Defenses Against Infection

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Questions and Answers

What characterizes artificially acquired active immunity?

It provides immediate but temporary protection.

It is stimulated by vaccination using antigens. (correct)

It results from natural exposure to a pathogen.

It involves the direct transfer of antibodies from mother to child.

In which stage of infection does the pathogen begin to multiply without causing noticeable symptoms?

Prodromal Stage

Illness Stage

Incubation Period (correct)

Convalescence Stage

Which factor does NOT increase the risk of developing infections?

Tobacco use

Chronic illnesses

Regular exercise (correct)

Poor air quality

What is the correct distinction between primary and secondary infections?

Primary infections are the initial infections in a patient. Signup and view all the answers

Which description accurately defines systemic infections?

Affects the entire body and spreads through the bloodstream. Signup and view all the answers

What is NOT one of the six links in the chain of infection?

Environmental Factor Signup and view all the answers

Which immunity type develops as a result of exposure to and recovery from a disease?

Naturally Acquired Active Immunity Signup and view all the answers

What is a key characteristic of latent infections?

They may remain dormant for long periods without symptoms. Signup and view all the answers

Which of the following is a method by which pathogens exit their reservoirs?

Portal of Exit through body fluids Signup and view all the answers

Which of the following correctly describes the decline stage in the stages of infection?

Symptoms start to subside as the immune response gains control. Signup and view all the answers

What role does tears play in the immune defense system?

Tears contain enzymes that breakdown bacterial cell walls. Signup and view all the answers

Which of the following processes is characteristic of the innate immune response?

Phagocytosis by macrophages. Signup and view all the answers

What is the primary function of the complement cascade in the immune system?

Enhancing the immune response and marking pathogens. Signup and view all the answers

The acidic environment of the stomach primarily serves what purpose in immune defense?

Destroying many pathogens ingested with food. Signup and view all the answers

What is the main role of cilia in the respiratory tract?

To trap pathogens in mucus and expel them. Signup and view all the answers

How does active immunity differ from passive immunity?

Active immunity involves the body producing antibodies, while passive immunity involves transfer of antibodies. Signup and view all the answers

Which of the following statements about fever is true?

Fever can inhibit the growth of pathogens and enhance immune cell activity. Signup and view all the answers

What feature of the skin contributes to its role as the first line of defense?

Thickness and multiple layers providing structural integrity. Signup and view all the answers

What role does the flow of urine play in the immune system?

Flushing out pathogens from the urinary tract. Signup and view all the answers

Which immune cells are primarily responsible for specific immunity?

T and B cells. Signup and view all the answers

Study Notes

Primary Defenses Against Infection

Skin: Forms a physical barrier preventing pathogen entry, composed of epidermis and dermis.
Respiratory Tract: Mucus and cilia trap and remove pathogens. Mucus catches particles, cilia move mucus out of airways.
Eyes: Tears contain lysozyme, an enzyme that breaks down bacterial cell walls, providing chemical defense.
Mouth: Saliva contains enzymes (amylase, lysozyme) to break down pathogens and food.
Gastrointestinal (GI) Tract: Stomach's acidic environment (pH 1.5-3.5) destroys many ingested pathogens.
Genitourinary (GU) Tract: Urine flow flushes pathogens from the urinary tract.

Secondary Defenses Against Infection

Phagocytosis: Macrophages and neutrophils engulf and digest pathogens.
Complement Cascade: Series of proteins enhancing immune response by marking pathogens and promoting inflammation. Activated by antibodies or pathogen surfaces.
Inflammation: Increased blood flow and vessel permeability to allow immune cells to reach infection site; triggered by tissue damage or infection.
Fever: Increased body temperature inhibits pathogen growth and enhances immune cell activity; a systemic response to infection.

Tertiary Defenses Against Infection

Active Immunity: Body produces its own antibodies in response to infection or vaccination, providing long-term protection.
Passive Immunity: Transfer of antibodies from one individual to another (e.g., maternal antibodies to infant); provides temporary protection.
Specific Immunity: Immune cells (T and B cells) recognize and target specific pathogens, creating a tailored immune response.
Cellular Immunity: T cells (mature in thymus) identify and destroy infected cells, crucial for adaptive immunity.
Humoral Immunity: B cells (originate from bone marrow) produce antibodies targeting antigens, neutralizing pathogens.

Types of Immunity

Naturally Acquired Immunity

Naturally Acquired Active Immunity: Immunity develops from exposure and recovery from an illness. Provides lifelong immunity for some diseases (e.g., measles), while others provide shorter-term protection.
Naturally Acquired Passive Immunity: Transfer of antibodies from mother to infant (placenta, breast milk); provides temporary immunity.

Artificially Acquired Immunity

Artificially Acquired Active Immunity: Created by vaccinations; introduces antigens (dead or inactivated microbes or toxins) to stimulate an immune response without illness.
Artificially Acquired Passive Immunity: Injection of antibodies (animal or human origin) for immediate, temporary protection.

Factors Increasing Infection Risk

Developmental Stage: Infants/young children-immature immune systems. Older adults-weakened systems.
Breaks in Primary Defense: Skin injuries (cuts, abrasions), mucous membrane damage.
Illness/Injury: Chronic conditions (diabetes, COPD), acute illnesses (flu, pneumonia).
Tobacco Use: Damages respiratory tract, impairs immune system.
Substance Abuse: Alcohol/drugs weaken the immune system.
Multiple Sexual Partners: Increased risk of STIs.
Environmental Factors: Crowded/unsanitary conditions; poor air quality.
Chronic Diseases: HIV/AIDS, cancer, autoimmune diseases.
Medications: Immunosuppressants (corticosteroids, chemotherapy); antibiotics that alter normal flora.
Invasive Procedures: Catheterization, IV lines, surgery.

Stages of Infection

Incubation Period: Time between exposure and symptom onset; pathogen multiplies, host shows no signs.
Prodromal Stage: Mild, nonspecific symptoms (fatigue, headache); pathogen multiplication continues, immune response begins.
Illness Stage: Severe, specific symptoms; pathogen at peak activity, immune response strongest.
Decline Stage: Symptoms subside as immune system gains control; pathogen numbers decline.
Convalescence Stage: Recovery; body repairs; symptoms disappear.

Localized vs. Systemic Infections

Feature	Localized Infection	Systemic Infection
Definition	Confined to a specific area	Affects entire body
Symptoms	Redness, swelling, pain	Fever, chills, fatigue
Spread	Does not spread	Spreads through bloodstream
Treatment	Localized treatments (creams, ointments)	Systemic treatments (oral/IV antibiotics)

Infection Classifications

Local vs. Systemic: Local—limited harm; Systemic—pathogen invades blood/lymph, spreads throughout body.
Primary vs. Secondary: Primary—initial infection; Secondary—follows primary infection.
Exogenous vs. Endogenous: Exogenous—acquired from environment; Endogenous—originates from patient's normal flora.
Acute vs. Chronic vs. Latent: Acute—rapid onset, short duration; Chronic—slow onset, long duration; Latent—no symptoms for extended periods.

Chain of Infection

Infectious Agent: Pathogen (bacteria, virus, fungus, parasite).
Reservoir: Where pathogen lives and multiplies (humans, animals, environment).
Portal of Exit: Pathogen's route from reservoir (body fluids, etc.).
Mode of Transmission: How pathogen spreads (direct contact, airborne, vector-borne).
Portal of Entry: Pathogen's route into new host (mucous membranes, wounds).
Susceptible Host: Individual vulnerable to infection (age, immune status, health conditions).

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Description

Explore the primary and secondary defenses the body uses to combat infections. From physical barriers like skin to immune responses like phagocytosis, this quiz will test your knowledge on how our body protects itself from pathogens. Learn about the mechanisms involved and their importance in maintaining health.