PHGY 209 Lecture Notes - Jelly Doughnut, Litre, Yolk Sac
21 Nov 2012
School
Department
Course
Professor
Document Summary
The function of red blood cells is to facilitate transport of respiratory gases between the lungs and cells. It has a biconcave disk shape that curves inward on both surfaces. It looks like a jelly donut, but the cross-section looks like a dumbbell, thinner in the middle and thicker at the edges. There are 2 advantages of having such a shape. One, the shape provides maximal surface area and minimal diffusion distance for its volume. The narrow middle allows gases to diffuse in and out very rapidly, and increases the efficiency of oxygen and co2 diffusion. Two, the shape has a high degree of flexibility to it. Red blood cells can flex itself to fit into small capillaries. The flexibility allows the cell to squeeze through narrow capillaries. If the red blood cell was spherical, it would not be able to squeeze through.
