Phagocytosis and Nonspecific Defense Mechanisms

Questions and Answers

What triggers a phagocyte to engulf a pathogen?

The presence of a specific type of pathogen

The color of the pathogen

The size of the pathogen

The recognition of proteins on the surface of the pathogen (correct)

What is the end product of phagocytosis?

The pathogen is eliminated from the body

The phagocyte is destroyed by the pathogen

The pathogen is digested by the phagocyte

The pathogen is surrounded by a membrane called a phagosome (correct)

What type of cells can act as phagocytes?

Macrophages, dendritic cells, and B cells

Neutrophils, dendritic cells, and T cells

Macrophages and neutrophils only

Macrophages, neutrophils, and dendritic cells (correct)

What happens to the engulfed pathogen inside the phagocyte?

It is digested and broken down Signup and view all the answers

What is the significance of phagocytosis?

It helps to eliminate pathogens from the body Signup and view all the answers

How does the phagocyte engulf a pathogen?

By using its receptors to recognize proteins on the pathogen Signup and view all the answers

What is the outcome of phagocytosis?

The pathogen is neutralized and eliminated Signup and view all the answers

What is the purpose of phagocytosis?

To eliminate pathogens from the body Signup and view all the answers

What is the function of lysosomes in phagocytosis?

To dump particles that break up the pathogen Signup and view all the answers

What is the term for short chains of amino acids?

Polypeptides Signup and view all the answers

What is the purpose of Major Histocompatibility Complexes (MHC) in phagocytosis?

To present antigens to other immune cells Signup and view all the answers

What type of immune response do B cells participate in?

Adaptive immune response Signup and view all the answers

What is unique about the variable ends of membrane-bound antibodies on B cells?

They are specific to certain pathogens Signup and view all the answers

What is the term for the parts of a pathogen that are recognized by specific chains of antibodies?

Epitopes Signup and view all the answers

What happens to the pathogen after it is engulfed by a phagocyte?

It is broken down into its constituent molecules Signup and view all the answers

What type of MHC proteins are presented by phagocytes such as macrophages or dendritic cells?

MHC class II Signup and view all the answers

How many different combinations of antibodies can be produced by B cells?

Billions Signup and view all the answers

What is the purpose of antigen presentation by MHC proteins?

To activate T cells Signup and view all the answers

What is the term for the part of the pathogen that binds to the B cell's variable sequencer?

Epitope Signup and view all the answers

What happens to the pathogen after it binds to the B cell?

It gets engulfed by the B cell Signup and view all the answers

What do plasma B cells produce after they get activated?

A ton of antibodies Signup and view all the answers

What is the function of MHC II proteins?

To present pieces of pathogens on the surface of cells Signup and view all the answers

What is the term for cells that engulf and present pathogens, such as B cells and phagocytes?

Professional antigen presenting cells Signup and view all the answers

What is the term for the part of the pathogen that is presented on the surface of cells?

Antigen Signup and view all the answers

What is the difference between professional and non-professional antigen presenting cells?

Professional cells engulf and present pathogens, while non-professional cells only present Signup and view all the answers

What is the function of helper T cells in relation to MHC II proteins?

They recognize MHC II proteins Signup and view all the answers

What is the term for the process by which B cells take pieces of pathogens and present them on their surface?

Antigen presentation Signup and view all the answers

What is the significance of histocompatibility in relation to MHC II proteins?

It refers to the compatibility of transplanted tissues with the immune system Signup and view all the answers

Study Notes

Phagocytosis and Antigen Presentation

Phagocytosis is a nonspecific defense mechanism where phagocytes (e.g., macrophages, neutrophils, dendritic cells) recognize and engulf pathogens, breaking them down into constituent molecules.
The phagocyte's membrane surrounds the pathogen, forming a phagosome, which then fuses with a lysosome to break down the pathogen.
The phagocyte processes the broken-down pathogen, binding pieces of it to major histocompatibility complex (MHC) class II proteins, which are then presented on the surface of the phagocyte.

Antigen Presentation by Phagocytes

Phagocytes act as professional antigen-presenting cells, engulfing pathogens, breaking them down, and presenting pieces of them on their surface using MHC class II proteins.
MHC class II proteins are recognized by helper T cells, which play a crucial role in activating other parts of the immune system.

B Cells and Antigen Presentation

B cells have membrane-bound antibodies that recognize specific epitopes (parts of pathogens) and bind to them.
When a B cell binds to a pathogen, it engulfs and breaks down the pathogen, presenting pieces of it on its surface using MHC class II proteins.
B cells also act as professional antigen-presenting cells, taking in pathogens, breaking them down, and presenting antigens on their surface.

Comparison of Phagocytes and B Cells

Both phagocytes and B cells engulf and break down pathogens, presenting pieces of them on their surface using MHC class II proteins.
However, phagocytes are nonspecific, recognizing pathogens based on general markers, whereas B cells are specific, recognizing pathogens based on specific epitopes.
Both types of cells are professional antigen-presenting cells, playing a crucial role in activating other parts of the immune system.

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Description

Learn about phagocytosis and how phagocytes recognize and engulf pathogens through nonspecific defense mechanisms. Understand the role of receptors and markers in this process.