing the risk of heart disease. Risk factors can be congenital (present at birth) or acquired (develop after birth).
• Pathogenesis: The sequence of cellular and tissue events that occur from initial contact with an etiologic agent until the expression of the disease; the evolution of the disease.

Introduction

• Pathophysiology: Combines the words pathology and physiology. Pathology is the study of structural and functional changes, while physiology focuses on the function of the human body. Hence, pathophysiology explores how disease affects the body's overall function, including examples like traumatic brain injury leading to neuron degeneration and Alzheimer's.
• Pathophysiology can also be defined as the physiology of altered health.

Morphology and Histology

• Morphology: Study of the fundamental structure and form of cells and tissues. Morphological changes are key to disease characterization.
• Histology: Focuses on the study of cells and the extracellular matrix of body tissues; crucial in disease diagnoses, such as cancer.

Clinical Manifestations

• Disease manifestations: Can include signs and symptoms.
• Symptoms: Subjective complaints noted by the person experiencing the disorder, like pain, breathing difficulty, and dizziness.
• Signs: Objective manifestations observed by an observer, such as fever or a rash.
• Syndrome: A compilation of signs and symptoms characterizing a particular abnormality or condition like Chronic Fatigue Syndrome or Down Syndrome.

Diagnosis

• Diagnosis process: The process of identifying the cause of a disease, often involving taking the patient's history, performing a physical examination, and conducting laboratory tests.
• Lab tests' purposes: Validate a problem, confirm a diagnosis, and determine related health problems.

Clinical Course

• Clinical course: Describes the evolution and behavior of the disease over time, including acute (sudden onset, rapid progression, self-limiting), subacute (between acute and chronic), and chronic (continuous, long-term progression with exacerbations and remissions).

Cellular Adaptation, Injury, and Death

• Cell adaptations/responses to stress: Normal cells maintain a steady state called homeostasis. When cells encounter physiologic or pathologic stimuli (e.g., hormonal changes, workload increase), they can adjust their function and structure to survive, these processes can also be pathogenic.
• Adaptation can be physiologic (e.g. enlargement of the breast during pregnancy), or pathologic (e.g. myocardial hypertrophy due to hypertension).

Hypertrophy

• Hypertrophy means an increase in the size of a cell, which leads to an increase in the size of the organ it pertains to. Hypertrophy can be physiologic (e.g., uterus during pregnancy) or pathologic (e.g., heart due to hypertension

Hyperplasia

• Hyperplasia refers to an increase in the number of cells in an organ or tissue. Hyperplasia is often linked with hypertrophy from similar stimulus. It's key that the cells able to undergo mitotic division for the tissue to undergo hyperplasia

Atrophy

• Atrophy is the shrinkage in the size of the cell; resulting from the loss of cell substance. Atrophied cells may have decreased function, but are not dead. Causes include reduced workload, loss of innervation, decreased blood supply, malnutrition, and loss of hormonal stimulation.

Metaplasia

• Metaplasia is a reversible change in which one adult cell type (epithelial or mesenchymal) changes to another adult cell type. This often occurs in response to chronic irritation or inflammation and promotes a more resistant cell type to potentially severe stimulus. An example is smokers' tracheas and bronchi which are lined by stratified squamous epithelial cells rather than normal columnar epithelial cells to adapt to environment.

Cell Injury and Death

• Causes of cell injury: Physical agents (mechanical forces, temperature extremes, electrical forces), radiation injuries, chemical injuries (chemical burns, drugs, toxins), biological agents, and nutritional imbalances.

• Mechanisms of cell injuries: Free radical formation, hypoxia and ATP depletion, and disruption of intracellular calcium homeostasis.

Necrosis

• Necrosis – a form of cell death characterized by enzymatic digestion of the cell's components in response to severe injury.

Apoptosis

• Apoptosis: Programmed cell death that is either physiological or pathologic. Physiological apoptosis maintains a consistent number of cells in a tissue. Pathological apoptosis may be due to excessive accumulation of misfolded proteins or DNA damage. Two main pathways are involved, the extrinsic (death receptor-dependent) and intrinsic (mitochondrion-induced) pathway.

Neoplasia

• Neoplasia: Uncontrolled and disorderly proliferation of cells leading to tumor or neoplasm formation.
• Benign neoplasms: Well-differentiated cells that remain clustered, grow slowly, and do not spread to distant sites.
• Malignant neoplasms: Less well differentiated cells, grow rapidly, and can metastasize (spread) to distant sites.
  • Nomenclature: Classification and naming of tumors, considering tissue types (epithelial or connective tissue).
  • Carcinoma in situ: Localized pre-invasive cancer where cancer cell growth remains contained within its original location, not spreading to surrounding tissues.
• Characteristics: Tumor size, growth rate, differentiation (resemblance to cells of normal tissue), and invasiveness (ability to spread).
• Carcinogenic agents or pathways may cause mutations, which may lead to cancer development. Initiation, promotion, and progression are crucial stages in this process.

Perspectives on Health and Disease in Populations

• Epidemiology: Study of the occurrence and distribution of diseases in populations, assessing risk factors, incidence (new cases), and prevalence (existing cases)
• Mortality: Statistics on the number of deaths due to a particular disease during a specific period.
• Morbidity: Statistics on the functional impact of a disease of a particular disease on a population's health, during a specific period.