Foramen of Panizza
Encyclopedia : F : FO : FOR : Foramen of Panizza
The Foramen of Panizza is a shunt, which connects the left and right aorta in the crocodile heart. It plays an important role in the crocodile’s ability to switch from a terrestrial circulatory pattern to an aquatic one. When on land, the Foramen of Panizza is open and connects the left and right aorta. The oxygenated blood from the lungs, pumped from the left ventricle to the left aorta, is able to flow into right aorta. This maintains a high pressure in both the left and right aorta and keeps the semi-lunar valve of the right aorta closed. Thus, deoxygenated blood from the right ventricle is forced into pulmonary circulation and only oxygenated blood is delivered to the systemic circulatory system. However, once the crocodile is submerged under water, there is no longer a supply of oxygenated blood from the lungs. As the crocodile dives, sensors in the nostrils send signals for the Foramen of Panizza to constrict, cutting off contact between the left and right aorta. The right aorta is no longer maintained at a high pressure, and its semi-lunar valve opens, allowing blood returning from the body to bypass the now useless pulmonary circulation and be distributed to the body through the right aorta. This increases the total amount of oxygen received by body tissues. Furthermore, some gas exchange is able to occur through the skin
External links
- [Hot-blooded crocodiles?]
- [Crocodiles of Sri Lanka]
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.