Special Senses

Question 1

outline the sequence of events involved in taste

Answer 1

taste buds detect (sweet, sour, salty, bitter) chemicals dissolved in food (stimulus), sensory transmissions via cranial nerves 7,9,10

Question 2

outline the sequence of event involved in smell

Answer 2

chemicals in the air called odorants go into nose -> olfactory receptor cells are modified neurons with tiny cilia attached -> olfactory tract via Cranial Nerve 1 -> olfactory cortex

Question 3

name the bones (ossicles) of the middle ear

Answer 3

malleus
incus
stapes

Question 4

describe the route of soundwaves from the oval window to the sensory cortex

Answer 4

• sound waves enter oval window, sets up fluid movement causing vibration of basilar membrane
• this causes movement of hair cells of the organ of Corti against tectorial membrane
• depolarization → action potential transmitted in cranial nerve 8 → thalamus → auditory cortex (relay in inferior colliculi)

Question 5

what is the function of the eye lens?

Answer 5

changes shape to focus via ciliary muscles

Question 6

what is accomodation?

Answer 6

• Aim is to focus an image on the retina by changing the shape of the lens
• Increased curvature of the lens for near vision
• Therefore, the degree of refraction is subject to change

Question 7

what is myopia?

Answer 7

an image of a distant object becomes focused in front of the retina, making distant objects appear out of focus

Question 8

what is hyperopia?

Answer 8

an image of a distant object becomes focused behind the retina, making objects up close appear out of focus.

Question 9

what is the function of the pupil?

Answer 9

controls amount of light entering the eye > through constriction or dilation of pupillary smooth muscle attached to the iris

Question 10

what is convergence?

Answer 10

the way your eyes move together and point inward when you look at nearby objects

Question 11

what is the function of the retina?

Answer 11

• A lot of Rods at periphery of the retina
• Fovea Centralis - cones only, highest visual acuity here
• Photons of light absorbed by Visual Pigments derived from Rhodopsin
• Causes neurotransmitter release and Action potentials in the optic nerve

Question 12

what is the fovea?

Answer 12

a small depression within the neurosensory retina where visual acuity is the highest

Question 13

what is the visual pathway from the back of the eye to the occipital lobe?

Answer 13

Action potentials in cranial nerve II - two routes:
1. To visual cortex in occipital lobe for sensory processing i.e. “What is it?”
2. To superior colliculus for control eye movements and pupil size i.e. “Where is it?”