IBDP Biology- The ear

In this IBDP Biology Blog post, it will highlight the structure of the ear, as well as enable us to understand how humans generally hear.

Diagram of Ear

How sound is perceived by the ear 

1. Eardrum: 

• Soundwaves reach eardrum and makes it vibrate. 
• Vibration consists of rapid movements towards and away from the middle ear. 
• The eardrum picks up "sound" and sends it to the middle ear.

2. Bones of middle ear: 

• The ossicles are connected to each other and the first to the ear drum, the third to the oval window. 
• Transmits sound waves to the oval window. 
• Reducing the amplitude of the waves but increases the amplitude 20 times. The oval window helps in amplifying. 
• Muscles atteched to the ossicles help protecting the ear from loud sounds.

3. The oval window: 

• Transmits sound waves to the fluid filling the cochlea. 
• The fluid is incompressible so second membranous window is needed: round window.

4. Hair cells in the cochlea: 

• When the sound waves pass through the fluid in cochlea, the hair bundles vibrate. 
• Each hair cell resonates in response to specific wavelengths of sound due to gradual gradations in width and thickness of cochlear membrane when hair bundles vibrate. 
• Hair cells transmit action potentials across synapse with auditory nerve  -->travel to auditory cortex in brain 

That's the end of the blog regarding how sound is perceived by ear!

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References:

• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F500040364850403667%2F&psig=AOvVaw3JdzDnl16hMGncd9TGSZOp&ust=1627290156689000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCLjfzrDu_fECFQAAAAAdAAAAABAJ

Drafted by Venetia (Biology)