This document discusses pathophysiology and psychodynamics of disease causation. It begins with an introduction and outline. Then, it discusses various theories of disease causation from old theories like humoral theory to current biopsychosocial model. It also discusses pathogenesis of disease, concepts like iceberg phenomenon, and pathophysiological changes including alterations in fluid, electrolytes, immune response, and acid-base balance. It examines concepts like hypersensitivity, autoimmunity, and immunodeficiencies as they relate to immune system alterations.

1. PATHOPHYSIOLOGY AND
PSYCHODYNAMICS OF
DISEASE CAUSATION
Chestha Arora
Msc. Nursing I year 1

2. OUTLINE
• Terminology related to pathophysiology and
psychodynamics of disease causation
• Concept of Disease causation
• Pathogenesis Of disease
• Alteration in fluid and Electrolytes
• Alteration in Immune response
• Acid Base disorders
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3. INTRODUCTION
• Health and diseases have always been matters of concern of the
society
• Various concepts on health, diseases and treatment emerged,
thereby the practice of medicine got refined on scientific basis.
• In spite of development in more theories and concepts, there is a
consensus that health and well-being does not simply mean the
absence of pain and suffering or the lack of disease, disability,
defect and death, but has a positive dimension.
• Based on concepts of theories, develop models of treatment.
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4. TERMINOLOGY RELATED TO PATHOPHYSIOLOGY AND
PSYCHODYNAMICS OF DISEASE CAUSATION
Physiology Health Disease
Pathophysiology Psychodynamics Pathology
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5. Disability Acute Disease
Carrier
Illness
Handicap
Chronic
Disease
Sickness
Sub Clinical
condition
Mechanism
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6. Concept of
Disease Causation
Theories
Pathogenesis Of
Disease
Iceberg
Phenomenon
CONCEPT OF DISEASE CAUSATION
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7. THEORIES
A. Old theories
1. Demonic theory:
• Religion recognized multiplicity of Gods, both good and evil.
• Evil spirit as a messenger of Gods giving warnings in the form of
diseases
• Other concept was a human enemy with supernatural powers,
send evil spirits to harm others.
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8. 2. PUNITIVE THEORY
• The human body contains
blood, phlegm, yellow bile
and black bile.
• Health is primarily that
state in which these
constituent substances are
in the correct proportion to
each other, both in strength
and quantity, and are well
mixed.
Its origin with the religion
with the belief that one's
attitude toward the deity is
responsible as a cause of
sickness.
3. Humoral Theory
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9. 4. CONTAGION THEORY
• Diseases such
as cholera, chlamydia infection,
or the Black Death were caused
by a miasma, a noxious form of
“bad air” emanating from
rotting organic matter.
Galen’s ‘seeds’ were
intended to explain why
some people contracted a
particular disease while
others escaped and he
located them within the
body.
5. Miasma theory
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10. B. GERM THEORY
• Proposed by Louis Pasteur
(1822 –1895) and Robert Koch
(1843 –1910)
• Every human disease is caused
by a microbe or germ, which is
specific for that disease
• Organisms that cause disease
inside the human body are
called pathogens.
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11. C. BIOMEDICAL MODEL
• Disease as a result of malfunctioning of organs or cells
• Drawback : only focuses on cause-and-effect relationship but not on psychosocial
component
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12. D. THEORY OF MULTIFACTORIAL CAUSATION
• Suggested by Pettenkofer of Munich
• Many diseases are infectious, other causative factors such as Genetic,
Nutritional, Immunological, Metabolic, Cytological factors were identified
as the cause for specific diseases
Web Of Causation
• Given by Mac Mohan and Pugh.
• Considers all predisposing factors or risk factors and their interaction.
• Provides a model which shows a variety of possible interventions that
could be taken .
• In a multifactorial event, individual factors are by no means all of the equal
weight. 12

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14. E. EPIDEMIOLOGICAL TRIAD
• States that an external agent can cause diseases on a susceptible host
when there is a conducive environment.
• Applied to non-infectious diseases where the agent could be ‘unhealthy
behaviors, unsafe practices, or unintended exposures to hazardous
substances’
• The agent is known as a ‘necessary’ factor.
• For the disease to occur it needs the combination of what have been
called ‘sufficient’ factors.
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16. F. LAZARU’S THEORY OF STRESS RESPONSE
• Developed by Lazarus and Folkman (1984)
• Stress as resulting from an imbalance between perceived
external or internal demands and the perceived personal and
social resources to deal with them.
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17. G. WOLFF'S THEORY OF STRESS, ORGAN MALADAPTATION
AND DISEASES
• Studied people’s response to chronic stressors, like a
frustrating job or unhappy life style
• Believed that a person’s total life situation profoundly
affects person’s susceptibility to disease
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18. H. HOLMES AND RAHE’S THEORY OF LIFE
CHANGE
• In 1967, psychiatrists Thomas Holmes and Richard Rahe
decided to study the links between stress and illness.
• They discovered that higher the person’s life change score,
greater will the likelihood illness will occur.
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19. I. PSYCHODYNAMIC THEORY
• Originating in the work of Sigmund Freud
• Emphasizes unconscious psychological processes and
contends that childhood experiences are crucial in shaping
adult personality.
• The id is the primitive and instinctual part of the mind that
contains sexual and aggressive drives and hidden
memories, the super-ego operates as a moral conscience,
and the ego is the realistic part that mediates between the
desires of the id and the super-ego.
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22. J. ALFRED ALDERS THEORY
• Suggested that every person has a sense of inferiority.
• From childhood, people work toward overcoming this
inferiority by "striving for superiority."
• Adler believed that this drive was the motivating force
behind human behaviors, emotions, and thoughts.
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23. K. BIOLOGICAL THEORY
Genetics
• Monogenic disorder
• Multifactorial inheritance
disorder
Neurotransmitters
• Neurotransmitter imbalance
can cause Depression,
anxiety, panic attacks,
insomnia, irritable bowel,
hormone dysfunction,
eating disorders,
Fibromyalgia, obsessions,
compulsions etc.,
Stress related factors
• Stress seems to worsen or
increase the risk of
conditions like heart
disease, Alzheimer's disease,
diabetes, depression,
gastrointestinal problems
etc.
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24. L. SELYE’S THEORY OF GENERAL ADAPTATION
• Hans Selye (1907- 1982) was a hungarian endocrinologist, first
to give a scientific explanation for biological stress
• Stress model based on physiology and psychobiology as
General Adaptation Syndrome (GAS).
• GAS is the three-stage process that describes the physiological
changes the body goes through when under stress.
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26. M. SOCIOCULTURAL THEORY
• Important to distinguish between beliefs about the natural and
supernatural causes of illness and disease.
According to Murdock, supernatural causes include:
 Theories of mystical causation i.e. fate, ominous sensation,
contagion, and mystical retribution
 Theories of animistic causation (i.e., soul loss, and spirit
aggression)
 Theories of magical causation (i.e., sorcery and witchcraft).
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27. N. CURRENT THEORY: BIOPSYCHOSOCIAL MODEL
OF MENTAL ILLNESS
• An inter-disciplinary model
• Looks at the interconnection between biology , psychology,
and socio-environmental factors.
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29. PATHOGENESIS OF DISEASE
Pathogenesis is defined as the origination and development
of a disease.
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30. I. PRE-PATHOGENESIS
PHASE
Host Factors
Environmental Factors
Agent Factors
 Period preliminary to
the onset of disease
in man.
 This situation is
frequently referred
to as “man exposed
to the risk of
disease”.
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31. AGE FACTORS
• Physical environment
• Sociocultural environment
• Biological environment
* Age
* Sex
* Literacy level
* Occupation
* Marital status
* Ethnicity
* Lifestyle
ENVIRONMENTAL FACTORS
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32. AGENT FACTORS
Mechanical
Agents
• Friction
• Force
• Injury
• Sprain
Nutritional
Agents
• Excess or
deficiency of
proteins, fats,
carbohydrates
, vitamins and
minerals.
Chemical
Agents
• urea
• Uric acid
• Bilirubin
• ketones
• Calcium
oxalate
Exogenous
Agents
• Dust
• Gas
• Fumes
• Metals
• Allergens
Biological
Agents
• viruses
• Bacterria
• Fungi
• Protozoa
• Arthropods
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33. II. PATHOGENESIS PHASE
Entry of the disease “agent” in the susceptible human host
Agent multiplies and induces tissue and physiological changes
Disease progresses through the period of incubation
Period of early and
late pathogenesis
Recovery, Disability
or Death
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34. NATURAL HISTORY OF DISEASE
• The progression of a disease process in an individual
over time, in the absence of treatment
• E.g untreated infection with HIV causes a spectrum of
clinical problems beginning at the time of
seroconversion (primary HIV) and terminating with AIDS
and usually death
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36. ICEBERG PHENOMENON OF DISEASE
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37. PATHOPHYSIOLOGICAL CHANGES OF DISEASE
CAUSATION
• Cells are the complex units dynamically responding to the responding to the changing
demands and stressors of daily life.
• They possess two of the following functions:
1. Maintenance Function
2. Specialized Function
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38. CELLULAR ADAPTATIONS AND INJURY
• Some diseases represent spontaneous alterations in the ability of a cell
to proliferate and function normally,
• In other cases, disease results when external stimuli produce changes in
the cell's environment that make it impossible for the cell to maintain
homeostasis.
• These adaptations include hyperplasia, hypertrophy,
atrophy, and metaplasia, and can be physiologic or pathologic,
depending upon whether the stimulus is normal or abnormal.
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39. A. HYPERPLASIA
Increase in the number of cells is called
hyperplasia.
Types of Hyperplasia
Physiologic hyperplasia
• Increase in thickness of
endometrium during menstrual
cycle
Pathologic hyperplasia
• Growth of adrenal glands due
to production of
adrenocorticotropic hormone
(ACTH) by a pituitary adenoma
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40. B. HYPERTROPHY
• Increase in the size of the cell
Types of Hypertrophy
Physiologic hypertrophy
Occurs due to a normal stressor. For
example, enlargement of skeletal
muscle with exercise
Pathologic hypertrophy
Occurs due to an abnormal stressor.
For example, increase in the size of
the heart due to aortic stenosis.
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41. C. ATROPHY
Shrinkage of a tissue or organ due to a decrease in size and/or number of
cells.
Types of Atrophy
Physiological
for example when the uterus decreases in size
after birth following the cessation of production
of hormones which stimulated its growth
Pathological
for example atrophy of an organ due to
inadequate blood or nutritional supply.
e.g Atrophy of disuse
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42. D. METAPLASIA
• Reversible change of one differentiated cell type to another.
• Usually occurs in epithelial tissues as an adaptive response to cell stress; cells
can be substituted by those types better suited to the environment.
• Occurs via altered stem cell differentiation
• Metaplastic cells are fully differentiated, unlike dysplastic epithelium which is
abnormally differentiated.
• Examples of metaplasia include:
 Bronchial pseudostratified ciliated epithelium becoming stratified
squamous epithelium in response to cigarette smoke.
 Stratified squamous epithelium in the oesophagus becoming gastric
epithelium when exposed to persistent acid reflux (Barrett’s oesophagus)
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43. E. DYSPLASIA
• The presence of abnormal cells within a tissue or organ.
• Not cancer, but it may sometimes become cancer.
• Dysplasia can be mild, moderate, or severe, depending on
how abnormal the cells look under a microscope and how
much of the tissue or organ is affected.
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45. CELL INJURY OR
DAMAGE
This can caused by following:
 Physical agents such as heat or
radiation
 Impaired nutrient supply, such
as lack of oxygen.
 Metabolic: Hypoxia and
Ischemia
 Chemical Agents
 Microbial Agents:-Virus &
Bacteria
 Immunologic Agents: Allergy
and autoimmune diseases such
as Parkinson's and Alzheimer's
disease.
 Genetic factors: Such as Down's
* Variety of changes of stress
that a cell suffers due to
external as well as internal
environmental changes
* Reversible or irreversible
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47. ALTERATION IN FLUID AND
ELECTROLYTES
• A fluid imbalance may occur when individual loses more
water or fluid than body can take in.
• It can also occur when individual take in more water or
fluid than body is able to get rid of.
• Alteration in fluid cause edema or dehydration.
• Fluid excess can occur in two main ways in the body,
water intoxication and edema.
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48. WATER INTOXICATION
• The excess of both solutes and water,
which is also termed isotonic volume
excess.
• The additional fluid is retained in the
extracellular compartment resulting
in fluid accumulation in the
interstitial spaces.
• Signs seen maily are weight gain,
excess fluid, dependent edema,
pitting edema, increased blood
pressure, neck vein engorgement,
effusions (pulmonary, pericardial,
peritoneal) and even Chronic heart
failure.
The result of an excess of
extracellular water without
having an excess of solutes.
Due to this imbalance, the
extracellular fluid (ECF)
becomes diluted causing water
to move into cells to equalize
solute concentration on each
side of the cell.
Hyponatremia, a potentially
lethal situation, may occur if
high volumes of water are
consumed without solute
EDEMA
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49. DEHYDRATION • Moderate dehydration: include dry
mouth, lethargy, weakness in
muscles, headache and dizziness.
• Severe dehydration: loss of 10-15%
of the body’s water
• Characterized by extreme versions
of the symptoms above as well as:
lack of sweating, sunken eyes,
shriveled and dry skin, low blood
pressure, increased heart rate,
fever, delirium, unconsciousness.
• Occurs when more water and
fluids leave the body than enter it.
• The body can also move water
around to areas where it is needed
most if dehydration begins to
occur.
• The first symptoms of dehydration
include thirst, darker urine, and
decreased urine production.
• It is important to note that,
particularly in older adults,
dehydration can occur without
thirst.
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50. ALTERATION IN ELECTROLYTES
• Electrolytes are minerals in body that have an electric charge.
• They are in blood, urine, tissues, and other body fluids.
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52. CAUSES FOR AN ELECTROLYTE IMBALANCE
 Loss of body fluids from prolonged vomiting, diarrhea, sweating or high
fever
 Inadequate diet and lack of vitamins from food
 Malabsorption -body may be unable to absorb these electrolytes due to
a variety of stomach disorders, medications, or may be how food is taken
in
 Hormonal or endocrine disorders
 Kidney disease
 A complication of chemotherapy is tumor lysis syndrome. 52

53. ACID BASE DISORDERS
• Acid-base disorders are pathologic changes in carbon dioxide
partial pressure (PCO2) or serum bicarbonate (HCO3
−) that
typically produce abnormal arterial pH values.
 Acidemia is serum pH < 7.35.
 Alkalemia is serum pH > 7.45.
 Acidosis refers to physiologic processes that cause acid
accumulation or alkali loss.
 Alkalosis refers to physiologic processes that cause alkali
accumulation or acid loss.
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55. ALTERATION IN IMMUNE RESPONSE
Hypersensitivity Autoimmunity
Immunodeficienc
Disorders
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56. HYPERSENSITIVITY
• Normal immune response that is inappropriately triggered or
excessive or produces undesirable effects on the body.
• The basic mechanism that triggers hypersensitivity is a specific
antigen-antibody reaction or a specific antigen-lymphocyte
interaction.
• Hypersensitivity types I, II, and III are mediated by antibodies
produced by B lymphocytes.
• Type IV hypersensitivity is mediated by T cells.
• The complex interactions between immune system inflammatory
mediators, cytokines, T cells, B cells, and mast cells characterize
hypersensitivity reactions.
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58. AUTOIMMUNITY
• Occurs when the immune system recognizes a person’s own cells
(“self”) as foreign and mounts an immune response that injures self
tissues.
• Failure of self tolerance. Identification and tolerance of self antigens
occur during embryonic development.
• The adaptive immune response is the responsibility of antigen-specific
T cells and B cells that learn to identify “self” in the thymus and bone
marrow.
• The thymus gland is principally responsible for eliminating self-reactive
cells
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59. IMMUNODEFICIENCY DISORDERS
• Impair the immune system's ability to defend the body
against foreign or abnormal cells that invade or attack it
(such as bacteria, viruses, fungi, and cancer cells).
• As a result, unusual bacterial, viral, or fungal infections or
lymphomas.
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60. REFERENCES
 Aryal, S. (2021, December 1). Theories of Disease. The Biology Notes. Retrieved December 30, 2021,
from https://thebiologynotes.com/theories-of-disease/
 B. (n.d.). Introduction to Health Psychology | Boundless Psychology. Lumen. Retrieved January 1,
2022, from https://courses.lumenlearning.com/boundless-psychology/chapter/introduction-to-
health-psychology/
 Causation of Diseases | National Health Portal of India. (n.d.). National Heath Portal. Retrieved
December 30, 2021, from https://www.nhp.gov.in/causation-of-diseases_mtl
 Cellular Adaptations - Cell Populations - Metaplasia. (2021, May 4). TeachMePhysiology. Retrieved
January 2, 2022, from https://teachmephysiology.com/histology/tissue-structure/cellular-
adaptations/
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61. REFERENCES
 Higuera, V. (2018, October 6). What Is General Adaptation Syndrome? Healthline. Retrieved
January 1, 2022, from https://www.healthline.com/health/general-adaptation-syndrome#stages
 Kahissay, M. H. (2017, January 26). Beliefs and perception of ill-health causation: a socio-
cultural qualitative study in rural North-Eastern Ethiopia - BMC Public Health. BioMed
Central. Retrieved January 1, 2022, from
https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-017-4052-y
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