Immunology Overview Quiz

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Questions and Answers

What type of immunity is present at birth and provides nonspecific resistance to infection?

Acquired immunity

Innate immunity (correct)

Passive immunity

Adaptive immunity

Which line of defense includes protective cells and fluids such as inflammation and phagocytosis?

First line of defense

Second line of defense (correct)

Third line of defense

None of the above

How do the lines of defense in the immune system interact?

They are strictly compartmentalized with no overlap

They overlap and are redundant in some effects (correct)

They only activate sequentially, one after the other

They function in isolation from one another

What is the main function of the third line of defense in the immune system?

To identify pathogens and create memory cells Signup and view all the answers

Which of the following is NOT a category of the first line of defense?

Cell-mediated immunity Signup and view all the answers

What is the primary role of white blood cells?

To recognize and differentiate foreign materials Signup and view all the answers

What are pathogen-associated patterns (PAMPs)?

Shared molecules by microorganisms Signup and view all the answers

Which body compartment is NOT associated with immune function?

Digestive system Signup and view all the answers

What is the significance of pathogen recognition receptors (PRRs) on white blood cells?

They identify and bind to PAMPs Signup and view all the answers

How does the immune system ensure effective responsiveness?

Through constant communication between fluid compartments Signup and view all the answers

What characterizes the third line of defense in the immune system?

Involvement of B and T lymphocytes and antibodies Signup and view all the answers

Which of the following best describes the difference between innate and adaptive immunity?

Adaptive immunity requires prior exposure to pathogens; innate does not. Signup and view all the answers

Which of the following lists the primary roles of a healthy immune system?

To eliminate pathogens, identify self from non-self, and develop memory Signup and view all the answers

What is the role of phagocytes in the immune system?

To engulf and digest pathogens Signup and view all the answers

Which statement accurately describes the lymphatic system?

It circulates lymph and aids in the immune response. Signup and view all the answers

What initiates the assembly of the membrane attack complex (MAC)?

C5b Signup and view all the answers

How many C9 units can ring the central core of the membrane attack complex?

15 Signup and view all the answers

Which of the following describes the action of the membrane attack complex?

Causes lysis of microbial cell membranes Signup and view all the answers

Which component acts to convert C5 into C5b?

C3b Signup and view all the answers

What is a role of the products C3a and C5a in immune response?

Stimulate mast cell degranulation Signup and view all the answers

What constitutes the first line of defense in host defenses?

Chemical barriers Signup and view all the answers

What triggers the second line of defense in the immune response?

Presence of infectious agents Signup and view all the answers

Which component aggregates with C5b to form the membrane attack complex?

C6 Signup and view all the answers

What are the primary functions of phagocytes?

To survey tissue compartments and ingest foreign materials. Signup and view all the answers

Which phagocyte is specifically attracted to parasitic infections?

Eosinophils Signup and view all the answers

What is the key role of Toll-like receptors (TLRs) in macrophages?

To detect foreign molecules and signal for immune response. Signup and view all the answers

What process occurs when a phagocyte engulfs a pathogen?

Phagosome formation Signup and view all the answers

What is caused by the respiratory burst during phagocytosis?

Generation of antimicrobial substances. Signup and view all the answers

Which type of interferon is produced specifically by T cells?

Interferon gamma Signup and view all the answers

What is a function of the complement system in the immune response?

Destroys bacteria and viruses through a cascade reaction. Signup and view all the answers

In the complement cascade, what does opsonization refer to?

The process of marking pathogens for phagocytosis. Signup and view all the answers

What happens to monocytes after leaving the bloodstream?

They transform into macrophages or dendritic cells. Signup and view all the answers

How do erythrocytes contribute to the immune response?

By collecting pathogenic cell-free DNA. Signup and view all the answers

What primarily characterizes erythrocytes?

They are simple biconcave sacs of hemoglobin. Signup and view all the answers

What is the primary function of the lymphatic system?

To return extracellular fluid to the circulatory system. Signup and view all the answers

Which of the following best describes lymph?

A plasma-like liquid with water and dissolved salts. Signup and view all the answers

What distinguishes primary lymphoid organs from secondary lymphoid organs?

Primary organs include the thymus and bone marrow, secondary include lymph nodes. Signup and view all the answers

What role does inflammation play in host defenses?

It helps to restore homeostasis and clear away invading microbes. Signup and view all the answers

What is the correct sequence of events at the initial stage of an inflammatory response?

Vasoconstriction, blood clots, chemokine release. Signup and view all the answers

Which of the following is NOT a component of an inflammatory response?

Cooling of the tissue. Signup and view all the answers

What is the primary role of the spleen in the lymphatic system?

Filtering circulating blood to remove worn out red blood cells. Signup and view all the answers

Lymphatic vessels are unique because they:

Carry lymph in a unidirectional flow toward the heart. Signup and view all the answers

What primarily occurs in the bone marrow related to lymphocytes?

Origin and maturation of B-cells. Signup and view all the answers

What is the main focus of the first line of defense in the immune system?

Blocking invasion at the portal of entry Signup and view all the answers

What type of immunity requires previous exposure to a foreign substance?

Acquired immunity Signup and view all the answers

Which of the following best describes the role of chemical defenses in the body's immune response?

They provide a nonspecific barrier to pathogens. Signup and view all the answers

What is the significance of the overlapping nature of the immune defense mechanisms?

To ensure redundancy in protection against infections. Signup and view all the answers

Which line of defense is primarily associated with nonspecific cellular responses to pathogens?

Second line of defense Signup and view all the answers

What are the common signs and symptoms of secondary stage syphilis?

Skin rash and muscle aches Signup and view all the answers

Which internal organs can be affected in the late stages of syphilis?

Brain and heart Signup and view all the answers

When does the latent stage of syphilis begin?

When secondary symptoms disappear Signup and view all the answers

Which of the following is NOT a symptom of secondary stage syphilis?

Severe joint pain Signup and view all the answers

What might happen during the late stages of untreated syphilis?

Damage to the internal organs Signup and view all the answers

What is a characteristic feature of the third line of defense in the immune system?

It develops memory for specific pathogens. Signup and view all the answers

Which type of lymphocyte is primarily involved in the adaptive immune response?

B lymphocytes Signup and view all the answers

How are specific host defenses developed in the immune system?

By the action of specialized white blood cells. Signup and view all the answers

Which of the following best describes the function of antibodies in the immune system?

They mark pathogens for destruction by other immune cells. Signup and view all the answers

What is the role of memory cells in the immune response?

They remember past infections, enabling faster responses. Signup and view all the answers

What organism is associated with the disease syphilis?

Treponema pallidum Signup and view all the answers

What is the primary mode of transmission for syphilis?

Sexual contact or saliva Signup and view all the answers

Which demographic saw an increase in syphilis cases starting in 2000?

Men who have sex with men (MSM) Signup and view all the answers

What was the age group with the highest rates of primary and secondary syphilis in 2011?

Men aged 20-29 Signup and view all the answers

How many cases of gonorrhea were reported in 2015?

395,216 Signup and view all the answers

What is the primary reservoir for Treponema pallidum?

Humans Signup and view all the answers

What spirochete structure allows Treponema pallidum to be motile?

Axial filament Signup and view all the answers

How many cases of syphilis were reported in 2020?

133,945 Signup and view all the answers

What is the role of C5b in the complement cascade?

It initiates the polymerization of membrane attack complexes. Signup and view all the answers

What do C3a and C5a contribute to the immune response?

They stimulate mast cell degranulation and enhance chemotaxis. Signup and view all the answers

What occurs during vascular reactions in the inflammatory response?

Increased vascular permeability and fluid leakage Signup and view all the answers

Which of the following describes the role of diapedesis in the immune response?

Migration of cells towards infection due to chemical signals Signup and view all the answers

Which component is the final one to bind during the formation of the membrane attack complex?

C9 Signup and view all the answers

What is the primary mechanism by which fever enhances the immune response?

It increases metabolic rate and stimulates protective processes. Signup and view all the answers

How does the membrane attack complex damage target cells?

By creating pores in the cell membrane. Signup and view all the answers

Which of the following describes the action of the complement in the second line of defense?

It enhances the inflammatory response and opsonization. Signup and view all the answers

Which statement accurately describes the function of chemical mediators in inflammation?

They initiate the clotting process and trap pathogens. Signup and view all the answers

What characterizes edema during the inflammatory response?

Collection of fluid, leading to swelling Signup and view all the answers

What characterizes the first line of defense in host defenses?

It primarily consists of anatomical and physiological barriers. Signup and view all the answers

Which type of pyrogens is produced by infectious agents that lead to fever?

Exogenous pyrogens Signup and view all the answers

During the polymerization phase in the complement cascade, which components aggregate with C5b?

C6, C7, C8 Signup and view all the answers

What is the main purpose of pus formation during inflammation?

To trap and eliminate bacteria and dead cells Signup and view all the answers

What is the primary consequence of the complement cascade's activation?

Lysis of target cell membranes. Signup and view all the answers

What initiates the immune response and repair of injury during the resolution phase of inflammation?

Migration of macrophages, lymphocytes, and fibroblasts Signup and view all the answers

Study Notes

Host Defenses and Innate Immunities

Innate, natural defenses are present at birth and provide nonspecific resistance to infection
Adaptive immunities are specific and must be acquired
The body has multiple lines of defense against pathogens
The first line of defense is any barrier that blocks invasion at the portal of entry; these are nonspecific
The second line of defense are protective cells and fluids, including inflammation and phagocytosis; these are nonspecific
The third line of defense acquired with exposure to foreign substance; produces protective antibodies and creates memory cells; these are specific defenses

Overview of Host Defense Mechanisms

Host defenses consist of multiple barriers, cells, and chemicals to protect against pathogens (disease-causing agents)
A table outlines the lines of defense, indicating whether they are innate or acquired, and the specific or nonspecific nature of their action
The first line of defense comprises physical and chemical barriers, as well as genetic resistance
The second line of defense utilizes innate responses like inflammation and phagocytosis
The third line of defense is adaptive immunity, involving lymphocytes, antibodies, and memory

Types of Host Defenses

Physical or anatomical barriers are the body's first line of defense (e.g., skin, mucous membranes, tears, saliva, sweat, acid, low pH).
Chemical defenses are also part of the first line of defense and include secretions like sebaceous secretions, antimicrobial secretions, lysozyme, defensins, lactic acid, and acidic pH, digestive enzymes, tears, saliva.
Genetic barriers involve inherited factors that provide resistance to certain pathogens

Genetic Defenses

Some hosts are genetically resistant to diseases of others
Viruses have high specificity for host receptors
Genetic differences in susceptibility exist for various pathogens within species
Humans with the sickle-cell anemia gene are resistant to malaria

Immunology

Immunology is the study of the body's second and third lines of defense
Primary functions of a healthy immune system: surveillance, recognition and differentiation of normal versus foreign substances, attack against and destruction of foreign entities.

White Blood Cells

White blood cells (leukocytes) have the job of recognizing and differentiating from foreign material (nonself) versus normal body material (self)

PAMPs and PRRs

Pathogen-associated molecular patterns (PAMPs) are molecules shared among microorganisms
Pathogen recognition receptors (PRRs) are receptors on white blood cells (WBCs) that recognize PAMPs

Body Compartments and Immune Function

Body compartments participating in immune function include the reticuloendothelial system, extracellular fluid, bloodstream, and lymphatic system
Activities in one fluid compartment must communicate with other compartments for effective immunity

Reticuloendothelial System (RES)

The RES is a network of connective tissue that interconnects other cells and meshes with the connective tissue surrounding organs
The RES contains phagocytic cells, particularly macrophages, which are ready to attack and ingest microbes that have bypassed the first line of defense

Blood

Whole blood consists of plasma (liquid portion) and formed elements (blood cells)
Serum is the liquid portion of blood after a clot is formed, minus clotting factors
Plasma is primarily water with proteins, globulins, clotting factors, hormones, chemicals, and gases

Blood Cells

Hemopoiesis is the production of blood cells from stem cells
Primary cell lines include platelets, red blood cells, and leukocytes (white blood cells)
Granulocytes have lobed nuclei, while Agranulocytes have unlobed, rounded nuclei

Granulocytes

Neutrophils (55-90% of WBCs) are phagocytes, reacting to bacteria and damaged tissue
Eosinophils (1-3% of WBCs) destroy eukaryotic pathogens and are involved in allergy
Basophils (0.5% of WBCs) release chemical mediators in inflammatory events and allergy
Mast cells are nonmotile elements found in connective tissue, involved in inflammatory responses, allergies, and anaphylaxis

Agranulocytes

Lymphocytes (20-35% of WBCs) are involved in specific immunity (B cells, humoral, and T cells, cell-mediated)
Monocytes (3-7% of WBCs) mature into macrophages and dendritic cells, which are phagocytic cells
Macrophages are responsible for final differentiation from monocytes after leaving the circulation system, engulfing foreign materials
Dendritic cells trap pathogens and participate in immune reactions

Syphilis

The causative agent is Treponema pallidum, a spirochete
Syphilis has three stages: primary, secondary, and late/latent
Primary stage involves a chancre sore at the infection site.
Secondary stage includes a skin rash and other symptoms, potentially followed by a latent stage with no symptoms.
Late syphilis can cause significant organ damage, including the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints; it can also result in difficulty coordinating muscles, paralysis, numbness, blindness, and potentially even death.
Congenital syphilis can affect newborns, leading to deformed bones, severe anemia, enlarged liver and spleen, jaundice, brain/nerve problems, blindness, deafness, meningitis, or skin rashes
Prevention includes safe sexual practices and treatment when diagnosed.

Lymphatic System

The lymphatic system provides an auxiliary route for returning extracellular fluid to the circulatory system.
It serves as a drain-off system for the inflammatory response.
The lymphatic system also renders surveillance, recognition, and protection against foreign material.

Lymphatic Fluid (Lymph)

Lymph is a plasma-like fluid carried by lymphatic circulation
Formed when blood components leave the blood vessels and enter extracellular spaces
Its composition includes water, dissolved salts, and proteins (2–5%)
Transports white blood cells, fats, cellular debris, and infectious agents

Lymphatic Vessels

Lymphatic capillaries permeate all body parts except the CNS, bone, placenta, and thymus.
Thin walls allow for easy permeation by extracellular fluid
Contraction of skeletal muscles moves fluid within lymphatic vessels through skeletal muscles.
Lymph flow is unidirectional, toward the heart, and eventually returns to the bloodstream.

Lymphoid Organs and Tissues

Primary lymphoid organs: Thymus (T cell maturation) and bone marrow (B cell maturation).
Secondary lymphoid organs/tissues: Lymph nodes, spleen, MALT, GALT are circulatory-based locations where encounter with microbes happens

Inflammation

Inflammation is a response to tissue injury, aiming to restore homeostasis.
It involves redness, warmth, swelling (edema), and pain (dolor).
Inflammatory mediators are released in response to chemical mediators.
Blood vessels dilate and leak fluid, attracting white blood cells (WBCs) including phagocytes.

Phagocytosis

Phagocytosis is a key component of the second line of defense
Phagocytes: survey tissues to discover microbes or damaged cells.
Ingest and eliminate these materials
Extract immunogenic information from foreign matter.
Major types: Neutrophils, eosinophils, and macrophages. Neutrophils typically react first, followed by other phagocytes.

Interferon

Interferon is a small protein produced by certain WBCs and tissue cells in response to viruses, RNA, immune products, and antigens.
Three major types: IFN alpha, IFN beta, and IFN gamma, produced by different cells (lymphocytes, macrophages, fibroblasts, and epithelial cells).
All three IFN types bind to cell surfaces and stimulate expression of antiviral proteins, reducing cancer gene expression.
IFN alpha and beta stimulate phagocytes, and IFN gamma acts as an immune regulator of macrophages and T and B cells.

Complement

Complement consists of at least 30 blood proteins working together to eliminate bacteria and viruses by lysis and opsonization
Complement proteins are activated by cleavage.
Three features: Membrane attack complex (MAC), opsonization, Recruitment of inflammatory mediators, resulting in a cascade reaction.

Review of Concepts

Innate vs. adaptive immunity
Three lines of defense
Components and connections of the immune system
Cellular characteristics of each granulocyte and agranulocyte type
Lymphatic circulation
Lymphoid organs and tissues
Inflammatory response mechanisms
Phagocytosis mechanisms and types of phagocytes
Interferon production and function
Complement activation, function, and cascade stages

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Test your understanding of the immune system with this comprehensive quiz. Questions cover all three lines of defense, the roles of white blood cells, and the interaction of various immune components. Perfect for students looking to reinforce their knowledge on immunology.