Physiology II Special Senses

Retina - Amacrine cells

Communicate with multiple bipolar and ganglion cells -generally help analyze and sort visual signals

Retina - Horizontal cells

Communicate with multiple rods/cones + bipolar cells, providing lateral inhibition (increasing contrast of vision)

Where do 3rd order neurons synapse in the hearing pathway?

Contralateral inferior colliculus of midbrain (to side of stimulus)

Where do 2nd order neurons synapse in the hearing pathway?

Contralateral superior olivary nucleus of the pons

Phototransduction

Conversion of light energy into electrical signals (vision)

What structure houses the hair cells within the Semicircular Canals?

Crista Ampullaris

What system within the brain is tied together with olfaction but also responsible for emotion and memory?

Limbic system

Which eye muscles are used to look laterally & medially (left-right)

Lateral (CN6)/ Medial rectus (CN3)

Long & floppy fibers of the basilar membrane have an affinity for which frequency?

Lower frequencies (200-20 Hz)

What structures provide perception of the reference/ pull of gravity?

Otoliths & Otolithic membrane

Cones:

Photoreceptor that responds to large changes in light and in 3 wavelength ranges (COLOR) -low sensitivity to light -wavelength ranges - red, green, & blue -high visual acuity -3 million in each retina

Rods:

Photoreceptor that responds to small changes in light (NO COLOR) -highly sensitive to light -low threshold - functions well in low light conditions -low acuity -100 million in each retina

Photopsin

Photosensitive pigment protein -chemically transformed when light hits -hyperpolarizes the cell ending in closure of its cation channels preventing release of inhibitory neurotransmitters -deals with RGB wavelength perception

Rhodopsin

Photosensitive pigment protein -chemically transformed when light hits it -hyperpolarizes the cell ending in closure of its cation channels preventing release of inhibitory neurotransmitters

LR6-SO4/3 (over three)

Pneumonic for the extra ocular eye muscles innervation: -Lateral Rectus (CN6) -Superior Oblique (CN4) -ALL others (CN3)

Which eye muscles are used to look up & down?

Superior/ Inferior rectus (CN3)

Long & floppy fibers are found at which portion along the length of the basilar membrane?

The apex (distal)

Short & stiff fibers are found at which portion along the length of the basilar membrane?

The base

How does angular equilibrium function?

The hair cells respond to movement of endolymph within the semicircular canals as a result of movement of the head/ body in any of the 3 planes. Movement of these hair cells triggers the opening of K+ channels resulting in depolarization.

True/ False: Gustation receptor cells are quickly adapting

True

Images are flipped in what orientation(s)

Upside down Left to right

Retina - Pigmented cells

Utilize melanin to help absorb light

What causes sensation of fainting dizziness?

Vascular/ psychological issues

Saccules are oriented in what direction?

Vertically (detects rising or falling)

What causes "spinning room or self" dizziness?

Vestibular issues (central or peripheral)

What is a generalized name of the pathway used to perceive balance?

Vestibular pathway

Does visual information from the temporal fields cross at the optic chiasm?

information DOES cross

Does visual information from the nasal fields cross at the optic chiasm?

information does NOT cross

Papillae on the tongue house what structures?

Chemoreceptors responsible for taste (taste buds)

Signal pathway to the cortex

-*visual information reaches ganglion cells of retina* -travels thru axons exiting the eye at the optic disc -pass thru the optic chiasm crossing to contralateral -synapse on the lateral geniculate nucleus in the thalamus -travel to the primary visual cortex

Which ions are responsible for sour taste?

H+

Which layers of the eye does light pass through in order to reach the photoreceptors?

-cornea -aqueous humor -lens -vitreous humor

Myopia - Nearsighted

-strong refraction or eye is too long (causes) -point of focus is in front of retina -concave lens is used to correct (diverges light)

Hyperopia - Farsighted

-weak refraction or eye is too short (causes) -focus is behind retina -convex lens is used to correct (focuses light)

Taste pathway:

1st order: neurons travel to solitary tract nuclei in brainstem 2nd order: neurons travel to VPM of thalamus 3rd order: neurons travel to primary gustatory cortex in parietal lobe

Hearing range in heathy people (Hz)

20-20,000

How many layers must light pass through to reach photoreceptors in the eye?

4

Hearing range in those with Presbycusis (Hz)

50-8,000

Depolarization = ?

Activation/ excitation

What is the function of the auditory ossicles?

Amplifies vibrations

Our Semicircular Canals provide us with what sense due to their orientation?

Angular Equilibrium, due to each of them being oriented in 3 different planes (X,Y,&Z)

Retina - Ganglion cells

Axons make up the optic nerve

What cranial nerve Carrie's gustatory signals from the epiglottis & pharynx?

CN10

What cranial nerve carries gustatory signals from the ANTERIOR 2/3rd of the tongue?

CN7

What cranial nerve carries gustatory signals from the POSTERIOR 1/3rd of the tongue?

CN9

What does bending of the stereocilia do?

Causes opening of K+ ion channels resulting in action potential & neurotransmitter release

What causes poor coordination or imbalance dizziness?

Cerebellar/ proprioceptive isssues

Hyperpolarization = ?

Deactivation/ inhibition

What happens when the stereocilia bend toward the kinocilium?

Depolarization (excitation) Opens mechanically gated K+ channels Glutamate is released

True/ False: Olfactory receptor cells are slowly adapting

False - quickly adapting

What is responsible for detection of sweet, bitter, & umami?

G-protein coupled receptors

What neurotransmitter causes hair cells to depolarize?

Glutamate

Short & stiff fibers of the basilar membrane have an affinity for which frequency?

Higher frequencies (20,000-2,000 Hz)

Olfactory receptors are what & rely on what for depolarization?

Highly specific Chemoreceptors that rely on G-protein coupled receptors for activation

Utricles are oriented in what direction?

Horizontally (detects acceleration or deceleration)

What happens when the stereocilia bend away from the kinocilium?

Hyperpolarization (inhibition)

Transduction involves what?

Hyperpolarization; turning off release of inhibitory neurotransmitters

Are photoreceptors defaulted to a state of inhibition or activation?

Inhibition Transduction induces hyperpolarization of these cells (turning off their inhibition)

Which eye muscles rotate to keep the visual field upright?

Superior (CN4)/ Inferior Oblique (CN3)

Where do 4th order neurons synapse in the hearing pathway?

Medial geniculate nucleus of the thalamus

Which ions are responsible for salty taste?

Na+

Where do 5th order neurons synapse in the hearing pathway?

Primary auditory cortex in temporal lobe (BMA 41-42)

Retina - Bipolar cells

Relays information to ganglion cells via depolarization

Retina - Photoreceptor cells

Rods and cones

Order that sound passes thru the cochlea:

Scala Vestibuli -> Cochlear Duct (Scala Media) -> Scala Tympani

What is the function of the Vestibular apparatus?

Senses balance & equilibrium

Sound processing pathway:

Stimulus hits tympanic membrane -> vibrations are transferred to auditory ossicles -> oval window -> perilymph of cochlea (scala vestibuli)

Amplitude refers to what attribute sound?

Volume