Immune System Summary

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Questions and Answers

What is unique about the membrane-bound antibodies on a specific B cell?

They have a variable portion that differs from other B cells (correct)

They are only specific to a single antigen

They are all identical

They are only found on the surface of activated B cells

What is required for a B cell to get activated?

Binding of the pathogen to the membrane-bound antibody and stimulation by a T cell (correct)

Binding of the pathogen to an MHC II complex

Only stimulation by a T cell

Only binding of the pathogen to the membrane-bound antibody

What happens to the pathogen once it binds to the membrane-bound antibody on a B cell?

It is sucked in, broken down, and presented on an MHC II complex (correct)

It is immediately destroyed by the B cell

It is stored in the B cell for later use

It is released back into the system

What role do B cells play in addition to being antigen-presenting cells?

They can differentiate into effector cells or memory cells Signup and view all the answers

What is true about the variable portion of the T cell receptor on a helper T cell?

It is specific to a specific antigen Signup and view all the answers

What is the function of the MHC II complex on a B cell?

To present broken-down pathogen peptides to T cells Signup and view all the answers

What can activated B cells differentiate into?

Either effector cells or memory cells Signup and view all the answers

Why are B cells able to respond to different antigens or pathogens?

Because each B cell has a unique membrane-bound antibody with a variable portion Signup and view all the answers

What is the primary function of effector B cells?

To produce antibodies Signup and view all the answers

What is the common term for effector B cells that produce antibodies?

Plasma cells Signup and view all the answers

What do antibodies produced by effector B cells do?

Tag antigens for phagocytosis Signup and view all the answers

What is the primary function of CD4 positive T cells?

To help activate other immune cells Signup and view all the answers

What do CD8 proteins on T cells bind to?

MHC I complexes Signup and view all the answers

What is the primary function of CD8 positive T cells?

To directly kill infected cells Signup and view all the answers

Why do memory cells stick around for a long time?

To increase the likelihood of a faster response to future infections Signup and view all the answers

What is the role of macrophages in the immune response?

To engulf and digest foreign particles and cellular debris Signup and view all the answers

What is the difference between CD4 and CD8 positive T cells?

CD4 positive T cells help activate other immune cells, while CD8 positive T cells directly kill infected cells Signup and view all the answers

Why is it important to understand the different types of T cells?

To appreciate the complexity of the immune response Signup and view all the answers

What is the role of CD8 cells in the immune system?

To kill infected cells or cancerous cells Signup and view all the answers

What type of complex is presented by dendritic cells to activate helper T cells?

MHC II complex Signup and view all the answers

What is the primary function of effector helper T cells?

To activate B cells and release cytokines Signup and view all the answers

What type of cells do CD8 cells target and eliminate from the body?

Infected cells or cancerous cells Signup and view all the answers

What is the primary function of cytokines released by effector helper T cells?

To act as alarm bells to activate other immune cells Signup and view all the answers

What is the role of MHC I complex in the immune system?

To present antigens to cytotoxic T cells Signup and view all the answers

What type of cells produce antibodies against pathogens?

Plasma cells Signup and view all the answers

What is the primary function of memory cells in the immune system?

To respond quickly to future infections Signup and view all the answers

What type of cells are professional antigen-presenting cells?

Dendritic cells Signup and view all the answers

What is the role of helper T cells in the immune system?

To activate B cells and release cytokines Signup and view all the answers

Study Notes

B Cells

Each B cell has its own specific membrane-bound antibodies with a variable portion, allowing it to respond to different antigens or pathogens
When a B cell gets activated, it needs binding of a pathogen to its membrane-bound antibodies and sometimes stimulation by a T cell
B cells are also antigen-presenting cells, which means they can suck in an antigen, break it down, and present it on an MHC II complex to activate a helper T cell
Once activated, B cells differentiate into effector cells and memory cells
Effector B cells (also known as plasma cells) produce antibodies that can bind to antigens and tag them for pickup by macrophages or other phagocytes
Memory B cells stick around longer, making the response faster in case of future infections

T Cells

There are two main types of T cells: CD4 positive (helper) and CD8 positive (cytotoxic)
CD4 positive T cells have CD4 proteins and are usually helper T cells, binding to MHC II complexes
CD8 positive T cells have CD8 proteins and are usually cytotoxic, binding to MHC I complexes
Helper T cells release cytokines, which are alarm bells that tell other immune cells to get in gear
Cytotoxic T cells kill infected cells or cancer cells that express antigens on their MHC I complexes
Once activated, both helper and cytotoxic T cells differentiate into effector and memory cells
Effector T cells perform their respective functions (releasing cytokines or killing cells), while memory T cells stick around, ready to respond faster in case of future infections