Special Senses Flashcards
Eyebrows
Functions
Muscles controlling
Shade/protection from perspiration
Corrugator supercilii: medial movement
Orbicularis oculi: depresses eyebrow
Eyelids (palpebrae)
Space between eyelids:
Connection points for eyelids
Part that produces white secretions
Muscles for opening/closing
Palpebral fissure
Medial/lateral comissures
Lacrimal caruncle
Orbicularis oculi, levator palpebrae superioris
Does conjunctiva line cornea? Why
No, would distort image
Tear pathway
Produced in lacrimal gland (upper/lateral eyelid)
Wash across lower eyelid (lateral -> medial)
Collect at lacrimal Punctum
Enter lacrimal Canaliculi
Lacrimal sac
Drain into nasolacrimal duct
lacrimal caruncle not involved
Eye muscles
4 rectus (functions)
2 obliques (functions)
Sup/Inf/Lat/Med rectus (pull eye in that direction)
Sup/Inf oblique: (pull in opposite direction)
Eyeball tunics (functions)
Sclera
Choroid
Retina
Scelra: white of eyes (outermost layer)
Choroid: provides nutrients for sclera/retina (dark brown staining)
Retina: seeing light
Functions:
Ciliary muscle
Sphincter papillae (+NS association)
Dilator papillae (+NS association)
Controls shape of lense
Closes pupil (parasympathetic)
Opens pupil (sympathetic) see more of scary situation
Sensory tunic (retina)
Outer pigmented layer: function
Transparent inner neural layer: function
Prevent light scattering/remove dead cells
Contains photoreceptors
Age-related macular degeneration (AMD)
Dry vs wet AMD
Dry AMD:degradation of pigmented layer (loss of macula)
Wet AMD: choroid blood vessels grow abnormally (loss of macula)
Retinopathy
What happens
Is clot removed?
Weak blood vessels leak, cause clot in vitreous humour (blindness)
Clot not removed (fluid is not renewable)
Posterior segment
Where
Which fluid
What type of pressure provided
behind the lens
vitreous humour
Intraocular pressure (holds retina against choroid)
Anterior segment (two chambers)
Where
Which fluid (function)
Fluid pathway (produce, pass, drainage)
Pressure
Anterior/Posterior chambers
Lens-Cornea
Aqueous humour (nourishes/removes waste)
Produced by ciliary processes, posterior -> anterior chambers -> drains through scelral venous sinus (Schlemm)
Intraoculuar pressure
Glaucoma
Bad drainage of what fluid
Causes what
Common in who
Aqueous humour, pressure builds up causing damage to optic nerve
Common cause of blindness in old people
Lens
Shape
Flexible?
Vascular? (why)
How does aging affect?
Biconvex
Flexible +transparent
Avascular (not to hinder light passage)
Lens becomes more dense (loses elasticity-> vision loss)
Cataracts:
Improper clumping of what protein
Improper clumping of crystalline protein
Light can’t pass through lens
Which wavelengths can we see? (nm)
400-700 nm
What do each lens do?
Concave:
Convex
How is the image flipped in the brain
Concave: diverges light
Convex: converges light
Brain flips image across x and y axis (to make it normal)
Pathway of light (start from cornea)
Cornea
Aqueous humour
Lens
Vitreous humour
Retina
Photoreceptors
Light pathway to photoreceptors, then to brain
Ganglion cells (no rxn), Bipolar cells (no rxn), Rods/Cones
Rods/cones, bipolar cells, ganglion cells, optic nerve, brain
Focusing for distant vision (>6m)
Rays come in …
How much change is needed by ciliary muscles
Which ANS controls?
Parallel
Minimal change
Sympathetic system
Focusing for close vision (<6m)
What does ciliary muscle do to lens:
What does spincter papille muscle do
Rotation of the eyeball: medial or lateral?
Which ANS controls?
Rays come in divergent
Ciliary muscle: contracts, lense BULGES
Sphincter papillae constricts pupil (to reduce divergent rays)
Eyeballs rotate medially (convergence)
Parasympathetic
Vision correction
Emmetropic?
Myopia: what’s wrong, what’s needed
Hyperopia: what’s wrong, what’s needed
Good focusing ability
Myopia: near sighted, need concave lens (open up/diverge light)
Hyperopia: far sighted, need convex lens (converge light)
Fovea:
Within which structure:
Why is it high detail focus?
Within retina
High concentration of cones, no bipolar/ganglia cells in the way of light here
Rods/cones
Two main segments: outer/inner
Position (post/ant)
contents
Outer segment: posterior, contains rhodopsin discs
Inner segment: anterior, contains organelles/mitochondria for energy
Rods
dim/bright light?
Quality/colour of images
Convergence?: benefits/drawbacks
Dim light
Low quality, gray images
Yes convergence, enhances weak light signals but results in fuzzy image
Cones
dim/bright light?
Quality/colour of images
3 types of cone cells (defined by opsin colour)
Convergence?: benefits/drawbacks
which areas are high in cones
Bright light
High quality, coloured images
Red/Blue/Green Opsin
NO CONVERGENCE
Fovea/macula
Sight
Relies on which chemical
What 2 isomers does it have? (which is activated by light)
Retinal
11-Cis (no light) and All Trans (light)
Steps of phototransduction
- Light isomerizes 11-Cis retinal -> All trans retinal
- Opsin activates tansducin
- Transducin activates PDE (phosphodiesterase)
- PDE converts cGMP -> GMP
- GMP induces hyperpolarization -> inhibits neurotransmitter release
*Since neurotransmitter is INHIBITORY, LIGHT CAUSES OVERALL ACTION POTENTIAL (inhibits the release of inhibitory NT)
Low cGMP = AP
Adaptation to light
what happens to rods/cones in:
Bright light
Dim light (+ how is retinal converted, how long does adjustment take?
Bright light: cone function gained, rod function lost (more sharpness)
Dim light: Cone function lost, rod function gained (all-trans retinal is recycled to 11-cis retinal, takes 20 mins to adjust)
What do receptive fields of ganglion cells help with?
Object/line/facial expression recognition
Visual pathways
Which sides of each eye travel to:
Right visual cortex
Left visual cortex
Why?
Right visual cortex (through right geniculate nuclei): right side of right eye, righ side of left eye
Left visual cortex (through Left geniculate nuclei): left side of right eye, left side of left eye
To help with depth perception
Olfactory (smell)
Steps of transduction
- odor binds to GPCR receptor
- G(olf) protein binds to GPCR, GTP activates G(olf)
- Activated G(olf) activates adneylate cyclase, uses ATP to activate cAMP
- cAMP activates cationic channel (allows Na/Ca into cell) -> dopolarization -> ACTION POTENTIAL
Taste buds
How many do you have
Location of:
Foliate TBs
Circumvallate TBs
Fungiform TBs
~10,000
Foliate: sides of tongue
Circumvallate: back of tongue
Fungiform: front of tongue
Which cell of the taste bud does the tasting
Gustatory cell
Steps of tasting
- Taste ligand binds to receptor
- Signal causes increase in Ca2+ concentration
- Neurotransitter released from taste bud -> ACTION POTENTIAL
Sweet receptors: sensitive to, what receptors used
sugars, saccharins, alcohol, some AAs, GPCRs
Bitter receptors: sensitive to
alkaloids (quinine, nicotine)
Umami: sensitive to, what receptors used
glutamate, GPCRs
Salty: sensitive to, what receptors used
metal ions (Na+), Ion channels
Sour: sensitive to, type of channel
H+ ions, ion channel
Which cranial nerves are involved in taste
VII (facial): taste from front 2/3s of tongue
IX (glossopharyngeal): taste from back 1/3 of tongue
X (vagus): taste from back of tongue
Outer ear, functions of structures
Auricle (pinna)
Ceruminous glands
Tympanic membrane
Auricle: funnels sound into ear
Ceruminous glands: produce wax (antibacterial)
Tympanic membrane: vibrates in response to sound, send signal to middle ear
Which are equalizes pressure between middle ear and external air pressure
Pharyngotympanic (auditory tube)
Auditory ossicles, in order from tympanic membrane
Transmit vibration to..
Vibrations dampened by…
Malleus, Incus, Stapes
to oval window
dampened by tensor tympani/stapedius muscles
cochlea
how many turns (coils)
how many chambers + names
2.5 turn
3 chambers (scala vestibuli, media, tympani)
Mechanism of hearing (steps)
- Sound flows through pinna/ear canal, beat against tympanic membrane
- Eardrum pushes against ossicles (MIS), stapes presses fluid against oval window
- Shearing force pulls on hair cells
- Cochlear nerve stimulated, impulse sent to brain
Sound
Humans can hear which frequencies?
Represented by what kind of wave
Pitch vs amplitude?
20-20,000 hertz (differences in pitch heard >200hz)
Sine wave
Pitch: perception of different frequencies
Amplitude: sound intensity (dB)
Where does amplification of sound in the ear occur? (what happens to frequency)
External?
Middle?
Inner?
External: no amplification
Middle: amplification of sound waves, same frequency
Inner ear: amplitude decreases progressively, same frequency
frequency NEVER CHANGES
What kind of fibers encode for different friequencies?
Basal membrane fibers
Where are frequencies encoded for (relative to oval window)
High frequencies:
Low frequencies:
Delay?
High: close to oval window (short, stiff hairs)
Low: far from oval window (long, flexible hairs)
Low frequency causes delayed hearing (farther distance from oval window
What is heard when frequencies are above/below audible frequencies?
Why?
No sound
No corresponding hair cells excited
If hair cells vibrate who do they send signals to?
Organ of corti (sits above basilar membrane)
Auditory pathway to brain (starting with cochlea)
- cochlea -> cochlear nuclei
- Medulla
- Midbrain -> inferior colliculi
- Auditory cortex (both sides from both ears)
Which side of auditory cortex does right ear signal to
BOTH sides, both ears signal to both sides
Auditory processing, what processes:
Pitch
Loudness
Location of sound
Pitch: primary auditory cortex + cochlear nuclei
Loudness: cochlear cells + number of cells stimulated
Location: superior olivary nuclei “sound from left will take longer to reach right ear”
2 types of Vestibular receptors? (purpose)
What are they used for (how are kinocilia/stereocilia oriented?)
static equilibrium + straight acceleration
Urtricular receptors: horizontal movement (cilia are oriented vertically)
Saccular receptors: vertical movement (cilia are oriented horizontally)
3 types of semicircular canals (purpose)
What are they used for
dynamic + angular acceleration
Anterior (superior) canal: nodding head YES
Posterior canal: tilting head left/right
Lateral (horizontal canal): shaking head NO
How do semicircular canals work (fluid movement)
Fluid + capula flow over crista amplullaris (IN OPPOSITE DIRECTION TO MOVEMENT)
3 receptors required to maintain balance
Vestibular receptors
Visual receptors
Somatic receptors
Vestibular input is sent to which part of the cerebrum?
which part is in turn signalled
Somatosensory cortex
Primary motor cortex
