Phys.II Test One: Ear

Question 1

When does the external ear end?

Answer 1

Tympanic membrane

Question 2

What is the pressure in the middle ear?

Answer 2

760mmHg it is equal to atmospheric perssure because the eustachian tube connets pharynx to middle ear

Question 3

What is the Bony labrynth divided into?

Answer 3

• Cochlea
• Vestibule
• Three Semi circular canals

Question 4

What is the bony labrynth filled with?

Answer 4

Perilymph

Question 5

What is the membranous labyrinth divided into?

Answer 5

• Cochelar duct within the cochlea
• Utricle and saccule within the vestibule
• three semi circular ducts within the canals

Question 6

Where is endolymph and perilymph found with regards to the membranous labyrinth?

Answer 6

Perilhymph is surrounding the membranous labyrinth and endolymph is filling it

Question 7

Where is the scala vestibuli and tympani in regards to the cochelar duct?

Answer 7

Vestibuli is above the cochlear duct and filled with perilymph

Tympani is below the cochelar duct and also filled with perilymph

Question 8

Where does the cochlear duct begin?

Answer 8

Oval window

Question 9

What is the round window?

Answer 9

Where the inner ear scala tympani connects to the middle ear

Question 10

____ _____ is related to sound’s loudness.

Answer 10

Wave amplitude

Question 11

__ ___ determines sound’s pitch.

Answer 11

Wave frequency

Question 12

Describe the path that audible sound waves take?

Answer 12

They are transferred from the scala vestibuli across the cochlear duct to the basilar membrane. They move from “top” to “bottom”

Question 13

What opens the mechanically gated cation channels in the organ of corti?

Answer 13

The basilar membrane vibrates moving hair cells, but stereocilia stay embedded in the tectorial membrane causing them to bend back and forth. The bending towards one direction will open the cation channels and cause an influlx of K to depolarize the hair cell.

Question 14

When the mechanically gated cation channels open and deoplarize the hair cells what happens next?

Answer 14

The depolarization causes calcium voltaged gated channels to open and calcium flows in triggering cells to release Glutamate onto the sensory neuron. Depolarization occurs in bursts so Glutamate is released in bursts.

Question 15

What does Glutamate do?

Answer 15

Increases AP production in sensory neurons

Question 16

What do the “stiff” fibers close to the oval window resonate to?

Answer 16

High frequency pressure waves (high pitch)

Question 17

What do the “floppy” fibers,near the cochlea apex, resonate to best?

Answer 17

Low frequency pressure waves (low pitch)

Question 18

Where do fibers of the sensory neurons synapse?

Answer 18

With interneurons in the brain (Medulla Obl.)

Question 19

How can the brain differentiate which direction sounds come from?

Answer 19

Sensory input can converge on the same interneuron, but there will be different arrival times and intensities which allows for determining the direction.

Question 20

Describe the neural path from the interneuron to the primary auditory complex.

Answer 20

1. from the interneuron(s) to the inferior colliculi in the midbrain
2. Inferior colliculi to the medial geniculate nucleus of thalamus
3. MGN to synapse with interneurons that will carry info to the primary auditory complex in the temporal lobe of cerebrum