Module 3: Inflammation, Infection, Immunity, and Vaccines

What is the immune system’s main purpose?

To protect the body from infection and harmful substances, while recognizing its own cells.

Is the immune system one organ?

No—it’s a network of cells, tissues, and organs that work together across the body.

What types of threats does the immune system defend against?

Bacteria, viruses, fungi, parasites, cancer cells, toxins, and anything foreign.

How does the immune system know what is “self” vs. “non-self”?

Cells have special markers on their surfaces. The immune system is trained to ignore “self” and attack “non-self.”

What is the role of the bone marrow in the immune system?

It produces white blood cells, including B cells and the early form of T cells.

What happens in the thymus?

T cells mature and learn to recognize which cells to attack and which to leave alone.

What do lymph nodes do?

They act as filters. They catch invaders in the lymph fluid and help activate immune cells.

What is the function of the spleen?

It filters the blood, removes old red blood cells, and helps detect bloodborne pathogens.

What are tonsils and Peyer’s patches?

Specialized tissues that monitor what enters through the mouth and GI tract.

How do skin and mucous membranes act as a defense?

They block entry and contain chemicals that trap or kill microbes.

What is the lymphatic system?

A fluid-carrying system that runs parallel to blood vessels and moves immune cells throughout the body.

What is the first line of defense in immunity?

Physical and chemical barriers like skin, mucus, tears, stomach acid, and normal bacteria.

What is the second line of defense?

Innate immunity: includes inflammation, fever, white blood cells, and the complement system.

What is the third line of defense?

Adaptive immunity: a specific, memory-based response by B and T cells.

What makes innate immunity “innate”?

It’s built-in at birth and works the same way for every threat, every time.

How quickly does innate immunity respond?

Within minutes to hours of detecting a problem.

Does innate immunity have memory?

No, it responds in the same way each time.

What makes adaptive immunity “adaptive”?

It adapts to specific threats, learns over time, and remembers past infections.

What cells are involved in innate immunity?

Neutrophils, macrophages, natural killer cells, mast cells.

What cells are involved in adaptive immunity?

B cells (make antibodies), T cells (kill infected cells, coordinate other cells).

What is the role of cytokines?

They are chemical messengers that help immune cells talk to each other and coordinate action.

What do interleukins do?

Help white blood cells communicate, grow, and activate other cells.

What do interferons do?

Help fight viruses by interfering with their ability to replicate.

What does tumor necrosis factor (TNF) do?

Triggers inflammation and fever; helps destroy abnormal cells.

How is the immune system like a security system?

It monitors for threats, sends alarms (cytokines), and deploys a targeted response.

Why do some people get very sick from a germ while others don’t?

It depends on their immune system strength, memory, and how quickly they respond.

What is immune “memory”?

After fighting a specific pathogen, the immune system remembers it and responds faster next time.

What are helper T cells?

They don’t kill invaders directly but help activate B cells and killer T cells.

What are cytotoxic (killer) T cells?

They destroy cells infected with viruses or that have become cancerous.

What do B cells do?

They produce antibodies that attach to pathogens and help neutralize or destroy them.

What are natural killer (NK) cells?

Innate immune cells that can kill infected or cancerous cells without needing prior exposure.

What are phagocytes?

Cells like neutrophils and macrophages that “eat” pathogens and debris.

What is the microbiome’s role in immunity?

Healthy bacteria help crowd out harmful microbes and support immune balance.

What is inflammation?

A protective response of the body to injury or infection that helps contain damage, fight invaders, and begin healing.

Why is inflammation considered “double-edged”?

Because while it helps the body heal, if it becomes chronic or uncontrolled, it can damage tissues and contribute to disease.

What are the three main goals of inflammation?

1. Eliminate the initial cause of injury 2. Remove damaged cells 3. Start repair and regeneration

What are the five cardinal signs of inflammation?

Redness, heat, swelling, pain, and sometimes loss of function.

What causes redness and heat in inflamed tissue?

Blood vessels dilate (widen), bringing more warm blood to the area.

What causes swelling?

Fluid, proteins, and white blood cells leak from blood vessels into surrounding tissues.

What causes pain during inflammation?

Swelling puts pressure on nerves, and chemicals like prostaglandins stimulate nerve endings.

What is the first thing that happens when inflammation begins?

Blood vessels dilate and become more permeable, allowing immune cells to leave the bloodstream and enter tissues.

What are mast cells, and what do they do?

Immune cells that release histamine and start the inflammation process.

What does histamine do?

Increases blood flow and makes blood vessels leaky so immune cells can reach the area.

What is vasodilation?

The widening of blood vessels to increase blood flow to the site of injury.

What is vascular permeability?

The ability of blood vessel walls to let fluid and cells pass through—causes swelling.

What are neutrophils?

Fast-acting white blood cells that arrive first to engulf pathogens and dead tissue.

What are macrophages?

Longer-lasting immune cells that clean up and promote tissue repair.

What role do eosinophils play?

Help fight parasites and are active in allergic reactions.

What is the role of lymphocytes in inflammation?

Participate in adaptive immune responses, especially during prolonged or chronic inflammation.

What are cytokines?

Chemical messengers that help immune cells communicate and coordinate their response.

What are prostaglandins?

Chemicals that contribute to fever, pain, and swelling; targeted by anti-inflammatory drugs.

What do chemokines do?

Attract white blood cells to the site of injury or infection (like a chemical “GPS”).

What are complement proteins?

A group of proteins that help tag invaders, recruit immune cells, and destroy pathogens.

What are the four main phases of the inflammatory response?

1. Initiation 2. Amplification 3. Resolution 4. Repair and regeneration

What happens during the initiation phase?

Mast cells and damaged tissue release histamine and other signals to start inflammation.

What happens during the amplification phase?

White blood cells flood the area, cytokines recruit more cells, and inflammation increases.

What happens during the resolution phase?

If the threat is removed, anti-inflammatory signals stop the response and begin cleanup.

What happens during repair and regeneration?

Damaged tissue is rebuilt with new cells, collagen, and blood vessels.

What is chronic inflammation?

Long-lasting inflammation that persists after the initial cause is gone or unresolved.

What causes chronic inflammation?

Ongoing infection, autoimmune disease, environmental toxins, or metabolic issues like obesity.

What immune cells are involved in chronic inflammation?

Macrophages, lymphocytes, and plasma cells.

What are granulomas?

Clusters of immune cells that form when the body tries to contain something it can’t eliminate.

How can chronic inflammation lead to disease?

It can damage healthy tissue, promote scarring, and contribute to diseases like diabetes, cancer, or heart disease.

What are the phases of wound healing?

Hemostasis, inflammation, proliferation, and remodeling.

What happens during hemostasis?

A clot forms, and platelets release chemicals to stop bleeding and signal healing.

What happens during proliferation?

Fibroblasts make collagen, new blood vessels form, and skin cells regrow.

What happens during remodeling?

Scar tissue strengthens, and blood vessels shrink as healing completes.

What is primary intention healing?

Wound edges are closed (e.g., with stitches), healing is fast with minimal scarring.

What is secondary intention healing?

Wound is left open to heal from the bottom up, often slower and with more scarring.

What is dehiscence?

When a closed wound reopens unexpectedly—needs prompt attention.

What is a keloid?

A thick, raised scar that grows beyond the original wound area.

What is a hypertrophic scar?

A raised scar that stays within the original wound boundary.

What is a contracture?

A tightening of skin or scar tissue that limits movement—common after burns.

What is delayed epithelialization?

When new skin cells grow slowly over the wound, delaying healing.

Why does understanding inflammation matter in nursing care?

Early recognition helps prevent complications; nurses monitor, support healing, and educate.

What is immunization?

A process that trains the immune system to recognize and fight a specific germ before you get sick.

How is immunization different from vaccination?

Vaccination is the act of giving a vaccine; immunization is the result—being protected from disease.

What is the main goal of a vaccine?

To safely expose the body to a harmless version of a pathogen so it can build memory and protection.

How does the immune system “remember” after a vaccine?

By creating memory B and T cells that quickly respond if the real germ shows up later.

What are antigens?

Molecules found on the surface of germs that trigger an immune response.

What part of the immune system responds to vaccines?

The adaptive immune system, which learns and builds specific memory.

Why might someone get mild symptoms after a vaccine?

It’s a sign the immune system is responding—not a sign of illness.

What is a booster shot?

An additional vaccine dose that "reminds" the immune system and increases protection.

Why do some vaccines need boosters?

Because antibody levels and memory may fade over time. Boosters help maintain protection.

What is active immunity?

When the body creates its own antibodies and memory after infection or vaccination.

What is passive immunity?

When a person is given ready-made antibodies from another source.

What is natural active immunity?

Gained by surviving an infection and developing long-term protection.

What is artificial active immunity?

Gained through vaccination, which stimulates the immune system safely.

What is natural passive immunity?

Antibodies passed from mother to baby through the placenta or breast milk.

What is artificial passive immunity?

Antibodies given by injection to provide quick, short-term protection (e.g., rabies treatment).

How long does active immunity last?

Often years to life—especially if memory cells are formed.

How long does passive immunity last?

Usually only a few weeks to months—no memory cells are made.

Why is passive immunity helpful?

It provides fast protection in emergencies or to people who can't make antibodies yet (e.g., infants).

What is herd immunity?

When enough people are immune to a disease, it can’t spread easily—even to unvaccinated people.

Why is herd immunity important?

It protects newborns, people with immune conditions, and others who can’t get vaccinated.

What is the herd immunity threshold for measles?

Over 90% of the population must be immune to stop spread.

What are live attenuated vaccines?

Vaccines made from weakened viruses or bacteria that still stimulate a strong immune response.

What are inactivated vaccines?

Vaccines made from killed germs; safe but often need boosters.

What are subunit or conjugate vaccines?

Vaccines that use only specific pieces of the germ—like a protein or sugar.

What are toxoid vaccines?

Vaccines that protect against toxins made by bacteria (not the bacteria itself).