Introduction to Pathophysiology

Introduction to Pathophysiology

  • Course Code: NSG 3280

  • Focuses on the physiological aspects of disease,
      incorporating the following concepts:
      - Etiology
      - Pathogenesis
      - Clinical manifestations
      - Treatment implications

Pathophysiology Concepts

  • Framework based on the common presentations of disease in physiological functioning of humans.

  • Topics interrelated to provide a comprehensive understanding of pathophysiology.

Etiology

  • Definition: The study of the cause or reason (risk factor) for a particular phenomenon.

  • Key Points:
      - Identifies causal factors that, acting together, provoke a particular disease or injury.
      - Types of Etiology:
        - Idiopathic: Cause is unknown.
        - Iatrogenic: Causes resulting from unwanted or unintended medical treatment.
      - Risk Factor: A factor that increases the likelihood of disease when present.

Pathogenesis

  • Definition: The development of disease, from initial stimulus to final expression.

  • Key Points:
      - Describes how etiological factors alter physiological function leading to clinical manifestations observed in specific disorders/diseases.

Clinical Manifestations

  • Signs: Observed or objective manifestations of disease.
      - Examples: Blood pressure, heart rate.

  • Symptoms: Subjective feelings of abnormality reported by the patient.
      - Examples: Patient states they are nauseated or in pain.

  • Syndrome: A set of clinical manifestations without an identified etiology.

Stages and Clinical Course

  • Latent Period: Time between tissue exposure to an injurious agent and the appearance of signs/symptoms.
      - Known as the Incubation period in infectious diseases.

  • Prodromal Period: Time during which first signs/symptoms indicating disease onset appear.

  • Acute Clinical Course: Short-lived with severe signs/symptoms.

  • Chronic Clinical Course: Lasting months to years; may follow an acute course.

  • Exacerbation: Sudden increase in severity of disease or symptoms.

  • Remission: Decrease in severity; may indicate disease is cured. >5yrs

  • Convalescence: Recovery stage after disease, injury, or surgery.

  • Sequela: Subsequent pathological condition resulting from an illness.

Factors Affecting Patterns of Disease

  • Epidemiology: Study of disease patterns within populations.
      - Endemic Disease: Local or native presence.
      - Epidemic Disease: Spreads to many individuals at the same time.
      - Pandemic Disease: Spreads across a large geographic area.

  • Factors influencing disease patterns:
      - Ethnicity
      - Age
      - Gender
      - Socioeconomic factors ——→ ex, access to healthcare/ health insurance
      - Lifestyle ——→ exercise, work environment
      - Geographic location

Levels of Prevention

  • Primary Prevention: Altering susceptibility or reducing exposure.
      - Examples: Vaccines, exercise, diet, education.

  • Secondary Prevention: Early detection, screening, and management.
      - Examples: Colonoscopy, mammogram, self-testicular exam, treatment/medications.

  • Tertiary Prevention: Rehabilitation, supportive care, reducing disability = goal.
      - Example: Pulmonary or cardiac rehabilitation.

Homeostasis and Allostasis

  • Homeostasis: State in which body systems are in balance or equilibrium despite alterations within the body.

  • Allostasis: Successful adaptation to changes through complex regulatory processes controlled by the brain.

  • Allostasis represents a dynamic process that maintains or re-establishes homeostasis in response to environmental and lifestyle changes.

The Concept of Stress

  • Stress: Actual physical and mental state produced by tension; can be physical, chemical, or emotional.

  • Stressors: Can be real or perceived threats to homeostasis and may be direct (conscious) or indirect (unconscious).

General Adaptation Syndrome (GAS)

  • Three stages:
      1. Alarm Stage ——→ fight or flight. Increased HR, RR, BP, pupil dilation. Corticosteroids, epi/nor-epi released, glucocorticoids, cortisol, aldosterone, immune cytokines (inflammatory response)
      2. Resistance / Adaptation ——→ able to begin to get over the stress and return to a stable state.
      3. Exhaustion——→ chronic stress, the body can’t adapt or move on from the stress. fatigue, loss of motivation, v/s abnormal, overeating, extra O2 to the brain, insomnia, confusion/scrambled thoughts. The heart = abnormal rate/rhythm, can develop heart disease/stroke. GI = can be very slow or very fast. GU = frequent UTI, urgency/frequency to urinate.

Neuroendocrine Interactions in Response to Stress

  • Stressors (internal or external stimuli) excite receptors, triggering:
      - Hypothalamus activation
      - Anterior pituitary response
      - Adrenocorticotropic hormone (ACTH) secretion
      - Sympathetic pathways inhibition
      - Release of catecholamines and corticosteroids.

  • Stress Response of Body Tissues:
      - Elevation of cardiac output
      - Vasomotor changes
      - Lipolysis (fat breakdown)
      - Glycogenolysis (glucose release)
      - Insulin suppression
      - Increased respiration
      - Enhanced blood coagulation
      - Gluconeogenesis (sugar production from fat/proteins)
      - Protein catabolism (breakdown)
      - Inhibition of glucose uptake
      - Stabilization of vascular reactivity
      - Immune response suppression.

Stages of Stress Response

  • Alarm Stage: Initial reaction to stressor, involving fight-or-flight response; physiological changes include:
      - Dilated pupils
      - Pale or flushed skin
      - Rapid heart rate and breathing
      - Trembling.

  • Resistance / Adaptation Stage: Body attempts to adapt to stressor; may involve increased glucocorticoid hormone secretion followed by normalization.

  • Exhaustion Stage: Loss of resistance to stressor; potential for serious illness or death due to chronic stress.

Effects of Allostatic Overload on Body Organs and Systems

  • Nervous System: Neuropsychological effects such as anxiety, fatigue, and loss of motivation.

  • Integumentary System: Skin conditions like eczema, psoriasis, and acne.

  • Cardiovascular System: Issues including hypertension and risk of stroke.

  • Respiratory System: Increased respiratory issues like asthma.

  • Immune System: Opportunistic infections due to immunosuppression.

  • Gastrointestinal System: Disorders like gastritis and irritable bowel syndrome.

  • Endocrine System: Issues like hyperglycemia leading to diabetes mellitus.

  • Genitourinary System: Conditions like irritable bladder and menstrual irregularities.

  • Musculoskeletal System: Tension headaches and muscle contractions.

Adaptation, Coping, and Illness

  • Stressors: Agents that produce stress and disrupt homeostasis.

  • Distress: A perceived inability to cope with stressors.

  • Adaptation: The biopsychosocial process of change in response to altered circumstances, which can be internal or external.

  • Coping: Behavioral adaptive responses using culturally based mechanisms.

Hormonal Response to Stress

  • Catecholamines:
      - Norepinephrine:
        - Constricts blood vessels, raises blood pressure,
        - Reduces gastric secretions,
        - Increases night and far vision (pupil dilation).
      - Epinephrine:
        - Enhances myocardial contractility,
        - Increases heart rate and cardiac output,
        - Causes bronchodilation,
        - Increases glucose release from the liver (glycogenolysis) and elevates blood glucose levels.

  • Adrenocortical Steroids:
      - Cortisol:
        - Primary glucocorticoid affecting metabolism,
        - Promotes appetite,
        - Exhibits anti-inflammatory effects;
        - Chronic levels may lead to pro-inflammatory effects.
      - Aldosterone:
        - Primary mineralocorticoid promoting sodium and water reabsorption,
        - Increases blood pressure.

  • Endorphins and Enkephalins:
      - Natural pain relievers that raise pain threshold and produce sedation and euphoria.

  • Immune Cytokines:
      - Secreted by macrophages during stress response,
      - Enhance immune response but may suppress functioning with prolonged stress.

  • Sex Hormones:
      - Impact stress responses influencing allostasis; examples include estrogen and testosterone.

  • Other Hormones:
      - Growth hormone (somatotropin), prolactin, oxytocin.

Practice Questions

  • Question #1: Which stage of the general adaptation syndrome facilitates the individual’s allostatic restoration of homeostasis?
      A. Alarm
      B. Resistance
      C. Exhaustion
      D. Allostatic load

  • Question #2: Which of the following is an example of a stressor?
      A. Using a cell phone while driving
      B. Being exposed to air pollution
      C. Running in the dark
      D. Having inadequate immunizations

  • Question #3: A physiological response to the release of catecholamines during the stress response would be:
      A. Increased gastrointestinal motility.
      B. Constriction of the pupils.
      C. Increased glycogenolysis.
      D. Decreased heart rate.

References

  • Banasik, J. L. (2022). Pathophysiology (7th ed.). Elsevier.