Immune

"... excreting waste, growing or shrinking, adapting or failing to adapt. It will almost certainly outlive your tenure. It has a metabolism, a lifecycle, immune responses that attack foreign ideas. Here's what you may not have realized: look at the words again. Organ. Organism."

"...outside the cell - hormones, neurotransmitters, growth factors - and trigger responses inside. Recognition proteins act like ID badges, allowing immune cells to distinguish your cells from bacterial invaders. Here's the crucial part: the membrane must maintain a delicate balance."

"By biological metrics, this is survival insurance. The blue whale's blubber looks inefficient until the six-month fast begins. Your immune system is "wasteful" - using energy to maintain defenses against threats that may never come. But organisms without immune systems die at the first i..."

"...sm respond to changing needs? What if you need to suddenly produce more blood cells after an injury? Or grow new skin to heal a wound? Or develop new immune cells to fight an infection? Answer: stem cells. Stem cells are undifferentiated cells - they haven't committed to becoming a specific type yet."

"Mild metabolic stress leads to improved metabolic efficiency. Vaccines are hormetic. A weakened pathogen triggers an immune response stronger than necessary for that specific threat, conferring protection against future encounters. The biological logic is straightforward:..."