Chapter 1
Introduction to Pathophysiology
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Pathophysiology
Pathophysiology involves the study of functional
or physiologic changes in the body that result
from a disease process
 Pathophysiology deals with disease
development and the associated changes to
normal anatomy or physiology
 Pathophysiology includes some aspects of
pathology

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Homeostasis

Homeostasis—the maintenance of a relatively
stable internal environment regardless of
external changes
 When homeostasis is maintained, good health is
generally maintained.
 When homeostasis is not maintained, disease may
develop.
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Health and Disease

Health
 Physical, mental, and social well-being

Disease
 Deviation from the normal state of homeostasis
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Health Indicators
“Normal” values occur within a range of values
and may vary depending on technology used for
measurement.
 Adjustments caused by the following:

 Age
 Gender
 Genetics
 Environment
 Activity level
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Seven Steps to Health
Be a nonsmoker and avoid second-hand smoke.
 Eat 5 to10 servings of vegetables and fruit a day.
Choose high-fiber, lower fat foods. Limit alcohol intake.
 Physical activity on a regular basis
 Protection from the sun
 Follow cancer screening guidelines.
 Doctor or dentist visit if any changes in the normal state
of health
 Follow health and safety guidelines at home and at work
when using, storing, and disposing of hazardous
materials.

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Concept and Scope of Pathophysiology
Functional (physiologic) changes in the body as
a result from disease
 Uses knowledge of basic anatomy and
physiology.
 Includes aspects of pathology, which describes
structural changes in body tissues caused by
disease.
 Cause and effect relationships, defined by signs
and symptoms, guide the study of a specific
disease.

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Prevention of Disease

Has become a primary focus in health care
 Maintaining routine vaccination programs
 Participation in screening programs
 Community health programs
 Regular routine doctor visits
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Stages of Research Process

Stage 1
 “basic science”
 Identification of technology to be used
 Work done in the laboratory
 Might require animal or cell/tissue cultures

Stage 2
 Small number of human subjects

Stage 3
 Clinical trials
 Involving a large number of patients with the disease or
risk of the disease
 “double blind studies"
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Medical History
Current and prior illnesses
 Allergies
 Hospitalizations
 Treatment
 Specific difficulties
 Any type of therapy or drugs

 Prescription
 Nonprescription
 Herbal items, including food supplements
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New Developments and Trends
Constant updating of information and knowledge
 Improved diagnostic tests
 Development of more effective drugs
 New technologies

 3D-printing, robotics, nanotechnology

Extensive research in efforts to prevent, control,
or cure many disorders
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Basic Terminology

Gross level
 Organ or system level

Microscopic level
 Cellular level

Biopsy
 Excision of small amounts of living tissue

Autopsy
 Examination of the body and organs after death
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Disease Process

Diagnosis
 Identification of a basic disease
• Evaluation of signs and symptoms
• Laboratory tests

Etiology
 Causative factors in a particular disease
• Congenital defects
• Inherited or genetic disorders
• Microorganisms
• Immunologic dysfunctions
• Degenerative changes
• Malignancy
• Metabolic, nutritional problems
• Trauma, burns, environmental factors
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Causes of Disease

Idiopathic
 Cause of disease is unknown.

Iatrogenic
 Error/treatment/procedure may cause the disease.

Predisposing factors
 Age, gender, inherited factors, environment etc.

Prophylaxis
 Preserve health; prevent spread of disease

Prevention
 Vaccinations; dietary/lifestyle modifications;
prevention of potentially harmful activities etc.
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Characteristics of Disease (1 of 5)

Pathogenesis
 Development of the disease

Onset of disease
 Sudden/acute
 Insidious: gradual, vague or mild signs

Acute disease
 Short-term, develops quickly
 High fever, severe pain etc.

Chronic disease
 Develops gradually
 Milder symptoms, often intermitted with acute episodes
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Characteristics of Disease (2 of 5)

Subclinical state
 Pathologic changes, no obvious manifestations

Latent state
 No symptoms or clinical signs evident
 In infectious diseases: incubation period

Prodromal period
 Early development of the disease
 Signs are nonspecific or absent

Manifestations
 Clinical evidence with signs and symptoms
• Local: at site of the problem
• Systemic: general indicators of illness, i.e. fever
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Characteristics of Disease (3 of 5)

Signs
 Objective indicators of disease

Symptoms
 Subjective feelings

Lesions
 Specific local change in the tissue

Syndrome
 Collection of signs and symptoms

Diagnostic tests
 Various laboratory tests
 Appropriate to manifestations and medical history
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Characteristics of Disease (4 of 5)

Remissions and exacerbations
 Mark the course or progress of a disease
 Remission: period which manifestations subside
 Exacerbation: a worsening of severity

Precipitating factor
 Condition that triggers an acute episode

Complications
 New secondary or additional problems
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Characteristics of Disease (5 of 5)

Therapy
 Measures to promote recovery/slow progress

Sequelae
 Potential unwanted outcomes

Convalescence or rehabilitation
 Period of recovery and return to healthy state
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Disease Prognosis (1 of 4)
Prognosis defines the probability or likelihood for
recovery or other outcomes.
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Disease Prognosis (2 of 4)

Morbidity
 Disease rates within a group

Mortality
 Relative number of deaths resulting from the disease

Autopsy
 Postmortem examination

Epidemiology
 Tracking the pattern or occurrence of disease
 Major data collection centers: WHO and CDC
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Disease Prognosis (3 of 4)

Occurrence of disease
 Incidence
• Number of new cases in a given population within a given
time period
 Prevalence
• Number of new, old, or existing cases within a given
population and time period

Epidemics
 A higher number of expected cases of an infectious
disease occur within an area

Pandemic
 Involve a higher number of infectious diseases in
many regions of the globe
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Disease Prognosis (4 of 4)

Communicable diseases
 Infectious disease that can spread from one person to
another

Notifiable or reportable diseases
 Must be reported by the physician to designated
authorities
 Authority varies with local jurisdiction.
 Required diseases to be reported may change over
time
 Reporting is intended to prevent further spread of the
disease.
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Occurrence of Disease
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Cellular Changes
Cells can adapt their growth and differentiation
to altered conditions in the body.
 Tissues may be modified to du hormonal
stimulation or environmental stimuli (i.e.
irritation).
 Disease may develop when cell structure and
function are changed to the point when
homeostasis cannot be maintained.

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Cellular Adaptations (1 of 2)

Atrophy
 Decrease in the size of cells
• Results in reduced tissue mass.

Hypertrophy
 Increase in cell size
• Results in enlarged tissue mass.

Hyperplasia
 Increased number of cells
• Results in enlarged tissue mass.
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Abnormal Cell Growth Patterns
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Cellular Adaptations (2 of 2)

Metaplasia
 Mature cell type is replaced by a different mature cell
type.

Dysplasia
 Cells vary in size and shape within a tissue.

Anaplasia
 Undifferentiated cells, with variable nuclear and cell
structures

Neoplasia
 “New growth”―commonly called tumor
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Cell Damage (1 of 3)

Apoptosis
 Refers to programmed cell death
• Normal occurrence in the body

Ischemia
 Deficit of oxygen in the cells

Hypoxia
 Reduced oxygen in tissues


Nutritional deficits
Pyroptosis
 Results in lysis causing nearby inflammation.
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Cell Damage (2 of 3)

Physical damage
 Excessive heat or cold
 Radiation exposure

Mechanical damage
 Pressure or tearing of tissue

Chemical toxins
 Exogenous: from environment
 Endogenous: from inside the body
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Cell Damage (3 of 3)

Microorganisms
 Bacteria and viruses, for example

Abnormal metabolites
 Genetic disorders
 Inborn errors of metabolism
 Altered metabolism

Imbalance of fluids or electrolytes
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Necrosis (1 of 3)
Necrosis: Dying cells cause further cell damage
due to cellular disintegration
 Liquefaction necrosis

 Dead cells liquefy because of release of cell enzymes

Coagulative necrosis
 Cell proteins are altered or denatured―coagulation
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Necrosis (2 of 3)

Fat necrosis
 Fatty tissue broken down into fatty acids

Caseous necrosis
 Form of coagulation necrosis
 Thick, yellowish, “cheesy” substance forms
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Liquefaction Necrosis in the Brain
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Coagulative Necrosis of the Kidney
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Fat Necrosis in the Mesentery
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Necrosis (3 of 3)

Infarction
 Area of dead cells as a result of oxygen deprivation

Gangrene
 Area of necrotic tissue that has been invaded by
bacteria
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Dry Gangrene of the Toe
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