Introducing 

Prezi AI.

Your new presentation assistant.

Refine, enhance, and tailor your content, source relevant images, and edit visuals quicker than ever before.

Loading content…
Transcript

Pathogens!

and the immune system.

Antigens

are molecules that stimulate an immune response

Antibodies

are protein molecules that can identify and neutralise antigens

Cell signalling

is the communication between cells that allows effective coordination of a response

Pathogen

an organism that causes disease, they live by taking nutrition from their host, but also cause damage in the process

  • are molecules that stimulate an immune response
  • are usually large molecules that have specific shape
  • a foreign antigen will be detected by the immune system and will stimulate the production of antibodies
  • antibodies will be specific to each antigen

Antigens

  • our own antigens are recognised by our immune system and do not stimulate any response.
  • are large proteins and are also known as immunoglobulins
  • are protein molecules that can identify and neutralise antigens
  • are released in response to an infection
  • are produced by the lymphocytes in the immune system
  • each have a different specific shapes to complement different antigens

Antibodies

  • antibodies attach to antigens and render them harmless

Neutralisation

Antibodies covering the pathogen binding-sites prevent the pathogen from binding to a host cell and entering the cell.

How antibodies work...

Agglutination

A large antibody can bind to many pathogens together. The group of pathogens is too large to enter a host cell.

Cell Signalling

  • the communication between cells that allows effective coordination of a response
  • it involves a coordinated response between a wide range of cells
  • this communication is achieved through cell surface molecules and through the release of hormone-like chemicals called cytokines
  • in order to detect a signal, the target cell must have a cell surface receptor
  • B lymphocytes and T lymphocytes have receptors that are complementary in shape to the foreign antigen.
  • when the antigen is detected, the lymphocyte is activated or stimulated

What sort of information is communicated?

Identification

The first signalling is done by the pathogen. The pathogen carries antigens on its cell surface, these act as flags that say 'I AM FOREIGN'. These are detected by our body cells.

Sending Distress Signals

The internal cell organelles such as lysosomes will attempt to fight the invader. Parts of the pathogen often end up attached to the host plasma membrane.

  • they act as a distress signal and can be detected by cells from the immune system.
  • they also act as markers to indicate that the host cell is infected.

Antigen Presentation

This process has been taken a step further by the macrophages in the lymph nodes. They act like phagocytes to engulf and digest the pathogen. But they do not fully digest it. They separate the antigens and link them into a cell surface molecule. This is exposed on the surface of the macrophage, which becomes known as antigen-presenting cell. It has to find the lymphocytes that can neutralise that particular antigen.

Instructions

Communication using cytokines includes the following:

  • macrophages release monokines that attract neutrophils
  • macrophages release monokines that can stimulate B cells to differentiate and release antibodies
  • T cells, B cells and macrophages release interleukins- stimulate proliferation and differentation in B and T cells.
  • many cells release interferon, which can inhibit virus replication and stimulate the activity of T killer cells.

Communication between cells in the specific immune response

Pathogen engulfed by cells from the immune system

Removal of antigens from pathogen

Antigens presented on surface of engulfing cells

(antigen presentation)

(clonal selection)

Production of T helper cells

(clonal expansion)

Release of interleukins

Activation of B cells

(clonal expansion)

Some B cell clones differentiate to make plasma cells

Plasma cells manufacture antibodies

Reproduction of B cells

Some B cell clones differentiate to make B memory cells

Memory cells circulate in body providing immunological memory

Selection of correct T killer cells and T helper cells

Production of T killer cells

(clonal expansion)

T killer cells search for infected cells

T killer cells attach to infected cells

T killer cells secrete toxic substances into affected cells to kill cell and the pathogens it contains

Osmosis Jones pt1

  • are usually a protein or glycoprotein in/on the plasma membrane
Learn more about creating dynamic, engaging presentations with Prezi