Test 3 The Special sense Flashcards
What are the special senses of the human body?
- smell
- hearing
- equilibrium
- taste
- sight
where are the special sensory receptors located?
localized and confined to the head region
the chemical senses
- olfaction
- gustation
Where does the taste receptors occurs?
in the taste buds in the mucosa of the mouth and pharynx
- tongue palate, inner cheeks
how many taste buds do we have?
10000
most taste buds occur in?
papillae
what is papillae
two types of peg like projections of the tongue mucosa
the two types of papillae
fungiform papillae
circumvallate papillae
fungiform papillae
- small
- occur over the entire surface of the tongue
circumvallate papillae
- large
- arranged in an inverted V near the back of the tongue
where does the taste buds occur?
within the epithelium that covers the papillae, on the apical surface of fungiform papillae, and in the side walls of the circumvallate papillae
each taste bud is a globular collection of
50-100 epithelial cells that resemble a closed tulip
each taste bud consists of how many major cell types and what are they?
3
- supporting cell
- gustatory cell
- basal cells
supporting cells
- most abundant
- insulates the gustatory taste cells from each other and from the surrounding epithelium of the tongue
gustatory cells
receptor cells
basal cells
- immature cells
- regularly replace the other two cell types
sensory nerve fibers enter the taste buds and synapse with?
the receptor cells
long microvilli project from? and extend through?
- project from receptor cells and supporting cells
- extend through a taste pore to the surface of the epithelium
cells of taste buds are replenished every?
7-10 days by the division of the basal cells
taste information reaches the brain stem and cerebral cortex through the?
gustatory pathway
where does the sensory fibers carrying taste information from the tongue primarily occur?
in two cranial nerves
- facial nerve (VII)
- glosspharyngeal nerve (IX)
facial nerve VII
transmits impulses from taste reeptors in the aneterior two - thirds of the tongue
glossopharyngeal nerve IX
carries sensations from the tongues posterior one third
tthe receptors for smell are part of??
olfactory epithelium that overs the superior nasal concha and the superior part of the nasal septum
what kind of epithelium is olfactory epithelium
pseudostratified columnar
olfactory epithelium contains and surrounded by?
contains millions of bipolar cells called olfactory receptor cells and surrounded by columnar supporting cells
basal cells
- at the base of the epithelium; short
- undifferentiated cells that continually form new olfactory receptor cells
where the cell bodies of the olfactory receptor cells located?
olfactory epithelium
each receptor cell has?
an apical dendrite that projects to the epithelial surface and ends in a knot from which long olfactory cilia radiates
the surface of the epithelium is coated with?
a layer of mucus secretd by the supporting cells and olfactory glands in the underling CT
what is the function of the cilia?
move objects
what is the function of the mucus
captures and dissolves odor molecules from the air
and it is contantly renewed
olfaction axons gather into nerve bundles called?
filaments of the olfactory nerve (cranial nerve 1), which penetrate the cribiform plate of the eithmoid bone and enter the overlying olfactory bulb of the forebrain
what happens in the olfactory bulb
the olfactory nerve axons branch profusely and synapse with neurons called mitral cells in complex synaptic clusters called glomeruli
what does mitral cells do?
relay olfactory information to other parts of the brain
how many % of the receptors are in the eye
70%
how much p% of the cerebral cortex is involved in processing visual information
40
the ratio of the visible eye
1/6 of the eyes surface is visible
accessory structures
eyebrows eyelids conjunctiva lacrimal apparatus extrensice eye muscle
eyebrows
consist of corase haris in the skin on the brow ridges of the skull
eyebrows function
shade the eyes from sunlight and prevent persperiatieyelids (on from running down the forehead from reaching the eyes
eyelids (palpebrae)
the upper and lower lids are separated by the palpebrae’s fissure (eye slit) and meet each other at the medial and lateral angles (canthi)
lacrimal caruncle
reddish elevation at the medial canthus
tarsal plates
connective tissue within the eyelids that serves as attachment sites for obicularis oculi
eyelashes
project from the free margin of each eyelids
what are the glands in the eyelids
tarsal glands
cilliary glands
tarsal glands
modified sebacious glands embedded in the tarsal plates
- produces oil that spreads over the entire surface of the eye, slowing the evaporation of water
ciliary glands
associated with the hair follicles of eyelashes
infection of tarsal gland
chalazion “swelling”
infection of ciliary glands
sty
conjunctiva
vascularized transparent mucous membrane that covers the inner surfaces of the eyelids and folds back over the anterior surface of the eye
palpebral conjuctiva
cover the inner surfaces of the eyelids
bulbar conjuctiva
a very thin membrane that covers the white of the eye but not the cornea
when the eye is closed, the slitlike space that forms between the eye surface and the eyelids is the?
conjunctival sac
conjunctiva consists of?
stratified columnar epithelium underlain by a thin lamina propria of loose connective tissue
conjunctivitis
inflammation of the conjunctiva that causes them to appear red
- red eye/pink eye
lacrimal aparatus
- lacrimal gland
- lacrimal sac
lacrimal gland
produces lacrimal fluid - The lacrimal glands are superior to the lateral aspect of each eye. They continually release a dilute salt solution (tears) that flows onto the anterior surface of the eyeball.
lacriml sac
fluid empties into nasal cavity
the tear flush across the eyeball into the?
lacriminal canals medially then into the lacrimal sac, and finally into the nasolacrimal duct which empties into the nasal cavity
the lacrimal secretion contains?
lysozyme, an antibacterial enzyme
that cleans and protects the eye surface as it moistens and lubricates it
six muscles that control movement of the eye
- Originate in the walls of the orbit
- Insert on outer surface of the eyeball
- Annular ring – origin of the four rectus muscles
the wall of the eye is constructed of three tunics or coats, what are they?
1) Fibrous tunic
2) Vascular tunic
3) Sensory tunic
The outermost fibrous tunic is a
1) protective layer composed of dense
avascular connective tissue
the two different regions of fibrous tunic
-The opaque white sclera forms the posterior 5/6 of the tunic.
Provides shape and an anchor for eye muscles
-The anterior-most portion is the transparent cornea, through which
light enters the eye.
The sclera part of the limbus contains a
large vessel called the scleral
venous sinus that drains aqueous humor out of the eye.
The transparency of the cornea is due to? and Corneas function is?
The transparency of the cornea is due to the regular alignment of
collagen fibers.
- Function: protection; allow light to pass into the eye; forms part of
the light-bending apparatus of the eye
the cornea is avascular so where does the cornea get oxygen and nutrients?
front - air through cornea
back - coriod coat
-Touching the cornea causes
reflexive blinking and an increased
secretion of tears.
-The cornea has the ability for regeneration
the vascular tunic has three parts
choroid
cilliary body
iris
• Choroid coat:
the blood-rich nutritive layer, highly pigmented layer
that forms the posterior 5/6 of the eye.
- The blood vessels nourish the other tunics
The brown color is due
to the presence of melanin which helps
absorb light…preventing light from scattering within the eye and
creating visual confusion.
ciliary body
thickened ring of tissue that encircles the lens
- Composed of smooth muscle called ciliary muscle which act to
focus the lens
Ciliary processes:
posterior surface of the
ciliary bod
Ciliary zonule
(suspensory ligament):
Attached around entire
circumference of the lens
• Iris:
the most anterior part of
the vascular tunic; visible
colored part of the eye
- base is attached to the ciliary body
iris contains
Contains both circularly arranged and radiating smooth muscle, the sphincter and dilator pupillae muscles, that act to vary the size of the pupil
pupil
the round, central opening of the iris.
-Allows light to enter the eye
iris eye color
All people (except albinos) have a layer of pigmented cells on the posterior surface of the iris. Vascular Tunic: Iris/Eye Color -Although irises come in many colors… they contain only brown pigment.
eye colors
-Brown eyes: pigmented cells on the posterior surface of the iris +
pigment cells in the body of the iris
-Blue eyes: pigmented cells on the posterior surface of the iris + no
pigment in the body of the iris
-Hazel eyes: pigmented cells on the posterior surface of the iris +
some pigment cells in the body of the iris
the inner most sensory tunic of the eye and its layers
retina.
a) Pigmented layer: single layer of melanocytes
b) Neural layer: contains the photoreceptors, rods and cones,
which begin the chain of electrical events that result in vision.
• Lateral to each blind spot, and directly posterior to the lens, is
an area
called the macula lutea (yellow spot), an area of high cone density. In
its center is the fovea centralis, a minute pit which contains mostly
cones and is the area of greatest visual activity.
the three main types of neurons of retina
Photoreceptor cells
Bipolar cells
Ganglion cells
rods
the specialized receptors
for dim light (gray tones)
cones
color receptors that permit high levels of visual acuity, but they function only under conditions of high light intensity (no color vision is possible under moonlight)
ganglion
Ganglion: light must pass
through this layer the bipolar
neuron layer to reach and excite
rods and cones.
as a result of light stimulation
1) The photoreceptors undergo changes in their membrane potential that influence the bipolar neurons. 2) This then stimulates the ganglion cells, whose axons leave the retina in the tight bundle of fibers known as the optic nerve
The photoreceptor cells are distributed over the entire neural retina,
except where the optic nerve leaves the eyeball…what is this site called
This site is called the
optic disc or blind spot.
The lens and ciliary zonules (suspensory ligaments) divide the eye
posterior segment cavity
anterior segment cavity
) Posterior segment (cavity)
-Filled with vitreous humor: Clear, jelly-like substance that
transmits light and supports the posterior surface of the lens.
Helps maintain intraocular pressure
b) Anterior segment
(cavity) :
Divided into anterior and posterior chambers filled with aqueous humor, which is renewed continuously, formed as a blood filtrate, and supplies nutrients to the lens and cornea -Anterior chamber (between the cornea and iris) -Posterior chamber (between the iris and lens
the ear
The ear is a complex structure containing sensory receptors for
hearing and equilibrium.
the ear is divided into three major areas
outer ear: functions in hearing
- middle ear: functions in hearing
- inner ear: functions in both hearing and equilibrium
external ear is composed of?
- auricle (pinna)
- external acoustic meatus
- tympanic membrane.
auricle pinna
is the skin-covered cartilaginous structure
encircling the auditory canal opening.
-Function: collects and directs sound waves into the external
acoustic meatus/canal
The external acoustic meatus (external auditory canal) is
a short,
narrow chamber carved into the temporal bone.
-Lined with skin and contain hairs, subaceous glands, and ceruminous
glands (secretes wax)
middle ear
A small air-filled chamber called the tympanic cavity
found within the temporal bone
tympanic cavity
The tympanic cavity is spanned by three small bones, collectively
called the ossicles (malleus, incus, stapes), which articulate to form a
lever system that amplifies and transmits the vibratory motion of the
eardrum to the fluids of the inner ear via the oval window (deep to
stapes).
the smallest bone in the body
the ossicles
• Two skeletal muscles occur in
the middle ear cavity
a) Tensor tympani muscle
b) Stapedius muscle
- These muscles contract
reflexively to limit the vibration
of the ossicles when the ears are
assaulted by very loud sounds.
The pharyngotympanic tube (auditory tube)
connects the middle ear
chamber with the pharynx.
-Note: The eardrum doesn’t vibrate properly unless the pressure on
both of its surfaces is the same. The auditory tube allows for the
equalization of the pressure of the middle ear cavity with the external
air pressure.
inner ear
The inner ear is a bony labyrinth…a cavity within the
temporal bone consisting of two main divisions:
a) the bony labyrinth
b) the membranous labyrinth
Bony labyrinth:
cavity consisting of a system of twisting channels
that has three parts.
-Has three parts: a) semicircular canals, b) vestibule, and c) cochlea
Membranous labyrinth
: a continuous series of membrane-walled
sacs and ducts that fit loosely within the bony labyrinth.
-Main parts: a) semicircular ducts, b) utricle and saccule, and c)
cochlear duct
the wall of the membranous labyrinth is a
te: “membrane”
composed of a thin layer of C.T. lined by a simple squamous epithelium
The membranous labyrinth is filled with a clear fluid called
.
endolymph
• The bony labyrinth is filled with another clear fluid called
.
perilymph
vestibule
• Vestibule: the central cavity of the bony labyrinth. Suspended within
its perilymph are the utricle (“leather bag”) and saccule (“little sac”)
utricle is continuous with? the saccule with?
- semicircular duct
- cochlear duct
macula
a: a spot of sensory epithelium found in both the utricle and
saccule.
static equilibrium
a: a spot of sensory epithelium found in both the utricle and
saccule.
linear acceleration
These receptor cells also monitor straight-line
changes in the speed and direction of head movements…
Each macula is a patch of epithelium
containing
columnar supporting cells and
scattered receptors called hair cells, which
synapse with sensory fibers of the vestibular
nerve
Hair cells have many
stereocilia and a
single kinocilium (“true cilium”) protruding
from its apex.
-The hairs are embedded in
an overlying
otolithic membrane…a jellylike disc that
contains heavy crystals of calcium carbonate
called otoliths (“ear stones”).
Semicircular canals (anterior, posterior, and lateral):
house
receptors for rotational acceleration of the head…lie posterior and
lateral to the to the vestibule.
Anterior and posterior semicircular canals:
lie in the vertical plane
at right angles
lateral semicircular canal: lies in the
horizontal plane
Semicircular duct: snakes through each semicircular canal
-Houses a structure called a
crista ampullaris… has an epithelium
that contains supporting cells and receptor hair cells
The crista ampullaris measures
rotational (angular) acceleration
of the head
The hairs project into a tall,
jellylike mass that resembles a
pointed cap…called the
cupula.
The crista within each of the
three semicircular ducts responds
to
head rotation in a different plane
of space.
• The cochlear duct lies between
two chambers (scala vestibuli & scala tympani) and contains receptors for hearingv
cochlear duct chambers
The vestibular membrane: the roof of the cochlear duct
-The basilar membrane: the floor of the cochlear duct
• The cochlear duct contains receptors for hearing:
- The spiral organ of Corti is the receptor epithelium for hearing and
consists of supporting cells and the inner and outer hair cells
(receptor cells).