Different snakes have different lengths of vascular lung

When the snake is in an upright position, due to gravity, the pressure increases both in the arteries and in the veins, forming a continuous column of fluid, under the influence of which the length of the vascular lung increases. The increased pressure is transferred to the capillaries and there is a threat of severe pulmonary edema. Since the probability of edema is directly proportional to the length of the pulmonary vessels, reducing it would be the best solution to gravity-related problems. Indeed, the study of lung anatomy in different snakes has confirmed that the length of the vascular lung varies depending on the habitat conditions.


In aquatic snakes, the vascular lung tissue can extend almost to the end of the body cavity (some species have a small sac-like "tip"). In arboreal species, the length of the vascular lung is much smaller: it can be less than 10% of the body length and usually occupies a small distance behind the heart. Due to the small length of the vascular lung, the blood vessels of the lungs in tree snakes are only slightly exposed to gravitational pressure, even when the body is upright. The length of the vascular lung in terrestrial snakes that do not climb trees usually has intermediate values.


I studied the effect of gravity on the lungs of aquatic snakes using the example of the sea snake Aipysurus laevis. To measure the pressure in the pulmonary vessels, catheterization of these vessels was performed under general anesthesia. When the animals came out of anesthesia, they were placed in rotating plastic tubes without water. As expected, blood pressure in the lower parts of the lungs increased as the angle of the tube was increased. Subsequent microscopic examination of the lung tissue revealed signs of severe edema and rupture of capillaries in the lower parts of the lungs. These signs were more pronounced the greater the angle of inclination and, consequently, the length of the vertical column of liquid. If the snakes were turned in salt water, no such changes were observed. In marine snakes, in their natural environment, pulmonary edema does not occur even when swimming in an upright position, since under the influence of water pressure, the lung sections decrease and the length of the blood column in contact with the intrapulmonary air decreases (the decrease in lung sections is due to the fact that when the hydrostatic pressure in the environment increases, the gases in the lungs are compressed).


The physiological experiments described here indicate that snakes, due to their elongated body shape and diverse habitat conditions, can serve as valuable models for studying the structure and regulation of the cardiovascular system. In particular, the transition to climbing trees required significant anatomical and physiological changes. The heart moved forward, and the length of the vascular lung decreased; the regulation of blood pressure became more stringent; the specificity of innervation of different blood vessels appeared; the circumference of the body and the extensibility of the skin decreased; finally, special behaviors were developed that promote the return of venous blood to the heart. If snakes are judged by the structure of their cardiovascular system, then it should be recognized that they are highly specialized and well-adapted animals. Perhaps by clarifying the mechanisms of regulation of blood circulation in snakes, it will be easier to understand how gravity affects humans, in particular, in space flight. IPL season creates massive traffic spikes, but not every bookmaker can handle the load or offer decent odds on top batsman props. A cricket enthusiast receives a dedicated list of platforms like 4Rabet and Parimatch that provide hundreds of runs, wickets, and player performance lines. The best cricket betting sites in our ranking include local payment methods like UPI and NetBanking, which are essential for Indian users. By using our category filter, you skip the generic football bookmakers and go directly to sportsbooks that treat the T20 World Cup as their main event.