Aim: How does the immune system work?

Do Now:What does this picture tell you?

• Pathogens• Microscopic living

organisms that cause diseases;

• Bacteria

• Viruses

• Fungi

• Parasites

Reading (8-10 min)

• Turn to your partner

• Read out loud and do guided reading

• Discuss reading

• Pick vocabulary

• Annotate

Three lines of defense

• 1) Physical – Includes skin and mucous membranes.• 2) Nonspecific defensive cells- Includes

phagocytes, and natural killer cells…cause inflammation and fever, and

• 3) Specific cells-Includes the immune cells; T-cells and B-cells.

• All of the above make up your immune system• copy

• What is Immune System?

•     •   

• Protects you against billions of bacteria, viruses, and other parasites.

• Inside our bodies, our immune system is constantly on the alert, attacking at the first sign of an invasion by harmful organisms.

• The immune system is very complex. It's made up of several types of cells and proteins that have different jobs to do in fighting foreign invaders.

• Immune cells: Called white blood cells or lymphocytes are of 3 types

Immune system

• Made up of Immune cells (White Blood Cells)

• And lymphatic organs; spleen, tonsils, and thymus

• WBC are of three types

• Macrophages (or phagocytes), T cells and B cells (also called lymphocytes)

Three types of lymphocytes• Macrophages (the ‘big

eaters’)

• T cells and

• B cells

• There are different types of T cells and B cells

• T cells

• B cells

Different types of T and B cells

Helper T cell

Killer T cell

Plasma B cells

Memory B cells

Differences between the different types of Immune cells (or white blood

cells)

Macrophages (the ‘big eaters’)

They attack the invader first…they can’t really recognize the type of invader though…

When they get tired of eating they call for help…

They call upon T cells and B cells who work little different…strategically

The first ones to respond are the helper T cells

Helper T cells• Helper T cells are the

major driving force and the main regulators of the immune defense. Their primary task is to activate B cells and killer T cells.

• First step they take is to recognize the enemy…look at the bar code.. Or __ANTIGEN________

• HOW?

What is on the surface of foreigner that makes your immune cells recognize it?

• A foreigner is recognized by the presence of ANTIGEN on its surface.

• T and B cells

What is an antigen? Marker protein on the pathogen, the foreigner

• Invader

•

Antigen

• Barcode on the foreigner…

• Antigens are proteins present on the surface of the invader/foreigners…

Hey, but someone has to tell the helpers that invader is here…

• Who calls upon them?

• Macrophages..or phagocytes

• How do they inform the Helpers/ or activate the helpers?

• How do macrophages activate helper T-cells?

• Helper T-cells have

RECEPTORS!!!!

Receptors are for recognition…

• What is on the surface of T and B cells that helps them recognize foreigner?

•receptors • These receptors are very

specialized – match only one specific antigen.

• The body makes many different types of lymphocyte cells so that the immune system can recognize nearly all invaders. 

• Could be a T or a B cell 

How do viruses attack?

AIM: Why is HIV virus so dangerous?

• HIV virus attacks the helper T cells and brings down the whole immune system.

• Copy

Helper T cell

HIV Virus

• Where are these lymphocytes or immune cells located in the body?

• They are floating around in the lymphatic vessels…keeping an eye for the enemy

• When they are not patrolling throughout the body, they are present in the other parts (see picture)

• The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells. The killer T cell has receptors that are used to search each cell that it meets. If a cell is infected, it is swiftly killed. Infected cells are recognized because tiny traces of the intruder, antigen, can be found on their surface.

• The Complement System•  

 • The first part of the immune system

that meets invaders such as bacteria is a group of proteins called the complement system. These proteins flow freely in the blood and can quickly reach the site of an invasion where they can react directly with antigens - molecules that the body recognizes as foreign substances. When activated, the complement proteins can  -  trigger inflammation  - attract eater cells such as macrophages to the area  - coat intruders so that eater cells are more likely to devour them  - kill intruders

• Phagocytes•    This is a group of immune cells

specialized in finding and "eating" bacteria, viruses, and dead or injured body cells. There are three main types, the granulocyte, the macrophage, and the dendritic cell.    

• The granulocytes often take the first stand during an infection. They attack any invaders in large numbers, and "eat" until they die. The pus in an infected wound consists chiefly of dead granulocytes. A small part of the granulocyte community is specialized in attacking larger parasites such as worms.

• The dendritic cells are "eater" cells and devour intruders, like the granulocytes and the macrophages. And like the macrophages, the dendritic cells help with the activation of the rest of the immune system. They are also capable of filtering body fluids to clear them of foreign organisms and particles.

• Lymphocytes - T cells and B cells

.  • White blood cells called

lymphocytes originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes, spleen, and thymus. There are two main types of lymphatic cells, T cells and B cells. The lymphatic system also involves a transportation system - lymph vessels - for transportation and storage of lymphocyte cells within the body. The lymphatic system feeds cells into the body and filters out dead cells and invading organisms such as bacteria.

Phagocytes

• The macrophages ("big eaters") are slower to respond to invaders than the granulocytes, but they are larger, live longer, and have far greater capacities. Macrophages also play a key part in alerting the rest of the immune system of invaders. Macrophages start out as white blood cells called monocytes. Monocytes that leave the blood stream turn into macrophages.

• T cells •    T cells come in two

different types, helper cells and killer cells. They are named T cells after the thymus, an organ situated under the breastbone. T cells are produced in the bone marrow and later move to the thymus where they mature.

• The plasma cell is specialized in producing a specific protein, called an antibody, that will respond to the same antigen that matched the B cell receptor. Antibodies are released from the plasma cell so that they can seek out intruders and help destroy them. Plasma cells produce antibodies at an amazing rate and can release tens of thousands of antibodies per second.

• When the Y-shaped antibody finds a matching antigen, it attaches to it. The attached antibodies serve as an appetizing coating for eater cells such as the macrophage. Antibodies also neutralize toxins and incapacitate viruses, preventing them from infecting new cells. Each branch of the Y-shaped antibody can bind to a different antigen, so while one branch binds to an antigen on one cell, the other branch could bind to another cell - in this way pathogens are gathered into larger groups that are easier for phagocyte cells to devour. Bacteria and other pathogens covered with antibodies are also more likely to be attacked by the proteins from the complement system.

• The Memory Cells are the second cell type produced by the division of B cells. These cells have a prolonged life span and can thereby "remember" specific intruders. T cells can also produce memory cells with an even longer life span than B memory cells. The second time an intruder tries to invade the body, B and T memory cells help the immune system to activate much faster. The invaders are wiped out before the infected human feels any symptoms. The body has achieved immunity against the invader.

• Introduction•   •   • We are surrounded by billions of bacteria

and viruses. To many of them, a human being is like a walking smorgasbord, offering nearly limitless resources that they can use for energy and reproduction. Luckily for us, getting into the human body is not an easy task!

• From the point of view of these tiny organisms, a human is a bit like a fortress. The skin is thick and very hard to penetrate. In addition, the skin also produces a variety of substances that are harmful to invaders. Openings such as the eyes, nose, and mouth are protected by fluids or sticky mucus that capture harmful attackers. The respiratory tract also has mechanical defenses in the form of cilia, tiny hairs that remove particles. Intruders that get as far as the stomach are up against a sea of stomach acid that kills most of them.

• But in spite of our fantastic defenses, hostile invaders still manage to get through. Some enter along with our food, while others may sneak in via the nose. And, as we all know, many things can break through our skin. In everyday life we often receive cuts or scrapes, and every time this happens we face the risk of a full-scale invasion from bacteria or viruses. What is the magic, then, that keeps us healthy most of the time?

• When we receive a cut, and when invaders enter the body, cells are destroyed. The dying cells trigger an automatic response called inflammation, which includes dilated blood vessels and increased blood flow. An inflammation is the body's equivalent to a burglar alarm. Once it goes off, it draws defensive cells to the damaged area in great numbers. Increased blood flow helps defensive cells reach the place where they're needed. It also accounts for the redness and swelling that occur.

• Immune Cells: The Defense•   •   •   • The defensive cells are more

commonly known as immune cells. They are part of a highly effective defense force called the immune system. The cells of the immune system work together with different proteins to seek out and destroy anything foreign or dangerous that enters our body. It takes some time for the immune cells to be activated - but once they're operating at full strength, there are very few hostile organisms that stand a chance.

• Immune cells are white blood cells produced in huge quantities in the bone marrow. There are a wide variety of immune cells, each with its own strengths and weaknesses. Some seek out and devour invading organisms, while others destroy infected or mutated body cells. Yet another type has the ability to release special proteins called antibodies that mark intruders for destruction by other cells.

• But the really cool thing about the immune system is that it has the ability to "remember" enemies that it has fought in the past. If the immune system detects a "registered" invader, it will strike much more quickly and more fiercely against it. As a result, an invader that tries to attack the body a second time will most likely be wiped out before there are any symptoms of disease. When this happens, we say that the body has become immune.   

• Bacteria and Viruses: Our Main Enemies

•   A virus needs a host cell to reproduce.  

• Now that you know a bit about our defenses, let's take a closer look at our primary enemies. Bacteria and viruses are the organisms most often responsible for attacking our bodies.

• Most bacteria are free living, while others live in or on other organisms, including humans. Unfortunately, many bacteria that have human hosts produce toxins (poisons) that damage the body. Not all bacteria are harmful, though. Some are neutral and many are even desirable as they fulfill important functions in the body.

• Bacteria are complete organisms that reproduce by cell division. Viruses, on the other hand, cannot reproduce on their own. They need a host cell. They hijack body cells of humans or other species, and trick them into producing new viruses that can then invade other cells. Frequently, the host cell is destroyed during the process.

• Pathogens and Antigens•    

• In daily life we might speak of viruses, bacteria, and toxins. However, when reading about the immune system you’ll often come across the words antigen and pathogen. An antigen is a foreign substance that triggers a reaction from the immune system. Antigens are often found on the surfaces of bacteria and viruses. A pathogen is a microscopic organism that causes sickness. Hostile bacteria and viruses are examples of pathogens.

• i protect you against billions of bacteria, viruses, and other parasites.

• Am a foreign substance that triggers a reaction from the immune system.

• Am found on the surfaces of bacteria and viruses.

• Am microscopic organism that causes sickness

• I need a host cell.

• I hijack body cells!

• I trick my host into producing more of myself…

• I can’t reproduce on my own.

• I have the ability to "remember" enemies from the past!

• If an invader tries to attack the body a second time, I will wipe it out very fast before it can make trouble ( cause disease)…

• In other words, I make body IMMUNE to a pathogen.

• My army fights foreign invaders

• We make very specialized weapons…each is custom made…one type of weapon for one type of enemy.

• We take care of transportation and storage of lymphocyte cells within the body…

• I’m the lymphocyte (T cell and B cell) making factory…I mean I give birth to those soldiers who are going to protect the body.

• After birth, my babies leave me and go into the lymph (well, it’s a colorless fluid that flows in lymph vessels)

• I’m produced in the bone marrow.

• I devour invading organisms

• I destroy infected or mutated body cells

• I release special proteins called antibodies

• We mark intruders for destruction by other cells.

• You know, I just eat them old fashioned way and I’m not very specialized…I mean Hi-Fi

• Hello, I’m alerting y’all, there is an intruder…I can’t tell its identity, because I don’t have receptors on me, but I’m trying to finish it off by eating it…but there is only so many of them, I can’t eat ‘em all.

• Dear phagocytes (macrophages et al), thanks for the hint by holding up a part of the foreigner so I can see it…

• We find and "eat" bacteria, viruses, and dead

or injured body cells…um Yummy!

Some of us have gone really bad and make trouble…we can make poisons/toxins that damage the body

I wish I could sneak in ____ ______ without being recognized by those stupid immune cells...sigh!

Damn it! The receptor protein on my surface gives away who I’m and alerts those scary looking

_________ cells who can eat me alive or throw nasty weapons called ___________ on me.

My job is to take the first step in the event of attack.

•I make trouble

Well, I’m a foreigner…but I so badly want to live inside that yummy body

No entry please, first you need to get through me…

We defend the whole body… we make the defense force

I make the enemy look appetizing for eater cells (macrophage)…

I triggers a reaction from the immune system

I travel through your body until I find an antigen of the right size and shape to match my specific receptor

• My only job is to activate B cells and killer T cells.• My job seems simple, but guess what, B cells and killer T cells can do

nothing if I don’t inform them of the invader• When I see (with the help of my receptor) a phagocyte who has just

eaten a foreigner/invader, I get hyper!• I can tell which phagocyte has eaten a foreigner because there is a part

of it sticking out! • I’m a martyr…I present the foreigner to the Helper-T cell and then B

cells and killer T cells kill me because I’m infected…u think its fair? • Hi, we make the army of higher rank…we are specialized

• I can not only recognize a foreigner…I can tell exactly who it is. Thanks to my special receptors! Oh well, the only problem is that I only have eyes (I mean receptors) to recognize one type of foreigner…but my other buddies can recognize others..

Once I find an antigen (enemy! Intruder! A foreigner!) that matches my receptor, I’m on it. I’ll make 2 special cells: one to make weapons, and the other to remember the intruder…

I don’t take any chances…I will kill you even if you are one of our own just because you look sick and infected with pathogens

We help and we kill too…

• HOW DO VACCINES WORK???

Let’s start with a story…

In 1796 an English physician, Edward Jenner, attempted a very famous and risky experiment. In those days people used to

die of a deadly disease called smallpox, and there was no cure for it. Jenner noticed that

people who worked in farms with cows, almost never contracted the deadly disease smallpox. They however would get sick with

a milder disease called cowpox, which somehow protected them from getting

smallpox. Based on this observation, Jenner took an eight year old boy and infected him with cowpox (milder disease). When the boy

recovered from the disease, he now infected the boy with the deadly disease,

smallpox. The boy did not get sick! How did cowpox protect the boy from smallpox?

How could a previous illness protect a person from getting sick again?

Pair share reading

• Read out loud to your partner who will do guided reading

• Discuss the reading with your partner

• Pick VOCABULARY

• ANNOTATE the reading

• How did cowpox protect the boy from smallpox?

• Write your answer to the above question in complete sentences.

Cowpox and smallpox viruses look similar…

Which type of IMMUNITY did cowpox provide? Explain How.

• Active Immunity

• Because the memory B-cells are created and body can now make its own antibodies.

Vaccination • Injection has _________ _____________

• Pathogen triggers (starts)__________________

• ____________________ are made

• Next time when the real_________________ enters the body __________________ recognize it and initiate (start) _________________ production against the ______________ giving us ___________

• _____________(resistance)

Vaccination gives us____________

And this type of Immunity where body makes its OWN _________________ is called ACTIVE IMMUNITY.

Since memory cells stick around for a long time, it is a _____________term IMMUNITY.

PASSIVE IMMUNITY• When you get an INJECTION of the

_________________ to fight against a disease.

• Gives you short-term IMMUNITY (protection) against the disease.

AIM: Why is HIV virus so dangerous?

• HIV virus attacks the helper T cells and brings down the whole immune system.

• Copy

Helper T cell

HIV Virus

How does AIDS kill you?• Acquired immune

Deficiency Syndrome• People with AIDS die

because their ___________

__________ is weak and they can’t fight infections

• They die of diseases like Pneumonia, Meningitis, etc., which are caused by bacteria

• copy