Patho2 notes

Pathophysiology PTA 1003 Lecture Notes

Chapter 4: The Immune System

What is Immunity?

  • Definition: The body’s defense system; the ability to recognize, fight, and protect against harmful substances such as bacteria, viruses, toxins, and abnormal cells.

  • Function: Resists disease.

Importance of a Healthy Immune System

  • Functions:
      - Prevents infections.
      - Eliminates abnormal cells.
      - Maintains balance between defense and tolerance.

  • Consequences of Dysfunction:
      - Immunodeficiency
      - Hypersensitivity
      - Autoimmunity

  • Case Example: A cancer patient receiving chemotherapy develops pneumonia due to weakened immune defenses.

Organs of the Immune System

  • Referred to as lymphoid tissues.

  • Primary Lymphoid Organs:
      - Bone Marrow
      - Thymus

  • Role: Central sites for all cells of the immune system and the differentiation of B- and T-cells.

Factors That Alter the Immune System

  • Influential Factors Include:
      - Aging
      - Sex and hormonal influences
      - Nutrition and malnutrition
      - Environmental pollution
      - Exposure to toxic chemicals
      - Trauma
      - Burns
      - Sleep disturbances
      - Presence of concurrent illnesses and diseases
      - Malignancy
      - Diabetes mellitus
      - Chronic renal failure
      - HIV infection
      - Medications (immunosuppressive drugs)
      - Hospitalization and surgery
      - Stress, psychosocial, spiritual well-being, socioeconomic status.

Types of Immunity

  • Innate Immunity:
      - Provides rapid, non-specific protection.
      - Acts quickly and uniformly but lacks memory.
      - Includes barriers like skin, mucous membranes, inflammation, and fever.
      - Example: A person with a small cut develops classic signs of innate inflammatory response (redness, heat, swelling, pain).

  • Acquired Immunity:
      - Develops over time (can be active or passive).
      - Highly specific and remembers pathogens (involves B and T lymphocytes).
      - Example: A vaccinated person exposed to measles virus does not succumb due to acquired immunity.

Active vs. Passive Immunity

  • Active Immunity:
      - Long-lasting protection.
      - Results from infection or vaccination.

  • Passive Immunity:
      - Temporary protection.
      - Occurs when antibodies are transferred from another person or source (e.g., maternal antibodies through breast milk, providing initial protection for newborns).

Effects of Exercise on Immunity

  • Dose-Dependent Effects:
      - Moderate Exercise: Strengthens immunity.
      - Excessive/Intense Exercise: May temporarily suppress immunity.
      - Sedentary Lifestyle: Average illness risk.
      - Moderate Exercise: Lowest illness risk.
      - Excessive Exercise: Increased illness risk.

  • Mechanisms of Action:
      - Increased blood and lymph flow enhances the efficiency of immune cell travel.
      - Improved ability to detect and destroy pathogens.
      - Reduces chronic low-grade inflammation by lowering pro-inflammatory cytokines.
      - Helps to prevent conditions associated with immune dysfunction (e.g., diabetes, cardiovascular disease).
      - Modulates stress hormones (lower chronic stress improves immune resilience).

Role of PTA in Immunity

  • Exercise aids illness prevention and healthy lifestyle, as well as immunodeficiency intervention.

  • Importance of staying updated in exercise immunology due to the decline in immune function with age.

  • Targeted Populations:
      - Elderly individuals.
      - Post-surgical patients.
      - Immunocompromised patients.

  • Recommendations:
      - Encourage moderate activity.
      - Avoid overexertion.

Clinical Guidelines – “Neck Check”

  • Rule for Exercise During Infectious Episodes:
      - Above the Neck Symptoms:
        - Runny nose, sneezing, scratchy throat: Exercise cautiously at half-speed.
        - If symptoms improve after 10 minutes, resume normal pace; if symptoms worsen, stop and rest.
      - Below the Neck Symptoms:
        - Fever, cough, muscle aches, gastrointestinal issues: No exercise.

  • Goal: Maximize cardiopulmonary and musculoskeletal function without harming immunity.

Definition of Immunodeficiency

  • Definition: The immune response is absent or weakened due to primary or secondary disorders.

Primary Immunodeficiency

  • Causes: Inherited defects in T cells, B cells, NK cells, phagocytes, or complement proteins; over 95 genetic disorders identified.

  • Consequences: Higher risk of infections, autoimmunity, cancer.

  • Clinical Relevance: Rarely encountered in clinical practice.

Secondary Immunodeficiency

  • Common Causes: Prolonged disease, treatments, or external factors (e.g., leukemia, diabetes, chronic illness, HIV/AIDS).

  • Associated Factors: Viral/bacterial infections, malnutrition, aging, steroid therapy, chemotherapy, radiation.

  • Consequences: Impaired immune defenses and increased vulnerability to illness.

Consequences of Immunodeficiency

  • Increased risk of infection leading to opportunistic infections (e.g., Candida can become pathogenic).

  • Everyday pathogens (e.g., influenza virus) can pose higher dangers to immunocompromised individuals.

  • Additional risk factors include:
      - Poor overall health.
      - Advanced age.
      - Coexisting diseases.
      - Invasive procedures.
      - Treatments (chemotherapy, radiation).

Acquired ImmunoDeficiency Syndrome (AIDS)

  • Definition: Progressive destruction of T-cell (CD4) immunity with changes in humoral and autoimmune response.

  • Pathogenesis: HIV retrovirus infects CD4 helper T cells, macrophages, and B cells, leading to gradual depletion of CD4 and weakened immune response.
      - High mutation rate results in multiple viral strains and immune evasion.

Consequences of AIDS

  • Increased risk of opportunistic infections such as:
      - Tuberculosis (TB)
      - Pneumonia
      - Candidiasis

  • Higher risk of cancers (Hodgkin’s disease, Kaposi’s sarcoma, non-Hodgkin’s lymphoma).

  • Frequent co-infections (e.g., Hepatitis C).

HIV Infection Spectrum

  • Stages:
      - Asymptomatic HIV seropositive
      - Early symptomatic HIV
      - Advanced HIV (AIDS)

Epidemiology of HIV

  • Estimated ~38,500 new infections annually in the U.S. (2015).

  • High-Risk Groups: Men who have sex with men (MSM), injection drug users, minority youth.

  • Transmission Methods: Blood and body fluids (not casual contact).

Pathogenesis & Clinical Manifestations of HIV/AIDS

  • Stages and Symptoms:
      - Asymptomatic (CD4 > 500): Normal activity; potential mild viral-related illnesses.
      - Early Symptomatic (CD4 200–500): Fatigue, weight loss, night sweats, infections.
      - Advanced Disease (AIDS) (CD4 < 200): Dementia, severe opportunistic infections, malignancies.

  • Clinical Features by System:
      - Musculoskeletal: Pain, arthritis, wasting, myopathy.
      - Neurologic: Dementia, neuropathy, seizures, gait issues.
      - Cardiopulmonary: Pneumonia, TB, cardiomyopathy.
      - Dermatologic: Kaposi’s sarcoma, rashes, ulcers.
      - Systemic: Fever, night sweats, fatigue, GI disturbances.

Hypersensitivity Disorders

  • Types:
      - Type I (Immediate/Allergic): IgE-mediated (e.g., anaphylaxis, hay fever, asthma).
      - Type II (Cytotoxic): IgG/IgM-mediated against cell-surface antigens (e.g., hemolytic anemia).
      - Type III (Immune Complex): Antigen-antibody complex deposition (e.g., lupus, rheumatoid arthritis).
      - Type IV (Delayed/Cell-Mediated): T-cell mediated (e.g., contact dermatitis, TB test reaction).

  • Definition: Exaggerated, inappropriate, or harmful immune responses to antigens leading to tissue injury or disease.

Clinical Manifestations of Hypersensitivity Disorders

  • Type I Symptoms: Wheezing, swelling, urticaria, rhinorrhea, anaphylaxis.

  • Type II Symptoms: Malaise, weakness, hives, respiratory distress, cardiovascular effects, CNS symptoms.

  • Type III Symptoms: Headache, back pain, chest pain, nausea, hematuria.

  • Type IV Symptoms: Fever, arthralgias, lymphadenopathy, urticaria, anemia.

Special Implications for the PTA

  • Type IV Reactions: Can occur from lanolin in lotions, ultrasound gels, etc.; monitor skin hypersensitivity.

  • Latex Sensitivity: Increased since glove use; reactions range from contact dermatitis to anaphylaxis. PTA considerations include:
      - Avoid latex if allergic; use powder-free, low-powder, or non-latex gloves to minimize risk.

Chapter 5: Infectious Disease

Definition of Infectious Disease

  • Clinically evident illness caused by invasion/multiplication of microorganisms (bacteria, viruses, fungi, parasites) in the body, establishing a parasitic relationship with the host.

  • Types of Organisms: Viruses, mycoplasmas, bacteria, rickettsiae, chlamydiae, protozoa, fungi, helminths, mycobacteria, prions.

  • Chain of Transmission: Depends on the pathogenic agent, reservoir, portal of exit, portal of entry, and susceptible host.

Signs and Symptoms of Infectious Disease

  • Systemic Symptoms: Fever, chills, malaise, enlarged lymph nodes.

  • Integumentary Symptoms: Purulent drainage, rashes, bleeding.

  • Gastrointestinal Symptoms: Nausea, vomiting, diarrhea.

  • Cardiovascular Symptoms: Petechial lesions, tachycardia, hypotension.

  • Central Nervous System Symptoms: Altered consciousness, confusion, seizures, headache.

  • Genitourinary Symptoms: Dysuria, flank pain, hematuria, urgency, frequency.

  • Upper Respiratory Symptoms: Cough, dyspnea.

Diagnosis of Infectious Diseases

  • Basic laboratory techniques include:
      - Direct visualization of organisms.
      - Detection of microbial antigen.
      - Host immune response clues.
      - Detection of specific microbial nucleotide sequences.
      - Isolation of organism in culture.

Pathogens and Their Effects

  • Definition: Any organism capable of causing disease.

  • Pathogen Actions:
      - Invade and destroy cells (viruses, bacteria).
      - Release toxins (e.g., tetanus, diphtheria).
      - Alter genetic makeup (e.g., influenza mutations).

  • Two Types:
      - Principal pathogens cause disease in healthy hosts.
      - Opportunistic pathogens cause disease in weakened or immunocompromised hosts.

Types of Infectious Organisms (Pathogens)

  • Viruses: Depend on host cells; made up of DNA or RNA.

  • Mycoplasmas: Self-replicating bacteria sensitive to some antibiotics.

  • Bacteria: Single-celled; can grow independently.

  • Rickettsiae: Require a host for replication, spread via insect vectors.

  • Chlamydiae: Depend on host cells for replication, contain RNA and DNA.

  • Protozoa: Single cell unit; minimal specialization.

  • Fungi: Can exist as yeasts or molds.

  • Prions: Protein-based infectious agents, transmitted from animals to humans.

Chain of Transmission

  • Infection requires 6 links:
      - Pathogen
      - Reservoir
      - Portal of Exit
      - Mode of Transmission
      - Portal of Entry
      - Susceptible Host

  • Breaking any link prevents infection.

Healthcare Associated Infections (HAI)

  • Common nosocomial infections affecting hospitalized or facility-based patients.

  • 1 in 31 hospitalized patients contracts an HAI in the U.S.; prolonged hospital stays, increased costs, morbidity, mortality.

  • Prevention goals include standard precautions, hand hygiene, isolation.

Lines of Defense Against Infection

  • First Line: Intact skin, mucous membranes, cilia, normal flora.

  • Second Line: Inflammatory process, nonspecific response to all infections.

  • Third Line: Immune response, specifically tailored to individual pathogens.

Control of Transmission

  • Isolation and barriers used to prevent microorganism transmission.

  • Transmission-based precautions include:
      - Standard and barrier precautions (PPE, hand washing, etc.).
      - Immunization to decrease susceptibility.

Infection Control Procedures

  • Follow strict isolation techniques, observe patients for signs of infection, maintain personal hygiene (handwashing).

  • Ensure safe interactions with high-risk patients and environment.

Proper Handwashing Technique

  • Effective prevention method against pathogen transmission:
      - Wet hands, apply soap, scrub for 20 seconds, rinse, dry thoroughly (clean towel if possible).

Key Blood-Borne Viral Pathogens

  • High Risk to Healthcare Workers:
      - Hepatitis B Virus (HBV)
      - Hepatitis C Virus (HCV)
      - Human Immunodeficiency Virus (HIV)

Herpesviruses: Overview and Implications

  • Characterized by latency; can reactivate under stress with recurrent lesions.

  • Precautions: Standard barriers and sanitation to prevent spread during outbreaks.

Cytomegalovirus (CMV)

  • Common herpesvirus; generally mild or asymptomatic in healthy individuals but severe in immunocompromised individuals or newborns.

Lyme Disease Overview

  • Infectious multisystem disorder caused by Borrelia burgdorferi, transmitted by ticks.

  • Incidence and clinical considerations outlined, highlighting stages.

Oncology
Definition and Overview of Oncology

  • Branch of medicine focused on cancer study, diagnosis, treatment, and prevention.

Cellular Changes in Cancer

  • Differentiation, dysplasia, metaplasia, and hyperplasia explained.

Tumors Overview

  • Definition and classification of tumors into benign vs. malignant, and primary vs. secondary.

Cancer Risk Factors

  • Detailed factors including age, genetics, lifestyle, infections, hormonal factors, environmental exposures, and immune dysfunction.

Metastasis Process

  • Mechanism of metastasis (tumor cell travel and establishment in distant areas).

Main Treatment Modalities for Cancer

  • Various treatments like surgery, radiation therapy, chemotherapy, biotherapy, focused therapies.

  • Special considerations for cancer patients related to physical activity.

Role of the PTA in Cancer Management

  • Guidelines for encouraging patient participation, monitoring, and therapy considerations.