How the immune system works?

The human immune system stands as one of the most intricate biological systems, surpassed in complexity only by the human brain. Yet, many remain unfamiliar with its workings. Comprising numerous tiny and two significant organs, the immune system boasts its transport network intricately woven throughout the body. Each day, it generates billions of fresh cells, resembling a well-organized army with soldiers, captains, intelligence officers, heavy weapons, and even unconventional suicide bombers.

This immune system is not an abstract concept; it is an integral part of you—an intricate biological defense against the countless microorganisms aiming to consume you and your own cells turning aberrant, evolving into cancer. Its multifaceted nature defies concise coverage in a single video, prompting us to embark on a series exploring its various facets.

In today's exploration, we delve into what unfolds when your body faces invasion, and your initial lines of defense engage in a life-and-death struggle.

Imagine a normal day suddenly disrupted as an asteroid crashes, tearing the sky open, and alien life forms invade, poised to destroy cities, infrastructure, and devour civilians. This is the experience of your cells when you glance at your bleeding thumb, wounded by a dirty twig in the park—an inconvenience to you, but within the wound, a catastrophic event unfolds.

Dead cells, blood, and dirt scatter in disarray, while countless bacteria invade the warm caverns between your cells, exploring their new home, stealing resources, and leaving waste. The first stage of defense springs into action; surviving, hurt, or dying cells release chemical alarm signals, awakening your immune system. Macrophages, large cells akin to black rhinos in size, swiftly attack bacteria, stretching out like octopus arms to engulf and digest them alive.

As the battle intensifies, macrophages call for reinforcements, summoning hundreds of thousands of neutrophils from your blood. Neutrophils, intense suicide warriors, live solely to kill, even sacrificing themselves a few days after birth to prevent unintended harm to your body. They arrive vomiting deadly chemicals on bacteria or devouring them, sometimes resorting to explosive suicide attacks, casting toxic nets made from their DNA.

Amidst the battle, your blood vessels allow fluid to stream into the battlefield, causing inflammation—your thumb swells, turns red, and warms. Complement proteins, automated liquid weapons, join the fray, stunning and killing bacteria by ripping holes into them.

At this juncture, your immune system faces a crossroad. If the first line of defense succeeds, invaders perish quickly. If not, the dendritic cell, the intelligence officer of your immune system, takes the stage. While soldiers engage in combat, the dendritic cell collects samples by tearing bacteria into fragments, adorning itself like a soldier with the guts of a defeated foe.

Exiting the battlefield, the dendritic cell enters the immune system's superhighway—your lymph nodes, seeking a specific helper T cell with the right weapon for the bacteria in your wound. Rubbing itself against every helper T cell, still covered in bacteria parts, the dendritic cell eventually finds a match. The activated helper T cell signals the beginning of the second line of defense.

The activated helper T cell, having cloned itself into thousands, splits into two groups. The first group rushes to support your soldiers on the battlefield, where a tired macrophage is on the brink of surrender. The helper T cells revive the demoralized soldier, injecting a surge of energy and a fierce determination to continue the fight.

Simultaneously, the second group of helper T cells focuses on activating another line of defense—B cells, the antibody factories. Antibodies, protein super weapons resembling tiny crabs with two pincers, are tailored by specific B cells to combat each unique enemy.

The helper T cell seeks out the precise B cell capable of producing antibodies for the invading bacteria. After locating the right B cell, a process that takes a day or two, the B cell begins cloning itself, generating thousands of clones. Each B cell then starts producing up to 2,000 antibodies per second.

About a week after the injury, the second line of defense arrives in full force. The tiny army saturates the battlefield, immobilizing bacteria by clumping them together with antibodies. Your soldiers take advantage of this vulnerability, massacring the defenseless invaders. The tide turns swiftly.

As the last enemies are eradicated, some of your soldiers realize their services are no longer needed and willingly sacrifice themselves to save resources. However, a few helper T cells persist, transforming into memory cells to guard the tissue for years. Similarly, a handful of B cells continue producing a low amount of antibodies, granting immunity against the specific bacteria, perhaps for the rest of your life.

Days later, you wake up to find the wound healed, leaving only a faint red mark. Unbeknownst to you, this seemingly minor event was a monumental struggle for millions of cells, a desperate fight for survival. This narrative, though just the beginning, unfolds daily inside you—a tale of resilience, strategy, and victory told comprehensively in "Immune: A Journey into the Mysterious System That Keeps You Alive," written by Philip Detmer, the founder, and head writer of Kotzkozak. The book, an intricately illustrated deep dive into the immune system, promises to revolutionize your understanding of your body. With simplicity and a touch of humor, it explores the vastness of the immune system, its workings, and its battles against diseases from cancer to the flu.

Scheduled for release in six weeks, pre-ordering is encouraged and appreciated. This culmination of a decade-long personal journey awaits your exploration. Thank you for joining us on this fascinating odyssey into the marvels of the immune system.