Narrator: Every second of your life youare under attack. Billions of bacteria, viruses, and fungi are trying to make youtheir home. So our bodies have developed a super complex little army with guards,soldiers, intelligence, weapons factories and communicators to protect you from uh,well, dying. For this tutorial, let's assume the immune system has twelve different jobs. For example, kill enemies, communicate etc. And it has 21 different cells and twoprotein forces. These cells have up to four different jobs. Let's assign them. Here are the interactions. Now let's make this understandable. First of all, let's addcolors to the jobs. Now let's illustrate
the cells. The central color represents the main job of the cell, while the surrounding ones represent secondary duties. Now the immune system looks like this. Now the interactions. Isn't this complexity just awesomeé For this tutorial we will only talk about these cells and ignore the rest. So what happens in the case of an infectioné Music It's a beautiful day when suddenly a wild rusty nail appears and you cut yourself. The first barrier of the immune system isbreached: your skin. Nearby bacteria sieze
on the opportunity and enter your wound.They start using up the body's resources and double their numbers about every 20 minutes. At first they fly under the radar but when a certain bacteria population isreached, they change their behavior and start to damage the body by changing the environment around them. The immune system has to stop them as fast as possible. First of all your guard cells, known as macrophages, intervene. They are huge cells that guard every border region of the body. Most of the time they alone cansuffocate an attack because they can devour up to 100 intruders each. They swallow the intruder whole and trap it inside a membrane.
Then the enemy gets broken down by enzymesand is killed. On top of that, they cause inflammation by ordering the blood vesselsto release water into the battlefield so fighting becomes easier. You notice this as a very mild swelling. When the macrophages fight for too long, they call in heavy backup by releasing messenger proteins that communicate location and urgency. Neutrophiles leave their patrol routes in the blood and move to the battlefield. TheNeutrophiles fight so furiously that they kill healthy cells in the process. On top of that, they generate barriers that trap and kill the bacteria. They are indeed so deadly that they evolved to commit suicide
after five days to prevent them from causing too much damage. If this is not enough to stop the invasion, the brain of the immune system kicks in. The dendritic cell gets active. It reacts to the signals of the soldiers and starts collecting samples from the enemies. They rip them into piecesand present the parts on their outer layer. Now, the dendritic cell makes a crucial decision. Should they call for antivirus forces that eradicate infected body cells,or an army of bacteria killersé In this case, antibacteria forces are necessary.It then travels to the closest lymph node in about a day. Here billions of helper andKillerT cells are waiting to be activated.
When TCells are born they go through adifficult and complicated training process and only a quarter survives. The survivingcells are equipped with a specific setup. And the dendritic cell is on its way lookingfor a helper Tcell with a set up that's just right. It's looking for a helper Tcellthat combines the parts of the intruders which the dendritic cell has presented on its membrane. When it finally finds one, a chain reaction takes place. The helper Tcell is activated. It quickly duplicates thousands of times. Some become memory Tcells that stay in the lymph node and will make you practically immune to this enemy.Some travel to the field of battle to help
Cell vs virus A battle for health Shannon Stiles
You're in line at the grocery store when, uh oh, someone sneezes on you. The cold virus is sucked inside your lungs and lands on a cell on your airway lining. Every living thing on Earth is made of cells, from the smallest onecelled bacteria to the giant blue whale to you. Each cell in your body is surrounded by a cell membrane,
a thick flexible layer made of fats and proteins, that surrounds and protects the inner components. It's semipermeable, meaning that it lets some thing pass in and out but blocks others. The cell membrane is covered with tiny projections. They all have functions, like helping cells adhere to their neighbors
or binding to nutrients the cell will need. Animal and plant cells have cell membranes. Only plant cells have a cell wall, which is made of rigid cellulose that gives the plant structure. The virus cell that was sneezed into your lungs is sneaky. Pretending to be a friend, it attaches to a projection on the cell membrane, and the cell brings it through the cell membrane and inside.
When the virus gets through, the cell recognizes its mistake. An enemy is inside! Special enzymes arrive at the scene and chop the virus to pieces. They then send one of the pieces back through the cell membrane, where the cell displays it to warn neighboring cells
about the invader. A nearby cell sees the warning and immediately goes into action. It needs to make antibodies, proteins that will attack and kill the invading virus. This process starts in the nucleus. The nucleus contains our DNA,
the blueprint that tells our cells how to make everything our bodies need to function. A certain section of our DNA contains instructions that tell our cells how to make antibodies. Enzymes in the nucleus find the right section of DNA, then create a copy of these instructions, called messenger RNA. The messenger RNA leaves the nucleus to carry out its orders.