01:119:115 Lecture Notes - Lecture 42: Gastrovascular Cavity, Portal Vein, Extracellular Fluid
15 Feb 2018
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Document Summary
For animals with many cell layers, gastrovascular cavities are insufficient for internal distances because the diffusion transports are too great. In crocodilians, birds, and mammals, the ventricle is completely divided into separate right and left chambers. Concept 42. 2 double circulation in mammals depends on the anatomy and pumping cycle of the heart. For example, epinephrine from the adrenal glands increases heart rate: the rate of impulse generation by the pacemaker increases in response to increases in body temperature and with exercise. In large land animals, blood pressure is also affected by gravity. In addition to the peripheral resistance, additional pressure is necessary to push blood to the level of the heart. In a standing human, it takes an extra 27 mm of hg pressure to move blood from the heart to the brain. In an organism like a giraffe, this extra force is about 190 mm hg (for a total of 250 mm.
