Biology Journal 3/25/2014

Hair cells are the receptors inside of the cochlea that are stimulated by vibrations in the liquid in the cochlea. A person may go deaf by having these cells damaged. A cochlear implant uses a speaker on the side of the head and stimulates the hair cell receptors electronically, causing a user to hear sound.

Which parts in the hearing process are bypassed with a cochlear implant?

E.2 Perception of StimuliE.2.1 Outline the diversity of stimuli that can be detected by human sensory receptors, including:

Mechanoreceptors, chemoreceptors, thermoreceptors, photoreceptorsDetails of how each receptor functions are not required.

E.2.2 Label a diagram of the structure of the human eye. The diagram should include: sclera, cornea, conjunctiva, eyelid, lens, choroid, aqueous humour, pupil, iris, vitreous humour, retina, fovea, optic nerve, blind spot

E.2.3 Annotate a diagram of the retina to show the cell types and the direction in which light moves. Include names of rod and cone cells, bipolar neurons and ganglion cells.

E.2.4 Compare rod and cone cells. Include: use in dim light versus bright light one type sensitive to all visible wavelengths versus three types sensitive to red, blue and green light passage of impulses from a group of rod cells to a single nerve fibre in the optic nerve versus passage from a single

cone cell to a single nerve fibre

E.2.5 Explain the processing of visual stimuli, including edge enhancement and contralateral processing. Edge enhancement occurs within the retina and can be demonstrated with the Hermann grid illusion. Contralateral processing is due to the optic chiasma, where the right brain processes information from the left

visual field and vice versa. This can be illustrated by the abnormal perceptions of patients with brain lesions.

E.2.6 Label a diagram of the ear. Include: Pinna, eardrum, bones of the middle ear oval window, round window, semicircular canals auditory nerve, cochlea

E.2.7 Explain how sound is perceived by the ear, including the roles of the eardrum, bones of the middle ear, oval and round windows, and the hair cells of the cochlea.

Name of sensory neuron What it detects

1 Chemicals

2 Electromagnetic radiation

3 Temperature

4 Pressure, texture, vibration

What neurons go in the blanks?

Name of sensory neuron What it detects

1 Chemoreceptors Chemicals

2 Photoreceptors Electromagnetic radiation

3 Thermoreceptors Temperature

4 Mechanoreceptors Pressure, texture, vibration

What neurons go in the blanks?

Compare rods and cones in a Venn diagram.

Rods Both Cones• Stimulated by

light intensity• Photoreceptors • Stimulated by

color• Found all

over retina• Connected to bipolar

cells, ganglia, and optic nerve

• Found mostly in fovea

• Work under any amount of light

• Cooperate to make 1 image that is processed in the visual cortex of brain

• Only work under high-light conditions (not in the dark)

• 1 type • 3 types: blue, green, red

• Rod shaped • Cone shaped

1

1213 11 10

2

4 5

9

8

7

63

Name these parts of the eye. For extra credit, state what they do!

1. Pupilopening that lets light in

12. Scleraprotective outer layer

13. Conjunctivaprotective outer layer

of pupil, secretes mucus

11. Eyelidprotection, cleaning

10. Choroidlayer of light-

absorbing pigment

2. Aqueous Humor

transparent jelly

4. Irismuscles that control size of pupil; gives “eye color”

5. Vitreous humortransparent liquid

9. Retinamostly rod cells

8. Foveaarea of

concentrated cone cells

7. Blind Spot

no receptor cells

6. Optic Nerve

carries nerve impulses to brain

3. Lensadjusts to focus light

on retina

21

3

4

Name these parts of the retina!

Rod cell

Cone cell

Bipolar cell

Ganglion cell

Rod cell

Cone cell

Bipolar cell

Ganglion cell

1. When light hits the retina, list the order in which it passes through each of these cells.2. When an action potential happens, list the order in which it goes through each of these cells.

Rod cell

Cone cell

Bipolar cell

Ganglion cell

1. ganglion cells, bipolar cells, rods/cones

2. rods/cones, bipolar cells, ganglion cells

1. Where is vision processed in the brain?2. What is contralateral processing?

1. Vision is processed in the back of the brain, in an area called the primary visual cortex.

2. The left sides of both eyes are processed on the right side of the brain. The right sides of both eyes are processed on the left side of the brain.

1 3

5

4

67

8

2Name these parts of the ear. For extra credit, state what they do!

1. Eardrumvibrated by air pressure changers due to sound

waves

3. Semicircular Canals

balance (is not involved in hearing)

5. Cochleatiny hairs respond

to individual wavelengths of

sound, generating action potential

4. Auditory Nerve

transmits nerve signals

to brain

6.Oval Windowtransmits vibrations

from middle ear bones to inner ear

7. Round Windowdissipates vibrations

(lessens and lessens “old” sounds)

8. Pinnacollects sound waves

2. Middle Ear Bones

Stimulated by ear drum, knock against each other

to magnify sound

Hearing SightSound waves Light waves

Mechanoreceptors 1

2 Optic nerve

Hair cells 3

Cochlea 4

5 Pupil

Complete the table comparing the sense of hearing to the sense of sight!

Hearing SightSound waves Light waves

Mechanoreceptors Photoreceptors

Auditory Nerve Optic nerve

Hair cells Rods / Cones

Cochlea Retina

Pinna Pupil

Complete the table comparing the sense of hearing to the sense of sight!

Many parts of the ear vibrate in order to create the sense that we call sound. State, in order, which parts vibrate. Then, what converts the vibrations into action potentials?

The sequence of vibrating parts is:Eardrum

Middle ear bonesLiquid inside of cochlea

Hair cells inside of cochlea

When the hair cells vibrate, they turn the signal into an action potential!

What do the oval and round windows do?

The last bone of the middle ear bones presses against the oval window on the cochlea, causing vibrations. The round window dampens and gets

rid of “old” sounds.

Edge enhancement makes edges that you see seem darker. How does it work?

Photoreceptors (rods and cones) repress nearby photoreceptors of from the same wavelength. So, different wavelengths (edges) are not repressed; they’re made artificially sharper!