Bai 28. DIEN THE NGHI VA DIEN THE HOAT DONG
2. Cach lan truyen xung than liinh tren sgi than
- GV ke phieu hgc len bang va yeu cau nhdm ghi ket qua.
- GV nhan xet, danh va thdng bao dap diing.
tap cac
gia an
+ Ca nhan van dung kien thiic d boat ddng 1,2.
+ Nhan biet kien thiic mdi tCr tranh hinh.
+ Thao luan nhdm thdng nhai y kien ghi phieu hgc tap.
- Cac nhdm ghi dap an len bang va trinh bay tren tranh hinh each lan truyen xung than kinh.
- Cac nhdm khac theo ddi bd sung.
- Cac nhdm theo ddi tu sita chira.
Dap an phieu hgc tap
^ ^ - ^ ^ o a i sdi TK Noi dung ^ ^ ^ ^
Ca'u tao
Cach lan truyen
Van toe
Sdi than kinh khong co bao mielin
- Sdi than kinh khong c6 bao mielin bao boc ben ngoai.
- Xung than kinh dUdc lan truyen lien tuc tC/ vung nay sang vung khac tren sdi than kinh.
Cham 3-> 5 m/s.
Sdi than kinh c6 bao mielin
Sdi CO bao mielin bao boc
+ Bao mielin bao boc khong lien tuc, ngat quang tao thanh cac eo Ranvie.
+ Bao mielin c6 ban chat la phoi pho lipit CO mau trang va each dien.
Xung than kinh lan truyen theo each nhay c6c tCf eo Ranvie nay sang eo Ranvie khac.
- Nhanh hdn rai nhieu so vdi lan truyen tren sdi khong c6 bao mielin 120 m/s.
- GV ggi y de HS nhd lai kien thiic vat li ve qui luat lan truyen dien tren day din.
- GV yeu cau: Phan tich CO che' dan truyen xung than kinh tren sgi than kinh khdng cd bao mielin va cd bao mielin.
- GV nhan xet, danh gia va giiip HS hoan thien kien thiic.
- HS neu dugc:
Ddng dien lan truyen tCr noi cd dien the' cao (tich dien duong) sang noi cd dien the' thap (tich dien am).
- HS thao luan nhdm thd'ng nhai y kien: Su lan truyen xung than kinh do:
+ Su mat phan cue, dao cue, va tai phan cue.
+ Su ddng md kenh Na*, K*
+ Ddng dien boat ddng xuat hien va lan truyen sudt dgc hay nhay cdc tren sgi than kinh.
- HS tra Idi -> Idp nhan xet.
* Co che' lan truyen xung than kinh
- Sgi than kinh khdng cd bao mielin.
+ Kieh thich tai 1 diem, tai dd cdng Na" md va Na' di vao lam mat trong ciia mang thay ddi dien tich (tCi' am sang duong) xuat hien ddng dien lan truyen lam didm ben canh bi kich thich va cdng Na"
md, cii nhu vay ddng dien se lan truySn hei dgc sgi than kinh.
- Sgi than kinh cd bao mielin.
* Lien he:
GV hdi: Xung than kinh dugc lan truyen rat nhanh trong sgi than kinh cd y nghia gi?
- GV bd sung kie'n thiic:
+ Thuc te ddng dien boat ddng chay trong sgi true theo chieu tCr dau cho de'n hei sgi.
+ TCr eo 1 de'n eo 2 va qua eo 2 ve eo I, nhung d eo 1 phan hung phan vin cdn dugc tiep tuc tam thdi trd nen tro do dd hung phan d eo 2 truyen sang
- HS tra Idi dugc: Xung than kinh lan truyen trong sgi than kinh cd lien quan tdi cac phan xa, giiip sinh vat phan ung nhanh va chinh xac trudc cac tac nhan bai Igi ciia mdi trudng de tdn tai va phat trien.
- HS cd the thdc mac: Tai sao ddng dien khdng dugc truyen ngugc lai?
- HS thao luan tra Idi:
Hoat ddng song cua sinh vat tuan theo mot so qui luat vat li boa hgc nha't dinh.
+ Khi kich thich tai 1 eo Ranvie nao dd cdng Na*
md va xay ra hien tugng dao cue, xuat hien ddng dien hoat ddng va nhay bac sang eo Ranvie ke ben. Cir lien tuc nhu vay ddng dien nhay bac tut eo nay sang eo khac den hei soi than kinh.
eo 3 va su nhay bac nay se tiep dien cho de'n hei sgi true.
* Lien he: Trong y hgc con ngudi dung thuoc me cd tac dung ddng cdng Na'' thi xung than kinh khdng truyen dugc niia, xung than kinh mat dan, dan de'n giam xung thSn
kinh ve nao de giam dau. Ket luan chung: HS dgc
kei luan SGK.
IV. KIEM TRA DANH GIA
- HS tdm tat kie'n thiic co ban trong bai.
- HS tra Idi cau hdi trac nghiem.
1. Khi kich thich tdi ngudng thi tinh tha'm ciia mang noron d noi bi kich thich thay ddi lam cho:
a) Kenh Na* md rgng, ion Na* tir dich md vao dich bao b) Kenh K* md rgng ion K* tCr dich md vao dich bao
c) Kenh Na*, K* md rgng ion K*, Na* tCr dich md vao dich bao d) Kenh Na*,K* md rgng ion K*, Na* tii dich bao vao dich md
2. Khi lan truyen xung than kinh tren sgi true cd bao mielin, su thay ddi tinh tha'm ciia mang chi xay ra tai
a) Bao mielin
b) Nhan te' bao Sovan c) Eo Ranvie
d) Bao mielin va te' bao Sovan
3. Neu kich thich bat ki mot vi tri nao tren sgi true than kinh, xung thin kinh dugc hinhthanh se
a) Kh6ng lan truyen dgc sgi true b) Lan truyen theo ca 2 chieu
e) Lan truyen theo nhieu hudng xac dinh
d) Lan truyen theo mdt hay nhi^u hudng xac dinh V. DAN DO
- Hgc bai tra Idi cau hdi SGK.
- Doc muc "Em cd biei?"