Chapter 1: Introduction to Pathophysiology

pathophysiology

study of functional changes due to disease, study of abnormalities in physiologic functioning of living beings

(examines disturbances of normal mechanical, physical, biochemical functions either caused by a disease or the result of disease)

• derives from the intersection of 2 older related disciplines: pathology and phsiology

physiologic

an adjective that relates to the normal, healthy functions of the body and its living systems, rather than diseased or abnormal conditions

pathology

the study and diagnosis of disease through elimination of organs, tissues, cells, bodily fluids

physiology

the study of the mechanical, physical, biochemical functions of living organisms (the branch of biology that studies how living organisms, their organs, tissues, and cells perform physical and chemical functions

four interrelated topics of pathophysiology

1. etiology

2. pathogenesis

3. clinical manifestations

4. treatment implications

etiology

study of the causes or reasons for disease

1. idiopathic

2. iatrogenic

idiopathic

when the cause of disease is unknown

iatrogenic

if the cause of condition / disease is the result of an unwanted medical treatment

multifactoral

most diseases are this, having several different etiologic factors that contribute to development

risk factor

when the link between an etiologic factor and development of a disease is less certain, but the probability is increased when the factor is present, link is termed this (any attribute, characteristic, or exposure that increases the likelihood of developing a disease, injury, or negative outcome)

pathogenesis

the development or evolution of a disease from the initial stimulus to the ultimate expression of the manifestations of the disease

(development and progression of a disease, sequence of events from start o the disease and the progression over time)

*how disease develops

clinical manifestations

of some diseases may change significantly over time resulting in a completely different clinical presentation @ different stages

1. signs of disease

2. symptoms

3. syndrome

signs of disease

the manifestations of disease that are observed (objective data)

symptoms

the subjective feelings of an abnormality in the body (subjective data), can be reported only by affected individuals to an observer

syndrome

when the etiology of a particular set of signs and syndromes has not yet been determined (a collection of medical signs and symptoms that consistently occur together but do not necessarily have a single, clearly understood underlying cause)

stages and clinical course

1. latent period

2. prodromal period

3. acute phase

4. subclinical stage

5. exacerbations

6. remission

7. convalescence

8. sequela

9. complication of disease

latent period

the interval period between exposure of a tissue to an injurious agent and the first appearance of signs and symptoms (mild signs and symptoms sometimes during course of disease)

• called the incubation period in nfectious diseases

prodromal period

appearance of the first signs and symptoms indicating the onset of a disease (symptoms often non specific ie headache, anorexia, nausea)

acute phase

disease reaches full intensity and signs and symptoms reach greatest severity

subclinical phase

patient functions normally, although disease processes are well established

classification of clinical course

clinical course of disease can be classified as

1. acute

2. chronic

acute

severe manifestations but runs a short course measured in hours, days, or few weeks

chronic

lasts for months to years

exacerbations

sudden increase in severity of disease, signs, symptoms

remission

decline in severity of disease, signs, symptoms (permanent / cured = 5 years or longer)

convalescence

the stage of recovery after a disease, injury, or surgical operations

sequela

occasional subsequent pathologic condition created by inital disease (ie. sequela of inflammatory process could be scarring); condition results from a previous disease or injury

complication of disease

a new or separate process that may arise secondarily because of some change produced by the original problem (ie. bacterial pneumonia may be a complication of viral infection of the respiratory tract

concepts of normality in health

the ability to measure numerous structural, physiologic, biochemical, and genetic parameters in an individual allows the evaluation of information that is helpful in the diagnosis and monitoring of clinical diseases

• to determine whether a certain finding is indicative of disease or abnormal it must be compared with what’s normal (the expected range, not usually perfection)

• based on reference range (standard deviations)

• is individualized (age, gender, lifestyles, ethnicity may influence various physiologic parameters) - thus trends and changes in particular individuals are more reliable than single observations

epidemiology

the study of patterns of disease involving aggregates of people (populations); examine

1. occurrence

2. incidence

3. prevalence

4. transmission

5. distribution of diseases

factors affecting patterns of disease distribution

1. endemic disease

2. epidemic disease

3. pandemic disease

aggregate factors

principal factors affecting patterns of disease in human populations

types…

1. age

2. ethnic group

3. gender

4. socioeconomic factos

5. lifestyle considerations

6. geographic location

clinical course

the progression and evolution of a disease, condition, or symptom in a patient over time from its onset to the resolution or outcome

treatment implications

• early treatment can stop or slow disease development

• later treatment may focus on limiting damage

• restores or supports normal function

• treatment may prevent progression or promote repair

• early treatment improves outcomes

concept of normality pt 2

• disease disrupts normal function

• abnormal does not always mean illness

• subclinical disease may have no symptoms

• context is critical in assessment

occurrence

frequency and distribution of a disease

incidence

number of new cases in a specific time period

prevalance

ALL existing cases (new and old) at a specific point in time

transmission

how a disease spreads from one person (or source) to another

distribution

who gets the disease, where it occurs, and when it happens

endemic disease

• a disease that is native to a local region

epidemic disease

disease that spreads to many people at the same time

pandemic disease

viral epidemic that affects large geographic regions, spreading worldwide and millions of deaths

levels of prevention

1. primary

2. secondary

3. tertiary

primary prevention

altering susceptibility or reducing exposure for susceptible persons (an intervention implemented before there is evidence of a disease or injury, reduce or eliminate causative risk factors)

secondary prevention

early detection, screening and management of disease (an intervention implemented after a disease has begun, but before it is symptomatic, early identification ( through screening) and early treatment)

tertiary prevention

rehabilitation, supportive care, reducing disability, and restoring effecting functioning (an intervention implemented after a disease or injury is established, prevent sequelae stopping bad things from getting worse)

example of primary

encourage exercise and healthy eating to prevent individuals from becoming overweight

example of secondary

check body mass index (BMI) at every well checkup to identify individuals who are overweight or obese

example of tertiary

help obese individuals lose weight to prevent progression to more severe consequences

major components of disease

1. etiology - cause

2. pathogenesis - how the disease develops

3. clinical manifestations - signs and symptoms

4. diagnosis - identification of the disease

5. treatment - interventions to manage or cure disease

6. prognosis - expected outcome

diagnosis

identification of the disease

prognosis

expected outcome

the role of the nurse

1. assess

2. case finding

3. contact tracing

4. health teaching

assess

individuals and communities

case finding

identify infected or at risk individuals

contact tracing

determine exposure sources and prevent further spread

health teaching

educate communities about prevention and control