Innate Immunity

What is the main purpose of the innate immune system?

To provide a quick, nonspecific defense against pathogens.

What are the two lines of defense in innate immunity?

The first line (Physical and chemical) and the second line (internal defenses).

What are examples of physical barriers in the first line of defense?

Skin, mucous membranes, and cilia.

What are examples of secretions in the first line of defense?

Tears, saliva, mucus, sweat, sebum, and stomach acid.

What enzyme in tears and saliva destroys bacteria?

Lysozyme.

How does the skin protect the body?

Acts as a physical barrier and produces acidic secretions that inhibit microbes.

What is the function of mucus?

Traps pathogens and particles.

What happens if pathogens bypass the first line of defense?

The second line of defense (internal defenses) is activated.

What are the main cells involved in the second line of defense?

Phagocytes (like neutrophils and macrophages) and natural killer (NK) cells.

What is the role of neutrophils?

They are first responders that engulf and destroy pathogens.

What is the role of macrophages?

Engulf pathogens and present antigens to T cells to start adaptive immunity.

What is inflammation?

A response that increases blood flow and immune cell delivery to an infection site.

What are the four signs of inflammation?

Redness, heat, swelling, and pain.

What is the purpose of fever?

Slows pathogen growth and enhances immune reactions.

Does innate immunity have memory?

No — it responds the same way each time.