How your body defends itself with a special type of immunity
Imagine you are walking in the park and you get a cut on your finger. How does your body prevent the wound from getting infected by germs that are everywhere in the environment? The answer lies in a special type of immunity that you are born with, called innate immunity.
Innate immunity is a part of your immune system, which is your body’s defense system against harmful substances and organisms, such as bacteria, viruses, fungi, parasites, and even cancer cells. Your immune system consists of various cells and molecules that work together to protect you from infections and diseases. Your immune system has two main types: innate immunity and adaptive immunity.
Innate immunity is the immunity that you are born with. It consists of physical barriers, such as your skin and mucous membranes, and general immune cells and molecules, such as phagocytes, natural killer cells, complement proteins, cytokines, and interferons, that can recognize and destroy common types of germs. Innate immunity is fast and effective, but it is not very specific or long-lasting.
Innate immunity works by using different mechanisms to prevent or limit the entry of germs into your body, or to eliminate them if they manage to get in. These mechanisms include:
• Physical barriers, such as your skin and mucous membranes, that act as the first line of defense against germs. They prevent most germs from entering your body or reaching your internal organs. They also produce substances that can kill or inhibit germs, such as sweat, saliva, tears, mucus, stomach acid, and enzymes.
• Inflammation, which is a process that occurs when your tissues are damaged or infected by germs. It involves the dilation of blood vessels, the increase of blood flow, the leakage of fluid and immune cells into the affected area, and the production of chemical signals that attract more immune cells and molecules. Inflammation helps to isolate and destroy germs, remove dead cells and debris, and promote healing.
• Phagocytosis, which is a process that involves certain immune cells called phagocytes that can engulf and digest germs and other foreign particles. Phagocytes include neutrophils, monocytes, macrophages, dendritic cells, and mast cells. Phagocytes can also present parts of the germs to other immune cells to trigger an adaptive immune response.
• Natural killer cells, which are a type of immune cells that can recognize and kill infected or abnormal cells. Natural killer cells have receptors on their surface that can bind to molecules on the surface of other cells. If these molecules indicate that the cell is infected by a virus or transformed by cancer, natural killer cells release substances that create holes and trigger cell death.
• Complement system, which is a group of proteins that circulate in your blood and can be activated by germs or antibodies. The complement system can enhance the activity of phagocytes and natural killer cells by coating or marking germs for destruction. It can also form pores on the surface of germs and cause them to burst.
• Cytokines and interferons, which are chemical signals that help the immune system communicate and coordinate its actions. Cytokines can stimulate or inhibit the growth and activity of various immune cells and molecules. Interferons are a type of cytokines that can interfere with viral replication and activate other immune cells.
Innate immunity is important because it provides us with a quick and general defense against germs that we encounter every day. It also helps to activate the adaptive immune system, which is a more specific and long-lasting type of immunity that we acquire during our lifetime.
In summary, innate immunity is a basic and essential system that protects us from a variety of germs and tumors. It involves physical barriers and general immune cells and molecules that recognize and eliminate foreign substances with low specificity and memory. It also involves inflammatory processes that help to control infections and promote healing.
• Innate immune system – Wikipedia – This article provides an overview of the innate immune system, its components, functions, and mechanisms. It also explains how the innate immune system interacts with the adaptive immune system and how it differs from other types of immunity.
• Innate immunity (article) | Immune system | Khan Academy – This article gives a detailed explanation of the innate immune system, its role in defending the body from germs, and its various physical barriers and general immune cells and molecules. It also provides examples and illustrations to help understand the concepts.
• The innate and adaptive immune systems – InformedHealth.org – NCBI Bookshelf – This article compares and contrasts the innate and adaptive immune systems, their advantages and disadvantages, and their cooperation and regulation. It also describes some common diseases and disorders that affect the immune system.