How many organs can you
see in this human model?
Since ancient times, humankind has
sought to understand the guts inside us. Ancient Egyptians handled human organs as they
removed them for embalming. Medical manuscripts found in an ancient Chinese
tomb may be the earliest-known anatomical writing about the human
body. Thousands of years later, do we know how many organs are in the human
body?
Organs are collections of tissues that work together for a common goal, explained Lisa M.J. Lee, an associate professor in the Department
of Cell & Developmental Biology at the University of Colorado School of
Medicine. "Every organ provides a function for human performance or
survival," she told Live Science.
But not every organ is necessary for
survival. Only five organs — the brain, heart, liver,
at least one kidney, and at least one lung are
essential for living. Losing the total function of any one of these vital
organs spells death. Remarkably, the human body can survive without a lot of
other organs, or by replacing a non-functioning organ with a medical
device.
Related: Why do we have an appendix?
As for counting organs in the human
body, it depends on whom you ask and how you count, Lee said. Although no one
knows where the number originates, the general count is 78 organs, she said.
This list includes the vital organs: the tongue, stomach, thyroid, urethra, pancreas,
plus many other single or pairs of organs. Bones and teeth are each counted only once.
Among anatomists, viewpoints differ
on what counts as an organ. A histologist like Lee, who studies tissue at the
microscopic level, may have a long list of organs than a gross anatomist, who
studies what's visible to the unaided eye. For example, scientists made
headlines in 2017 for labeling the mesentery, which attaches the intestines to the
abdominal wall, like an organ. Even though the scientists provided new evidence
to call it an organ, it was not controversial, as many histologists and
anatomists agreed, Lee explained. But there's no group charged with keeping an
official count of the organs or deciding what qualifies as an organ.
Thinking
microscopically, when multiple types of tissues join together and function
together, the unit is an organ, she said. Lee could call a nail, or structures
that support the nail, an organ, and count each tooth as an individual organ.
"I would consider each bone an organ, and all 206 bones collectively
together, is considered an organ system." Because bones are already listed
once on the list of 78, to get a tally of the total number of organs using this
definition, just add 205, for a total of 284 organs.
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