I D I E N THE H O A T D O N G
Khi bi kich thich thi t l bdo thdn kinh hung phdn va xuai hien didn the boat ddng.
1. D6 thf didn thlThoot ddng
Hinh 29.1 la dd thi didn thi boat dgng eiia t l bdo thdn kinh mue dng trdn mdn hinh eiia may dao ddng kf didn tir.
mV +50 - +40 +30 +20 +10
-10 - -20 - -30 - -40 - -50 - -60 - -70
Giai do^n ddo ct/c
3 4 5 Glal dOQD tdi phdn ci^:
Olal do^n mit phtn ci,ic
Ol^n th4 nghi
•+• •+•
%o gidy
KIch thich
Hinh 29.1. Dd thi dien the boat ddng
Khi t l bao thdn kinh bi kfeh thfch, didn the nghi bien ddi thdnh dien thi boat ddng. Didn thi boat ddng gdm 3 giai doan : mai phan cue (khir cue), dao cue va tdi phan cue.
2. Co c M ' h I n h thdnh d i f n th§'hoat ddng
Khi bi kich thich, cdng Na"^ md rdng ndn Na"^ khulch tdn qua mang vdo bdn trong te bao gay ra mat phan cue va dao cue (hinh 29.2A). Tie'p dd, cdng K"^ md rdng hon, cdn cdng Na"^ ddng lai. K* di qua mdng ra ngodi te bdo ddn den tdi phan cue (hinh 29.2B).
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Nhu vay, dien tkikoqt ddng Id sU biin ddi dien the nghi, tU pkdn cue sang mdt pkdn cue, ddo cue vd tdi pkdn cue.
Qud trinh hinh thanh dien the boat ddng keo dai khoang 3 - 4 %o giay.
0 giai doan mat phan cue va giai doan dao cue, loai ion nao di qua mang te bao va sU di chuyen ciia ion dd cd tac dung gi ? - d giai doan tai
phan cue, loai ion nao di qua mang te bao va su di chuyen ciia ion dd cd tac dung gi ?
Ben trong te bao Cdng K\
Mang te bao
Ben ngoai te bao
K*
M,- - : e ^
Na* Na""
Na*
K* Na*
5 K-
Na*
Ben trong te bao Cong K*
md rdng^
Mang te bao
Ben ngoai te bao
Na*
. Cdng Na*
mo
K*-
Na*
Na* Na*
Na* , Na*
Na*
K*
^ K *
LTT Na* - Cong Na*
ddng
Hinh 29.2. Co che hinh thanh dien the hoat dgng A - Giai doan mat phan cue va dao cUc ;
8 - Giai doan tai phan cue.
II - LAN TRUYEN XUNG THAN KINH TREN SOI THAN KINH Didn thi boat ddng khi xuat hien dugc ggi la xung thdn kinh hay xung dien.
Xung thdn kinh xuai hien d noi bi kfeh thich se lan truyin dgc theo sgi than kinh.
Cdch lan truyin va tdc do lan truyin eiia xung thdn kinh tren sgi thdn kinh khdng ed bao mielin va tren sgi thdn kinh ed bao mielin Id khae nhau.
1 . Lan truyen xung than kinh tren soi t h a n kinh khong co bao mielin Tren sgi thdn kinh khdng ed bao
mielin, xung than kinh lan truyin lien tuc tir viing nay sang viing khdc kl ben. Xung thdn kinh lan truyin la do mat phan cue, dao cue va tai phan cue lien tie'p bet viing nay sang viing khdc tren sgi than kinh
(hinh 29.3). _ +
>- + + + + + +
+ v ^ _ ^ _ _ - - -
+ + + + +
Hinh 29.3. Xung than kinh lan truyen
tren sgi than kinh khdng cd bao mielin Chieu lan truyen cua xung than kinh
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Bao mielin
2. Lan t r u y e n xung t h a n kinh tren soi t h a n kinh co bao mielin Mdt sd sgi thdn kinh cd bao midlin bao quanh. Bao mielin bao bgc khdng lien tuc ma ngdt quang tao thanh cdc eo Ranvie. Bao midlin ed ban chat la phdtpholipit ndn cd mau trdng va ed tfnh chai each dien.
. Tren sgi thdn kinh ed bao mielin, xung than kinh lan truyin theo cdch nhdy edc, tir eo Ranvie nay sang eo Ranvie khae. Xung than kinh lan truyin theo each nhay cdc Id do mai phan cue, dao cue va tai phan cue lien tie'p tir eo Ranvie nay sang eo Ranvie khae (hinh 29.4).
Do lan truyin theo cdch nhay cdc ndn tdc do lan truyin cua xung thdn kinh trdn sgi cd bao mielin nhanh hon nhilu so vdi trdn sgi khdng cd bao mielin. Vf du, d ngudi, tdc do lan truyin xung than kinh tren sgi than kinh van ddng (ed bao mielin) la khoang 100 m/giay, eon trdn sgi than kinh giao cam (khdng cd bao midlin) la khoang 3 - 5m/giay.
[ y ^ y^\
V Eo Ranvie
Chieu lan truyen cua xung than kinh
Hinh 29.4. Xung than kinh lan truyen tren sgi than kinh ed bao mielin
- Tai sao xung than kinh lan truyen tren sgi than kinh cd bao mielin theo each nhay cdc ?
- Xung than kinh lan truyen theo cac bd sgi than kinh cd bao mielin tir vd nao xudng den cac ca ngdn chan lam ngdn chan co lai. Hay tinh thdi gian xung than kinh lan truyen td v6 nao xudng ngdn chan (cho bie't chieu cao cua ngUdi nao dd la 1,6m, toe do lan truyen la 100 m/giay).
r - Dien thi hoqt ddng Id su biin ddi dien thingki a mdng tibdo tdpkdn cue sang mdt phdn cue, ddo cue vd tdi phdn cue.
- Tren sai thdn kinh khdng cd bao mielin, xung thdn kink Ian truyin lien tuc td vung nay sang viing kkdc ki ben.
-Tren sai tkdn kink cd bao mielin, xung tkdn kinh lan truyen theo cdch nhdy cdc, td eo Ranvie nay sang eo Ranvie khdc. Do lan truyen theo Idi nhdy cdc nen tdc do lan truyin cua xung tkdn kinh tren sgi thdn kinh cd bao mielin nhank kan so vdi tren sgi tkdn kinh khdng cd bao mielin.
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Cau hoi va bai tap
1. Dien the boat ddng la gi ? Dien the boat ddng dugc hinh thanh nhu the nao ? 2. Danh da'u X vao d I I cho cac y dung ve dien the boat dgng.
LJ A - Trong giai doan mat phan cue, Na"^ khuech tan td trong ra ngoai te bao.
EH B - Trong giai doan mat phan cue, Na* khuech tan td ngoai vao trong te bao.
I ^ C - Trong giai doan tai phan cue, Na*" khuech tan td trong ra ngoai te bao.
LJ D - Trong giai doan tai phan cue, K* khuech tan td ngoai vao trong te bao.
3. So sanh each lan truyen cua xung than kinh tren sgi than kinh khdng co bao mielin va cd bao mielin.
Em eo bie> ?
TRAM P H A T t ) l | N D[Jd\ NL/dc
d Dia Trung Hai ed mdt loai ea dud'i san mdi mot each ki la. Khi gap loai ca nay, nhumg chu ca con, cua bien,... bdng run lay bay rdi nga lan ra chet. Ca dud'i chi viec bai den va danh chen con mdi. Cach san mdi ciia loai ca dud'i nay la phdng ra nhumg ludng dien manh de giet chet con mdi. Dien the ciia ddng dien do ca dudi dien phat ra dat tdi GOV va cudng do ddng dien la 60A. Mdt so loai ea khae song d nude nggt ed the phat ra ddng dien manh han nhieu. Vi du, dien the eda ddng dien do ea nheo dien phat ra la 400V, ciia ca chinh dien la 600V (nen nhd ring dien the ciia mang dien chung ta sddung hing ngay ehi la 220V).
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