AHN

1. Pathophysiology
Unit-I
Introduction to Pathophysiology
Sohaib Ali Shah
MSN (Scholar), BSN (KMU)
INS, KMU
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2. Objectives
At the end of this unit each learners will be able to:
1. Define Pathology & Pathophysiology
2. Differentiate among Pathophysiology and other biomedical
sciences
3. Discuss the basic concepts of disease and its development.
4. Briefly discuss each of the five components of the disease process:
Prevalence
Etiology
Pathogenesis
Clinical manifestation
Outcomes
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3. Pathology
• Derived from Greek word ‘pathos’ means “feeling or suffering”
and logia means “the study of”.
• Pathology is the study of the causes and effects of disease or
injury.
• Pathology is the study of disease.
• It is the bridge between science and medicine.
• It underpins every aspect of patient care, from diagnostic testing
and treatment advice to using cutting-edge genetic technologies
and preventing disease.
• Pathologist is a scientist who studies the causes and effects of
diseases, especially one who examines laboratory samples of body
tissue, blood and bodily fluids for diagnostic or forensic purposes.
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4. Types of Pathology
• Clinical pathology: diagnosis of disease based on the laboratory
analysis of bodily fluids such as blood and urine, as well as tissues,
using the tools of biochemistry, clinical microbiology, hematology,
immunology and molecular pathology e.g. PCR (polymerase chain
reaction).
• Clinical biochemistry (chemical pathology, clinical chemistry) is
the area of chemistry that is generally concerned with analysis of
bodily fluids for diagnostic purposes. Blood, urine or bodily fluid
for various tests e.g. RFTs, LFTs, RBS, FBS, Serum Albumin,
Serum Electrolytes etc.
• Clinical Microbiology deals with isolation and identification of
infectious agents such as bacteria, viruses, fungi and parasites that
cause disease. Specimens such as urines, faeces and swabs to
identify pathogens to select the appropriate treatment. e.g. Blood
C/S, Urine C/S, Sputum C/S
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5. Cont…
• Hematology Is the study of diseases which affect blood. E.g.
Complete blood count, ESR, Blood smear etc.
• Clinical Immunology is concerned with the diagnosis and
management of diseases arising from abnormal immune responses
i.e. under activity (immunodeficiency) or over activity
(autoimmunity and allergy) of the immune system.
• Molecular pathology Study and diagnosis of disease through the
examination of molecules within organs, tissues or bodily fluids.
Molecular pathology is commonly used in diagnosis of cancer and
infectious diseases. • E.g. DNA microarray, polymerase chain
reaction (PCR), genes analysis.
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6. Pathophysiology
• Pathophysiology (consisting of the Greek origin words “pathos” =
suffering; “physis” = nature, origin; and “logos” = “the study of”)
• The functional changes associated with or resulting from disease
or injury. e.g. inflammation in response to an injury.
• This area studies how the body reacts to injury or fights off
disease.
• Alteration in physiology enables the clinician to understand the
mechanisms underlying the disease and its clinical manifestations
to devise rational therapies.
• Pathogenesis: The word Pathogenesis comes from the Greek
pathos ("disease") and genesis ("creation"). • The pathogenesis of a
disease is the biological mechanism that leads to the diseased state.
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7. Difference B/W Pathology and
Pathophysiology
• Pathology studies cause and then finds treatment, whereas
pathophysiology studies the changes and then treats to the disease.
• Pathology is important to diagnose using the clinical signs and via
sample examination. However, pathophysiology could be performed
based on pathological findings.
• Pathophysiology always done comparing the normal healthy
functions studies from bottom to top of a disease, whereas pathology
goes from top to bottom.
• Pathophysiology is mainly related with quantifiable measurements,
whereas pathology is based on direct observations.
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8. Disease
• The term disease literally means “without ease” (uneasiness), when
something is wrong with bodily function.
• The term disease broadly refers to any condition that impairs the
normal functioning of the body.
• The opposite of health or any deviation from normal functioning or
state of complete physical or mental well being.
• Illness: Subjective state of the person who feels aware of not being
well.
• Sickness: A state of social dysfunction i.e. a role that the individual
assumes when ill (sickness role).
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9. Basic concept of disease and its development
Infection by pathogen is influenced by several factors:
• Mechanism of action: pathogens directly damage cells, interfere
with cellular metabolism, and render the cell dysfunctional because
of the accumulation of pathogenic substances and toxin production.
• Infectivity: ability of the pathogen to invade and multiply in the
host.
• Pathogenicity: the ability of an agent to produce disease depend on
its speed of production, extent of tissue damage, and production of
toxin.
• Virulence: the potency of a pathogen measured in terms of the
number of microorganisms of toxin required to kill a host.
• Immunogenicity: the ability of pathogens to induce an immune
response.
• Learning Objectives
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10. Cont…
• Toxigenicity: The ability of a pathogenic organism to produce
injurious substances that damage the host.
• Portal of entry: The rout by which a pathogenic organism infect
the host: direct contact, inhalation, ingestion, or bite of an animal
or insect.
• Spread of infection is facilitated by the ability of pathogens to
spread through lymph and blood and into tissue and organs, where
they multiply and cause disease.
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11. Natural History of Disease
• The natural history of disease is the course a disease takes place in an
individual from its pathological onset to its eventual resolution
through complete recovery, disability or death in the absence of
intervention.
• It has four stages
1) Stage of susceptibility
2) Stage of subclinical disease
3) Stage of clinical disease
4) Stage of recovery, disability or death
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13. Components of Disease Process
The components of disease process are:
1. Agent: A factor, such as a microorganism, chemical substance,
or form of radiation, whose presence, excessive presence, or
relative absence/deficient is essential for the occurrence of a
disease.
2. Reservoir: A host that carries a pathogen without injury to itself
and serves as a source of infection for other host organisms
(asymptomatic infective carriers).
3. Portal of exit: Body orifices, bodily fluids, tissue, excreta,
secretions
4. Mode of transmission: Direct, indirect, airborne
5. Portal of entry: through which microbes enter our body
6. The human host: A person or other living organism that
can be infected by an infectious agent under natural
conditions.
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14. Components of Disease Process
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15. Prevalence
• Prevalence refers to the total number of individuals in a population
who have a disease or health condition at a specific period of time,
usually expressed as a percentage of the population.
• the total number of cases in the population, divided by the number
of individuals in the population. •
• Prevalence: a divide by a+b
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16. Etiology
• The branch of medicine that deals with the causes or origins of
disease.
• For example, the etiology of cholera is known to be a bacterium that
contaminates food and drinking water in places with poor sanitation.
Types
• Intrinsic: diseases caused by an internal source within the person.
i.e. genetic disorders, cancer and endocrine disorders etc.
• Extrinsic: causes of disease which are originally found outside of
the body of a human. i.e. infectious illnesses, exposure to
radiation/chemicals/electricity
• Idiopathic: Any disease that is of uncertain or unknown origin may
be termed idiopathic. i.e. idiopathic scoliosis, idiopathic pulmonary
fibrosis etc.
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17. Clinical Manifestation
Means the features of disease or the physical result of some type of
illness or infection.
Symptoms: Subjective experience----chest pain, thirst, loss of
taste or smell and fatigue etc.
Sign: Objective/detected by the observer, Increase body temp or
an irregular pulse, jaundice etc. Sign usually emerge in physical
examination.
Syndrome: Characteristic combination of signs and symptoms.
Cushing’s Syndrome, metabolic syndrome.
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18. Outcomes
The consequence of disease or end of the disease is known as
outcome which may be in any of the following form:
• Complete Recovery
• Recovery with Disability
• Death
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19. References
 L.kathryn,(2002), THE BIOLOGIC BASIS FOR DISEASE ,chap
1st Ed 4th page 242_247.
 • www.google.com.
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