Me, Myself
& Microbes

Me, Myself & Microbes — A short story about bugs, guts & poop

• We have co-evolved with trillions of microorganisms comprised of bacteria,
• bacteria
• viruses
• viruses, fungi, and other microbes.
• fungi
• inside

• Their estimated populations are staggering, a whopping a hundred trillion
• gut
• bacteria live in our guts. Ten billion and in our mouths
• mouths
• and another one trillion on our skin. The belly
• skin
• belly
• button alone contains dozens of unique species. Microbes inhabits
• exposed
• every exposed body surface. Even the extremely acidic and harsh environment of the stomach.
• stomach

• With a surface area of about thirty two square meters,
• the gastrointestinal tract is the largest interface between us and our
• intestine
• environment. It contains the highest number and diversity of the microbiome.
• lumen
• Collectively, these microbes would weigh a hefty two to six pounds,
• up to twice the weight of an average adult human brain.
• villi

• There are many pathways for microbes to impact brain and behavior.
• One mechanism is by signalling to endocrine cells
• endocrine
• in the gut lining to produce neurotransmitters and neuropeptides.
• These could enter the blood stream or signal to neurons that reach
• neurons
• the brain. Another way is by interacting with the intestine's immense
• arsenal of immune cells. They constantly survey the
• immune
• environment and communicate with the nervous system.

• Individual microbes themselves can also produce neuroactive molecules.
• If these molecules manage to be absorbed through the gut lining and
• pass into the bloodstream they could eventually affect the brain as well.
• dna
• Major changes in the numbers and types of microbes that inhabit us are
• bacterium
• phage
• linked to many diseases and disorders including neurological conditions
• like Parkinson's disease, autism, and major depression.

• We're not merely hosts to these microbial inhabitants. In fact, some
• of what makes a microbe a microbe is now directly integrated into our
• own genetic makeup. It's estimated that viruses have cut their DNA
• eight
• and pasted it into our own so much that eight percent
• of our human genomes are derived from viruses.

• Sensory neurons that connect the gut to the brain are of great interest,
• like the vagus nerve, which serves as a super highway between the small
• vagus
• intestine and brain stem. The hope is that expanding our knowledge of how
• gut
• brain
• we interact with our microbiome could one day
• space
• inspired a new microbe based treatments for disease.
• theend

• The End