PNB 2250 Lecture Notes - Lecture 9: Countercurrent Exchange, Hemoglobin, Closed System
19 Sep 2016
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Learning goals: understanding the role of circulation in gas transport, understanding the factors that provide the force to pressure fluid, understand the parts and function of a circulatory system, understand the evolution of pumps. Problem: respiration requires a parallel system of fluid-filled tubes to move respiratory proteins around the body. Overcomes the limits imposed by diffusion: the ability to move respiratory proteins and oxygen around the body has a huge impact on animal size. Complex mixture of water, ions, proteins, peptides, lipids and cells: cells. Contain respiratory proteins, responsible for the color of blood. Immune, protection against foreign and internal threats, respiratory proteins must be protected. Blood volume: expensive to produce, about 5% of body volume, linked to oxygen need/respiratory proteins, tightly regulated. Have better control of the environment and affinity of proteins for oxygen. Transport system uses dilated epithelium to move seawater: no vessels, no pump, transfer is across the surface.
