Phagocytosis, Neutrophils & Macrophages

What two types of white blood cells perform phagocytosis?

Neutrophils and macrophages

What is the first step in phagocytosis?

The white blood cell recognizes the bacteria by its antigens.

What structure do neutrophils use to engulf pathogens?

Pseudopods.

What is formed when a neutrophil engulfs a bacterium?

A phagosome

What type of enzymes are found in lysosomes?

Hydrolytic enzymes

What is formed when a phagosome fuses with a lysosome?

A phagolysosome.

What is the process of releasing antigens from the neutrophil called?

Exocytosis.

What happens to antigens after they are released from the neutrophil?

They enter the lymph system and go to lymph nodes.

What occurs if the bacteria survives phagocytosis?

An oxidative burst is initiated.

What is NADPH's role in oxidative burst?

It donates electrons to oxygen, converting it into superoxide.

What are the products of oxidative burst?

Superoxide and hydrogen peroxide (H2O2).

What is hypochlorite commonly known as?

Bleach.

What happens to the neutrophil during oxidative burst?

It gets destroyed

What do histones do during the death of a neutrophil?

They bind with released DNA and antigens to form nets.

What are NETs?

Neutrophil extracellular traps formed by DNA and histones.

How do macrophages differ from neutrophils in processing antigens?

Macrophages present antigens on their cell membrane, while neutrophils exocytose them.

What is MHC class I (MHC-I)?

A receptor present on all nucleated cells that signals "self."

What is MHC class II (MHC-II)?

A receptor found on antigen-presenting cells like macrophages.

What is the function of macrophages in the immune response?

They present antigens to T cells and B cells in lymph nodes.

Why is the macrophage's antigen presentation crucial?

It activates adaptive immunity.

What type of immune response do neutrophils primarily participate in?

Innate immunity.

What is phagocytosis?

The process by which cells engulf and digest pathogens.

What role do hydrolytic enzymes play in phagocytosis?

They break down engulfed bacteria.

What can be produced from hydrogen peroxide during oxidative burst?

Hydroxide free radicals and hypochlorous acid.

How do neutrophils and macrophages handle bacteria differently after phagocytosis?

Neutrophils kill quickly with oxidative burst; macrophages present antigens for a longer-term response.

What happens to the DNA of neutrophils when they die?

It is released into the surrounding area.

What is the main purpose of NETs?

To trap and kill pathogens.

In which part of the immune system do T and B cells become activated?

In the lymph nodes.

What does oxidative burst help to enhance?

The killing of resilient pathogens.

Why are both neutrophils and macrophages essential for immune defense?

They provide immediate and adaptive immune responses to infections.