RT Book, Section
A1 Creager, Mark A.
A1 Loscalzo, Joseph
A2 Jameson, J. Larry
A2 Fauci, Anthony S.
A2 Kasper, Dennis L.
A2 Hauser, Stephen L.
A2 Longo, Dan L.
A2 Loscalzo, Joseph
SR Print(0)
ID 1155975344
T1 Diseases of the Aorta
T2 Harrison's Principles of Internal Medicine, 20e
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781259644016
LK accesspharmacy.mhmedical.com/content.aspx?aid=1155975344
RD 2024/04/20
AB The  aorta  is  the  conduit  through  which  blood  ejected  from  the  left  ventricle  is  delivered  to  the  systemic  arterial  bed.  In  adults,  its  diameter  is  ~3  cm  at  the  origin  and  in  the  ascending  portion,  2.5  cm  in  the  descending  portion  in  the  thorax,  and  1.8–2  cm  in  the  abdomen.  The  aortic  wall  consists  of  a  thin  intima  composed  of  endothelium,  subendothelial  connective  tissue,  and  an  internal  elastic  lamina;  a  thick  tunica  media  composed  of  smooth  muscle  cells  and  extracellular  matrix;  and  an  adventitia  composed  primarily  of  connective  tissue  enclosing  the  vasa  vasorum  and  nervi  vascularis.  In  addition  to  the  conduit  function  of  the  aorta,  its  viscoelastic  and  compliant  properties  serve  a  buffering  function.  The  aorta  is  distended  during  systole  to  allow  a  portion  of  the  stroke  volume  and  elastic  energy  to  be  stored,  and  it  recoils  during  diastole  so  that  blood  continues  to  flow  to  the  periphery.  Owing  to  its  continuous  exposure  to  high  pulsatile  pressure  and  shear  stress,  the  aorta  is  particularly  prone  to  injury  and  disease  resulting  from  mechanical  trauma.  The  aorta  is  also  more  prone  to  rupture  than  is  any  other  vessel,  especially  with  the  development  of  aneurysmal  dilation,  since  its  wall  tension,  as  governed  by  Laplace’s  law  (i.e.,  proportional  to  the  product  of  pressure  and  radius),  will  be  increased.