The Special Senses Flashcards
Where are the special senses processed?
In the CNS
What are the sensory systems?
Somatosensory system (pressure,warmth, vibration, limb position)
Sight (visual)
Hearing (auditory)
Taste (gustatory)
Smell (olfactory system)
What are the accessory structures of the eye?
Eyebrows
Eyelids or palpabrae
Eyelashes
Conjunctiva
Lacrimal apparatus
Extrinsic eye muscle
What are the characteristics of the conjunctiva?
Transparent mucous membrane
Important for lubrication and protection
What are the structures of the lacrimal apparatus?
Lacrimal gland (responsible for tears)
Nasolarimal duct (goes to nasal cavity)
What are the three layers of the eye wall?
Fibrous layer
Vascular layer
Nervous tissue layer
What is contained within the fibrous layer?
Sclera (white of the eye)
Cornea (front of the eye)
What is contained within the vascular layer?
Choroid (melanin containing cells)
Ciliary body (ciliary muscles change the thickness of the lens)
Iris (coloured part of the eye)
What is contained within the nervous tissue layer?
Retina
-outer= pigmented retina scatters light
-inner= sensory retina
What is the path of vision in the eye?
Iris allows light into the eye
Focused by the cornea, ,SNS, and humours onto the retina
The lights tricking the retina produces action potential that are relayed to the brain via the optic nerve
What are the two chambers of the eye?
Anterior segment (front of lens)
Posterior segment (behind the lens)
What is contained within the anterior segment of the eye?
Anterior chambers (between cornea and iris)
Posterior chambers (between iris and lens)
Aqueous humour (fills anterior segment) (maintains pressure, refracts light)
What is contained within the posterior segment?
Vitreous chamber
Vitreous humour
What are the two layers of the retina?
Outer thin pigmented layer (melanocytes)
Inner thicker neural layer (contain three types of neurones)
What neurones are contained within the inner thicker neural layer of the retina?
Photoreceptors
Bipolar cells
Ganglion cells
What are the regions of the (posterior) retina?
Macula (high res colour vision)
Optic disc (blood vessels enter eye, no photo receptors)
What is the process of light passage through the eye?
Light passes through anterior cavity
Focused by lens
Passes through vitreous humour
Pass between axons, ganglion cells and bipolar cells
Reach photoreceptors next to pigmented layer
What is the direction of travel of neuronal signal in the eye?
Photoreceptors synapse with bipolar cells
These synapse with ganglion cells
These run on internal surface and converge at posterior of the eye
These forms optic nerves which exits the eye
What are the two types of photoreceptors cells?
Rod cells
Come cells
What are the characteristics of rod cells?
Sensitive to light
Only black and white
Rhodopsin
What are the characteristics of cone cells?
Need bright light
Colour vision
What are the three sections of structures of photo receptor cell types?
Synaptic terminal
Inner segments
Outer segments
What is the process of phototransduction?
1) light causes retinol to change shape, which activates rhodopsin
2) activated rhodopsin stimulates cell changes that result in vision
3) following rhodopsin activation, retinal detaches from opsin
4)energy from ATP is required to bring retinal back to original form
5) retinal recombined with opsin to form rhodopsin
What is rhodopsin?
Protein opsin bound loosely to pigment called retinal
What are the main three parts of the ear?
Outer ear
Middle ear
Inner ear
What is contained within in the outer ear?
Pinna
External auditory canal
What is contained in the middle ear?
Tympanic membrane(ear drum)
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
What is contained within the inner ear?
Mechanoreceptors for hearing and balance
Vestibular apparatus
Semicircular apparatus
Cochlea
What are the two canals of the cochlea?
Middle (cochlear canal contains organ of corti)
Basilar membrane
What is the process of sound transmission in the ear?
1) sound waves vibrate tympanic membrane
2) auditory ossicles vibrate
3) stapes connected to oval window, sends vibration into cochlea
4) pressure wave pushes on basilar membrane of cochlea duct
5) hair cells bend, transmission of signal
6) neurotransmitters release activates sensory neurones, action potential to brain
What structure are the ossicles?
Malleus
Incus
Stapes
(3 bones that connect the ear drum to the inner ear)
What is the purpose of the vestibular apparatus?
Make static equilibrium with two chambers (saccule and utricle) which control balance
How is the middle ear and inner ear connected?
Oval window
What does the Eustachian tube do?
Equalises pressure between middle ear and outer atmosphere
Connects middle ear to pharynx
Where are hair cells found in the ear?
Present on basilar membrane
why stimulating different areas of your body give you different distances of a two-point system?
receptive fields are smaller in areas that are more sensitive, more than 2 receptive fields must be stimulated to recognise an individual stimuli.
would a two-point test have a different outcome on someone with a damaged somatosensory cortex?
yes
If someone had damage to their motor cortex would their results from the two point discrimination task be the same as if they had no damage?
Yes. If the damage was to the motor cortex the sensory pathways are still intact and the area of the brain interpreting the sensation is still intact
what is the physiological reason that you have a blind spot?
where the optic nerve leaves the eye and there are no phoreceptors
why cant you normally detect your blind spot?
brain fills in the details for you
Explain why it is often possible to smell (or “taste”) medications, such as eyedrops, that have been placed into the eyes
Eyedrops drain through nasolacrimal duct into nasal cavity – much of what is considered taste is actually smell – much of what is considered taste is actually smell
what is the term for drugs that bind to receptors and inhibit them?
antagonists
what type of receptor is involved in the sensations of sound and balance?
mechanoreceptors
what is the name of the organ in the inner ear that is most responsible for hearing?
organ of corti
the parts of the vestibular apparatus that tell our brain about our movements through space are called the _____?
semicircular canals
loud noises can cause action potentials to ____?
fire more frequently
