Nervous system part 2. special senses

Question 1

what is the role of the eye and the 3 layers

Answer 1

• detects energy (photons) and transmits information about intensity, colour and shape to the brain
• sclera: thick opque later which covers the eyeball (aka white of the eye)
• Choroid layer: beneath the sclera and helps to supply the retina with blood, its dark and pigmited that reduces relfection in the eye
• retina: innermost layer containing photoreceptors

Question 2

parts atht efront of the eye

Answer 2

• cornea: bends and focuses light rays, rays travel through opening called pupil
• muscular iris: pigminted and controls the diameter of the pupil

*iris responds to intensity of light in the surroundings (making pupil constrict)

• lens: light continues to the lens and is suspended behind the pupil
• ciliary muscles: controlls the shape and socal length of the lens to focus the image onto the retina

Question 3

what are the 2 types of photoreceptors

Answer 3

• transduce light into action potentials
• two main types of photoreceptors= cones and rods

Cones:

• respond to high intensity illumination and are sensitive to colour
• contain 3 pigments that absorb red, green and blue wavelengths

​ Rods:

• detect low intensity ilumination and are important to night vision
• rod pigment rhodospin ony aborbs a single wavelength

Question 4

how do photoreceptors work

Answer 4

• synapse onto bipolar cells which synapse onto ganglion cells
• axons of ganglion cells bundle to form the optic nerve which codnucts visual information to the brain
• the point at which the optic nerve exists the eye is called the blind spot bc photoreceptors not present there
• the fovea, a small area of the retina above the blind spot is densley packed with bones and is important for high-acuity vision

Question 5

what is the vitreous humour and the aqueous humour

Answer 5

• vitreous humour = jelly like material that helps to maintain the shape of the eye and optical properties
• aqueous humour is more watery and fils the space between the lens and the cornea

Question 6

Answer 6

Question 7

what is myopia

Answer 7

• nearsightedness
• occurs when the image is focused in the front of the retina

Question 8

what is hyperopia

Answer 8

• farsightedness
• occurs when image is focused behind the retina

Question 9

what is astigmatism

Answer 9

• irregularly shaped cornea

Question 10

what are cataracts

Answer 10

• develop when the len becomes opaque: light cannot enter the eye and blindess results

Question 11

what is glaucoma

Answer 11

• inc of pressure in the eye bc of blocking of the outlfow of the aqueous humour
• results in optic nerve damage

Question 12

what is the role of the ear and the 3 regions

Answer 12

• transduces sounf energy (pressure waves) into impulses perceived by the brain as a sound
• pass thorugh 3 regions as enter the ear: outer middle and inner

Question 13

what is the outer ear

Answer 13

consists of auricle (external ear) and the auditory canal

Question 14

what consists of the middle ear

Answer 14

Middle Ear

• tympanic membrane (eardrum): at end of auditory canal vibrates at the same frequency as incoing sound
• 3 bones (ossicles): malleus, incus and stapes (also called hammer, anvil and stirrup)
• amplify the stimulus and transmit it thorugh the oval window which leads to fluid-filled inner ear

Question 15

what consists of the inner ear

Answer 15

• consists of cochlea and vestibular apparatus involed in maintaining equilibrium
• vibration of the ossicles exerts pressure on the fluid in the cochles stimulating hair calls in the basilar membrane to transduce pressue into action potentials
• AP travel via auditory (cochlear) nerve to brain for processing

Question 16

Answer 16