lab 6: senses Flashcards
describe sclera
Tough outer coat
White of eye
describe cornea
Transparent area of sclera in front of eye
Light can pass through
describe choroid
Pigmented middle layer of eyeball
Absorbs stray light
describe retina
Inner layer of eyeball
Photoreceptor cells
describe fovea
Area of retina in centre of field of vision
describe optic nerve
Carries sensory input to brain (integrating centre)
describe blind spot (optic disc)
Area of retina occupied by optic nerve
Photoreceptors absent
describe lens
Focuses light rays to form image of object on retina
Held in place by suspensory ligaments
describe ciliary body
Ciliary muscles can change shape of lens
Ex = accommodation to near objects
describe iris
Circular muscle
Controls the amount of light entering eye
describe pupil
Opening in iris
Light passes through
describe conjunctiva
Thin protective layer covering cornea, exposed sclera and inner eyelids
describe aqueous humour
Fluid filling anterior chamber of eye
describe vitreous humour
Fluid filling posterior chamber of eye
describe central area of eye
primarily cones = high sensitivity receptors utilized under daylight conditions (photopic vision)
describe fovea in greater detail
area of retina with highest resolution
made of ALL cones
as you move outwards from fovea towards periphery of retina what do you find
number of cones decrease and number of rods increase
what are rods
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
what stimulates cones
high light intensities
describe blind spot in greater detail
optic disc
Location on retina where blood vessels and nerve fibres exit
No rods or cones
what is accommodation
describes how the shape of the lens can be layered by ciliary muscles
to focus on objects farther away or closer
describe myopia
Distance from lens to retina too far
Nearsightedness
Eye can’t focus on object further away
describe hyperopia
Distance from lens to retina too short
Farsightedness
Eye can’t focus on objects too close
what is presbyopia
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
describe visual pathway
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
describe hearing - pathway kinda / all info
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
describe touch (skin)
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
describe skin receptors (touch)
Superficial receptors sense light touch and temperature
Deeper receptors detect pressure
Describe smell
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
what is olfactory adaptation
(nose-blindness) = when olfactory sensory cells become less sensitive to stimuli after being exposed to that stimuli for a certain amount of time
describe taste (types - 5)
Characterized as sweet, sour, salty, bitter and umami - depends on stimuli they are exposed to
describe taste - pathway
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)
describe miraculin protein
in miracle berry = taste modifier by binding to receptors on tongue that are sensitive to sweet stimuli
makes sour things taste sweet
