Lecture 9 Biological Gas Transport Part I
Tuesday, 13 August 2013
Lungs: Total surface area of 70m , total volume of 5L. Gas exchange occurs between the
alveoli and capillaries, there are over 700,000,000 alveoli in the lungs. The diffusion distance is
0.3 micrometers. There is a mucus layer that protects the lungs and provides a wet surface for
the oxygen to dissolve into and diffuse across the endothelial and pneumocytes.
RBC: very elastic due to protein network. Contains haemoglobin so blood isn't too viscous and
prevents toxicity. Biconcave disc, passes through the entire circulatory system in 25s, 120 life
cycle. 7.5 microns by 3 microns. Haematocrit of 40% RBC. 5mM of haemoglobin per a RBC. No
nucleus or organelles so cannot repair itself.
Heart: pumps 5L per a minute. Requires 10% of total resting energy.
Dissolves 20ml per 100ml of blood. Protein of four subunits consisting of 2 alpha and 2 beta.
Alpha genes are encoded on chromosome 16 while the beta are encoded on chromosome 11.
Each of the globin genes consists of three exons and two introns. These genes are
approximately 1500bp long, the alpha chain results in 141 amino acids while the beta chains
are 146 amino acids.
Gene expression: LCR (locus control region) is a promoter present at the 5' end of the genes, is
controlled by non-translated 3' structures. The