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.)