Chapter 16: Sense Organs Flashcards
sensory receptors
structure is specialized to detect a stimulus, some are bare nerve endings and others are true sense organs
What is the electrical signal on a nerve?
action potential
What kind of energy is the output energy of cell receptors?
electrical
transduction
conversion of one form of energy to another
receptor potential
small local electrical charge on a receptor cell brought by an initial stimulus
sensation
a subjective awareness of the stimulus
What are the somatosensory projection pathways?
- First Order neurons- from body, enter dorsal horn of spinal cord via spinal nerves
- Second order neurons- decussation to opposite side in spinal cord, ends in thalamus
- third order neurons- thalamus to primary somesthetic cortex of cerebellum
modality
type of stimulus of the sensation it produces
-vision, hearing, taste
location
encoded by which nerve fibers are issuing signals to the brain
receptive field
area that detects stimuli for a sensory neuron
intensity
encoded in 3 ways:which fibers are sending signals, how many fibers are doing so, and how fast these fibers are firing
duration
how long the stimulus lasts
sensory adaptation
if stimulus is prolonged, the firing of the neuron gets slower over time and we become less aware of the stimulus
phasic receptor
generate a burst of action potentials when first stimulated , then quickly adapt and sharply reduce or stop signaling even though stimulus continues
tonic receptor
adapt slowly and generate nerve signals more steadily
fast pain
myelinated fibers
-sharp localized stabbing pain perceived w/ injury
slow pain
-unmyelinated fibers
-longer lasting dull feeling
-somatic pain arises from skin
-visceral pain from stretch, chemical irritants
endogenous opioids
produced by CNS under stress, found in dorsal horn of spinal cord, acts as neuromodulators blocking the transmission of pain
-enkephalinm, endorphins
gustation
sensation of taste resulting from the action of chemicals in the taste buds
filiforms
no taste buds and important for texture
foliate
no taste buds
fungiform
at rear of tongue and contain 1/2 of taste buds
basal cells
stem cells that replace taste cells every 7-10 days
supporting cells
resemble took cells w/o taste hairs, synaptic vesicles, or sensory roles
What sense has the only neurons in the body directly exposed to the external environment?
the nose
What is the only sense that can bypass the thalamus and go straight to the cerebral cortex?
the nose
outer ear
includes auricle and external auditory meatus, ends at eardrum
middle ear
air-filled space containing auditory ossicles
has oval window and auditory tube
inner ear
passageways in temporal bone, filled with perilymph and houses the vestibule, semicircular canals, and the cochlea
parts of the external ear
auricle/pinna
external auditory meatus
tympanic membrane
auricle/pinna
elastic cartilage covered w/ skin
external auditory meatus
lined with hairs and ceruminous glands
produce cerumen
tympanic membrane
sound waves cause it to vibrate
border between external and middle ear
-eardrum
oval window
connection between middle ear and inner ear
auditory tube
equalizes pressure
ossicles
malleus, incus, stapes
inner ear
passageways in temporal bone
filled w/ perilymph
-include the vestibule, semicircular canals, and cochlea
vestibule
contains saccule and utrile
saccule
continuous with cochlear duct
-located in vestibule
utricle
continuous with semicircular canals
semicircular canals
line each canal and communicate with the utricle
cochlea
the three parts are scala vestibuli, scala media, and scala tympani
scala vestibuli
abuts the oval window and contains perilymph
scala media
contains endolymph and cochlear duct
scala tympani
terminates at the round window and contains perilymph
sound
any audible vibration of molecules, vibrating object pushes air molecules into eardrum
frequency
how fast sound waves occur
amplitude
the size of sound waves, loudness
Which membrane vibrates with sound?
basilar membrane
Pathway of Sound
sound travels through the auditory canal and hits the tympanic membrane, goes to the malleus where it vibrates the incus, the incus vibrates the stapes which lies on the oval window,
the scala vestibule and the perilymph vibrates the basilar membrane and the pressure of the fluid is relieved by the round window
conduction deafness
blocked sound conduction to the fluid of the internal ear
sensorineural deafness
damage to the neural structures at any point from the cochlear hair cells to the auditory cortical cells
tinnitus
ringing or clicking sound in the ear in the absence of auditory stimulus
static equilibrium
perception of head orientation
dynamic equilibrium
perception of motion or acceleration
What mechanism perceives linear acceleration?
the macula
What mechanism perceives angular acceleration?
crista
crista ampullaris
sensory organ of rotation
What mechanism perceives nearly half of all visual info?
cerebral cortex
palpebral fissue
separates eyelids
lacrimal caruncle
contains oil and sweat glands
conjunctiva
mucous membrane that lines the eyelids and covers anterior surface of eyeball
What are the 3 layers of the wall of the eyeball?
fibrous, vascular, sensory
fibrous layer/tunica fibrosa
contains sclera and cornea
vascular layer/tunica vasculosa
contains choroid, ciliary body, and iris
sensory layer/tunica interna
contains retina and optic nerve
sclera
protects and shapes eyeball
cornea
bends light as it enters the eye and contains numerous pain receptors
choroid region
supplies blood to all layers of the eyeball
ciliary body
holds lens shape and suspensory ligaments holds lens in place
iris
colored part of the eye, has pupil which regulates the amount of light
retina
contains rods and cones
rods
responsible for black and white, night vision
cones
photopic and day vision
optic disc
has no receptor cells and called the blind spot
refraction
bending of light rays
emmetropia
eyes relaxed and focused on distant object receive parallel light waves and focus w/o effort
near response
focus on object closer
myopia
nearsighted
myopia
nearsighted
hyperopia
farsighted
