Re: [考古] 基四考古題訂正

[Ck900406 (猩猩)]

※ 引述《allanwei (一切都是幻想)》之銘言：
: 第一頁第四題
: 答案請改成A
: 一個國外網站寫的...
: Nerves and blood vessels carry relatively more current with less heat
: generation, whereas bone tends to convert more of the electrical energy into
: heat.
: 另外一句
: For this reason, the thermal damage caused by a current passing up through an
: upper extremity is concentrated at the wrist and elbow, the places with less
: tissue cross-sectional area and more resistive structures (bone and tendon).
: 所以好像是骨頭受傷害比較多耶...
: 跟共筆上寫的不一樣= =
: 參考的網站：http://www.emedicine.com/derm/topic859.htm

幫老屋補充

The tissue damage inflicted by most electrical currents can be primarily

attributed to the thermal energy (or heat) generated by the current,

 as predicted by Joule's law:

  Heat = current x voltage x time of contact
         = I x V x T
         = I x (I x R) x T  (from Ohm's Law)
         = (I)2 x R x T


Resistance is a function of the area of contact, pressure applied,

and the presence of moisture. Tissues with higher resistance have a

tendency to heat up and coagulate, rather than transmit current.

Skin, bone, and fat have high resistances, while nerves

and blood vessels have lower resistances.

The resistor that has the greatest effect on the severity of an electrical

injury is the skin. Dry skin has a resistance of approximately 100,000 ohms

; however, this drops to less than 2500 ohms when the skin is dampened [8].

 Thus, in some cases, a lower voltage applied to tissue with low resistance

can generate more current and be more damaging than higher voltage

applied to tissue with high resistance.

內容取自最新的醫學資料庫

反正講義上各個組織的resistance是沒錯的

只是傷害是跟resistance成正比

所以傷害的大小就直接是bone>FAT>tendon>SKIN muscle > nerve >vessel

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