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CHAPTER 1Introduction to Pathophysiology
FRAMEWORK FOR PATHOPHYSIOLOGY
Etiology• Study of causes/reasons for phenomena• Identifies causal factors acting in concert
that provoke a particular disease or injury• Idiopathic
• Cause is unknown• Iatrogenic
• Cause results from unintended or unwanted medical treatment
Etiology• Study of causes or reasons for phenomena• Identifies causal factors acting in concert
that provoke a particular disease or injury• Idiopathic
• Cause is unknown• Iatrogenic
• Cause results from unintended or unwanted medical treatment
Framework for Pathophysiology (Cont.)
• Risk factor• A factor that when present increases the likelihood
of disease• Pathogenesis
• Development or evolution of disease, from initial stimulus to ultimate expression of manifestations of disease
Framework for Pathophysiology (Cont.)
Clinical Manifestations• Symptoms: subjective feeling of
abnormality in the body• Signs: objective or observed manifestation
of disease• Syndrome: a set of signs and symptoms not
yet determined to delineate a disease
Framework for Pathophysiology (Cont.)
Stages and Clinical Course• Latent period: time between exposure of
tissue to injurious agent and first appearance of signs and/or symptoms
• Prodromal period: time during which first signs and/or symptoms appear or onset of disease occurs
• Latent period also refers to a period during an illness when signs/symptoms temporarily become mild or silent
Framework for Pathophysiology (Cont.)
Stages and Clinical Course• Subclinical stage: patient functions
normally; disease processes are well established
• Acute clinical course: short-lived; may have severe manifestation
• Chronic clinical course: nay last months to years, sometimes following an acute course
Framework for Pathophysiology (Cont.)
Stages and Clinical Course• Exacerbation: increase in severity, signs, or
symptoms• Remission: decrease in severity, signs, or
symptoms; may indicate disease is cured• Convalescence: stage of recovery after a
disease, injury, or surgical procedure• Sequela: subsequent pathologic condition
resulting from an acute illness
Framework for Pathophysiology (Cont.)
CONCEPTS OF NORMALITY IN HEALTH AND DISEASE
CONCEPTS OF NORMALITY IN HEALTH AND DISEASE (CONT.)• Statistical normality: estimate of diseases in
a normal population, based on a bell-shaped curve
• Reliability: test’s ability to give the same results in repeated measurements
CONCEPTS OF NORMALITY IN HEALTH AND DISEASE (CONT.)• Validity: degree to which a measurement
reflects the true value of what it intends to measure
• Predictive value: extent to which a test can differentiate between presence or absence of a person’s condition
• Sensitivity: probability that a test will be positive when applied to a person with a particular condition
• Specificity: probability that a test will be negative when applied to a person without a particular condition
Concepts of Normality in Health and Disease (Cont.)
Individual Factors• Cultural considerations: each culture
defines health and illness in a manner that reflects their experience
• Age and biologic factors linked: a normal value for a person at one age may not be normal for a person at another age
Concepts of Normality in Health and Disease (Cont.)
• Gender differences: relevant in both health and disease
• Situational differences: determine whether a derivation from normal should be considered abnormal or an adaptation mechanism
• Time variations: may impact how the body responds from day to night, or at varying times
Concepts of Normality in Health and Disease (Cont.)
CONCEPTS OF EPIDEMIOLOGY• Epidemiology: study of the patterns of
disease involving populations• Endemic disease: native to a local region• Epidemic disease: spread to many people
at the same time• Pandemic disease: spread to large
geographic areas
CONCEPTS OF EPIDEMIOLOGY (CONT.)
Factors Affecting Patterns of Disease• Age• Ethnic group• Gender• Socioeconomic factors/lifestyle
considerations• Geographic location
Levels of Prevention• Primary: altering susceptibility; reducing
exposure for susceptible persons• Secondary: early detection, screening, and
management of disease• Tertiary: rehabilitation, supportive care,
reducing disability, and restoring effective functioning following disease
Concepts of Epidemiology (Cont.)