A + P Nervous System III Flashcards
special senses
smell
taste
sight
hearing and balance
smell
- sense of smell name
- what provides it?
sense of smell
-olfaction
what provides it
-a pair of olfactory organs in the nose
what does each olfactory organ consist of
olfactory epithelium
olfactory glands
olfactory epithelium
-composition
olfactory receptors (chemoreceptors)
supporting cells
basal cells
olfactory glands
-function
continuously secrete a mucous layer inside the nose which covers epithelium and keeps the area free of dust, debris, and overpowering smells
what must odors do before the stimulate the olfactory receptors
- how is the stimuli received
- what must a substance have to have an odor?
must diffuse into the mucus received -each receptor has cilia extending into the mucus to receive the stimuli odor -must be a complex molecule -wetness -freshness
how does olfactory reception begin?
-dissolved chemicals first change the permeability of the receptor membrane which produces an AP
-axons from the olfactory receptors then join together into 20 or more bundles and attach to the olfactory bulbs
-AP is carried through the olfactory nerve to the hypothalamus where it is relayed to the olfactory cortex
olfactory cortex is closely connected to the limbic system which deals with emotions, moods, and memories
-olfaction is also the only sensory information that bypasses the thalamus which normally filters all sensory information
-therefore the sense of smell can produce profound emotional behavioral responses
Taste
- sense of taste name
- -dependent on…
gustation
-dependent upon gustatory receptors (chemoreceptors) along the surface of the tongue, and adjacent portions of the pharynx and larynx
taste receptors
- location
- why are they there?
location
-found in organs called taste buds
-located along the sides of epithelial projection called papillae
why?
-protected from mechanical stress involved in chewing food
taste buds composition
gustatory cells with microvilli extending through taste pores
supporting cells between the gustatory cells
five primary taste sensations (location)
sweet (tip of tongue) salty (tip of tongue) bitter (middle of tongue) sour (middle/rear of tongue) umami/savory (back of tongue)
taste sensation threshold
each sensation varies
respond more to unpleasant, rather than pleasant, tastes
where to the taste APs travel to?
carried through axons to vagus, facial, and glossopharangeal nerves to the medulla oblongata
relayed to the thalamus and ultimately the gustatory cortex
which system is the gustatory cortex closely linked to?
limbic system
two cavities of the eyeball
anterior cavity
posterior cavity
anteror cavity
- locatioun
- composition
- -function
location
-between lens and retina
composition
-contains a jelly-like substance called vitreous humor
-function
–keeps the eyeball “inflated” in a shperical shape
posterior cavity
- location
- division
- composition
- -function
location -between lens and cornea division -anterior and posterior chambers -separated by the iris composition -filled with a less viscous, clear fluid called aqueous humor --nourishes the lens, iris, and cornea
three layers of the eye
fibrous
vascular
neural
fibrous layer
- location
- functions
- composition
location -outermost layer functions -support and protection -provides a place of attachment for the extrinsic eye muscles -assists in the focusing process composition -sclera -cornea
sclera
white of the eye
cornea
transparent part of the eye where light passes through to the lens
vascular layer (uvea)
- location
- composition
location
-middle layer
composition
-blood vessels, lymphatics, iintinsic eye muscles found in the iris and around the lens
vascular layer composition
iris
ciliary body
choroid
iris
- composition
- function
composition
- pigmented cells for eye color
- two layers of smooth muscle which contract to change the diameter of the central opening of the eye (pupil)
ciliary body
- composition
- suspensory ligaments function
ciliary msucle
-band of muscle attached to the suspensory ligaments
suspensory ligaments function
-position the lens so light will pass through the center of the lens
-contraction and relaxation of the ciliary muscle enables the lens to change shape in the focusing process
relaxed vs. contracted ciliary muscle
relaxed
-diameter increased and lens is flattened
contracted
-diameter decreases and lens becomes more spherical
choroid
- location
- composition
- -function
location -under the fibrous tunic and posterior to the ciliary body composition -capillary network --delivers oxygen and nutrients
neural layer (retina) -two layers
pigmented part (self-explanatory) neural part
neural part
- composition
- forms a …
composition
-a thick inner layer that makes up the neural retina
-houses the photoreceptors
forms a “cup which makes up the posterior and lateral boundaries of the posterior cavity
retina organization
photoreceptors horizontal cells bipolar cells ganglion cells optic nerve
rods and cones
-function
rod
-night and dim light vision
cone
-color vision and clearer vision
number of rods on the sides of the retina
125 million
cones
- types
- # on the bottom of the eye
- macula lutea
- fovea
types -red, green, blue # -6 million cones macula lutea -yellow spot -where the image arrives if you look directly at something -no rods, only cones fovea -center of the macula lutea -center of color vision and the site of sharpest vision where cones are concentrated the most
visual pigments
- location
- derivatives of…
location
-membrane discs of the photoreceptors
derivatives of rhodopsin
rhodopsin
- composition
- made of…
- difference in rods and cones
composition
-enzyme call opsin bound to the pigment retinal
made of…
-vitamin A
identical in both rods and cones
-opsin is different in each rod and the three types of cones
horizontal cells
-function
regulate the information between the photoreceptors and ganglion cells to adjust the sensitivity of the retina
bipolar cells
-function
process input from the photoreceptors and horizontal cells and relay impulses to ganglion cells
ganglion cells
-function
relay impulses from bipolar cells to the optic disc
optic disc
- location
- composition
- special characteristic
location
-circular region medial to the fovea and the origin of the optic nerve
composition
-axons from 1 million ganglion cells emerge here and transmit impulses to the optic nerve and then to the thalamus
no photoreceptors and is called the blind spot
photoreception (vision) steps
light is focused by the lens on the retina
a photon strikes a rhodopsin molecule in the membrane discs
photon is absorbed and a change in the retinal component activates opsin
rhodopsin breaks down into retinal and opsin, causing a cascade of chemical transformation in other cones/rods to amplify the signal
once the membrane potential of the photoreceptor changes, it initiates an AP along the optic nerve, which gives rise to the optic chiasm and optic tract
ultimately, the visual APs are carried to the thalamus (mostly), then passed on to the visual cortex
what affects how light is focuses on the retina
shape of the cornea, lens, and eyeball affect how light is focused through the lens onto the retina
farsighted vs. nearsighted
farsighted: light is focused behind the retina
nearsighten: light is focused on the retina
where else are some visual APs sent
midbrain and pineal gland for various vision-related processes (i.e. reflexive action, sleep regulation)
hearing
enables us to detect and interpret sound waves
equilibrium
informs us of the position of our body in space by monitoring gravity, linear acceleration, and rotation
three components of the ear
external ear
middle ear
inner ear
parts of the external ear
auricle (pinna) external acoustic meatus (external auditory canal) tympanic membrane (eardrum)
auricle (pinna)
-function
protects the opening into the ear
provides directional sensitivity to the ear
external acoustic meatus
- function
- composition
carries sound to the eardrum
composition
-contains ceruminous glands that secrete cerumen (ear wax)
–slows the growth of microorganisms, reducing the chances for infection
-contains outwardly projecting hairs that prevent insects and foreign objects from entering
tympanic membrane (eardrum) -function
transmits sound from air into the ossicles of the middle ear
middle ear composition
tympanic cavity
auditory ossicles
-tensor tympani
-stapedius
tympanic cavity
- filled with…
- function
filled with air from the nasopharynx through the auditory tube
permits an equalization of pressure on each side of the eardrum
auditory ossicles
- composition
- function
three tiny bones (melleus, incus, stapes)
connect the tympanum with the inner ear
how is the stapes attached to the inner ear?
by way of a membrane called the oval window
tympanic membrane vs. oval window
much larger than oval window and is very sensitive
sound is amplified into the oval window and loud noises can be controlled by two muscles
those two muscles
tensor tympani
stapedius
tensor tympani
-function
pulls on the tympanum to reduce vibrations from the tympanic membrane
stapedius
-function
pulls on the stapes to reduce vibrations in the oval window
inner ear structures
membranous labyrinth bony labyrinth -vestibule -semicircular canals -cochlea hair cells
membranous labyrinth
-composition
collection of tubes and chambers filled with a fluid called endolymph
contains the receptors for equilibrium and hearing
bony labyrinth
- location
- what is found there
- what are the three parts
shell of bone surrounding the membranous labyrinth perilymph is found there three parts -vestibule -semicircular canals -cochlea
vestibule
- composition
- function
contains two membraneous sacs -saccule -utricle function -receptors in them provide sensations of gravity and linear acceleration
semicircular canals
- composition
- function
contain semicircular ducts
function
-contain receptors that are stimulated by the rotation of the head
cochlea
-function
contains receptors that provide the sense of hearing
hair cells
- function
- free surface supports…
mechanoreceptors in the inner ear that communicate with a sensory neuron
supports microvilli called stereocilia
movement of the stereocilia does what?
distorts the hair cell surface
-in one direction it stimulates hair cells and in the other direction it inhibits the hair cells
equilibrium types
rotational movement
gravity and linear acceleration
rotational movement
- detected by
- each can contains…
- what are embedded in each ampulla
detected by the semicircular canals (anterior, posterior, and lateral) each in a different plane
each canal contains a swollen region called the ampulla, which contains the sensory receptors (mechanoreceptors)
stereocilia are embedded in each ampulla
what stimulates movement during rotation
when rotation occurs in the plane of a canal, hair cells are stimulated by movement of the endolymph
what happens when hair cells are stimulated
APs from hair cells are sent on the vestibulococchlear nerve to the pons, which are then relayed to the auditory cortex
duct stimulation examples
- shaking head (NO): stimulates the lateral duct
- nodding head (YES): stimulates the superior duct
- tilting head side to side: stimulates the posterior duct
gravity and linear acceleration
- detected by…
- what are found in it?
detected by the maculas in the vestibule hair cells (mechanoreceptors) are found on inner surfaces, to which are attached tiny spheres of calcium carbonate known as statoconia that are dense and heavy
what does the movement of hair cells do?
APs are generated from movement of the hair cells, which are then sent along the vestibulocochlear nerve to the pons
then relayed to the cerebellum, thalamus, and auditory cortex
examples
gravity normally pulls the otolith downward
-when you initially start going down or up in an elevator the otolith lags behing
-the hair cells have less distortion and we become aware of the initial downward movement
once the elevator reaches a constant speed and the otolith catches up, the hair cell distortion is removed and we are no longer aware of it
three ducts in the cochlea (hearing)
vestibular duct
cochlear duct
tympanic duct
vestibular duct contains
perilymph
cochlear duct contains
endolymph
tympanic duct contains
perilymph
where is sound detected
by hair cells (mechanoreceptors) in the organ of Corti, which is housed in the cochlear duct
how are frequency and intensity of sound determined
frequency: part of the cochlear duct stimulated
intensity: number of hair cells stimulated
organ of Corti (vestibular organ)
- location
- function
sits atop the basilar membrane
separates cochlear duct from tympanic duct
how are hair cells arranged
longitudinal rows
stereocilia are in contact with…
tectorial membrane (attached to the inner wall of the cochlear duct)
what happens when basilar membrane bounces up and down
stereocilia are distorted when pushed against the tectorial membrane (in response to pressure waves in the perilymph caused by sound waves hitting the tympanum)
where are APs carried on/to
on the vestibulocochlear nerve to the pons
relayed to the cerebellum, thalamus, and auditory cortex
