Other sensory systems

photoreceptors

detection of changes in light

mechanoreceptors

detection of changes in pressure

hair cells

specialized mechanosensory cells

cochlea

allows us to hear diff frequencies; narrow part of basilar membrane is stiff + vibrates in response to high frequencies; wide part of basilar membrane is flexible + vibrates in response to low frequencies

two ranges of sounds humans can’t hear but others can

infrasound, ultrasound

vestibular sense

hair cells in the inner ear are moved by a gel pocket called cupula

specialized system for underwater mechanoreception

lateral line system, statocyst + statolith

lateral line system

series of canals running along head to body and hair cells within canals have kinocilia/sterocilia embedded in cupula; water enters canals via pores bending kinocilia and activating sensory neurons

statocyst and statolith

statocyst contains small, free moving calcium mass called statolith; normally rests at bottom of organ but when tipped, statolith moves and presses against receptors not at bottom, signaling brain to activated muscles to return to normal orientation via action potential

chemoreceptors

detection of specific molecules

two senses of chemoreceptors

taste (gustatory) and smell (olfactory)

why are specific molecules relevant to transduction of chemosensory cues

influences depolarization in action potential

why would so many olfactory receptor genes in mammals be nonfunctional

does not need all senses, sensory overload, filtration

phermones

secreted chemicals affecting behavior/physiology of conspecifics (same species); detected in vomeronasal organ (VNO) - humans have vestigial VNO with no sensory capacity

olfactory receptor neurons..

… bind to specific odorants and strength of signal is proportional to number of molecules

odorants

airbone molecules conveying info about food (environment then enters nose then arrives to olfactory neurons)

thermoreceptors

detection of changes in temperature; in skin + brain (to detect/respond to internal body temp for homeostatis)

vipers

special thermosensitive organ called pits

nocireceptors

detection of harmful stimuli, responds in extreme temperature, pressure, and certain chemicals

three pieces of evidence that fish feel pain

fish have nocireceptors
fish learn to avoid hooks/sharks
BUT nocireceptors are diff from us

umwelt

an organisms experience of the world

electroreceptors

detection of electric fields

electroreceptive

can detect electric fields

electrogenic

can actively produce an electric field

electric organ

made from modified muscle cells

magnoreceptors

detection of magnetic fields

emlen funnel

apparatus used to study bird migration

multimodel signaling

combining two types of sensory signals, enhancing signal (car sickness, VR)

summing multiple action potential…

facilitates continuous variation in response (not just all or nothing)

bird experiment

birds sat at one end of cage at beginning of migration with no visual cues
in circular chambers with artificial magnetic fields birds orientated in reaction to field
when magnetic field disrupted, birds were confused and did not navigate properly

bird beak experiment

hypothesis: sensory neruons in beak have iron deposits
cutting off beak found that these neurons prevented birds from reacting to magnetic fields