Biology - Endocrine System

→ THE EAR

- 2 functions of the ear: Balance & Hearing
→ Eustachian Tube is needed for BOTH (equalization of pressure)
● Eustachian Tube
- Needed for BOTH (equalization of pressure)
- Connects the throat to the middle ear
- Sneezing, swallowing, yawning = opening of the tubes (balancing air pressure for
proper vibrations of the eardrum)
- Blocked tubes = painful stretching of the tympanum (eardrum).
→ disrupts hearing, causes balancing problems.

Balance
● Semicircular canals
- Ataxia is here?
- 3 small fluid filled tubes
- Keep balance during head & body rotation.
- Mvmnt of the head = mvmnt of liquid inside the canals = hair cells sending action
potentials through sensory neurons to cerebellum.

Hearing
Pinna funnels sound waves into the Auditory Canal.
↓
Tympanum (eardrum) sends its vibrations through the Ossicles (tiny bones of mid ear) and to the Cochlea
of inner ear.
↓
Mvmnt of fluid in Cochlea = vibration of hair cells in Corti Organs.
↓
Hair cells convert vibrations into action potentials, sent through auditory nerve to temporal lobe,
translated into sounds.

⭐︎ 3 Parts
● Outer: Pinna, Auditory Canal, Tympanum [Amplifies sound]
● Middle: Ossicles, Eustachian Tube [Amplifies sound]
● Inner: Semicircular canals, Cochlear base [Hair cells convert stimuli into action potential]

Pathway of Sound
1. Pinna
2. Auditory Canal
3. Tympanic Membrane
4. Ossicles
5. Cochlea
6. Auditory Nerve
7. Temporal Lobe