أسباب وأعراض الحمل خارج الرحم

 💢فسيو العصبي 7 السمع

#physiology_of_CNS 7

#CNS

## اليوم راح نشرح موضوع جديد

*⃣Audition ::

1⃣ Sound waves:👇👇

■ Frequency is measured in hertz (Hz)👌👇

##👆هاد وحدة قياس تردد السمع👂

■ Intensity is measured in decibels (dB) 👌👇

## هاد وحدة قياس حدة السمع👂

2⃣Structure of the ear :👇👇

🔷 وهذه الفقرة مهمة جداا👌 انتبهو 😄

A:Outer ear(الاذن الخارجية)👂:👇

■directs the sound waves into the auditory canal👌

B:Middle ear( الاذن الوسطى)👂:👇

■ is air filled 👌

■ contains the tympanic membrane and the auditory ossicles (malleus, incus, and stapes). The stapes inserts into the oval window, a membrane between the middle ear and the inner ear 👌👌

■ Sound waves cause the tympanic membrane to vibrate. In turn, the ossicles vibrate, 

pushing the stapes into the oval window and displacing fluid in the inner ear👌👌

■ Sound is amplified by the lever action of the ossicles and the concentration of sound  

waves from the large tympanic membrane onto the smaller oval window👌👌

C:Inner ear( الاذن الداخلية)👂:👇

■ is fluid filled👌

■ consists of a bony labyrinth (semicircular canals, cochlea, and vestibule) and a series  

of ducts called the membranous labyrinth. The fluid outside the ducts is perilymph;the fluid inside the ducts is endolymph👌

(1) Structure of the cochlea:three tubular canals:👇👇👇

(a) The scala vestibuli and scala tympani contain perilymph, which has a high [Na+] 👌

(b) The scala media contains endolymph, which has a high [K+]👌

■ The scala media is bordered by the basilar membrane, which is the site of the organ of Corti. 

(2) Location and structure of the organ of Corti:👇👇👇

قد يعجبك ايضا

■ The organ of Corti is located on the basilar membrane👌

■ It contains the receptor cells (inner and outer hair cells) for auditory stimuli👌👇

#🔷organ of Corti👉 audatory receptor👌👌👌

##👆👆 هاد مهم 👌😄 لا تنسوه ي حلوين اوك😄💪😍

 🔷Cilia protrude from the hair cells and are embedded in the tectorial membrane👌

■ Inner hair cells are arranged in single rows and are few in number👌

■ Outer hair cells are arranged in parallel rows and are greater in number than the  

inner hair cells👌

■ The spiral ganglion contains the cell bodies of the auditory nerve [cranial nerve (CN) VIII], which synapse on the hair cells👌

🛑Steps in auditory transduction by the organ of Corti:

*⃣The cell bodies of hair cells contact the basilar membrane. The cilia of hair cells are  

embedded in the tectorial membran 👌👌👌

1⃣Sound waves cause vibration of the organ of Corti 👌

2⃣Bending of the cilia causes changes in K+ conductance of the hair cell membrane 👌👇

 🔷Bending in one direction causes depolarization 👌

🔷bending in the other direction causes hyperpolarization👌Leading to 👇

🔴The oscillating potential that results is the cochlear microphonic potential 👌

3⃣The oscillating potential of the hair cells causes intermittent firing of the cochlear nerves👌

🔵The base of the basilar membrane (near the oval and round windows) is narrow and stiff.It responds best to high frequencies👌

🔵The apex of the basilar membrane (near the helicotrema) is wide and compliant. It responds best to low frequencies👌

🔴✔️Central auditory pathways :👇👇

🔷#كلهم خطوتين 🙈 احفظوهم ي حلوين😄 تمام💪👌😍👇

■ Fibers ascend through the lateral lemniscus to the inferior colliculus to the medial geniculate nucleus of the thalamus to the auditory cortex.👌

■ Fibers may be crossed or uncrossed. As a result, a mixture of ascending auditory fibers represents both ears at all higher levels. 👌

 🔶Discrimination of complex features (e.g., recognizing a patterned sequence) is a property of the cerebral cortex.