Title: THE SPECIAL SENSES
1THE SPECIAL SENSES
- PETER REONISTO, MD
- MOORPARK COLLEGE
2TRADITIONAL SENSES
- Smell
- Taste
- Sight
- Hearing
- Equilibrium
3SPECIAL SENSES RECEPTORS
- Localized and confined to the head region
- Not free nerve endings of sensory neurons
- Distinct receptor cells
- Receptor cells neuron-like epithelial cells
that transfer sensory information to other
neurons in afferent pathways to the brain - Sensory receptor cells are housed in complex
sensory organs (eye or ear) or in distinctive
epithelial structures (taste buds or olfactory
epithelium) - Sensory information travels via cranial nerves
4CHEMICAL SENSES
- TASTE (Gustation)
- Taste receptors- located on
- tongue surface
- posterior palate
- Inner surface of cheek
- Posterior pharyngeal wall
- epiglottis
- SMELL (Olfaction)
- Smell receptors- called olfactory epithelium
located on - Superior nasal concha
- Superior nasal septum
5Taste
- 10,000 taste buds in your mouth
- Sweet and salty are least sensitive
- Bitter ones are most sensitive
-
- Your tongue picks up four types of taste sweet,
sour, bitter, and salty.
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7TASTE
- Tongue mucosa (papillae)
- 1) Fungiform papillae- scattered over the entire
surface of the tongue. - 2) (Circum)vallate papillae- inverted V near the
back of the tongue
8Taste Buds
- 10,000 taste buds in the tongue
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10Tastebuds closeup
- Molecules of food stimulate the taste cells to
send messages to your brain. The sweet and salty
buds are the least sensitive and the bitter ones
are the most sensitive.
11Lower pharynx, epiglottis
Anterior 2/3
VAGUS NERVE
Posterior 1/3, pharynx
12THALAMIC NUCLEI
Solitary Nucleus (Medulla Oblongata)
CN VII, IX, X
Taste Buds
13SMELL
- Odor particles drift into your nose and cause
your smell receptors to send messages to your
brain.
14OLFACTORY BULB (SMELL)
- The smell part of the brain is in the limbic
region, and is connected to feeling and memory. -
Limbic Lobe
Olfactory bulb (CN I)
Olfactory epithelium
Olfactory receptor cell
- Olfactory epithelium- pseudostratified columnar
epithelium - Olfactory receptor cell- bipolar neurons
15Vision
- Your eyes gather visual information, which is
sent to your brain to be processed and
understood.
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17ANATOMY OF THE EYE
1) SCLERA
2) CHOROID
Ciliary Body
Iris
Cornea
3) RETINA
CONJUNCTIVA
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20Vision (retina)
- Vision Retina
- Rods sense brightness
- Cones sense color
- The retina, in the back of your eye, has cells
that are sensitive to light. They connect
directly to your brain.
21VISUAL PATHWAY
22Light/ Image
Aqeous Humor
Vitreous Humor
Optic Nerve
Rods or Cones (Photoreceptors)
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25RETINAL/GANGLION CELLS
OPTIC NERVE
OPTIC CHIASM
OPTIC TRACT
LATERAL GENICULATE NUCLEUS
OPTIC RADIATION
VISUAL CORTEX
26VISUAL FIELD DEFECTS
27Hearing
- Sound waves make your eardrum vibrate. Then, the
small bones in your ear vibrate, and the
vibrations go through the snail-like cochlea,
which turns them into nerve impulses to your
brain.
28THE EAR HEARING AND EQUILIBRIUM
- Regions
- Outer (External) Ear
- Middle Ear
- Inner (Internal) Ear
29EXTERNAL EAR
- Components
- a) Auricle (Pinna)
- b) External Acoustic (Auditory) canal
- c) Hair, sebaceous gland, modified apocrine
sweat gland (ceruminous gland) - d) Tympanic membrane
302/3 Temporal bone
1/3 Elastic cartilage
31MIDDLE EAR
- Boundaries Petrous part of temporal bone
- a) Medial boundary
- (1) superior oval window (vestibular)
- (2) inferior round window (cochlear)
- b) Lateral boundary
- (1) Tympanic membrane
- c) Superior boundary
- (1) Petrous bone
- d) Posterior wall
- (1) Mastoid antrum- leadsto the mastoid air
cells - e) Anterior wall
- (1) Pharyngotympanic tube- leads to the pharynx
- f) Inferior boundary
- (1) thin bony floor where the internal jugular
vein lies
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34MIDDLE EAR
- Components
- Ossicles
- (1) Malleus (hammer)
- (2) Incus (anvil)
- (3) Stapes (stirrup)
- b) Skeletal muscle
- (1) Tensor tympani
- (2) Stapedius
35Origin cartilage part of Pharyngotympanic
tube. Insertion malleus
Origin Posterior wall Middle ear Insertion
Stapes
36INNER EAR (LABYRINTH)
- Bony labyrinth (petrous bone cavity) filled
with perilymph - Semicircular canals
- Vestibule
- cochlea
- Membranous labyrinth- membrane-walled sacs and
ducts) filled with endolymph - Semicircular ducts
- Utricle and saccule
- Cochlear duct
37COCHLEA
- Spiraling chamber
- Coils for about 2 ½ turns around a pillar called
modiolus - Consist of coiled part of the membranous
labyrinth called cochlear duct (scala media)
which contains the receptors for hearing - Cochlear nerve runs through the core of the
modiolus
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39Ends with the vestibule
Cochlear duct
Ends at the round window
401 row of inner hair cells
Spiral Organ of Corti
3 rows of outer hair cells
41AUDITORY PATHWAY
Acoustic area (temporal lobe cortex)
Medial geniculate body
Brachium of inferior colliculi
Inferior colliculi (midbrain)
Lateral Lemniscus
Nuclei of lateral lemniscus
Cochlear nuclei (medulla)
Cochlear division CN VIII
Spiral ganglion
Hair cells (Organ of corti)
42SEMICIRCULAR CANAL AND VESTIBULE
- Handles EQUILIBRIUM PATHWAY
- 1) Cupula (semicircular canals)
- 2) Macula (Vestibule)
Cupula and Macula
Vestibular nerve
Reflex centers
Vestibular Nuclei in medulla
Vestibular Nuclei in cerebellum
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44END