Special senses Flashcards
Eyes use _____________ to help form visual images of the environment
photoreceptors
what are the functions of the accessory structures of the eye?
*protect against foreign objects
*ensure eye surface remains clean and moist
Eye’s accessory structures include:
*eyebrow, eyelid, eyelashes,
*conjunctiva [mucous membrane covering eye surface]
*Lacrimal apparatus [tears produced]
What are the layers of the eye wall from out to in?
*fibrous tunic
*vascular tunic
*retina
What are the 2 regions that compose the fibrous tunic of the eye wall?
*Sclera [majority], white of eye that provides shape and protects internal eye; dense irregular CT
*cornea [transparent avascular layer]; stratified squamous CT
What 3 regions compose the vascular tunic layer of the eye wall?
*choroid [vast network of capillaries supplying retina with oxygen/nutrients]
*ciliary body- ciliary muscles and processes that causes lens to change shape
*iris- most anterior; pigmented portion that defines pupil
what are the 2 layers of the retina?
Pigmented layer- absorbs light passing through neural layer; provides photoreceptors with nutrients & oxygens
Neural layer- houses photoreceptors and associated neurons; receives light and convert energy to impulses
Pupil is?
what surrounds it?
Pupil is the spot/black hole at the center of the eye; allows light to strike retina
iris surrounds it [colorful part]
in the dark, the pupil gets:
wider
Iris muscles control-
pupil dilation [pupil size]
[pupillary light reflex]
The __________ is a depression in the retina that contains the highest proportion of cones which are responsible for high quality vision and almost no rods
fovea/fovea centralis
The dark area around the fovea is called:
macula [dense center, back of eye with hig conc. of cones and rods]
Rods are important in
dim light
cones are important for
color & precise vision
What are the 3 layers of the neural layer of the retina?
1) Photoreceptor cells- outermost layer made of rods and cones
2) bipolar cells- middle layer with photoreceptors
3) ganglion cells: innermost layer of retina; its axons can leave retina and form optic nerve (CN II)
cone cells and rod cells differ in shape
true or false?
true
rod cells are highly sensitive to:
light
cone cells provide high-acuity ________________
color vision
density of rods and cones variest across the retina
true or false?
true
Does the retina have more cones or rods?
Rods
the lens is held in place by _______________ that suspend from the ciliary body
suspensory ligaments
photoreceptors convert light to:
neural signals > sent to bipolar&ganglion cells
each optic nerve is conducting visual stimulus information at the :
optic chiasm
Ear is divided into 3 regions:
inner, middle, external
External ear
skin-covered, funnel-shaped, elastic cartilage-supported structure called the auricle
middle ear contains:
tympanic cavity [medial to tympanic membrane]
3 auditory ossicles
small bones that transmit sound waves from tympanic membrane to inner ear
*malleus
*incus [middle]
*stapes [between incus and oval window which opens into inner ear]
vibrate to transmit sound waves to the inner ear
what 2 small muscles contract to restrict movement of the ossicles during loud noises?
stapedius [smallest muscle in body that stabilizes stapes]
tensor tympani muscles
3 regions of the inner ear
cochlea- houses membraneous cochlear duct
vestibule- houses utricle and saccule responsible for static equilibrium
semicircular canals- dynamic equillibrium
static equilibrium
*sense housed in the vestibule- houses utricle and saccule
*awareness of head position
maculae of ear
structures located within walls of utricle and saccule within vestibules of inner ear
*have hair cells with stereocilia that project into a gelatinous layer overlayed with otoliths (tiny rocks); this is all called the otolithic membrane
dynamic equilibrium is housed within:
semicircular canals & ampulla
Semicircular canals are responsible for detecting:
rotational movement of head due to fluid endolymph pressing on cupula and bending stereocilia of hair cells in the crista ampullaris of ampulla
Cochlea structure & composition
snail-like, spiral shape
*composed of 3 fluid filled ducts in the spiral
*cochlear duct- hearing, hair cells
*scala tympani [tympanic duct]
*scala vestibuli [vestibular duct]
what is the pathway of sound
pinna/auricle of ear collects sound waves > external acoustic meatus > eardrum/tympanic membrane vibrates > ossicles move as a unit & amplify sound > stapes knocks on oval window, causing pressure within scala vestibuli > pressure waves through cochlea > cochlear duct > tectorial membrane > cochlear nerve > scala tympani > exit through the round window
our bodies are constantly exposed to sensory info called:
stimuli
__________ is the activation fo receptors for stimuli
sensation
our conscious awareness to stimuli is called:
perception
stimuli are detected by:
sensory receptors in our body
There are receptors for general and special senses.
General senses include:
special senses include:
general senses: temperature, pain, touch, stretch, pressure
special senses: gustation, olfaction, vision, equilibrium, hearing
receptors exhibit ____________ : with prolonged exposure to a constant stimulus, they decrease action potential firing
adaptation
Tonic receptors show:
limited adaptation
phasic receptors :
rapidly adapt to constant stimuli
Where are general sense receptors distributed?
throughout the skin and organs
special sense receptors are housed in:
complex organs in the head
What are 3 criteria used to describe receptors?
receptor distribution
stimulus origin
modality of stimulus
General sense somatic receptors are found in:
general sense visceral receptors are in:
-skin, mucous membranes
-walls of internal organs, blood vessels
exteroceptors
detect stimuli from external environment
interoceptors
detect stimuli in internal organs
proprioceptors
detect stimuli pertaining to body position
Chemoreceptors
detect specific molecules dissolved in fluid
thermoreceptors
detect changes in temperature
photoreceptors
detect changes in intensity, color, and light position
mechanoreceptors
detect touch, pressure, vibration, stretch
—Baroreceptors detect pressure changes within body structures
nociceptors
detect painful stimuli
_________ receptors are the most numerous type of sensory receptor
tactile
tactile receptors are mechanoreceptors that react to:
touch, pressure, vibration
where are tactile receptors located?
dermis and subcutaneous layer
what are the 2 types of tactile receptors?
1) unencapsulated [simple dendritic endings]
2) encapsulated [complex dendritic wrapped in CT or glial cells]
The sense of taste (gustation) is enabled by:
chemoreceptors
gustation is
special sense of taste
Gustatory cells
taste cells/ taste receptors housed in specialized structures called taste buds
regenerate every 7-9 days
taste buds are located
dorsal side of tongue in papillae
olfaction takes place:
specialized olfactory epithelium in the nose
the cochlear duct contains hair cells that convert sound waves into :
nerve impulses
Receptors in the walls of blood vessels that respond to changes in gas concentrations in the blood are called:
chemoreceptors
The arrangement of tunics in the eye, from the center (inside) to the periphery (outside), is:
retina, vascular, fibrous
The photoreceptors that perceive color and sharp vision are:
cones
Which sensory structure has stereocilia of hair cells embedded in a gelatinous structure called a cupula?
semicircular duct
Unencapsulated, terminal branches of dendrites are called:
free nerve endings
proprioceptors detects
tension in tendons, position of joints
auditory ossicles are the
malleus, incus, stapes
endolymph
fluid in the membranous labyrinth
basilar membrane
supports the spiral organ (organ of Corti)
[inferior, thicker, highly specialized membrane separating tympanic duct from cochlear duct]
choroid
pigmented, darkly colored membrane; middle layer of eye
*displays an iridescent coloration - tapetum lucidum
-gives some animals night vision
suspensory ligaments attach to
lens
adaptation
sensitivity reduced due to constant stimulus
olfaction
sensation of smell
within the inner ear, there are 2 special sensory organs:
Cochlea [hearing]
Vestibular apparatus [static and dynamic equillibrium]
tectorial membrane
gelatinous flap forming a roof over hair cells; ensures bending of the stereocilia
Spiral organ (of corti)
specialized region of the basilar membrane composed of auditory hair cells
*movement of basilar membrane causes stereocilia to be bent against tectorial membrane, stimulating hair cells to release neurotransmitters and initiate action potential via vestibulocochlear nerve to the CNS
The vestibular duct [scala vestibuli] and the tympanic duct [scala tympani] are filled with:
perilymph
within the ampullae of the semicircular canals, are sensory structures called:
cristae ampullaris- sense rotation motion as endolymph moves through ampulla, bending stereocilia in the cupula
in front of the lens is the:
behind the lens is the:
anterior cavity
posterior cavity
What muscle constricts to reduce the size of the pupil in high light conditions?
sphincter pupillae of the iris
Salivary glands are important in taste/gustation because:
they provide the fluid in which tastants are dissolved
17 in the above image indicates:
cornea
The space indicated by #17 would be filled with:
aqueous humor
The receptors for dynamic equilibrium are found in what structure in the above image?
1
Identify A, B, C, D
A- Vestibular duct (W/ perilymph)
B- Tympanic duct (W/ perilymph)
C- Tectorial membrane
D- Spiral organ (of corti)
Identify E, F, G
E- Cochlear duct (W/ endolymph)
F- vestibular membrane
G- Basilar membrane
identify
cochlea
identify
Vestibule
Identify A and B
A- utricle
B- saccule
[of vestibule of ear]
identify
Semicircular canals
identify
optic nerve
Identify 1-5
1- conjunctiva
2- cornea [fibrous tunic]
3- lens
4- retina [neural tunic]
5- optic nerve
identify X
sclera
[fibrous tunic]
identify A and B
A- pupil
B- Iris
[vascular tunic]
identify
choroid [vascular tunic]
Identify X
ciliary body [vascular tunic]
identify G
optic disc [neural tunic]
“blind spot” is the
optic disc
region where optic nerve exits the eye [no photoreceptors here]
anterior eye chamber
in the anterior eye cavity
space between cornea and iris
*filled with aqueous humor
