This week, our learning focuses on the topic of toxicity. It is natural to wonder whether or not something might be harmful. From life experience, we know that things we eat, drink, breathe, or touch can injure us or make us sick. Our bodies are constantly working hard to keep out things that might harm us. Examples include:
- Our skin forms a protective barrier to keep the inside in and the outside out.
- Our mucous membranes are sticky and “catch” bacteria, viruses, and other particles that we inhale.
- Our liver filters our blood, removing toxins from anything we might eat through the collective actions of dozens of enzymes within the Cytochrome P450 family.
- Our innate immune system owes its existence to our evolutionary ancestors. The innate immune system consists of a variety of molecules that detect common environmental pathogens, like bacterial cell wall components or viral DNA – structures not found in our bodies and therefore indicate an infection. One important family of cell surface receptors, the Toll-like Receptors (TLRs) were originally discovered in fruit flies, and then scientists found them in humans as well!
- Our adaptive immune system protects us from new threats. For example, we are currently under attack by COVID-19, a coronavirus never before encountered by humans. While our innate immune system may recognize aspects of the virus as a threat (resulting in flu-like symptoms), it’s our adaptive immune response that takes a few weeks to really get going. Our B cells will produce antibodies against the virus, killing it. Our T cells will recognize virus-infected cells, and our T cells will kill those cells, thus preventing the spread of the virus.
After browsing through the links provided, return to the Week 31 – Toxicity post.