immune-system

Blood types are inherited molecular markers on red blood cells. The ABO polymorphism has been kept alive in primates for at least 20 million years, and infections such as malaria, cholera, and norovirus are the leading explanation for why.

Sneezing launches mucus at up to 35 meters per second through a trigeminal nerve reflex arc. Here is the real physiology, the genetics of sunlight sneezing, and the risks of holding one in.

Wound healing is a four-stage biological process triggered immediately after injury and lasting weeks to years. Within seconds, platelets plug the wound; within hours, immune cells flood the area and initiate inflammation; over days to weeks, fibroblasts synthesize collagen and new blood vessels form; over months to years, tissue remodels and scars form. Despite apparent simplicity, the process involves coordinated signaling across dozens of cell types, growth factors, and immune mechanisms. Understanding wound healing is critical for treating chronic wounds (affecting 2 percent of the global population) and improving outcomes after surgery, trauma, and burn injuries.

A fever is not an illness but a weapon—your immune system's coordinated response to infection that raises your body's set-point temperature. When pathogens invade, immune cells release signaling molecules called pyrogens that travel to the brain and reset the temperature thermostat from 37°C to 39°C or higher. This increase is controlled and purposeful: the higher temperature slows bacterial growth, accelerates immune cell activity, and enhances antiviral proteins. Understanding fever as an adaptive defense explains why suppressing it indiscriminately can sometimes hinder recovery, yet also reveals when dangerous fevers require immediate treatment.

When a virus enters your body, it triggers a response that unfolds in stages over hours, days, and weeks. The innate immune system fires within minutes, buying time while the adaptive immune system — which can generate targeted weapons against any pathogen — prepares a precise counterattack. The two systems do not operate independently: each depends on signals from the other, and the timing of their interaction determines whether the infection is cleared in a week or becomes severe.

The immune system is not a single organ or a single type of cell — it is a distributed surveillance network that distinguishes your own tissue from foreign invaders within minutes, then builds custom molecular weapons if the first response is not enough. Here is how.

How vaccines work: from your first encounter with an antigen to lifelong immunity. Covers mRNA tech, adjuvants, herd immunity math, and 2026's cancer vaccine pipeline.

What does the appendix actually do? The microbiome safe-house hypothesis, immune function, appendicitis, and why it's not really useless.

Your skin hosts ~1,000 bacterial species, fungi, viruses, and mites. How the skin microbiome shapes acne, eczema, odor, and immunity.

Explore how the immune system defends your body — from skin barriers to T cells, vaccines, autoimmunity, and cancer immunotherapy.

Rhinovirus causes most common colds. How it enters nasal cells, why there are over 100 types, why no vaccine exists, and what the evidence says about remedies.

Why long COVID symptoms persist for months: viral reservoirs, immune dysregulation, EBV, microclots, gut and brain changes, and what trials have found so far.