lab 6: senses

Question 1

describe sclera

Answer 1

Tough outer coat
White of eye

Question 2

describe cornea

Answer 2

Transparent area of sclera in front of eye
Light can pass through

Question 3

describe choroid

Answer 3

Pigmented middle layer of eyeball
Absorbs stray light

Question 4

describe retina

Answer 4

Inner layer of eyeball
Photoreceptor cells

Question 5

describe fovea

Answer 5

Area of retina in centre of field of vision

Question 6

describe optic nerve

Answer 6

Carries sensory input to brain (integrating centre)

Question 7

describe blind spot (optic disc)

Answer 7

Area of retina occupied by optic nerve
Photoreceptors absent

Question 8

describe lens

Answer 8

Focuses light rays to form image of object on retina
Held in place by suspensory ligaments

Question 9

describe ciliary body

Answer 9

Ciliary muscles can change shape of lens
Ex = accommodation to near objects

Question 10

describe iris

Answer 10

Circular muscle
Controls the amount of light entering eye

Question 11

describe pupil

Answer 11

Opening in iris
Light passes through

Question 12

describe conjunctiva

Answer 12

Thin protective layer covering cornea, exposed sclera and inner eyelids

Question 13

describe aqueous humour

Answer 13

Fluid filling anterior chamber of eye

Question 14

describe vitreous humour

Answer 14

Fluid filling posterior chamber of eye

Question 15

describe central area of eye

Answer 15

primarily cones = high sensitivity receptors utilized under daylight conditions (photopic vision)

Question 16

describe fovea in greater detail

Answer 16

area of retina with highest resolution
made of ALL cones

Question 17

as you move outwards from fovea towards periphery of retina what do you find

Answer 17

number of cones decrease and number of rods increase

Question 18

what are rods

Answer 18

Do not detect colour
Receptors responsible for peripheral vision and vision under low light conditions (scotopic)
Ability of rods to function under low light conditions = due to lower sensitivity threshold

Question 19

what stimulates cones

Answer 19

high light intensities

Question 20

describe blind spot in greater detail

Answer 20

optic disc
Location on retina where blood vessels and nerve fibres exit
No rods or cones

Question 21

what is accommodation

Answer 21

describes how the shape of the lens can be layered by ciliary muscles
to focus on objects farther away or closer

Question 22

describe myopia

Answer 22

Distance from lens to retina too far
Nearsightedness
Eye can’t focus on object further away

Question 23

describe hyperopia

Answer 23

Distance from lens to retina too short
Farsightedness
Eye can’t focus on objects too close

Question 24

what is presbyopia

Answer 24

As people age ability of lens to accommodate and focus on near objects weakens
Need for reading glasses or bifocals - correct both farsightedness and nearsightedness

Question 25

describe visual pathway

Answer 25

begins at retina - axons of retinal nerve cells form optic nerve - terminates in thalamus
From thalamus visual info is relayed to occipital lobe of cortex for interpretation of aspects of visual stimulus

Question 26

describe hearing - pathway kinda / all info

Answer 26

Impacts on tympanic membrane of the ear (eardrum)
Specialized hair cells on eardrum send info to brain to be integrated for us to perceive sound
Impulses from inner ear = carried along auditory nerve to medulla → crossing over of fibre tracts takes place
Then, sensory info in sent through pons and midbrain to thalamus
In thalamus it is relayed to temporal lobe of cortex - for interpretation and integration

Question 27

describe touch (skin)

Answer 27

Patchwork quilt of sensations - each patch = has a single receptor and termed a receptor field
Skin receptors send impulse along spinal nerves to spinal cord
At spinal cord - impulses can be passed along spinal cord to medulla, thalamus and parietal lobe OR impulses passed directly to motor neurons within spinal cord

Question 28

describe skin receptors (touch)

Answer 28

Superficial receptors sense light touch and temperature
Deeper receptors detect pressure

Question 29

Describe smell

Answer 29

Receptors bind to volatile molecules in air - different shapes and sizes bind to specific receptors
Binding results in nerve impulses being sent to the olfactory bulb
Axons from olfactory bulb create olfactory tract - extends to the olfactory centres in temporal lobes

Question 30

what is olfactory adaptation

Answer 30

(nose-blindness) = when olfactory sensory cells become less sensitive to stimuli after being exposed to that stimuli for a certain amount of time

Question 31

describe taste (types - 5)

Answer 31

Characterized as sweet, sour, salty, bitter and umami - depends on stimuli they are exposed to

Question 32

describe taste - pathway

Answer 32

Sensed through specialized chemical receptors on tongue
Impulses being sent along cranial nerves to medulla - then relayed through thalamus to gustatory cortex (insular lobe and frontal lobe)

Question 33

describe miraculin protein

Answer 33

in miracle berry = taste modifier by binding to receptors on tongue that are sensitive to sweet stimuli
makes sour things taste sweet