6 Special Senses Flashcards
General senses of touch
- Temperature
- Pressure
- Pain
Special senses
- Smell
- Taste
- Sight
- Hearing
- Equilibrium
- are either large, complex sensory organs (eyes and ears) or
- localized clusters or receptors (taste buds and olfactory epithelium)
Special sense
receptors
_ percent of all sensory receptors are
in the eyes
70
Each eye has over a _ nerve fibers
million
Protection for the eye
* Most of the eye is enclosed in a _
* A cushion of fat surrounds most of the eye
bony orbit
8 Accessory Structures of the Eye
- Eyelids
- Eyelashes
- Meibomian glands
- Ciliary glands
- Conjunctiva
- Lacrimal apparatus (gland and canals)
- Lacrimal sac
- Nasolacrimal duct
empties lacrimal
fluid into the nasal
cavity
Nasolacrimal duc
kaya kapag umiiyak, sinisipon din
provides passage
of lacrimal fluid
towards nasal
cavity
Lacrimal sac
drains lacrimal
fluid from eyes
Lacrimal canals
produces lacrimal fluid
Lacrimal gland
- Membrane that lines the eyelids
- Connects to the surface of the eye
- Secretes mucus to lubricate the eye
Conjunctiva
modified sweat glands
between the eyelashes
Ciliary glands
modified sebaceous glands produce an oily secretion to lubricate the eye
Meibomian glands
2 Function of the Lacrimal Apparatus
- Protects, moistens, and lubricates the eye
- Empties into the nasal cavity
2 Properties of lacrimal fluid
- Dilute salt solution (tears)
- Contains antibodies and lysozyme
- Muscles attach to the outer surface of the eye
- Produce gross eye movements and make it possible to follow moving objects
Extrinsic (External) Eye Muscles
- The wall of the eye is composed of three tunics – _
- while the interior is filled with fluids called _
coats
humors
eye wall layer
outside layer
Fibrous tunic (sclera)
eye wall layer
middle
layer
Choroid
eye wall layer
inside
layer
Sensory
tunic
- White connective tissue layer
- Seen anteriorly as the “white of the eye
Sclera
a fibrous tunic
- Transparent, central anterior portion
- Allows for light to pass through
- Repairs itself easily
- The only human tissue that can be transplanted without fear of rejection – no blood vessels
Cornea
a fibrous tunic
- Blood-rich nutritive tunic
- Dark pigment prevents light from scattering inside the eye
Choroid Layer
a choroid layer that is smooth muscle to which the lens
is attached
Ciliary body
a choroid layer that is
* Pigmented layer that gives eye color
iris
rounded opening in the iris for light to
enter
pupil
Sensory Tunic (Retina)Sensory Tunic (Retina) have receptor cells: (photoreceptors)
- rods
- cones
Signals pass from photoreceptors via a two-neuron chain
- Bipolar neurons
- Ganglion cells
Signals leave the retina toward the brain
through the _
optic nerve
- Most are found towards the edges of the retina
- Allow dim light vision and peripheral vision
- Perception is all in gray tones
Rods
- Allow for detailed color vision in bright light
- Densest in the center of the retina
cones
_ – area of the retina with only cones – lateral to each blind spot
Fovea centralis
_ photoreceptor cells are at the optic disk, or blind spot – where the optic nerve leaves the eyeball
No
3 types of cones
- 420 nm blue cones
- 530 nm green cones
- 560 nm red cones
Color blindness is the result
of lack of _ cone type
one
Impulses received at the
same time are interpreted
as _ colors
intermediate
- Biconvex crystal-like structure
- Held in place by a suspensory ligament attached to the ciliary body
lens
Internal Eye Chamber Fluid
- Aqueous humor
- Vitreous humor
- Watery fluid found in chamber between the lens and cornea
- Similar to blood plasma
- Helps maintain intraocular pressure
- Provides nutrients for the lens and cornea
- Reabsorbed into venous blood through the canal of Schlemm
Aqueous humor
- Gel-like substance behind the lens
- Keeps the eye from collapsing inward by reinforcing it internally
- Lasts a lifetime and is not replaced
Vitreous humor
Cataracts form when the
lens becomes _ over time
requiring a transplant or
special glasses
increasingly
hard and opaque
_ results when the drainage of aqueous humor is blocked and pressure within the eye increases dramatically and compresses the delicate retina and optic nerve causing pain and blindness
Glaucoma
Light must be focused to a point on the _ for optimal vision – done by the lens
retina
The resting eye is set
for distance vision
over 20 ft away
The lens must change
shape to focus for
_ objects –
accommodation
closer
Images Formed on the Retina
Real image (reversed left to right, and upside down) formed on the retina
optic nerve croses at the _ to the opposite side
optic chiasma
In eyes
Fiber tracts that
result are the _
optic
tracts
The optic tract fibers
synapse with neurons in
the thalamus, whose axons
form _
optic radiation
Eye Reflexes
Internal muscles are controlled by the
_ nervous system
autonomic
Bright light causes pupils to constrict through action of radial and ciliary muscles _
photopupillary reflex
Viewing close objects causes accommodation
– _
accommodation pupillary reflex
Viewing close objects causes _ (eyes moving medially (toward nose))
convergence
ear houses 2 senses
- hearing
- equilibrium - balance
ear Receptors are _ –
respond to physical forces
mechanoreceptors
3 areas of ear
- outer ear - external
- middle ear
- inner ear - internal
Outer and middle ear structures involved in _ only while inner ear functions in both _
hearing
equilibrium and hearing
2 structures of external ear
- pinna (auricle) - the ear
- external auditory canal
- Narrow chamber in the temporal bone
- Lined with skin
- Ceruminous (wax) glands are present that secrete earwax – _
- Ends at the _ (eardrum) where sound waves hit and cause vibrations
External Auditory Canal
cerumen
tympanic membrane
Air-filled cavity within the temporal bon
Middle Ear or Tympanic Cavity
Two tubes are associated with the inner ear
- the oval window
- inferior membrane-covered round wind
The opening from the auditory canal is covered by the _
tympanic membrane
The auditory tube connecting the middle ear
with the _
Allows for equalizing _ during yawning or swallowing – This tube is otherwise collapsed
throat
pressure
Three bones span
the cavity – the
ossicles
- Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
Vibrations from eardrum move the _
These bones transfer sound to the inner ear
malleus
A maze of bony chambers within the temporal bone called the _
osseous or bony labyrinth
osseous or bony labyrinth consists of
- cochlea
- vestibule
- semicircular canals
Inner Ear or Bony Labyrinth
Filled with a plasma-like fluid called _
Inside is a membranous labyrinth that contains a thicker fluid called _
perilymph
endolymph
Located within the cochlea
Organ of Corti
Receptors = hair cells on the basilar
membrane –
hearing receptors
Gel-like _ membrane is capable of
bending hair cells
tectorial
Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on _ lobe
temporal
Vibrations from sound waves move
_
tectorial membrane
In ears,
An action potential starts in the _
cochlear
nerve
Continued stimulation can lead to
adaptation – _ responding to those sounds
stop
hindi na magugulat since nasanay na yung ears
organs of equilibrium
Receptor cells are in two structures
vestibule
semicircular canals
Equilibrium has two functional parts
- static equilibrium
- dynamic equilibrium
static equilibrium
– receptors in the vestibule
maculae
static equilibrium
- Report on the position of the head with respect to gravity – help determine up from down
- Send information via the vestibular nerve
maculae
Anatomy of the maculae
- Hair cells are embedded in the _ membrane
- _ (tiny stones) float in a gel around the hair cells
- Movements cause 2_ to bend the hair cells which send impulses along the vestibular nerve to the cerebellum
otolithic
Otoliths
dynamic equilibrium
receptors in the
semicircular canals
Crista ampullaris
Crista ampullaris consists of
- tuft of hair cells
- cupula (gelatinous cap) covers the hair cells
Receptors respond to angular or rotatory
movements of the head
dynamic equilibrium
dynamic equilibrium
- The cupula stimulates the hair cells – _
- An impulse is sent via the vestibular nerve to the cerebellum
gelatinous cap
taste and smell uses what kind of receptors
chemical senses/
chemoreceptors
Taste has _ types of receptors
four
Smell can differentiate a _ range of
chemicals
large
Both taste and smell senses complement each other and respond to many of the _ stimuli
same
are in the roof of the
nasal cavity
Olfactory receptors
olfaction
Neurons with long cilia
olfactory hairs
In smell,
Chemicals must be dissolved in _ for detection
mucus
Impulses are transmitted via the _ which makes up the olfactory nerves
olfactory filaments
Interpretation of smells is made in the
_
olfactory cortex
gustatory
_
house the
receptor
organs
Taste buds
Location of taste buds
- most are on tongue
- soft palate
- inner cheeks
The dorsal tongue is covered with
projections called _
papillae
papillae sharp with no taste buds
Filiform papillae
papillae rounded with taste buds
Fungiform papillae
– large papillae with
taste buds
Circumvallate papillae
Taste buds are found on the _ of
papillae
sides
The specific cells that respond to chemical dissolved in saliva are _ -
Gustatory cells are the receptors
epithelial cells
Gustatory cells Have _ (long microvilli)
gustatory hairs
Surrounded by supporting cells in the taste bud
taste buds
Hairs are stimulated by chemicals dissolved in
_
saliva
Impulses are carried to the _ by several cranial nerves because taste buds are found in different areas
gustatory complex
taste buds can be found
- facial nerve - anterior tongue
- glossopharyngeal nerve
- vagus nerve
4 taste sensations
- sweet receptors
- sour receptors
- bitter receptors
- salty receptors
Sweet receptors
- Sugars
- Saccharine
- Some amino acid
- May respond to the OH-
Sour receptors
- Acids
- May respond to the H+
Bitter receptors
Alkaloids
Metal ions in solution
Salty receptors
Developmental Aspects of the Special Senses
- Formed early in embryonic development
- Eyes are _ of the brain
- All special senses are _ at birth
outgrowths
functional
