1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
1.1: Introduction to Pathophysiology
20:15
Pathophysiology is the study of the body’s response to altered function or disease. The word
pathophysiology comes from two words, pathology and physiology.
Pathology comes from the Greek pathos, meaning “disease,” and is the study of the structural
and functional changes that occur in cells, tissues, and organs of the body as a result of
disease processes.
Physiology is the study of body function.
Therefore, pathophysiology can be defined as the changes that occur with disease at the organ and
cellular level as well as the effects that these changes have on total body function.
The World Health Organization (WHO) defines health as a “state of complete physical, mental, and
social well-being and not merely the absence of disease and infirmity.” However, this definition has
not been amended in many years and may be an unrealistic goal. The U.S. Department of Health
and Human Services in Healthy People 2020 defined health as the
following:
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,1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
1. Attain lives free of preventable disease, disability, injury, and premature death
2. Achieve health equity and eliminate
disparities
3. Promote good health for
all
4. Promote healthy behaviors across the life span
Disease can be defined as an illness leading to abnormal physiological function of an organ, body
structure, or an entire system. Someone can be born with a disease, or they can acquire it over the
course of their lifetime. The disease process includes the following steps: etiology, pathogenesis,
morphologic changes, clinical manifestations, diagnosis, and the clinical course.
Etiologic factors are the causes of a disease. Some known etiologic factors include physical forces
(trauma, burns, radiation), chemical agents (poisons, alcohol), biologic agents (bacteria, viruses),
genetic predisposition, and nutritional excesses or deficiencies. However, most etiologies are
idiopathic (unknown) and/or nonspecific in nature. These agents can affect several organs, an entire
system, or multiple systems as seen in cases of sickle cell anemia or cystic fibrosis. Other agents
may only affect a single organ or body structure as seen in the case of an isolated burn or a broken
bone. Most disease processes begin as a result of multiple etiologic factors as seen with cancer,
heart disease, or diabetes.
Risk factors predispose someone to a given disease. They can be categorized as either congenital,
meaning they were present at birth, or acquired, meaning they occur after birth. Congenital conditions
may be caused by heredity, environmental factors, or a combination of both. Acquired defects can be
brought on by a multitude of external factors including physical injury, exposure to infectious agents,
dietary deficiencies or excesses just to name a few. It is believed that most diseases are a result of
an interaction of heredity and the environment in which one lives.
Pathogenesis is the development of a disease process. It is the cascade of events occurring at the
cellular and tissue level from the initial point of contact with an etiologic agent to the ultimate
manifestation of a disease.
Morphology is the structure of cells or tissues. Morphologic changes can include gross and
microscopic changes that are characteristic of a given disease. Histology is the study of cells at the
tissue level. Diagnosis of many diseases is achieved by studying thin, histologic sections of human
tissue under a microscope. For instance, a lesion is a pathologic or traumatic injury of an organ or
tissue. Radiographs, ultrasonography, and/or biopsy can be used to evaluate morphological
characteristics of a lesion.
The Disease Process and Prevention
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,1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
Clinical Manifestations are the ways a disease presents itself. These manifestations can be seen
and heard through physical examination and taking a patient history. The terms used to describe the
changes that coincide with a disease are signs and symptoms. A sign is an objective manifestation,
while a symptom is a subjective complaint. For example, the experience of pain, difficulty breathing,
sensation of dizziness are all symptoms of a disease as told by the person experiencing them.
Objective signs can be seen and/or measured by the observer. Examples of clinical signs can be
fever, edema of an extremity or joint, changes in pupil size, or heightened/diminished reflexes. Signs
and symptoms can be manifestations of the primary disease, or they can be the body’s attempt to
compensate in the presence of a pathologic condition, i.e. increased respiratory rate that
accompanies the underlying condition of pneumonia. A syndrome is defined as a group of multiple
signs and symptoms occurring together. Complications are potential adverse effects of a disease
and/or treatment. Sequelae are lesions or impairments that follow or are caused by a particular
disease.
A diagnosis is the process of identifying the cause of a given health problem or disease (e.g.
myocardial infarction, acute otitis media, cholecystitis, etc.). The diagnostic process requires a careful
and thorough patient history, physical examination (PE), and sometimes diagnostic testing. Taking a
thorough history from a patient (or from their family/caregiver) is an important component of
determining symptomology and progression and coming to a list of differential diagnoses (possible
diagnoses given the patient’s subjective report.) The PE looks for signs of altered body structure or
function and can further narrow the list of potential disease processes. Diagnostic tests can be
ordered to confirm and/or rule out potential underlying problems.
Arriving at a diagnosis involves looking at the differential diagnoses and selecting the most
likely, based on the above criteria. A person’s age, gender, race, lifestyle, genetic background,
and locality are all important factors that need to be considered when deciding upon a
diagnosis. A confirmation of a diagnosis is made through the use of laboratory tests and
appropriate imaging techniques including X-ray, MRI, and computed tomography (CT) scans, to
name a few.
It is important to be able to interpret diagnostic tests as either normal or abnormal. A normal
value for a laboratory test is statistically determined from test results obtained from a select
sample of the population. Laboratory parameters are based on the reliability, validity, sensitivity,
and specificity of the measurement. These clinical laboratory measurements are all
standardized to increase the reliability of the measured values. Validity is how a tool measures
what it is intended to measure. An example would be comparing the use of a
sphygmomanometer (blood pressure cuff) with arterial catheters in measuring blood pressure.
Reliability is the likelihood of the same result occurring with repeated testing. This can depend
on the skill of the person taking the measurement (inter-rater reliability). Sensitivity is the
proportion of people with a disease who test positive for that disease. This is considered a true-
positive result. If a highly sensitive test shows a negative result, it can safely be assumed that
the person does not have a disease. Specificity are people without the disease who test
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, 1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
negative for that disease. This is called a true-negative result. Specificity can only be calculated
from people without the disease. A test that is 95% specific correctly identifies 95 of 100 normal
people. The other 5% are false positive results—results that incorrectly appear as positive when
in reality are truly negative. As such, a false positive test can put unnecessary stress on a
person. Conversely, a false negative test can delay diagnosis and treatment. Figure 1.1 shows
the relationship between a diagnostic test result and the occurrence of disease.
Figure 1.1 Testing parameters. There are two possibilities for the test result to be correct (true positive and true
negative) and two possibilities for the result to be incorrect (false positive and false negative).
Predictive value is the ability of a test result or observation to predict the presence of a given
disease or condition. A positive predictive value is the proportion of true-positive results that
occurs in a given population. In a breast cancer screening program, the group of women having
“suspect breast nodules” that were later found to have breast cancer would be considered the
positive predictive value. A negative predictive value are the true negatives in a given
population. These are the women without breast nodules that do not have breast cancer.
Predictive values rely in part on sensitivity and specificity; however, the prevalence of the
condition in the population plays a bigger role in determining predictive value.
The clinical course is the development of a disease. The clinical course can be categorized in 1 of 3
ways: (1) acute, (2) chronic, or (3) subacute. An acute disorder is somewhat severe, but self-limiting.
A chronic disease is long-term, usually continuous, with exacerbations of symptoms and remissions.
Subacute disease is in between the two, not as severe or prolonged as acute or chronic.
https://portagelearning.instructure.com/courses/917/pages/1-dot-1-introduction-to-pathophysiology?module_item_id=87041 4/7
1.1: Introduction to Pathophysiology
20:15
Pathophysiology is the study of the body’s response to altered function or disease. The word
pathophysiology comes from two words, pathology and physiology.
Pathology comes from the Greek pathos, meaning “disease,” and is the study of the structural
and functional changes that occur in cells, tissues, and organs of the body as a result of
disease processes.
Physiology is the study of body function.
Therefore, pathophysiology can be defined as the changes that occur with disease at the organ and
cellular level as well as the effects that these changes have on total body function.
The World Health Organization (WHO) defines health as a “state of complete physical, mental, and
social well-being and not merely the absence of disease and infirmity.” However, this definition has
not been amended in many years and may be an unrealistic goal. The U.S. Department of Health
and Human Services in Healthy People 2020 defined health as the
following:
https://portagelearning.instructure.com/courses/917/pages/1-dot-1-introduction-to-pathophysiology?module_item_id=87041 1/7
,1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
1. Attain lives free of preventable disease, disability, injury, and premature death
2. Achieve health equity and eliminate
disparities
3. Promote good health for
all
4. Promote healthy behaviors across the life span
Disease can be defined as an illness leading to abnormal physiological function of an organ, body
structure, or an entire system. Someone can be born with a disease, or they can acquire it over the
course of their lifetime. The disease process includes the following steps: etiology, pathogenesis,
morphologic changes, clinical manifestations, diagnosis, and the clinical course.
Etiologic factors are the causes of a disease. Some known etiologic factors include physical forces
(trauma, burns, radiation), chemical agents (poisons, alcohol), biologic agents (bacteria, viruses),
genetic predisposition, and nutritional excesses or deficiencies. However, most etiologies are
idiopathic (unknown) and/or nonspecific in nature. These agents can affect several organs, an entire
system, or multiple systems as seen in cases of sickle cell anemia or cystic fibrosis. Other agents
may only affect a single organ or body structure as seen in the case of an isolated burn or a broken
bone. Most disease processes begin as a result of multiple etiologic factors as seen with cancer,
heart disease, or diabetes.
Risk factors predispose someone to a given disease. They can be categorized as either congenital,
meaning they were present at birth, or acquired, meaning they occur after birth. Congenital conditions
may be caused by heredity, environmental factors, or a combination of both. Acquired defects can be
brought on by a multitude of external factors including physical injury, exposure to infectious agents,
dietary deficiencies or excesses just to name a few. It is believed that most diseases are a result of
an interaction of heredity and the environment in which one lives.
Pathogenesis is the development of a disease process. It is the cascade of events occurring at the
cellular and tissue level from the initial point of contact with an etiologic agent to the ultimate
manifestation of a disease.
Morphology is the structure of cells or tissues. Morphologic changes can include gross and
microscopic changes that are characteristic of a given disease. Histology is the study of cells at the
tissue level. Diagnosis of many diseases is achieved by studying thin, histologic sections of human
tissue under a microscope. For instance, a lesion is a pathologic or traumatic injury of an organ or
tissue. Radiographs, ultrasonography, and/or biopsy can be used to evaluate morphological
characteristics of a lesion.
The Disease Process and Prevention
https://portagelearning.instructure.com/courses/917/pages/1-dot-1-introduction-to-pathophysiology?module_item_id=87041 2/7
,1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
Clinical Manifestations are the ways a disease presents itself. These manifestations can be seen
and heard through physical examination and taking a patient history. The terms used to describe the
changes that coincide with a disease are signs and symptoms. A sign is an objective manifestation,
while a symptom is a subjective complaint. For example, the experience of pain, difficulty breathing,
sensation of dizziness are all symptoms of a disease as told by the person experiencing them.
Objective signs can be seen and/or measured by the observer. Examples of clinical signs can be
fever, edema of an extremity or joint, changes in pupil size, or heightened/diminished reflexes. Signs
and symptoms can be manifestations of the primary disease, or they can be the body’s attempt to
compensate in the presence of a pathologic condition, i.e. increased respiratory rate that
accompanies the underlying condition of pneumonia. A syndrome is defined as a group of multiple
signs and symptoms occurring together. Complications are potential adverse effects of a disease
and/or treatment. Sequelae are lesions or impairments that follow or are caused by a particular
disease.
A diagnosis is the process of identifying the cause of a given health problem or disease (e.g.
myocardial infarction, acute otitis media, cholecystitis, etc.). The diagnostic process requires a careful
and thorough patient history, physical examination (PE), and sometimes diagnostic testing. Taking a
thorough history from a patient (or from their family/caregiver) is an important component of
determining symptomology and progression and coming to a list of differential diagnoses (possible
diagnoses given the patient’s subjective report.) The PE looks for signs of altered body structure or
function and can further narrow the list of potential disease processes. Diagnostic tests can be
ordered to confirm and/or rule out potential underlying problems.
Arriving at a diagnosis involves looking at the differential diagnoses and selecting the most
likely, based on the above criteria. A person’s age, gender, race, lifestyle, genetic background,
and locality are all important factors that need to be considered when deciding upon a
diagnosis. A confirmation of a diagnosis is made through the use of laboratory tests and
appropriate imaging techniques including X-ray, MRI, and computed tomography (CT) scans, to
name a few.
It is important to be able to interpret diagnostic tests as either normal or abnormal. A normal
value for a laboratory test is statistically determined from test results obtained from a select
sample of the population. Laboratory parameters are based on the reliability, validity, sensitivity,
and specificity of the measurement. These clinical laboratory measurements are all
standardized to increase the reliability of the measured values. Validity is how a tool measures
what it is intended to measure. An example would be comparing the use of a
sphygmomanometer (blood pressure cuff) with arterial catheters in measuring blood pressure.
Reliability is the likelihood of the same result occurring with repeated testing. This can depend
on the skill of the person taking the measurement (inter-rater reliability). Sensitivity is the
proportion of people with a disease who test positive for that disease. This is considered a true-
positive result. If a highly sensitive test shows a negative result, it can safely be assumed that
the person does not have a disease. Specificity are people without the disease who test
https://portagelearning.instructure.com/courses/917/pages/1-dot-1-introduction-to-pathophysiology?module_item_id=87041 3/7
, 1/27/2021 1.1: Introduction to Pathophysiology: Pathophysiology-2020-Cekovich
negative for that disease. This is called a true-negative result. Specificity can only be calculated
from people without the disease. A test that is 95% specific correctly identifies 95 of 100 normal
people. The other 5% are false positive results—results that incorrectly appear as positive when
in reality are truly negative. As such, a false positive test can put unnecessary stress on a
person. Conversely, a false negative test can delay diagnosis and treatment. Figure 1.1 shows
the relationship between a diagnostic test result and the occurrence of disease.
Figure 1.1 Testing parameters. There are two possibilities for the test result to be correct (true positive and true
negative) and two possibilities for the result to be incorrect (false positive and false negative).
Predictive value is the ability of a test result or observation to predict the presence of a given
disease or condition. A positive predictive value is the proportion of true-positive results that
occurs in a given population. In a breast cancer screening program, the group of women having
“suspect breast nodules” that were later found to have breast cancer would be considered the
positive predictive value. A negative predictive value are the true negatives in a given
population. These are the women without breast nodules that do not have breast cancer.
Predictive values rely in part on sensitivity and specificity; however, the prevalence of the
condition in the population plays a bigger role in determining predictive value.
The clinical course is the development of a disease. The clinical course can be categorized in 1 of 3
ways: (1) acute, (2) chronic, or (3) subacute. An acute disorder is somewhat severe, but self-limiting.
A chronic disease is long-term, usually continuous, with exacerbations of symptoms and remissions.
Subacute disease is in between the two, not as severe or prolonged as acute or chronic.
https://portagelearning.instructure.com/courses/917/pages/1-dot-1-introduction-to-pathophysiology?module_item_id=87041 4/7
