The Immune System: Fighting Infection

Learning Objectives

Understand what the immune system is and what it does.

Be able to identify the 4 types of immune cells and an example of each.

Know what T-Cell is and its role in the body.

Know what antibodies are.

Your immune system is a group of cells, working together to defend you from all sorts of infection. These infectious villains are called pathogenic antigens.

Pathogenic Antigens (Figure 1) are the things that make you sick, like bacteria, viruses, and parasites.

(Figure 1) Pathogenic Antigens: Pathogenic Antigens include bacteria, viruses, and parasites.

To utterly destroy them, you have 4 different classes of murderous cells.

Let’s check them out!

First, there are the Phagocytes (Figure 2). This team includes Macrophage, Dendritic Cells, and Neutrophils. Phagocytes are soul eaters. They consume intruders and wear them like skins.

(Figure 2) Phagocytes: Phagocytes are immune cells that consume bacterial intruders.

This lets other cells, like T-Cell know more about the enemy and the best strategy to kill them.

Then there are Antiparasitic cells (Figure 3). Basophils, Mastic Cells and Eosinophils are 3 types of Antiparasitic cells in your body. These cells kill what Phagocytes can’t: parasites. They are too big to eat.

(Figure 3) Antiparasitic Cells: Antiparasitic Cells are immune cells that target parasites in the body.

But they can’t do everything in the spotlight! Someone has to kill the cells that are already infected. There’s a cell for that. They’re called Natural Killers(figure 4). These Ninja Assassins lurk in the shadows killing virus infected cells. This process is called “lysis” causing cells to undergo apoptosis. Instant cell death. Pretty cool! But they’re pretty general, and sometimes they screw up. Oh well.

(Figure 4) Natural Killers: Natural Killers kill cells that look like they might be infected or sick.

Finally, there are Humoral Intercellular Cells (Figure 5). The HIC. This team of T and B Cells are your adaptive immune gang. They make sure that you have all the bits you need to defend against new attackers.

(Figure 5) Humoral Intercellular Cells: These cells (HIC) control the human body’s adaptive immune response.

Check these guys out!

Helper T Cell reads the reports from phagocytes and decides what the other cells will do. It’s like the general commander.

B Cell makes antibodies based on T Cell’s specifications. These things mark intruding bacteria for death. Hard to hide when you’re glowing.

Cytotoxic Cells are a type of T Cell. But they don’t give the orders. Instead they selectively lyse cells.

And that’s your team! Together, these diverse cells defend your body from unwanted intruders; Keeping you healthy, one cell at a time.

Figures 1-5 by: Jarod Davis Provided by: University of Minnesota. License: CC BY-NC-ND 4.0




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