瑪姬咕咕的生活指南 magigugu.com
返回   瑪姬咕咕的生活指南 > 兩棲爬蟲動物 > 蛇類,蜥蜴,守宮

蛇類,蜥蜴,守宮
討論蛇類,蜥蜴,石龍子,變色龍,守宮,壁虎..等等;龜類除外。

回覆
 
主題工具
舊 2014-03-08, 07:46 PM   #1
野人
論壇管理員
 
野人 的頭像
 
註冊日期: 2004-05-16
文章: 9,973
野人 是一個將要出名的人 野人 是一個將要出名的人
預設 蛇可藉由控制血流量來增強視力

ScienceDaily - Snakes control blood flow to aid vision

研究報告的摘要:
The eyes of snakes are shielded beneath a layer of transparent integument referred to as the ‘reptilian spectacle’. Well adapted to vision by virtue of its optical transparency, it nevertheless retains one characteristic of the integument that would otherwise prove detrimental to vision: its vascularity. Given the potential consequence of spectacle blood vessels on visual clarity, one might expect adaptations to have evolved that mitigate their negative impact. Earlier research demonstrated an adaptation to their spatial layout in only one species to reduce the vessels' density in the region serving the foveal and binocular visual fields. Here, we present a study of spectacle blood flow dynamics and provide evidence of a mechanism to mitigate the spectacle blood vessels' deleterious effect on vision by regulation of blood flow through them. It was found that when snakes are at rest and undisturbed, spectacle vessels undergo cycles of dilation and constriction, such that the majority of the time the vessels are fully constricted, effectively removing them from the visual field. When snakes are presented with a visual threat, spectacle vessels constrict and remain constricted for longer periods than occur during the resting cycles, thus guaranteeing the best possible visual capabilities in times of need. Finally, during the snakes' renewal phase when they are generating a new stratum corneum, the resting cycle is abolished, spectacle vessels remain dilated and blood flow remains strong and continuous. The significance of these findings in terms of the visual capabilities and physiology of snakes is discussed.

Blood flow dynamics in the snake spectacle
野人 目前離線   回覆時引用此篇文章
回覆

書籤

主題工具

發文規則
不可以發表新主題
不可以發表回覆
不可以上傳附件
不可以編輯自己的文章

啟用 BB 代碼
論壇啟用 表情符號
論壇啟用 [IMG] 代碼
論壇禁用 HTML 代碼



所有時間均為 +8。現在的時間是 05:20 AM


Powered by vBulletin® 版本 3.8.4
版權所有 ©2000 - 2018,Jelsoft Enterprises Ltd.