Class blog for Anth 249: Evolution and human disease. We will be responding to class readings and engaging with the wider network of blogs and online content on evolutionary medicine. We might also make up some fun projects along the way.
Sunday, May 5, 2013
Responder: "Viruses and Us"
This post is in response to Nicholas's first readers post "Viruses and Us". Nicholas mentioned the relationship of gut flora and human
health in his post and I thought I would explore it a little further. Virtually
all multicellular organisms live in close association with surrounding
microbes, and humans are no exception. The human body is inhabited by a vast
number of bacteria, archaea, viruses, and unicellular eukaryotes. The
collection of microorganisms that live in peaceful coexistence with their hosts
has been referred to as the microbiota, microflora, or normal flora (Kunz et al,
2009). The composition and roles of the bacteria that are part of
this community have been intensely studied in the past few years. However, the
roles of viruses, archaea, and unicellular eukaryotes that inhabit the
mammalian body are less well known. It is estimated that the human microbiota
contains as many as 1014bacterial
cells, a number that is 10 times greater than the number of human cells present
in our bodies (Kunz
et al, 2009). The microbiota colonizes virtually every surface of the
human body that is exposed to the external environment. Microbes flourish on
our skin and in the genitourinary, gastrointestinal, and respiratory tracts (Neish, 2009).
By far the most heavily colonized organ is the gastrointestinal tract (GIT);
the colon alone is estimated to contain over 70% of all the microbes in the
human body (Neish,
2009). The human gut has an estimated surface area of a tennis
court (200 m2) and, as such a large organ,
represents a major surface for microbial colonization. Additionally, the GIT is
rich in molecules that can be used as nutrients by microbes, making it a preferred
site for colonization (Neish, 2009).
·Kunz C,Kuntz S,Rudloff, S. “Intestinal
flora”. Adv Exp Med Biol 639:67–79, 2009.
·Neish, AS “Microbes
in gastrointestinal health and disease”. Gastroenterology 136: 65–80, 2009.