ANFS345: Hearing, Taste, Smell, Vision

Types of Transduction

ionotropic, metabotropic

Ionotropic Transduction

stimulus triggers channels to open through direct action, ions, sodium

Metabotropic Transduction

stimulus triggers channels indirectly via secondary messengers

Mechanoreceptor

touch, pressure, proprioception, ionotropic

Vestibular Receptors

balance, body position and movement, ionotropic

Osmoreceptors

osmotic pressure, ionotropic

Auditory Receptors

sound, ionotropic

Thermoreceptors

heating and cooling, ionotropic

Electroreceptors

electric fields in water, ionotropic

Salty and Sour Chemoreceptors

taste sensation, ionotropic

Sweet, Bitter, Umami Chemoreceptors

taste sensation, metabotropic

Olfactory Chemoreceptors

chemicals from a distance, metabotropic, ionotropic in insects

Photoreceptors

light, metabotropic

Magnetoreceptors

magnetic fields, unknown transduction

Perception Pathway

different receptors generate similar action potentials that travel to specific brain areas

Insect Mechanosensory Mechanism

bristle shaft attached to mechanoreceptors, displacement is proportional to action potentials

Types of Mammalian Mechanoreceptors

meissner corpuscle, merkel disc, free nerve endings, ruffini ending, pacinian corpuscle

Meissner Corpuscle

touch, superficial dermis

Merkel Disc

touch and pressure, superficial dermis

Free Nerve Endings

pain, itch, temperature, superficial dermis

Ruffini Ending

pressure, dermis

Pacinian Corpuscle

vibration, deep dermis

Superficial Dermal Mechanoreceptors

meissner corpuscle, merkel disc, free nerve endings

Merkel Disc Signaling

tonic receptor, rapid signaling during changes, stabilizes as pressure stabilizes

Ruffini Ending Signaling

tonic receptor, more when changing pressure, stabilizes when constant

Meissner Corpuscle Signaling

phasic receptor, impulses only when stimulus is changing, during duration of change

Pacinian Corpuscle Signaling

extremely phasic receptor, only signals when stimulus changes, not during change

Tonic Receptors

merkel disc, ruffini ending

Phasic Receptors

meissner corpuscle, pacinian corpuscle

Ear Function

transform sound energy into neural signals

Sound Path in Ear

vibrations into outer ear to eardrum, movement of bones causes fluid vibration in cochlea

Basilar Membrane

contains small hairs, stereocilia, that signal to the auditory nerve at different frequencies based on cochlear fluid movement

Brainstem Hearing Function

detects differences in time and intensity between each ear, localization of sound

Ear Components

outer ear, middle ear, inner ear

Eardrum

tympanic membrane, vibrates due to sound waves

Sound Wave into Outer Ear Triggers

vibration of eardrum

Eardrum Vibration Triggers

movement of inner ear bones

Inner Ear Bone Movement Triggers

stapes hits semicircular canal

Semicircular Canal Contact Triggers

cochlear fluid vibration

Cochlear Fluid Vibration Triggers

basilar membrane stereocilia movement

Stereocilia Movement Triggers

auditory nerve signals to brain

Inner Ear Bones

malleus, incus, stapes

Tympanal Organ

hearing organ in insects, air sacs and sensory neurons

Hearing Frequencies

determined by basilar membrane ability to detect

Tongue Taste

entire tongue has receptors for all tastes

Salty Taste Transduction

nacl, ionotropic with sodium channels

Sour Taste Transduction

mediated by channels with a secondary protein, ionotropic

Sweet/Umami/Bitter Taste Transduction

protein coupled metabotropic systems, different cells but similar mechanisms

Nasal Cavity

allows intake of air and chemicals

Olfactory Bulb

brain structure connected to olfactory receptors

Olfactory Signal Pathway

mucous layer, sensory cilia, receptor cells, axon, glomerulus, mitral cells, granule cells, CNS

Mucous Layer Purpose

dissolves odorant molecules over the olfactory epithelium

Olfactory Neurons

40 million, replaced ever 4-6 weeks

Anosmia

inability to smell a scent

Olfactory Tract

amygdala, thalamus, neocortex

Smell and Taste

as food is eaten, scent travels to receptors, closely connected

Odorant Molecule on Cilia

connects with olfactory receptor and triggers secondary signalling to move into cilia

Vomeronasal Organ

common in terrestrial vertebrates, increases receptors, pheromones

Dogs Nose Characteristics

moist to capture scents, separated by nostril, lateral slits for exhaling air

Smell Evolution

one of the first senses, very primal, faster response

Eye

anything that can sense light

Rhodopsin

receptor that changes shape in response to light

PAX6

allows for development of vision

Lens

takes in visual cues and focuses on optic nerve

Optic Nerve

processes light information, to CNS

Arctic Reindeer Vision

eyes change color, blue in winter more sensitive to light

Bird of Prey Vision

many receptors and more processing power for stronger vision

Squid Vision

large eyes to take in more light and see better in darkness

Mantis Shrimp Vision

5 UV photoreceptors, most types of receptors

Fly Vision

many receptors and quick processing for detecting fast changes

Light on Rhodopsin

changes retinal from cis to trans formation

Retinal

compound in rhodopsin that changes shape in response to light

Compound Eye

insects and flies, many lenses for kaliedescope like vision, senses small changes in peripheral vision

Fovea

localizes information from lens near optic nerve, visual acuity

Ganglion Cells

bring information to the sensory system from retina

Rods

photoreceptors for low light vision

Cones

photoreceptors for daylight and color vision

Rod:Cone Ration

changes animal's visual ability

Photoreceptor Function

light coming through changes membrane potential, more change in bright light

Dark Photoreceptor Conditions

cGMP channels open, steady movement of sodium and potassium, ATP pump maintains concentration

Light Photoreceptor Conditions

cGMP channels close and cause sodium to drop off, potassium build up generates potential

Pupil Size Change Causes

light, drugs, emotion

Vertical Pupil Function

help judge distance for hunting, sharp forward focus

Horizontal Pupil Function

wide range of vision, detect predators and aid escape

Pseudopupils

appearance of pupils in insects with compound eyes

Round Pupil Function

general vision, foragers, recognition of others

Vertical Pupil Species

cats

Horizontal Pupil Species

goats

Round Pupil Species

humans