Y3V-T2-LSN5

• Biologie
• Voortgezet speciaal onderwijs
• Leerroute 3

Welcome, please get ready:

• notebook and pen
• laptop

Lines of defence

Overview of line 2

Line 1 fails: pathogens invade the body

Surviving tissue cells call for help

Macrophages start to devour pathogens and send out signs

Neutrophils arrive and join the battle. They massively kill off the pathogens and themselves

Proteins of the complement system start to kill pathogens by perforating them

Dendritic cells display parts of the pathogens on their membranes and travel to the lymph nodes

Activation of defence line 3: the adaptive immune system - the lymphocytes

Lines of defence

Learning goals

• You know what parts belong to the adaptive immune system
• You understand what role antigen presentation plays in the adaptive immune system
• You understand how the adaptive immune system works to achieve memory
• You understand what immunity is

Keywords

Innate immunity

Adaptive immunity

Antigen

Foreign

T-Lymphocyte/ T-cell

B-Lymphocyte/B-cell

Antibody

Memory cell

To what part of the immune system do these lines of defence belong?

Innate immune system

Adaptive immune system

Macrophage

B-Lymphocyte

T-Lymphocyte

Dendritic cell

Neutrophil

Antigens

• small parts coming from a pathogen
• presented by phagocytes (dendritic cells) to lymphocytes
• foreign vs self
• dendritic cells present them on their surface after disassembly
• 
  

• Antigen Presenting Cell or APC

Look at the image:
Two cells are visible. Cell A and Cell B

If you study the image well you can determine which of these cells is the dendritic cell.

Which cell is the dendritic cell?

1. cell A
2. cell B

Which of the numbered or lettered parts indicated in the image is the antigen?

1. part E
2. part F
3. part 4
4. part D

Recall from the video

Who is cell A?

To what type of cell does the dendritic cell present the antigens it found?

1. macrophages
2. neutrophils
3. B-lymphocytes
4. T-lymphocytes

Recall from the video

WHERE in the body does this antigen presentation takes place?

1. In the infected tissue
2. in the lymph node
3. in the blood vessels
4. in your pinky toe

Foreign vs Self

Foreign antigens

antigens that do not originate in the body themselves

Self antigens

antigens that originate in the body themselves

The adaptive immune system can distinguish between foreign and self antigens

Explain WHY the adaptive immune system must be able to distinguish between foreign and self antigens.

Recall from previous lesson/video

How is the adaptive immune system also called?

1. specific immune system
2. aspecific immune system
3. innate immune system
4. barrier system

Antigen specificity

T- and B-lymphocytes have been trained to recognize ONLY 1 antigen.

You continuously create new T- and B-lymphocytes to recognize different kinds of antigen. Even for antigens you'll never come across.

Only the T-cell that recognizes the antigen presented by the dendritic cell will become active

Antigen specificity

You have millions and millions of different lymphocytes ready to become active.

From 'naive' to 'active'

a non-active / sleeping lymphocyte is called naive. 

Antigen presentation and antigen recognition makes a lymphocyte active

naive T-lymphocyte

antigen recognition

active T-lymphocyte

Recall from the video

What is the first thing that happens after T-cell* activation?


* T-lymphocyte = T-cell

1. making worn-down macrophages active again
2. activating B-cells
3. dividing
4. having a glass of beer

Explain WHY the first step of the cell after activation is multiplying itself (cell division)

T-lymphocytes get to work

division

active T-lymphocyte

1. worn-down macrophages get reactivated

2. reactivated macrophages goes into overdrive and start to kill

1. T-cells activate specific B-cell

2. activated B-cells start to produce antibodies

B-cell

Activated T-cells look for the antigen-specific B-cell.

They activate this B-cell

naive B-cell

also antigen specific

active T-cell activates B-cell

by means of antigen recognition

active B-cell produce lots and lots of antibodies

On the previous slide:

"Activated T-cells look for the antigen-specific B-cell."

Explain this sentence in your owns words.

Antibodies

• proteins produced by activated B cells
• Y-shaped
• antigen-specific
• neutralize pathogen by preventing movement and interaction

Explain HOW activated T-cells, activated B-cells, antibodies and macrophages now work together to clear up the infection quickly

Be sure to include the role of ALL three cells and the role of antibodies.
Give an elaborate answer.

Memory cells and immunity

• a small part of the activated B- and T-cells remain present
• They turn into memory cells
• Memory B-cells produce low amounts of antibodies
• Memory T-cells keep looking for antigen

+

memory T-cells

memory B-cells

immunity

Explain in your own words what immunity is.

A COVID quick test is an example of an antigen test.

This test proves the presence of ... ?

1. the virus
2. macrophages
3. antibodies
4. an active adaptive immune system

The mantoux test is a test in which a small amount of M. tuberculosis antigen is introduced.

If the body has encountered this antigen before, the body quickly response with a big red stain.
Why does this stain appear?

1. because of the presence of the bacterium
2. because of the activation of B-cells producing antibodies
3. because of memory B-cells producing extreme amounts of antigens
4. because the nurse got bored and used red paint to kill the time

Well done!

You now understand how the adaptive immune system works.

To summarise...

Watch the same video again on the next slide. 

Wanna bet that you understand it way better now?

Lines of defence

Learning goals

• You know what parts belong to the adaptive immune system
• You understand what role antigen presentation plays in the adaptive immune system
• You understand how the adaptive immune system works to achieve memory
• You understand what immunity is

Homework

• Complete this lessonup
• Read pages 147-148 in the book 
• Complete the Assignments on lesson 5 on the classroom
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