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Adaptive Immunity

Adaptive Immunity

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This lesson will describe adaptive immunity as the body's third line of defense against pathogens.

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Tutorial

What's Covered

This lesson will look at the body's third line of defense against pathogens by looking at:

  1. Adaptive Immunity
  2. Types of Adaptive Immunity

1. Adaptive Immunity

Adaptive immunity is a specific type of immunity. This means that it has cells which have receptors for specific types of pathogen unlike other types of immunity where cells basically attack any type of pathogen regardless of the type. Adaptive immunity is the third line of defense against pathogens.

Term to Know

    • Adaptive Immunity
    • Also known as specific immunity, adaptive immunity is carried out by T & B lymphocytes and reacts to specific antigens of cells; adaptive immunity also produces memory cells to target the same pathogen if we are ever exposed to it again.

Adaptive immunity has three types of cells involved:

  • T cells-cells that kill abnormal cells and help to activate B cells
  • B cells-a type of cell that help to make antibodies
  • Phagocytes, which fight specific pathogens.

T cells and B cells are both lymphocytes, a type of white blood cell, which make receptors for one specific type of antigen and attack anything that has that antigen. Antigens are something that's recognized as not normal, and will elicit an immune response. These receptors and antigens fit together like a lock and a key. The receptors are a folded up protein with a specific shape, and antigens have this specific shape as well.

Think About It

How does your body know not to attack your own cells?

Within your cells, or on your cells, you have something called MHC markers. These MHC markers basically mark a cell as self. What this does is it allows pathogen fighting cells of the immune system to know which cells to target and which not to target.If a cell has these MHC markers that mark it as self, these pathogen fighting cells know not to attack these cells. These cells are part of the body and are supposed to be there. They'll focus their energy on attacking cells that are supposed to be attacked, or targeted.

Terms to Know

    • Antibodies
    • Specific protein markers that are created by the immune system for binding and reacting to specific antigens; antibodies are created by B cells during humoral immunity.
    • Antigens
    • A particle that has the potential to stimulate an immune response; antigens are basically the identity marker of cells for the immune system to see.
    • T cells
    • Also known as T lymphocytes, T cells carry out a version of specific immunity called cell-mediated immunity or cellular immunity. During cellular immunity the immune response is enhanced by helper T cells and cells are directly attacked by cyotoxic T cells.
    • B cells
    • Also known as B lymphocytes, B cell carry out a version of specific immunity called humoral immunity. During humoral immunity B cells form into plasma cells that mass produce antibodies to be secreted into our body tissue cavities.Antibody-mediated immunity of focuses mostly on B cells producing antibodies. While cell-mediated immunity focuses mostly on T cells, destroying pathogens.

Adaptive immunity takes about a week to develop, but it produces memory cells. If a person comes in contact with an illness or a disease or a pathogen that they've already had in the past, memory cells will be able to fight that off quicker if they encountered again. These memory cells allow the body to fight off this pathogen quicker the second time around. It basically produces us with immunity.

Term to Know

    • Memory Cells
    • Memory cells are genetically programmed cells that have gone through an initial exposure to a pathogen/antigen that can coordinate a much more specific and rapid response if we are ever exposed to that same pathogen/antigen.

2. Types of Adaptive Immunity

There are two types of adaptive immunity:

One type of adaptive immunity is called antibody-mediated immunity, also known as humoral immunity. An antibody is basically an antigen receptor; antibodies will flag a certain antigen to be picked up and disposed of. This type is associated mainly with B-cells and B cells are made in the bone marrow.

The other type of adaptive immunity is called cell-mediated immunity and cell-mediated immunity involves lymphocytes, which are a type of white blood cell. Specifically it involves T cells, which are made in bone marrow as well but they mature in the thymus, an organ at the base of your neck. They attack and destroy antigens found on specific cells.

Summary

Adaptive Immunityis carried out by the T and B lymphocytes. They will flag and attack only specific pathogens that enter the body. Once the B-cells have developed an antibody against a pathogen, adaptive immunity will create memory cells to protect the body against future attacks. There are two types of adaptive immunity. Antibody-mediated immunity involves flagging an antigen to be disposed of while cell-mediated immunity involves lymphocytes attacking the antigen.

Keep up the learning and have a great day!

Source: Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Antigens

    A particle that has the potential to stimulate an immune response; antigens are basically the identity marker of cells for the immune system to see.

  • Adaptive Immunity

    Also known as specific immunity, adaptive immunity is carried out by T & B lymphocytes and reacts to specific antigens of cells; adaptive immunity also produces memory cells to target the same pathogen if we are ever exposed to it again.

  • T cells

    Also known as T lymphocytes, T cells carry out a version of specific immunity called cell-mediated immunity or cellular immunity. During cellular immunity the immune response is enhanced by helper T cells and cells are directly attacked by cyotoxic T cells.

  • B cells

    Also known as B lymphocytes, B cell carry out a version of specific immunity called humoral immunity. During humoral immunity B cells form into plasma cells that mass produce antibodies to be secreted into our body tissue cavities.

  • Antibodies

    Specific protein markers that are created by the immune system for binding and reacting to specific antigens; antibodies are created by B cells during humoral immunity.

  • Memory Cells

    Memory cells are genetically programmed cells that have gone through an initial exposure to a pathogen/antigen that can coordinate a much more specific and rapid response if we are ever exposed to that same pathogen/antigen.