Immunology: Quiz #1

It is the first line of defense, always 'on', with a rapid, immediate response. It acts the same way for all pathogens.

What is innate (nonspecific) immunity?

Rapid response, no memory, non-specific, includes barriers and immune cells like macrophages and neutrophils.

What are the key features of innate immunity?

Skin, mucous membranes, and cilia.

Name three physical barriers in innate immunity.

Lysozyme (in tears/saliva), stomach acid, and antimicrobial peptides.

What are some chemical barriers in innate immunity?

A specific immune response that develops over time and creates memory for faster future responses.

What is adaptive (active) immunity?

Humoral immunity (B cells and antibodies) and cell-mediated immunity (T cells).

What are the two major types of adaptive immunity?

B lymphocytes (B cells) and T lymphocytes (T cells).

Which cells are essential to adaptive immunity?

Antibodies that bind to specific antigens.

What do B cells produce?

Activate B cells, cytotoxic T cells, and macrophages; coordinate the immune response.

What do helper T cells (CD4+) do?

Innate immunity

What is another name for nonspecific immunity?

Specific (adaptive) immunity.

What type of immunity are antibodies part of?

It means the immune system attacks all pathogens the same way, without targeting specific ones.

What does "nonspecific" mean in terms of immunity?

Innate immunity.

Which type of immunity is present at birth?

It targets particular antigens with tailored responses (e.g., antibodies made for specific viruses or bacteria).

What does "specific" mean in adaptive immunity?

Nonspecific/innate immunity.

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

Immediately—it's always "on."

How quickly does the innate immune system respond after exposure?

No—it is not targeted; it responds the same way to all pathogens.

Is innate immunity specific to certain pathogens?

It reacts the same way to mild and deadly pathogens—no distinction.

How does innate immunity handle different levels of pathogen danger?

Antibodies.

What is an example of adaptive (specific) immunity?

It targets specific pathogens and remembers them for future responses.

What does adaptive immunity do that innate immunity doesn't?

It doesn’t require activation by a specific pathogen—it’s ready to act at all times.

Why is the innate immune system described as "always on"?

Innate—it's immediate. Adaptive takes time to develop.

Which system is faster: innate or adaptive?

Adaptive (specific) immunity.

Which immune system creates memory cells for future protection?

“The always-on, nonspecific first response that reacts the same to any pathogen—fast but not targeted."

In one sentence, how would your professor likely define innate immunity?

1. Anatomical/Physical

2. Physiological

3. Phagocytic

4. Inflammatory

What are the 4 general types of innate immunity (defensive barriers)?

The skin—specifically, the epidermis and dermis.

What is the primary anatomical barrier of the body?

Multiple layers of tightly packed, dead, keratinized cells form a waterproof barrier that resists penetration.

How does the epidermis protect against pathogens?

Oil glands produce sebum (with lactic and fatty acids) that maintains acidic pH (~3–5), which inhibits microbial growth. Sweat also contributes to acidity.

What role does the dermis play in immunity?

They line the respiratory, gastrointestinal, and urogenital tracts; produce mucus, saliva, tears to wash away pathogens, and use cilia to mechanically sweep debris.

How do mucous membranes protect the body?

They out-compete pathogens for space and nutrients, helping prevent colonization.

What role does normal flora (microbiota) play in innate immunity?

• Body temperature

• pH (e.g., gastric acid, skin acidity)

• Soluble factors (e.g., lysozyme, cytokines, complement)

What are examples of physiological barriers in innate immunity?

An antibacterial enzyme in saliva, mucus, and tears that breaks down bacterial cell walls.

What does lysozyme do?

Signaling proteins made by immune cells that affect the behavior of other cells. Example: Interferons—produced by virus-infected cells to warn nearby cells and trigger an antiviral state.

What are cytokines and what do they do?

A group of serum proteins that:

• Tag pathogens with molecular flags

• Damage pathogen membranes

• Enhance immune cell recruitment

What is the function of the complement system?

The engulfment of particles by immune cells like macrophages or neutrophils.

What is phagocytosis?

It extends pseudopodia, surrounds the pathogen, and internalizes it into a phagosome for destruction.

How does a cell phagocytose a pathogen?

Infected or injured cells release chemical alarms.

What triggers the inflammatory response?

• Redness (rubor) – from vasodilation

• Heat (calor) – from increased blood flow

• Swelling (tumor) – from plasma entering tissues

• Pain (dolor) – from pressure on nerve endings

What are the 4 signs of inflammation?

To contain infection, recruit immune cells, and begin healing.

What is the overall goal of the inflammatory response?

The movement of immune cells from the blood into tissues by crossing blood vessel walls.

What is diapedesis?

During an immune response, especially when cells are needed at the site of infection or inflammation.

When does diapedesis occur?

Often yes, but persistent infections require adaptive (specific) immunity.

Is innate immunity always sufficient?

It is made and refined during infection—not present at full strength from the start.

When is adaptive immunity developed?

Targeted—it responds to specific pathogens or antigens.

Is adaptive immunity broad or targeted?

A molecule, macromolecule, particle, or cell that:

• Has a recognizable structure

• Is seen as non-self by the adaptive immune system

What does the term “antigen” (Ag) mean?

It must be foreign and contain a structure recognized by adaptive immune cells.

What qualifies something as an antigen?

Yes, but concurrent infections may complicate or slow the adaptive response, as each pathogen requires a specific response.

Can the immune system handle multiple infections at once?

It keeps most people healthy by stopping many infections before they cause harm.

What does innate immunity usually accomplish?

The adaptive immune system is activated to eliminate the remaining infection.

What happens if an infection survives the innate response?

It slows the infection, buying time for adaptive immunity to develop a targeted response.

What role does innate immunity play before adaptive kicks in?

The adaptive response to one infection does not affect a second infection unless they share antigens. Each response is pathogen-specific.

What happens during a concurrent infection?

A non-self molecule recognized by the adaptive immune system as foreign and potentially harmful.

What is an antigen?

A protein made by lymphocytes in response to an antigen. It can:

• Be secreted = antibody (Ab)

• Be B-cell-bound = immunoglobulin (Ig)

What is an antibody (immunoglobulin)?

It recognizes and binds to specific structures on antigens to help eliminate pathogens.

What is the function of an antibody?

1. Specificity – targets specific antigens

2. Diversity – recognizes billions of different molecules

3. Memory – faster, stronger response on re-exposure

4. Self/Non-self recognition – avoids attacking the body’s own cells

What are the four major characteristics of adaptive immunity?

No, they are interactive and mutually supportive systems.

Do innate and adaptive immunity work independently?

• Phagocytes from the innate response activate adaptive immunity

• Soluble factors (like antibodies or cytokines) from adaptive responses enhance phagocytosis

How do innate and adaptive immunity help each other?