Discovery - University of Dundee - Online Publications

Library & Learning Centre

Vascular Growth in the Fetal Lung

Vascular Growth in the Fetal Lung

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)

View graph of relations

Info

Original languageEnglish
Title of host publicationVasculogenesis and Angiogenesis - from Embryonic Development to Regenerative Medcine
EditorsDan Simionescu
Place of publicationCroatia
PublisherIn Tech - Open Access Publisher
Publication dateNov 2011
Pages49-72
Number of pages23
ISBN (Print)978-953-307-882-3
DOIs
StatePublished

Abstract

The structure of the lung is truly remarkable. It is primarily composed of three branched tubular networks (the airway, pulmonary artery and vein, bronchial artery and vein) which supply blood and air to the site of gas exchange and which maintain nutrient supply to supporting tissues. This complex interwoven network is packed into a chest cavity with a volume of 6 litres but yet it services a gas-exchange surface area of 130m2, the floor area of a comfortably sized Mediterranean holiday villa! Weibel (1991) tells us that if this surface area were arranged as a balloon it would possess a radius of 3m and a volume of 113,000
litres, more than 18 thousand times the space available in the chest cavity. The process which drives this exceptional packaging involves repeated cycles of ordered branching to create a fractal network of tubules whose core dimensions decrease at a precise and regular rate with each successive branch. This is a high “gain-of–structure” process. In the airway, 23 generations of branching form a conducting tubular network with 17 million branches and a combined length of more than 7km. This provides convective air flow to 480 million alveoli each of which are located along a path length that is no further than 45cm from the
external atmosphere. The pulmonary vasculature forms along side the airway but
undergoes an additional five generations of branching to form the capillary network that surrounds each alveolus. If you simply assumed that each alveolus (diameter ~200?m) was serviced by only one blood vessel you would calculate that the alveolar capillary bed alone runs to nearly 100 km in length. Realistic attempts at modelling this structure in three dimensions suggest that it is, in all probability, between 2 and 6 thousand km long (Muhlfield et al., 2010), illustrating the impressive capacity of fractal branching processes to package colossal structures into ever smaller spaces.

Download statistics

No data available

Documents

Library & Learning Centre

Contact | Accessibility | Policy