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Inkusning maqsadi nima?

Inkusning maqsadi nima?



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O'rta quloqdagi uchta suyak - dumg'aza, inkus va stapes - tovush to'lqinlarini ichki quloqqa (koklea) o'tkazishda rol o'ynaydi. Men malleus timpanik membranaga eng yaqin suyak ekanligini tushunaman (shuning uchun ma'lumotni asosiy qabul qiluvchisi) va stapeslar ma'lumotni kokleaya etkazish uchun javobgar ekanligini tushunaman ... shuning uchun nega hatto inkus suyagi bor?


Inkus odamlarda mavjud, chunki u bizning sutemizuvchilarning ajdodlarida mavjud va u bizning ajdodlarimizda mavjud, chunki sutemizuvchilarning uch suyak suyagi tizimi dastlabki amniotlardan meros bo'lib o'tgan.

Sutemizuvchilarning sinapsid ajdodlari artikulyar (keyinchalik malleus deb ataladi) va kvadrat (keyinchalik inkus deb ataladi) o'rtasida ajdodlarning jag' artikulyatsiyasiga ega edi. Bu pastdagi rasm. Ikki jag' bo'g'imlari mavjud bo'lgan o'tish shakliga ega qazilma turlari mavjud (masalan, Pachygenelus). Hozirgacha mavjud bo'lgan sutemizuvchilarda jag' bo'g'imi tish va skuamoz (chaqa suyagining bir qismi) o'rtasida joylashgan bo'lsa, eski bo'g'im va kvadrat suyakchalar tizimining bir qismidir (pastdagi yuqori rasm).

Internetda bu haqda juda ko'p materiallar mavjud:

Xulosa qilib aytganda, inkus mavjud, chunki sutemizuvchilar qulog'ining ajdodlar tizimidan boshqa yo'li yo'q edi. Uning o'ziga xos maqsadi yo'q, faqat u har doim (hech bo'lmaganda jag'li baliqlarga qaytib) stap va bo'g'imlarga (malleus) biriktirilgan.


Qisqa javob
The inkus bilan tutqich hosil qiladi malleus, shu bilan kiruvchi tovushni kuchaytiradi va o'rta quloqning impedansga mos keladigan funktsiyasiga yordam beradi.

Fon
Kmm ning mukammal evolyutsion istiqboliga qo'shimcha ravishda, men o'zimning ikki tsentimni funktsional afzalligi nuqtai nazaridan qo'shmoqchiman. inkus.

O'rta quloqdagi mayda suyaklar (suyakchalar) eshitish sezgirligini oshirish uchun muhim mexanizmdir. Ichki quloqning eshitish retseptorlari (soch hujayralari) suyuq muhitda ishlaydi, ammo akustik stimullar quloqqa havo orqali kiradi. Havodagi tovush suyuqlik chegarasiga tushganda (ya'ni, turli akustik impendanslarga ega bo'lgan muhitlar orasidagi chegara) kiruvchi tovushdagi energiyaning 99,9% ko'zgu tufayli yo'qolishi mumkin. Bu yo'qotish 30 dB ga teng, bu stimulning intensivligining sezilarli darajada pasayishi va tinglovchi uchun sezilarli darajada.

Shaxsiy anekdot sifatida menda genetik sabablarga ko'ra 125 dan 500 Gts chastota diapazonida taxminan 30 dB yo'qotish bor va bu mening nutqimni tushunishimni sezilarli darajada kamaytiradi, ayniqsa shovqinli muhitda.

Havo va suyuqlik impedansidagi nomuvofiqlikni bartaraf etish uchun timpanik membrana va oval oyna o'rtasida joylashgan o'rta quloq shunday mo'ljallangan. kuchaytirmoq kiruvchi ovoz. Bu jarayon deb ataladi impedans moslashuvi.

Ovozlarni passiv ravishda kuchaytiradigan ikkita asosiy o'rta quloq tuzilmasi mavjud:

  1. Timpanik membrana;
  2. The malleus-incus dastagi.

Quloq pardasining samarali maydoni stapes oyoq plitasidan taxminan 21 marta katta. Shunday qilib, quloq pardasi maydoniga ta'sir qiluvchi havodagi ma'lum bir tovush bosimidan kelib chiqadigan kuch suyakchalar orqali oyoq plitasining kichik maydoniga to'planadi, natijada bosim ikki tuzilmaning maydonlari nisbatiga mutanosib ravishda oshadi. , odamlarda, taxminan 21:1.

Yana shunday bo'ladiki, o'z burilishida aylana bo'lak suyagidan hosil bo'lgan dastagi inkusnikidan bir oz uzunroq bo'lib, bosimning yana bir 1,3 ga oshishini ta'minlaydi.

Baraban / oyoq plitasi maydoni nisbatining 21x, 1,3x qo'l koeffitsientiga ko'paytirilsa, bosimning taxminan 27,3x oshishiga olib keladi, bu esa 29 dB ni tashkil qiladi, shuning uchun havo/suyuqlik interfeysi tufayli nazariy 30 dB yo'qotishni engib o'tish mumkin. Demak, o'rta quloq havo va suyuqlik o'rtasidagi akustik impedansga mos keladi, shunday qilib havodan ichki quloq suyuqligiga energiya oqimini maksimal darajada oshirish (1-rasm).


1-rasm. o'rta quloqning impedansga mos keladigan xususiyatlari. Manba: Viskonsin universiteti

O'rta quloq orqali tovushning uzatilishining buzilishi o'tkazuvchan eshitish halokatini keltirib chiqaradi.

Manba
- Viskonsin universiteti


Eshitish suyaklari

Ushbu maqolada biz eshitish suyaklari, ya'ni malleus, incus va stapes haqida gapiramiz. O'rta quloqning ichki qismida tanadagi eng kichik suyaklar - eshitish suyaklari yoki quloq suyaklari joylashgan. Ta'rifga ko'ra, bu uchta suyak shakliga ko'ra nomlanadi: malleus ("bolg'a"), inkus (anvil) va tayoqlar (uzengi). Rivojlanish jarayonida eshitish suyaklari birinchi bo'lib to'liq ossifikatsiyalangan va tug'ilish vaqtida etuk bo'lgan suyaklar bo'lib, keyinchalik ular o'smaydi.

Suyak suyaklari ichida joylashgan o'rta quloq va ligamentlar bilan osilgan. Ular sinovial bo'g'inlar orqali bir-biri bilan bo'g'inlashib, o'rta quloqning uzunligi bo'ylab timpanik pardadan (lateral tomondan) oval oynaga (medial) zanjir hosil qiladi. Suyak suyaklari timpanik membrananing mexanik tebranishlarini ushbu zanjir bo'ylab oval oynaga o'tkazadi, bu erda ichki quloq suyuqliklari harakatlanadi va retseptorlarni qo'zg'atadi. Bu jarayon tovushni elektr signallariga aylantirish imkonini beradi, ular keyinchalik miyaga yuboriladi. Ushbu maqolada eshitish suyakchalarining funktsiyasi, ularning suyak xususiyatlari, artikulyatsiyasi, bog'langan mushaklari va ba'zi klinik jihatlari o'rganiladi.

Eshitish suyaklari haqida asosiy faktlar
Vazifalar Timpanik membrananing tebranishlarini oval oynaga o'tkazing
Malleus Tutqich, spatulatsiya jarayoni, lateral jarayon, oldingi jarayon, bo'yin, bosh
Inkus Tana, kalta a'zo, uzun oyoq/jarayon, lentikulyar jarayon
Stapes Bosh (kapitulum), old oyoq, orqa oyoq, tayanch (oyoq plitasi)
Artikulyatsiyalar Inkudomalleolyar bo'g'im, inkudostapedial bo'g'im, timanostapedial sindesmoz
Mushaklar Tensor timpani (Eustachian) mushaklari, stapedius mushaklari
Klinik eslatmalar Ossikulyar zanjirning uzilishi, giperakuziya


Anatomiya

Kokleaning spiral shakli turli xil tovush chastotalarini uzatish uchun zarurdir. Koklea taxminan 10 millimetr (mm) kengligida va agar koklea o'ralgan bo'lsa, uning uzunligi taxminan 35 mm bo'lar edi. -

Tuzilishi

Koklea suyuqlik (perilimfa va endolimfa) bilan to'ldirilgan va skala vestibuli, skala media va skala timpani deb ataladigan uchta kameraga bo'linadi. Ushbu suyuqlik bilan to'ldirilgan kameralarning ikkitasi bosim o'zgarishini (tovush tufayli), uchinchi kamerada esa Korti organi, koxlear kanal va bazilyar membrana mavjud.

Koxlear kanal - bu skala vestibuli va skala timpani o'rtasida joylashgan yana bir suyak ichi bo'sh naycha. Koxlear kanalda endolimfa mavjud. Skala timpani va koxlear kanal bazilyar membrana bilan ajralib turadi. -

Koklea ichida mayda soch hujayralari ham joylashgan. Ular ayniqsa Korti organida joylashgan va to'g'ri eshitish uchun zarurdir. -

Tug'ilganda bizda 12 000 ga yaqin soch hujayralari mavjud. Soch hujayralari hayotimiz davomida baland tovushlar yoki boshqa sharoitlardan zararlanishi va yo'qolishi mumkin va ular yo'qolganidan keyin bu hujayralar qayta tiklanmaydi. Eshitishdagi muhim rolini hisobga olgan holda, soch hujayralarining yo'qolishi doimiy sensorinöral eshitish qobiliyatini yo'qotishiga olib keladi. -

Manzil

Koklea ichki quloqni tashkil etuvchi ikkita asosiy tuzilmalardan biridir. Ichki quloq quloq pardasi orqasida va o'rta quloqning yonida joylashgan. Boshqa tuzilmalar yarim doira kanallari deb ataladi, ular koklea eshitishda ishtirok etganda muvozanat uchun javobgardir.

Quloq pardasi orqasida eshitishda muhim rol o'ynaydigan suyakchalar, mayda suyaklar joylashgan. Stapesning pastki qismida oval oyna, undan keyin yarim doira kanallar (shuningdek, labrintin deb ataladi) joylashgan.

Yarim doira kanallari endolimfa deb ataladigan suyuqlik bilan to'ldiriladi va tanani to'g'ri muvozanat hissi bilan ta'minlaydi. To'g'ridan-to'g'ri yarim doira kanallariga ulashgan, kokleani tashkil etuvchi salyangoz shaklidagi trubaning boshlanishidan oldin dumaloq oyna. -

Anatomik o'zgarishlar

Embrional ravishda ichki quloq homiladorlikning 4-haftasidayoq shakllana boshlaydi. Kokleaning o'zi odatda homiladorlikning 18-haftasida hosil bo'ladi. SOX2 geni asosan kokleaning shakllanishi uchun javobgardir va SOX2 mutatsiyalari sensorinöral eshitish qobiliyatini yo'qotish bilan bog'liq. -

Koklea koklear uzunliklari, burilishlar orasidagi burchaklar va bosh suyagi poydevoridagi holatida katta o'zgarishlarga ega. Bu koxlear implantatsiya jarrohligiga ta'sir qiladi.


Eshitishning evolyutsiyasi

Sutemizuvchilar infratovushli tovushlar bilan aloqa qiladigan fillardan tortib ultratovush chastotalarida aksolokatsiya chaqiruvlari orqali atrof-muhitda harakatlanadigan yarasalargacha eshitish hissiyotlarida ajoyib xilma-xillikni namoyish etadilar, ko'p odam bo'lmagan sutemizuvchilar odatdagi eshitish diapazonidan tashqarida eshitishadi. Qizig'i shundaki, tovushni idrok etishdagi bu katta farq o'z asosini sutemizuvchilarning eng kichik suyaklarida - o'rta quloqning suyaklarida topadi.

Sutemizuvchilarning o'rta qulog'i uchta suyakdan iborat: malleus, incus va stapes. Ularning tovush to'lqinlarini miya tomonidan qayta ishlash uchun ichki quloqqa o'tkazish funktsiyasi tushunilgan bo'lsa-da, bu mayda suyaklar (aslida inson tanasidagi eng kichik!) orqasidagi evolyutsiya tarixi paleontologiya sohalarida faol tadqiqot sohasi bo'lib kelgan. biologiya va antropologiya. Ushbu evolyutsion hodisani yaxshiroq tushunish uchun keling, umurtqalilar, sudraluvchilarga murojaat qilaylik.

Hech bir tur boshqasidan ko'ra "yaxshiroq" eshitish qobiliyatiga ega emas, ular faqat o'z muhitlarida fitnesni oshiradigan tarzda eshitishlari kerak.

Sutemizuvchilardan farqli o'laroq, kaltakesak va timsoh kabi hayvonlarning jag'ida ko'proq suyaklar va ichki qulog'ida faqat bitta suyak suyagi bor. Evolyutsion rivojlanish biologiyasining bir nechta dalillari va ajoyib darajada to'liq qazilma qoldiqlari shuni ko'rsatadiki, bu suyak nafaqat stapes bilan bir xil, balki sutemizuvchilar qulog'idagi qolgan suyaklar, malleus va inkuslar sudralib yuruvchilarning jag'ida joylashgan. Vaqt o'tishi bilan bu suyaklar sutemizuvchilarning o'rta qulog'iga kiritilgan. Bu sutemizuvchilarning sudralib yuruvchilarga qaraganda eshitish qobiliyati yuqori ekanligini anglatadimi? Mutlaqo emas - hech bir tur boshqasidan yaxshiroq eshitish qobiliyatiga ega emas, ular faqat o'z muhitlarida fitnesni oshiradigan tarzda eshitishlari kerak.

Evolyutsiya tarixining ushbu qismi uchun mashg'ulotlar to'plamini ishlab chiqish menga bakalavriat talabasi sifatidagi kundalik tajribamdan farqli o'laroq o'qituvchi sifatida ishlashga imkon beradigan ajoyib imkoniyat bo'ldi. Biroq, men o'zimning akademik tajribamda tez-tez bo'lishini orzu qilgan pedagogik usullar haqida o'ylagan edim, masalan, bir nechta o'rganish uslublariga murojaat qilish va fan institutini qulay, inklyuziv makon kabi his qilish. Ha, o'rta quloqning evolyutsiyasi qiziqarli mavzu, ammo agar faoliyat ilmiy bilimlarni ishtirokchilar uchun tushunarsiz his qilsa, ilm-fanga ta'sir qilish qanday ta'sir qiladi? Yosh olim sifatida ilm-fan sohasini qulay qilish uchun chegaralarni buzish ushbu to'plamni yaratishda asosiy tamoyil edi va mening kelajakdagi o'qituvchi sifatidagi faoliyatimda yo'l-yo'riq ko'rsatadi.

Eshitish faoliyatining evolyutsiyasi uch qismga bo'lingan: ishtirokchilar turli hayvonlarning dunyo bilan tovush orqali o'zaro ta'sirini o'rganadilar, evolyutsiya jarayonlarini kuzatish uchun bir nechta turlarning o'rta quloqlarining 3D modellarini yaratadilar va odamlar bir xil hayvonlar bilan qanday aloqa qilishlari mumkinligi haqida fikr yuritadilar. boshqa. Ushbu to'plamning mening shaxsiy sevimli qismi - bu sheriklik faoliyatida og'zaki, og'zaki bo'lmagan va yozma muloqotdan foydalaniladigan o'yin orqali erishilgan insoniy muloqotga oid aks ettirish.

Umid qilamanki, Eshitish evolyutsiyasi faoliyati ishtirokchilari nafaqat hech bir tur boshqasidan ustun eshitish qobiliyatiga ega emasligini, balki bu mantiq eshitish va odamlar o'rtasidagi muloqotga ham tegishli ekanligini tushunishadi. Inson dunyoni tovush bilan bog'liq holda qanday his qilishidan qat'i nazar, to'liq samarali va to'g'ri bo'lgan muloqot qilishning ko'plab usullari mavjud. Ushbu to'plam evolyutsion bilimlarni o'zlashtirish bilan birga inklyuzivlik bilan bog'liq muloqotni rivojlantirish mumkin bo'lgan muhitni yaratishga qaratilgan bo'lib, ma'ruzaga asoslangan faoliyatga erishish qiyin bo'lgan tarzda bo'sh joyni egallaydi.

Albatta, bu faoliyat doimo rivojlanib boradi, berilgan fikr-mulohazalarga moslashtiriladi va ushbu faoliyat o'rganish uslublari, til, madaniyat, foydalanish imkoniyati va boshqalar bo'yicha qanday qabul qilinishini hisobga oladi. Amaliyotim davomida ushbu to'plamni yaratish bebaho tajriba bo'ldi va men ushbu loyiha orqali NCSE missiyasiga hissa qo'shganimdan minnatdorman.

Anna Ginter UC Berkeley universitetida Integrativ biologiya va antropologiyani o'rganadi. U bir kun kelib kollej professori bo'lish niyatida biologiya fanlari bo'yicha magistr darajasini olishni rejalashtirmoqda. Eshitish qobiliyatining evolyutsiyasi to‘plami hali ishlab chiqarilmoqda, uning faoliyat bo‘yicha qo‘llanmasi tez orada taqdim etiladi. Ayni paytda, NCSE ning barcha faoliyat to'plamlarini tekshiring.


ICSE biologiya savol qog'ozi 2013 10-sinf uchun yechilgan

ICSE Paper 2013 BIOLOGY
I-BO'lim (40 ball)

(Urinish hamma Ushbu bo'limdagi savollar)

Savol 1:
(a) Quyidagilarni nomlang:
i) nerv hujayrasining hujayra tanasi.
(ii) Barg epidermisidagi mumsimon qatlam transpiratsiyani kamaytirish uchun mo'ljallangan.
(iii) biologik parchalanmaydigan pestitsid.
(iv) odamda genlarning jismoniy ifodasi.
(v) Bowman kapsulasi ichidagi qon kapillyarlarining tugunga o'xshash massasi. [5]

(b) Quyidagilarning aniq manzilini ko'rsating:
(i) xloroplast
(ii) Incus
(iii) korpus kallosum
(iv) himoya hujayralari
(v) O'pka yarim oylik qiymati [5]

(c) Quyida har biri to'rtta shartli oltita to'plam berilgan. Har bir to'plamda atama toq bo'lib, qolgan uchtasi tegishli bo'lgan toifaga birlashtirilmaydi. Har bir to'plamdagi toqni aniqlang va qolgan uchtasi tegishli bo'lgan toifani nomlang. Birinchisi misol sifatida amalga oshirildi:
Misol: fruktoza, saxaroza, glyukoza, kaltsiy.
Toq atama: Kaltsiy Turkum: Uglevodlar
(i) karbonat kislotasi, atsetip kislotasi, benzoy kislotasi, borik kislotasi.
(ii) tupurik, safro, ter, ko'z yoshlari.
(iii) kretinizm, miksedema, oddiy guatr, akromegaliya.
(iv) hapşırma, yo'talish, miltillash, xirillash.
(v) yarim doira kanallar, koklea, timpanum, utrikulus. [5]

(d) A ustunidagi elementlarni B ustunidagi eng mos keladigani bilan moslang. Mos juftlikni qayta yozing. [5]

A ustuni B ustuni
(1) Moyak (a) Buyrak
(2) Poliomielit (b) suv bug'i
(3) Transpiratsiya v) prostata bezi
(4) Qonning ivishi d) temir
(5) Siydik kanalchalari (e) bachadon
(f) Gonad
(g) Salk vaktsinasi
(h) suv tomchisi
(i) kaltsiy
(j) TAB vaktsinasi

(e) Quyidagi to'rtta variantdan to'g'ri javobni tanlang:
(i) Hujayra komponenti faqat hujayra bo'linishi paytida ko'rinadi:
(A) mitoxondriya (B) xloroplast (C) xromosoma (D) xromatin
(ii) Puls to'lqini asosan quyidagilardan kelib chiqadi:
A) Yurakchalar sistolasi (B) Yurakchalar diastolasi (C) Chap qorincha sistolasi (D) O‘ng qorincha sistolasi.
(iii) retsessiv gen o'zini quyidagicha ifodalaydi:
(A) Geterozigota holati (B) Gomozigota holati (C) F2 avlod (D) Y-bog'langan meros
(iv) Ham gormon, ham ferment chiqaradigan bez:
(A) gipofiz (B) oshqozon osti bezi (C) qalqonsimon bez (D) buyrak usti
(v) Orqa miyaning ventral ildiz ganglionida quyidagi hujayra tanachalari mavjud:
(A) motor neyron (B) sezgi neyron (C) oraliq neyron (D) assotsiatsiya neyron [5]

(f) Quyida ayrim tuzilmalar va ularning maxsus funktsional faoliyatiga misol keltirilgan:
Masalan: Ko'z va uision. Shunga o'xshash naqsh quyidagilarni to'ldiradi:
(i) neytrofillar:
(ii) Ureter:
(iii) neyrotransmitterlar:
(iv) ko'zning irisi:
(v) platsenta:

(g) Quyidagi rasm fotosintezning ma'lum bir tomonini ko'rsatish uchun tajribani ifodalaydi. "A" alifbosi kolba ichidagi ma'lum bir holatni ifodalaydi. [5]
(i) Tajribaning maqsadi nima?
(ii) kolba ichidagi maxsus holatni aniqlang.
(iii) KOH o'rniga ishlatilishi mumkin bo'lgan muqobil kimyoviy nom bering.
(iv) kraxmal sinovi oxirida 1 va 2 barglari qanday farq qiladi?

(h) Quyida atamalarning beshta guruhi keltirilgan. Har bir guruhda atamalarni mantiqiy ketma-ketlikda bo'lishi uchun to'g'ri tartibda joylashtiring va qayta yozing. [5]
Masalan: Implantatsiya, Tug'ilish, Ovulyatsiya, Homiladorlik, Urug'lantirish. Javob: Ovulyatsiya, urug'lantirish, implantatsiya, homiladorlik, tug'ish.
(i) gubkasimon hujayralar, yuqori epidermis, stoma, palisade to'qimalari, substomatal bo'shliq.
(ii) Orqa miya, motor neyron, retseptor, effektor, hissiy neyron.
(iii) Endodermis, korteks, tuproq suvi, Ksilem, ildiz tuklari.
(iv) metafaza, telofaza, profaza, anafaza, sitokinez.
(v) ichak, jigar, ichak arteriyasi, jigar venasi, jigar portal venasi.

Javoblar:
(a) (i) siton
(ii) kesikula
(iii) DDT
(iv) Fenotip
(v) glomerulus

(b) (i) Xoroplast: Ular o'simlik hujayralarida hujayra, membrana va yashil qismlarning ichki chetida joylashgan.
(ii) Incus: O'rta quloqda malleus va stapes o'rtasida joylashgan.
(iii) Korpus kallosum: Miyaning ikki bo'lagi, ya'ni miya yarim sharlari o'rtasida joylashgan.
(iv) Himoya hujayralari: Ular stomataning muhim tarkibiy qismlari bo'lib, qo'shni epidemal hujayralar bilan bog'langan.
(v) O'pka yarim klapanlari: O'pka magistralining tagida bu klapanlar joylashgan.

A ustuni B ustuni
(i) Oziq-ovqat konservantlari Borik kislotasi
(ii) Lizozimni o'z ichiga olgan sekretsiya Safro
(iii) Qalqonsimon bezning buzilishi Akromegali
(iv) shartsiz reflekslar Yozilmoqda
(v) ichki quloq qismlari Timpanum

A ustuni B ustuni
(i) testis (f) Gonad
(ii) Poliomielit (g) Salk vaktsinasi
(iii) Transpiratsiya (b) suv bug'i
(iv) qon ivishi (i) kaltsiy
(v) siydik kanalchalari (a) Buyrak

(e) (i) (C) Xromosoma
(ii) (C) Chap qorincha sistolasi
(iii) (B) Gomozigota holati
(iv) (B) oshqozon osti bezi
(v) (D) Assotsiatsiya neyronlari

(f) (i) Neytrofillar: Fagotsitoz
(ii) Ureter: Siydikni buyrakdan siydik pufagiga olib boradi.
(iii) Neyrotransmitterlar: Nerv impulsini o'tkazish.
(iv) Ko'z irisi: Ko'zga kiradigan yorug'lik miqdorini tartibga soladi.
(v) Plasenta: Xomilani ona bilan bog'laydi.

(g) (i) Tajribaning maqsadi C0 ekanligini ko'rsatishdir2 fotosintez uchun zarurdir.
(ii) kolba ichidagi barg yod bilan tekshirilganda ko'k qora rangga aylanmaydi.
(iii) NaOH (natriy gidroksid) muqobil sifatida ishlatilishi mumkin.
(iv) ) 1-barg ko'k qora rangga aylanmaydi, 2-barg esa kraxmal sinovi oxirida ko'k qora rangga aylandi,

(h) (i) Yuqori epidermis, Palisade to'qimalari, gubka hujayralari, substomatal bo'shliq, stoma.
(ii) retseptor, hissiy neyron, orqa miya, motor neyron, effektor.
(iii) Tuproq suvi, ildiz tuklari, korteks, endodermis, ksilem.
(iv) profilaktika, metafaza, anafaza, telofaza, sitokinez.
(v) ichak arteriyasi, ichak, jigar portal venasi, jigar, jigar venalari.

II-BO'lim (40 ball)

(Har qanday urinish To'rt Ushbu bo'limdagi savollar.)

2-savol:
(a) Quyida erkak moyakning lateral kesimining diagrammasi keltirilgan. Xuddi shu narsani o'rganing va quyidagi savollarga javob bering:
(i) Diagrammaning 1 dan 4 gacha raqamlangan qismlarini belgilang.
(ii) 1 va 3 bilan belgilangan qismlarning vazifalarini ayting.
(iii) Moyaklarning qorin bo'shlig'idan tashqaridagi skrotum xaltasida joylashganligi qanday ahamiyatga ega?
(iv) inguinal kanal qanday rol o'ynaydi?
(v) Sperma nima? [5]

(b) Quyidagilar uchun biologik I texnik atamalarni keltiring:
(i) qonda antijenlarga qarshi ta'sir qiluvchi kimyoviy moddalar.
(ii) ifloslanishni keltirib chiqaradigan tarkibiy qism.
(iii) yosh qizda hayz ko'rishning boshlanishi.
(iv) platsentani homila bilan bog'laydigan tuzilma.
v) miya pardasi qatlamlari orasida joylashgan suyuqlik.
(vi) Qadimgi yog'ochli poyaning po'stlog'ida ko'rinadigan doimiy ochiq tuzilmalar.
(vii) oziq-ovqat zanjirining boshlang'ich nuqtasi bo'lgan biologik jarayon.
(viii) Rag'batlantirish natijasida organizmdagi o'zgarish.
(ix) Ko'z yoshlarida mavjud bo'lgan antiseptik modda.
(x) suv molekulalarining nisbiy konsentratsiyasi va
hujayra membranasining har ikki tomonida erigan modda bir xil bo'ladi. [5]

Javob:
(a) (i) (1) Seminifer tubulalar.
(2) Moyak loblari
(3) Epididimlar
(4) Sperma kanali/vas deferens
(ii) 1-qismning funktsiyalari (yarim kanalchalar): Urug'li kanalchalarning hujayralari bo'linishda davom etadi va spermatogenez deb ataladigan jarayon orqali sperma hosil qiladi.
3-qismning vazifasi (Epididimlar):
(i) U spermatozoidlarni seminifer tubulalardan vas deferensga tashishda yordam beradi.
(ii) Shuningdek, u spermatozoidlarning etuklikka erishishiga yordam beradi.
(iii) Moyaklar skrotum xaltasida joylashgan, chunki u spermatozoidlarning pishib etishi uchun zarur bo'lgan tana haroratidan 2-3 °C past haroratni ta'minlaydi.
(iv) Inguinal kanallar moyakning qorin bo'shlig'idan skrotum qopiga yoki aksincha harakatlanishini osonlashtiradi.
(v) Urug' sperma va urug' suyuqligining ishqoriy birikmasidir.

(b) (i) immunoglobulinlar
(ii) ifloslantiruvchi
(iii) Menarx
(iv) kindik ichakchasi
(v) Orqa miya suyuqligi
(vi) Lentiklar
(vii) Fotosintez
(viii) Refleks harakati
(ix) Lizozim
(x) izotonik

3-savol:
(a) Vertikal kesmada ko'rinadigan inson ko'zining diagrammasini chizing va quyidagi tavsiflarga mos keladigan qismlarni belgilang:
(i) ko'zning fotosensitiv qatlami.
(ii) ko'z linzalarini o'z holatida ushlab turish uchun mas'ul bo'lgan struktura.
(iii) ko'z to'pi shaklini va ko'rmaydigan hududni saqlaydigan tuzilma.
(iv) ko'z linzalari oldida ko'rinadigan old kamera.
(v) ko'z to'pi oldida ko'rinadigan eng shaffof tashqi qatlam. [5]

(b) Qavs ichida aytilganlar asosida quyidagi juftlarni farqlang:
(i) fotoliz va fotofosforlanish. (ta'rif)
(ii) Bikuspid qopqog'i va Trikuspid qopqog'i. (Funktsiya).
(iii) Vazektomiya va tubektomiya. (tushuntirish)
(iv) Bosh miya va orqa miya. (Nerv hujayralarining joylashishi)
(v) Bowman kapsulasi va Malpigi kapsulasi. (Qismlar kiritilgan) [5]

Javob:
(a)

(b)

4-savol:
(a) Quyida Mendelning dumaloq urug'li eksenel gullari (AARR) va ajinli urug'li terminal gullari (aarr) bo'lgan shirin no'xat o'simliklarida o'tkazgan tajribasini ko'rsatadigan sxematik diagramma keltirilgan. Xuddi shu narsani o'rganing va quyidagi savollarga javob bering:
(i) F ning fenotipini keltiring1 nasl.
(ii) F ning fenotiplarini keltiring2 naslning o'z-o'zidan changlanishi natijasida hosil bo'lgan nasl.
(iii) F ning fenotipik nisbatini keltiring2 nasl.
(iv) Yuqoridagi kuzatishlar asosida Mendel induktsiya qilgan qonunni nomlang va tushuntiring. [5]

(b) 1 dan 10 gacha bo'sh joylarni tegishli shartlar bilan to'ldirib, quyidagi jadvalni to'ldiring. [5]
Javob:
(a)
(i) F1 nasli eksenel dumaloq.
(ii) F2 avlodlari eksenel dumaloq, eksenel ajinli, terminal dumaloq va terminal ajinli.
(iii) F ning fenotipik nisbati2 nasl 9: 3: 3: 1.
(iv) Yuqoridagi kuzatishlar Mustaqil assortiment qonuniga asoslanadi. Bu qonunda aytilishicha, turli belgilarni boshqaradigan omillar yoki genlar gametalarning shakllanishi jarayonida bir-biriga ta'sir qilmasdan mustaqil ravishda assortimentlanadi.

(b)

5-savol:
(a) Quyida keltirilgan diagrammada inson yuragi funktsional faoliyatining bir bosqichida tasvirlangan. Xuddi shu narsani o'rganing va quyidagi savollarga javob bering:
(i) Fazani nomlang.
(ii) 1, 2 va 3 qismlarini belgilang
(iii) Ushbu fazada yurakning qaysi qismi qisqaradi? Javobingizni qo'llab-quvvatlash uchun sabab bering.
(iv) Ular orasidagi strukturaviy farqlarni ko'rsatish uchun 1 va 2-qismlarning yaxshi belgilangan diagrammalarini chizing. [5]

(b) Quyidagilarning biologik sabablarini keltiring:
i) qorincha devori quloqchalarga qaraganda qalinroq.
(ii) Buyrak korteksi nuqtali ko'rinishga ega.
(iii) Musson mavsumida eshiklarning yog'och ramkalari tiqilib qoladi.
(iv) Tomoq infektsiyalari quloq infektsiyasiga olib kelishi mumkin.
(v) Qo'l o'ylamasdan avtomatik ravishda aylanish yo'nalishini ko'rsatadi. [5]

Javob: (a) (i) Arial sistola - faza.
(ii) 1. Aorta, 2. O‘pka arteriyasi, 3. Yuqori vena kava.
(iii) Yuqori kameralar, ya'ni ikkala atrium ham bu fazada qisqaradi, chunki qon pastga (qorinchalar tomon) oqadi.
(iv)

(b) (i) qorinchalar devori turli funktsiyalari bilan bog'liq bo'lgan mushaklarning har xil rivojlanishi tufayli atriumlar devorlaridan qalinroq. Qorinchalar, ayniqsa chap qorincha tortishish kuchiga qarshi yuqori bosim ostida qonni aortaga haydashi kerak. Shunday qilib, ular katta bosimga dosh berishga moslashgan.
(ii) Buyrak po'stlog'i nuqtali ko'rinishga ega, chunki u quyuq rangga ega va bu mintaqada nefronlar juda o'ralgan.
(iii) Eshik va derazalarning yog'och ramkalari singdirish jarayoni tufayli tiqilib qoladi. Bu jarayonda suv sirtni tortish orqali adsorbsiyalanadi yoki so'riladi. Yog'ochning suvga (gidrofil) kuchli yaqinligi bor. Shunday qilib, ular atrofdagi suv yoki namlikni o'zlashtiradilar yoki so'radilar va shishiradi.
(iv) O'rta quloqning old devorida to'g'ridan-to'g'ri Evstaki naychasiga tushadigan teshik mavjud. Bu naycha o'rta quloqni tomoqqa bog'laydi. Shuning uchun infektsiyaning o'tishi tez-tez uchraydi va bu quloq infektsiyasiga olib kelishi mumkin.
v) shartli reflekslar tufayli yuzaga keladi. Bu reflekslar organizmning hayoti davomida individual ravishda olingan ogohlantirishlarga o'rganilgan javoblardir.

6-savol:
(a) Quyidagi rasmda piyoz piyozchasining epidermis hujayralari ko'rsatilgan. Keyin bu hujayra bir tomchi shakar eritmasiga o'tkazildi.
(i) Kuchli shakar eritmasiga botirilgandan keyin paydo bo'ladigan epidermal hujayraning yaxshi belgilangan diagrammasini chizing.
(ii) Yuqoridagi (i) da ko'rsatilgan o'zgarishlar uchun qanday ilmiy atama qo'llaniladi?
(iii) Hujayrani asl holatiga qaytarish uchun nima qilish kerak?
(iv) Yuqoridagi (iii) bandda qilingan qadam natijasida hujayraning tiklanishi uchun ilmiy atamani keltiring.
(v) Osmos atamasini aniqlang. [5]

(b) Quyidagi atamalarni qisqacha tushuntiring:
(i) genlar.
(ii) o'simlik hujayralarida sitokinez.
(iii) ichak tutilishi.
(iv) diabet insipidus.
(v) dezinfektsiyalash vositalari. [5]

Javob:
(a) (i)

(ii) Plazmoliz yuqoridagi o'zgarish uchun ishlatiladigan texnik atama.
(iii) Hujayrani asl holatiga qaytarish uchun u plazmolizatsiya qilinganidan so'ng darhol gipotonik eritmaga joylashtirilishi kerak.
(iv) Deplazmoliz Bu yuqoridagi (iii) bandida amalga oshirilgan qadam natijasida hujayrani tiklash uchun ishlatiladigan texnik atama.
(v) Osmoz: Bu yarim o'tkazuvchan membrana orqali suv molekulalarining quyi konsentratsiyali hududdan yuqori konsentratsiyali hududga o'tishidir.

(b) (i) Genlar: Genlar - bu ma'lum xususiyatlarni (masalan, soch rangi, qon guruhi, ko'z rangi va boshqalar) aniqlaydigan irsiyat birliklari.
(ii) O'simlik hujayralarida sitokinez: Ko'p hujayrali o'simliklarning hujayralarida sentriolalar bo'lmaydi. Sitoplazmaning bo'linishi anafaza oxirida ekvatorial rejimda yangi hujayra devorining hosil bo'lishi bilan sodir bo'ladi. Telofazada yangi tsellyuloza zarralari asta-sekin ekvatorial zonada to'planadi. Zarrachalar har ikki tomonda, markazdan periferiyaga (markazdan qochma) to'liq hujayrani bo'linguncha cho'ziladi. Bu zarralar birlashib, nozik plastinka membranasini hosil qiladi.
(iii) Gutatsiya: Gidatodalar orqali barglarning chetlari bo'ylab suv tomchilari shaklida suv yo'qotilishi.
Bu hujayralar ichida hosil bo'ladigan gidrostatik bosimning oshishi tufayli sodir bo'ladi. To'liq turgid parenximatoz hujayralarda rivojlanadigan devor bosimi suvni tashqariga chiqarishga majbur qiladi.
(iv) Diapedes insipidus: Vaziyat gipofiz bezining orqa qismidan vazopressin (diuretiklarga qarshi gormon) ning kam sekretsiyasi tufayli yuzaga keladi. Kasallik ko'p miqdorda siydik chiqarish va keyinchalik suvsizlanish va chanqoqlik bilan tavsiflanadi. Siydikda shakar yoki albumin mavjud emas. Qandli diabet insipidusi og'ir bo'lgan odam bir necha kun davomida suvsiz bo'lsa, suvsizlanish tufayli o'lishi mumkin.
(v) Dezinfektsiyalash vositalari: Bu dog'lardagi mikroblarni yo'q qilish uchun ishlatiladigan kuchli kimyoviy moddalar, operatsiya xonalarini sterilizatsiya qilish joylari va jarrohlik asboblari. Ular kuchli korroziy tabiati tufayli tanaga qo'llanilmaydi, masalan. Cresol, fenol, lizol, DDT va boshqalar.

7-savol:
(a) (i) To'rtta xromosomaga ega bo'lgan o'simlik hujayrasida mitozning anafaza bosqichini ko'rsatish uchun yaxshi belgilangan diagrammani chizing.
(ii) kislotali yomg'irning har qanday ikkita zararli ta'sirini ayting.
(iii) Quyidagi biologik qisqartmalarni kengaytiring:
(1) NADP (2) ACT [5]

(b) (i) Qizil Xochning har qanday ikkita asosiy faoliyatini sanab o'ting.
(ii) Dunyoda aholi sonining ko'payishining ikkita asosiy sababini yozing.
(iii) DNK molekulasidagi to'rtta azotli asoslarning nomlarini yozing. [5]

Javob:
(a) (i)

(ii) Kislota yomg'irining zararli ta'siri: U quyidagi ta'sirlarga ega:
(a) Kislota yomg'irlari binolar va metall konstruktsiyalarni korroziyaga olib keladi.
(b) Kislota yomg'irlari tuproqni kislotali qiladi, bu esa etishtirish uchun yaroqsiz holga keladi. Bundan tashqari, o'simliklarga zarar etkazadi.
(iii) (1) NADP: Nikotinamid adenin dinukleotid fosfat (2) ACT: Adrenokortikotropin.

(b) (i) Red Gross faoliyati: Bular quyidagilar:
(a) Urush paytida va tabiiy ofatlar, masalan, ocharchilik, qurg'oqchilik, suv toshqini, zilzila va boshqalar paytida ijtimoiy va tibbiy yordam ko'rsatishga qaratilgan.
(b) Favqulodda vaziyatlarda tez yordam mashinasini va onalik va bolalikni muhofaza qilish markazlarini ta'minlash.
(ii) Dunyo aholisining ko'payishi sabablari: Buning sabablari quyidagilardan iborat:
(a) Yaxshiroq tibbiy yordam tufayli barcha yosh guruhlarida sog'liqni saqlashni yaxshilash va o'limni kamaytirish.
(b) yuqumli kasalliklarga qarshi keng ko'lamli immunizatsiya.
(c) o'sib borayotgan bolalar uchun muvozanatli va yaxshilangan ovqatlanish.
(d) ko'proq bolalar reproduktiv yoshga etadi.
(iii) DNK molekulalarining azotli asoslari:


Inson qulog'ining tuzilishi va funktsiyasi

Eshitish kanali bir oz ‘‘S’’ shaklidagi naycha bo'lib, quloq mumini chiqaradigan ko'plab o'zgartirilgan ter bezlari bilan tukli teri bilan qoplangan.

Eshitish kanali o'rta va tashqi quloq o'rtasida joylashgan timpanik membranaga (quloq tamburiga) cho'ziladi.

O'rta quloq (timpanik bo'shliq) - chakka suyagi ichidagi havo bilan to'ldirilgan bo'shliq.

U oddiy epiteliy bilan qoplangan.

O'rta quloqning medial devorida oval oyna va yumaloq oyna deb ataladigan ikkita teshik mavjud.

Oval oyna stapes deb ataladigan kichik suyak bilan qoplangan.

Dumaloq oyna nozik tolali to'qima bilan qoplangan.

O'rta quloq bo'ylab timpanik pardadan oval oynagacha cho'zilgan uchta juda kichik suyaklar (quloq suyaklari) malleus, incus va stapes deb ataladi.

Ular bir-biri bilan harakatlanuvchi bo'g'inlar va oval oynada bo'shliqning medial devorini hosil qiladi.

Malleus timpanik membrana bilan aloqa qiladi va inkus bilan harakatlanuvchi bo'g'in hosil qiladi.

Inkus oval oynaga mos keladigan stapes bilan bo'g'imlanadi.

Yevstaki naychasi deb ataladigan uzun naycha o'rta quloqni farenks bilan bog'laydi.

Ichki quloq chakka suyagidagi kanallar va bo'shliqlar tarmog'idan hosil bo'ladi, ular suyak labirint deb ataladi.

Ichki quloq uchta asosiy hududdan iborat:

uchta yarim doira kanali

Vestibyul o'rta quloq yaqinidagi kengaytirilgan qismdir.

Uning yon devorlarida oval va yumaloq derazalar mavjud.

Vestibyulda ikkita membranali qopchalar mavjud - utrikula va sakkul.

Yarim doira kanallari bir-biriga to'g'ri burchak ostida joylashgan uchta naycha bo'lib, ulardan biri fazoning uchta tekisligining har birida joylashgan.

Ular vestibyul bilan uzluksiz.

Koklea - bu vestibyul bilan uzluksiz bo'lgan keng asosli o'ralgan struktura.

yuqori vestibulyar kanal

o'rta koklear kanal - yuqori va pastki kanallarni ajratib turadigan kichik kanal.

Vestibulyar kanal oval oynadan boshlanadi va timpanik kanal yumaloq oynada tugaydi.

Ikki kanal bir-biri bilan uzluksiz va perilimfa bilan to'ldirilgan.

Koxlear kanal membranali labirintning bir qismi bo'lib, endolimfa bilan to'ldirilgan.

Koxlear kanalning tagida Korti organi (spiral organ) joylashgan bazilyar membrana deyiladi.

U qo'llab-quvvatlovchi hujayralarni va quloqning mexanoreseptorlarini (eshitish retseptorlarini) o'z ichiga olgan maxsus koxlear soch hujayralarini o'z ichiga oladi.

Korti organi ustida osilgan tektorial membranaga ko'plab tuklar biriktirilgan.

Eshitish retseptorlari - bu sezgi nervlarining dendritlari bo'lib, ular miyaga eshitish nervini hosil qiladi.

Inson qulog'ining funktsiyalari

Eshitish

Vibratsiyali ob'ektlar atrofdagi havoda bosim to'lqinlarini hosil qiladi.

Eshitish jarayonida quloq bu bosim to'lqinlarini (mexanik qo'zg'atuvchi) nerv impulslariga aylantiradi, ular tovush sifatida qabul qilinadigan miyaga uzatiladi.

The outer ear collects and concentrates the sound waves and directs them along the auditory canal towards the tympanic membrane.

This causes the tympanic membrane to vibrate.

Tympanic membrane vibrations are transmitted va amplified through the middle ear by the movement of three jointed ear ossicles.

The ear ossicles transmit the vibrations to the oval window which is located on the membrane of the cochlear surface.

When the stapes vibrates against the oval window, pressure waves are created in the perilymph inside the cochlea.

When the fluid pressure waves enter the vestibular canal, they push down on the cochlea duct and the basilar membrane.

As a result, the basilar membrane and attached hair cells vibrate up and down.

This causes bending of hair projecting from the hair cell against the fixed tectorial membrane which lies above the hair cells.

This results in the stimulation of auditory receptors in the auditory hair cells and generation of nerve impulses.

These nerve impulses are passed to the auditory area of the brain (temporal lobe of the cerebrum) for sound perception.

After the sound perception, the fluid wave is finally dissipated into the middle ear by vibration of the membrane of the round window.

Eustachian tube maintains the air pressure on both sides of tympanic membrane at the atmospheric pressure level.

Muvozanat

Semicircular canals and vestibule located in the inner ear - provide information about the position of the head in space and contribute to maintain the posture and balance.

The semicircular canals arranged in three spatial planes detect angular movements of the head.

Within each canal, hair cells form a cluster with the hairs projecting into a gelatinous cap.

Changes in the position of the head causes movements in the perilymph and endolymph.

As a result, hair cells are stimulated and resulting nerve impulses are transmitted to the brain.

Utricle and saccule of the vestibule - perceive position with respect to gravity or linear movements.

Each of this perilymph filled chambers contain hair cells that project into a gelatinous material in which small calcium carbonate particles (otolith) are embedded.

When the head is tilted otoliths press on the hairs projecting into the gels. Hair cell receptors transform this deflection into an electrical signal and pass into cerebellum.


Dysfunctions of the ear

Karlik

Deafness refers to a loss of hearing, which may be temporary or permanent, partial or complete.

Conductive deafness

Conductive deafness occurs when sound waves are not properly conducted through the external and middle portions of the ear to set the fluid in the inner ear in motion. Possible causes include:

  • Physical blockage of the ear canal with earwax
  • Eardrum rupture
  • Middle ear infection with accompanying fluid accumulation
  • Restriction of the movement of the ossicles, due to bony adhesions between the stapes and oval window

Sensorineural deafness

In sensorineural deafness, the sound waves are transmitted to the inner ear, but they are not converted into nerve signals that are interpreted by the brain as sounds. The defect can lie in the organ of Corti or the auditory nerves, or rarely, in some pathways and parts of the brain.

Neural prebycusis

Neural prebycusis is one of the most common causes of partial hearing loss. It is a progressive age-related process that occurs over time as the hair cells “wear out” with use. Even exposure to ordinary modern-day sounds can eventually damage hair cells over long periods of time. An adult loses on average more than 40% of their cochlea hair cells by the age of 65. Those hair cells that process high-frequency sounds are the most vulnerable to destruction.

Vertigo

Vertigo refers to the sensation of rotation in the absence of equilibrium – in other words, dizziness. Vertigo can be caused by viral infections, certain drugs, and tumours such as acoustic neuroma. Vertigo can also produced normally in individuals through excessive stimulation of the semicircular ducts. In some individuals, excessive stimulation of the utricle can also produce motion sickness (carsickness, airsickness, seasickness).

Meniere’s syndrome

Meniere’s syndrome is a disease of the internal ear affecting both hearing and equilibrium. Patients initially experience episodes of dizziness and tinnitus (ringing noise in the ears), and later develop a low-frequency hearing loss. The causes relate to the blockage of a duct in the cochlea which drains excess endolymph away. Blockage of the duct causes an increase in endolymphatic pressure and swelling of the membranous labyrinth in which the inner ear hair cells are located.


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A: DNA is a molecule composed of two polynucleotide chains that coil around each other to form a double.

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Q: As pointed out in the section Evolution of the Y Chromosome, some researchers have predicted that th.

A: Chromosomes are long thread-like structures that carry coded genetic information in the form of DNA.

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A: Kidneys are the bean shaped organs of about 4 to 5 inches long. They are located in the abdomen towa.

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A: Introduction Turgor pressure: it is the pressure created by the water on the walls of the plasma me.

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A: The medical condition of cancer is generally characterized by the presence of a cluster of cells pos.

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A: To synthesize protein molecules, a cell must first transfer information from DNA to mRNA through the.


What is the purpose of the incus? - Biologiya

I. Generalized sensory system response.
The general system is diagrammed as follows: stimulus reception (stimulus received by a receptor) transduction (causes change in membrane potential, resulting in action potential) amplification (signal strength increased) transmission (signal propagated through nervous system) integration (processing of information by brain) perception.

We’ll study each stage in more detail and then give some specific examples of the sensory system in action.

II. Integration - Or, Lessons from the newly sighted.
Consider an individual blind since birth who suddenly is able to see. What would s/he see? We certainly cannot learn the answer to this question by doing an experiment. However, we can study the experiences of individuals with cataracts whose sight was restored when suitable surgical techniques were developed.

A passage will be provided from Goldstein and Goldstein (1984). The Experience of Science. Plenum Press. I think this issue is also addressed in some with Val Kilmer (Love at First Sight?)

Conclusion: the brain must learn to see and process information. Sight (and likely other senses) is not a purely mechanical processes. Thus, integration of sensations is crucial!

As an aside, this brings up an interesting philosophical question about facts - things are only what they seem because that’s the way we learned and perceive them. How do we know that our senses haven't been "tricked" (ya'ni optical illusions)?

III. Rag'batlantirish.
There are many different stimuli that activate the nervous system. These stimuli, which are essentially various types of energy, include:

  1. chemical energy - associated with chemical bonds/structure involved in taste and smell
  2. mechanical energy - associated with movement such as physical deformations caused by sound, pressure, vibrations, fluids, touch involved in touch and hearing and
  3. radiant or electromagnetic energy - such as light, heat, magnetism involved in vision.
  4. damage to tissue is another type of stimulus.

A. Receptors are usually modified sensory neurons or epithelial cells. They can occur singly or in groups.

B. A receptor converts the energy of a stimulus into an electrochemical signal (harakat salohiyati).

C. Some receptors monitor stimuli coming from within the individual (ya'ni., from internal stimuli - internoreceptors), others monitor external stimuli (externoreceptors).

    Photoreceptors - important in visual systems, respond to light (radiant energy) such as the eye. Light alters membrane potential

E. Receptors may: (1) occur in more than one location (i.e., somatic receptors such as pain receptors) or (2) be localized in specialized structures (ya'ni., the eye).

V. Transduction/Transmission/Amplification
This refers to the ability of a receptor to trigger an action potential upon receiving a stimulus. The stimulus typically cause a change in membrane permeability resulting in an action potential. This is the result of the stimulus causing ion channels in the membrane to open causing the release of neurotransmitter substances.

The stronger the stimulus the more action potentials (frequency) along a single neuron and the more axons that carry the message. Thus the response is baholangan.

The response of the sensory system is "hard-wired". In other words, a given sensory system will react in a predictable way, even to "other" stimuli. For example, when you rub your eyes you see flashes of light. Thus, a mechanical stimulus causes the same response as an electromagnetic stimulus.

Moslashuv - the sensory system soon adapts to continued stimulation and doesn't respond to the stimulus. Just like the villagers who stopped coming to aid the "boy who cried wolf", the system becomes adapted to the repeated stimulus and no longer responds.


VI. Touch - monitoring mechanical stimulation ( not covered in class not on exam )
Touch receptors are a type of mechanoreceptor. In humans, the fingertips and tongue are rich with receptors, but there are fewer in the back of the hand and neck. Touch receptors are free nerve endings or nerve endings that are surrounded by a capsule.

In skin, there are receptors to monitor: (a) light touch (b) deep pressure (c) pain (d) cold/hot (see below). Muscle spindles (stretch receptors) monitor muscle movements.


VII. Harorat - monitoring hot and cold ( not covered in class not on exam )
There are free nerve endings in skin to monitor: (a) heat and (b) cold. The hypothalamus processes these nerve impulses.


VIII. Pain - monitoring tissue damage ( not covered in class not on exam )
Pain is recepted by free nerve endings (dendrites), the nocireceptors. Prostaglandins sensitize tissue to pain. Aspirin works by inhibiting prostaglandin synthesis.


IX. Taste - an example of a chemoreceptor system.
Stimulus - chemical. Receptor - chemoreceptor. In humans, the chemoreceptors are "taste buds" located in circular papillae that are found in specific regions of tongue. Binding of chemicals to the receptors induces an action potential that is transmitted to the brain for perception as a "taste".

There are four basic tastes - bitter, sweet, salty, and sour. The locations of these receptors can be mapped (bitter - back of tongue sweet - front salt - front sour - sides). These tastes have different functions (sweet - suckling, bitter - avoid poisons, salt - obtain needed minerals, sour - maybe to avoid spoiled food?).


X. Odor - another chemoreceptor system
Odors are caused by the response of ciliated receptor cells that line the olfactory epithelium to different molecules. Humans have receptors for about 10,000 different chemicals. The signal is passed to olfactory bulb and olfactory cortex in the brain.

As anyone who has ever had a head cold knows, things don’t taste very good when you can’t smell them. Thus, a large component of taste is related to odor.

A. Structure.
The vertebrate ear is made of three regions: outer ear (receives signal), middle ear (amplifies signal) and inner ear (processes signal into action potential, transduction of signal).

Major parts of the ear include: malleus (hammer), incus (anvil), stapes (stirrups), cochlea, basilar membrane, organ of Corti, oval window, round window, tympanic membrane.

The middle ear is air filled - important for pressure equilibration. Middle ear is open to pharynx (via auditory tube = Eustachian tube) that is usually closed except when swallowing or yawning. Often need to equalize pressure as when scuba diving or changing altitude. Can be problematic for people with ear infections (ya'ni., when the middle ear is fluid-filled).

The malleus/incus/stapes serve to amplify sound waves. They increase the pressure 20x.

B. A brief primer on the physics of sound.
No sound in a vacuum - sound is transmitted by the movement of air molecules. Consider a vibrating tuning fork that alternately compresses and releases air molecules. Expressed in the terminology of waves: (1) Volume is related to amplitude (degree of compacting). The units are decibels and humans can easily detect 10 db. (2) Pitch is related to frequency - number of waves that pass a given point per unit time. Frequency is expressed as Hertz. Humans can hear from 20-20,000 Hz, though we hear best from 500-4000 Hz.

C. Mechanism of sound perception
Sound waves tympanic membrane (ear drum) vibrates malleus (hammer) incus (anvil) stapes (stirrups) oval window pressure waves in fluid of cochlea move from vestibular canal (scala vestibuli) around into tympanic canal (scala tympani) and then to round window ultimately causes basilar membrane to vibrate which pushes hair cells in organ of Corti to come into contact with tectorial membrane hair cells bend depolarization initiates action potential to brain "sound"

D. Different regions of basilar membrane respond to different frequencies
The distal region (nearest round window) narrowest and stiffest - responds to highest frequency sound proximal region (nearest oval window) widest and most flexible - responds to lower frequency sound.

E. Hearing damage
Loud sounds can damage hair cells. Permanent. Bummer.

F. Balance
Semicircular canals are important for detecting position. Contain hair cells surrounded by a fluid that responds to gravity. When hair cells bend due to movement of the fluid it initiates an action potential that can be processed into info concerning body position. Like a gyroscope and similar to the gravitropic response in plants (statolith idea)

G. Video
In class we saw a video clip concerning hearing and cochlear implants

A. Camera model.
The vertebrate eye is analogous to a camera (but oh so much more!). Let's review the structure of a standard camera: UV/haze filter or other lens cover (protects the lens from damage), lens (bends light, focuses so the light converges at a single plane), diaphragm (regulates amount of light that enters camera), film (photosensitive layer), camera body (serves as housing and protection). Check out Gink & Go Take Pictures

  • Sclera - like camera body, serves to protect the eye, "whites of the eye"
  • Cornea - clear protective layer that can be rapidly regenerated (ya'ni., when a child, my daughter Erin scratched her cornea. After a quick trip to the pediatrician we realized there was no cause for concern. The scratch was visualized with fluorescein and it's amazing how quickly it disappeared). Also serves to bend light and focus it onto photoreceptive surface. Thus, the cornea serves the function of both the UV/haze filter and lens of the camera
  • Iris - controls amount of light entering eye. Analogous to camera diaphragm
  • Retina - photoreceptive layer that absorbs and converts light, analogous to the film
  • Choroid layer - contains vascular tissue for nourishment and pigmented area to minimize light scattering. There is no good analogy to the camera except that cameras are typically black to minimize light scattering
  • Aqueous body - fluid inside the cornea, transmits light and maintains pressure analogous to air inside lens of camera
  • Vitreous body - fluid inside eye, transmits light, supports lens and eye, analogous to air inside camera body
  • Pupil - opening into eye controlled by diaphragm/iris, can be narrow or wide letting less or more light into eye (like F-stops on camera)
  • Optic disk - where optic nerve leaves eye, no photoreception ("blind spot" - can detect by making marks on paper 3" apart). Camera analogy?
  • Fovea - area of densely packed cones. area of best vision.

C. Image formation.
Light reaches eye and hits cornea which causes light to bend (refract), focusing the image on the retina. The cornea is primarily responsible for focusing. The effect of distance is adjusted by the lens. In a camera the lens is used to focus - it moves toward and away from the film. In the vertebrate eye, the lens doesn't move with respect to the retina, rather the lens changes its thickness. Bu deyiladi turar joy.

If the object is near, the lens is thicker (refracts light more) because the ciliary muscle contracts pulling the choroid toward lens thereby causing the ciliary fibers to become loose/slack (doesn't "pull" on lens so much).

If the object is far away, the lens is thinner because the ciliary muscle relaxes, thus the choroid layer moves away from the lens, making the fibers tight pulling on the lens.

    Rods - sensitive to dim light at periphery of eye, not sensitive to wavelength (color) approx. 100 million of them important in coarse perception of movements three regions - outer with lots of membrane stacks (another example of S/V ratios in action), middle region with the major organelles and inner area (synaptic terminal)

    located the membranes of rods and cones.

E. Summary.
We can summarize visual sensory pathway:

light rod/cone isomerization of rhodopsin in membrane opsin changes shape G protein (transducin) activates phosphodiesterase converts cGMP to 5GMP sodium channels that were previously held open by cGMP close hyperpolarization of membrane action potential release neurotransmitter stimulate other neurons (bipolar cells then ganglion cells) optic nerve thalamus visual cortex in brain sight

Required Reading: Purves et al. Chapter 45 (appropriate sections)


Anatomy of the Ear (Coloring)

Color the image below according to the directions. For each structure, write a short definition or describe its function.

Pinna (brown) _________________________________________
External Auditory Meatus (yellow) _________________________________________
Tympanum (gray) _________________________________________
Malleus (pink) _________________________________________
Incus (purple) _________________________________________
Stapes (black) _________________________________________
Semicircular Canals (purple) _________________________________________
Cochlea (red) _________________________________________
Vestibulocochlear Nerve (blue) _________________________________________
Round Window (orange) _________________________________________
Tympanic Cavity (light blue) _________________________________________
Eustachian Tube (green) _________________________________________

Ear Image By Jordi March i Nogué [1] (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons

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