Chapter 18: Special Senses

Sympathetic Division:

"Fight or flight" - Originates at the thoracic and lumbar region of the spinal cord - Includes: sympathetic chain ganglia, cervical ganglia, and collateral ganglia

Parasympathetic Division:

"Rest and digest" - Originate at the brainstem and sacral region of spinal cord - Includes: terminal ganglia and intramural ganglia

Taste receptors are located:

- Across the surface of the tongue - Portions of Pharynx and Larynx - Located within the walls of papillae, epithelia projections on the surface of the tongue.

Middle ear consists of:

- Auditory ossicles (malleus, incus, stapes) - Auditory tube (pharyngotympanic tube): provides connection between tympanic cavity and nasopharyngeal to equalize air pressure - Oval window - Tympanic cavity (air filled) - Tympanic membrane

External ear consists of:

- Auricle (pinna) - Elastic cartilage - External acoustic meatus (ear canal): ceruminous glands that produce waxy cerumen (earwax) that is antimicrobial and small projecting hairs that impeded insects and small objects - Tympanic membrane

Internal ear contains:

- Bony labyrinth subdivided into: - Vestibular complex (balance): semicircular canals, vestibules, utricle, saccule - Cochlea (hearing - snail shaped spirals): round window and oval window

Anterior cavity of the eye:

- Contains aqueous humor (fluid) and can be broken down into two chambers: anterior chamber and posterior chamber

Bipolar olfactory neurons sit in epithelium, pass through ______ to synapse with ______.

- Cribriform plate - Olfactory bulb Bipolar olfactory neurons sit in epithelium, pass through cribriform plate to synapse with olfactory bulb.

Membranous labyrinth of the internal ear:

- Filled with endolymph - Surrounded by perilymph inside the bony labyrinth - Divided into cochleae duct (hearing) and the vestibular complex (equilibrium) - Vestibular complex includes: semicircular ducts (rotation), utricle and saccule (gravity and linear acceleration)

The automatic nervous system (ANS):

- Functions outside of our conscious awareness - Makes routine adjustments in our body's system - Regulates body temperature & coordinates cardiovascular, respiratory, digestive, excretory, and reproductive functions.

Four special senses:

- Gustation (taste): chemoreceptors - Olfaction (smell): chemoreceptors - Hearing & Equilibrium: mechanoreceptors - Vision: photoreceptors

Mechanoreceptors:

- Hearing and equilibrium - Sensitive to physical distortion of cell membranes

Photoreceptors of the eye:

- In the inner layer of the eye (Retina) - Rods (night vision) - Cones (color vision)

Fovea of the eye:

- In the inner layer of the eye (retina) - Depression on the retina with the highest concentration of cones, where light hits directly, the area of sharpest vision.

Which cell population is the only group of cells in the retina that generate action potentials to the brain?

Ganglion cells

Axons from which neuron in the retina make up the optic nerve?

Ganglion cels

Papillae:

Epithelial projections of the surface of the tongue.

Hearing pathway:

External ear > Tympanic membrane > Malleaus-Incus-Stapes > Perilymph of vestibular/Tympanic duct > Basilar/Vestibular membrane > Enolymph of cochlear duct > organ of cortisones/spiral organ > hair cells > cochlear branch of vestibulocochlear nerve > pons > thalamus > temporal lobe of the brain

Which of these cranial nerves is part of the gustatory system? A) Olfactory B) Trochlear C) Trigeminal D) Facial

Facial

Name the four special senses:

Gustation (taste), olfaction (smell), mechanoreceptors (hearing & equilibrium), and photoreceptors (vision)

What cells can be found in the taste bud?

Gustatory cells, transitional cells, basal cells

Equilibrium pathway:

Hair cells in utricle, saccule, ampulla of semicircular canals > vestibular branch of vestibulocochlear nerve > medulla oblongata > cerebellum/cerebral cortex

The cochlea's in the ear is responsible for?

Hearing

Gustation (taste):

Provides information about foods and liquids that we consume. Includes taste receptors across the surface of the tongue, portions of the Pharynx and Larynx, located within the walls of the papillae (epithelial projections on the surface of the tongue).

Gustatory cells would be found in which special sense organ/tissue layer? A) Olfactory epithelium B) Organ of Corti C) Taste buds D) Ossicles

Taste buds

Pathway of vision:

light → cornea → pupil/iris → lens → retina → rods/cones → bipolar cells → ganglion cells → optic nerve → optic chiasma → occipital lobe

Scala media - cochlea:

Part of the cochlea (inner ear), cochlear duct, contains endolymph. In between the Scala vestibule and Scala tympani. Contains the organ of Cortisones (site for receptor cells)

Scala tympani - cochlea:

Part of the cochlea (inner ear), tympanic duct, contains perilymph.

Scala vestibuli- cochlea:

Part of the cochlea (inner ear), vestibular duct, contains perilymph.

______ is the conscious awareness of a sensation.

Perception

The conscious awareness of sensation is called:

Perception.

Cells of the retina:

Photoreceptors, bipolar cells, and ganglion cells

The vitreous humor (body) can be found ______ .

Posterior to the lens in the eyeball

The vitreous humor (body) can be found ______.

Posterior to the lenses in the eyeball.

Internal ear:

Within the skull and contains sensory organs for hearing and equilibrium. Responsible for sensing stimuli for hearing (in cochlea) and equilibrium (in semicircular canals) and for sending the nerve impulses.

Vascular layer of the eye:

- Iris, ciliary body, and choroid make up the vascular layer of the eye. - Provides a route for blood vessels and lymphatics to supply tissues of the eye - Regulates the amount of light entering the eye - Secretes and reabsorbs aqueous fluid (aqueous humor) - Controls the shape of the lens

The inner layer of the eye (Retina):

- Neural layer contains layers of cells (photoreceptors, bipolar cells, ganglion cells) - Fovea

5 Sensory receptors:

- Nociceptors: responds to the sensation of pain - Thermoreceptors: responds to changes in temperature - Mechanoreceptors: sensitive to physical distortion of cell membranes - Chemoreceptors: monitor the chemical composition of body fluids - Photoreceptors: responds to light

Loose connective tissue (lamina propria) of the Olfactory Organ:

- Olfactory glands (produce mucus) - Blood vessels and nerves

Olfaction (smell) consists of:

- Olfactory organ - Olfactory epithelium: olfactory sensory neurons, supporting cells, basal epithelial cells - Loose connective tissue (lamina propria): olfactory glands (produces mucus). blood vessels, and nerves

Olfactory epithelium:

- Olfactory sensory neurons -Supporting cells - Basal epithelial cells

Cilary body (muscle) of the eye:

- Part of the vascular layer of the eye - Contraction or relaxation of the cilary muscle changes the shape of the lens

Iris:

- Part of the vascular layer of the eye - Pigments creates the color of the iris - Smooth muscles contract to change the diameter of the pupil

Choroid of the eye:

- Part of the vascular layer of the eye - highly vascularized

Olfaction:

- Receptors are located in the nasal cavity, either side of the nasal septum. - Nasal epithelium lines inferior to the Cribriform plate surface - Bipolar olfactory neurons sit in epithelium, pass through cribriform plate to synapse with olfactory bulb

Inner layer of the eye:

- Retina and optic nerves make up the inner layer of the eye.

Fibrous layer of the eye:

- Sclera and cornea make up the fibrous layer of the eye. - Provides some degree of protection - Provides attachment sites for extra-ocular muscles - Contains structures associated with focusing (cornea). The cornea is sclera that is modified for transparency and is avascular.

The internal ear is responsible for ______ stimuli for hearing (in cochlea) and equilibrium (in semicircular canals) and for ______ the nerve impulses.

- Sensing - Sending The internal ear is responsible for sensing stimuli for hearing (in cochlea) and equilibrium (in semicircular canals) and for sending the nerve impulses.

Gustation primary tastes:

- Sweet - Salty - Sour -Bitter - Umami: brothy (amino acids) - Water: receptors present in pharynx There are no distinct distribution on the tongue

Chemoreceptors:

- Taste & smell - Monitor the chemical composition of body fluids.

Eye anatomy - The eye consists of:

- Three layers: Fibrous layer, vascular layer, inner layer. - Two cavities: anterior cavity and posterior cavity - Posterior orbital fat pad provides padding and insulation

3 cells found within the taste buds:

- Transitional cells - Gustatory cells - Basal cells

Taste buds consists of:

- Transitional cells - Gustatory cells - Basal cells - Taste hairs (microvilli) - Taste pores Papillae on the surface of the tongue

Photoreceptors:

- Vision - Respond to light

Perception of sound (from external sound to receptors):

1) Sonund waves are funned by the auricle into the external acoustic meatus. Sound wave represents alternating areas of high and low pressure 2) Tympanic membrane vibrates, transmitting sound to the inner ear. Typmpanic membrane vibrates in response to sound waves 3) The stapes moves the oval window, transmitting sound to the inner ear duct. Vibrations are amplified across ossicles 4) Pressure waves in the perilymph of Scala vestibule deform the cochlear duct. Vibrations against oval window set up standing wave in fluid of vestibuli 5) Hair cells are bent leading to impulses in the cochlear branch of the vestibulocochlear nerve. Pressure bends the membrane of the cochlear duct at a point of maximum vibration for a given frequency, causing hair cells in the basilar membrane to vibrate.

Hearing and equilibrium:

3 main ear regions: - Eternal ear: fleshy portion, auricle - Middle ear: eardrum area - Internal ear: within the skull Sensation involves: - vestibulochoclear nerve (CN VII) - vestibular and cochlear branch

The middle ear is responsible for ______ sound waves into strong signals for the hearing receptors to detect.

Amplifying

Semicircular canals in the ear are responsible for?

Balance and equilibrium

Internal ear consists of:

Bony labrynth which are: - Cochlea - Vestibule (balance) which houses two membranous sacs: the utricle and saccule - Semicircular canals (balance) each containing a membranous semicircular duct.

The olfactory organs:

Consist of receptors and supporting cells (basal/ columnar cells) in the nasal cavity: basal epithelial cell, cribriform plate, lamina propia, olfactory epithelium, mucous layer, supporting cells, olfactory sensory neurons, olfactory nerve fibers to the olfactory bulb, olfactory glands.

Nasal epithelium lines inferior to ______ surface

Cribriform plate

Starting with light rays, complete the path for vision:

Light rays > cornea > anterior chamber > pupil > posterior chamber > lens > vitreous humor > photoreceptors (rods & cones) > bipolar cell > ganglion cell > optic nerve > optic chiasma > thalamus > sensory cortex in occipital lobe.

What type of receptor cell is involved in the sensations of sound and balance? A) Photoreceptors B) Chemoreceptors C) Mechanoreceptors D) Nociceptor

Mechanoreceptors

_______ lines inferior to Cribriform plate surface.

Nasal epithelium

Olfactory pathway:

Olfactory receptors > Synapses > olfactory bulb > olfactory tract > temporal lobe of the brain

External (Outer) ear:

Outer fleshy structures (auricle) of the ear that collect sound. Responsible for transferring sound waves from the environment to the middle ear.

Nociceptors:

Respond to the sensation of pain

Thermoreceptors:

Responds to changes in temperature

Which part of the inner ear detects angular acceleration?

Semicircular ducts

The ______ detect angular acceleration (rotational movements, like head rotation).

Semicircular ducts The semicircular ducts detect angular acceleration.

Sensory information arriving at the CNS is called a _______:

Sensation

Sensory information arriving at the CNS is called:

Sensation

Sensation:

Sensory information arriving at the CNS. Axons from the olfactory nerve, which extends through cribriform plate and become olfactory tract as they enter the brain.

Stimuli:

Sensory or sensation information received by the body.

Information is "picked up" by _______, which are the interface between the nervous system and the internal and external environment.

Sensory receptors

Sensory receptors:

Specialized cells that detect stimulus information and transmit it to sensory (afferent) nerves and the brain.

Which ossicle of the middle ear almost completely fills the oval window? A) malleus B) incus C) stapes D) bony labyrinth

Stapes

Our bodies are constantly exposed to sensory information called:

Stilmuli

Gustatory pathways:

Taste bud innervation: - Facial (CN VII) - Glossopharyngeal (CN IX) - Vagus (CN X) Ultimate path for gustation: Gustatory receptor cells > cranial nerves > medulla > oblongata > thalamus > frontal & temporal lobe

Middle ear:

The chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window. Responsible for amplifying sound waves into strong signals for the hearing receptors to detect.

Perception:

The conscious awareness of sensation.

______ is responsible for sensing stimuli for hearing (in the cochlea) and equilibrium (in the semicircular canals) and for sending the nerve impulses.

The internal ear.

_______ is responsible for amplifying sound waves into strong signals for hearing receptors to detect.

The middle ear.

______ is responsible for transferring sound waves from the environment to the middle ear.

The outer ear.

Cochlea- Anatomy of the inner ear:

The receptor cells of hearing (hair cells) are located within the cochlea of the inner ear. The cochlea consists of "snail-shaped" spirals. Each spiral consists of three ducts: Scala vesibuli (vesitubular duct), Scala tympani (tympanic duct), and Scala media (cochlear duct).

Equilibrium in the ear:

The utricle and saccule detect static equilibrium and linear acceleration (e.g. running). The semicircular ducts detect angular acceleration (rotational movements, ex: head rotation). When the head moves or tilts, hair cells within these structures are bended.

The outer ear is responsible for ______ sound waves from the environment to the middle ear.

Transferring

T/F: Red cells in the retina are responsible for perception of black and white vision.

True

T/F: When a sound vibrates the eardrum, the movements are conducted to the perilymph of the inner ear by the movements of the stapes.

True

T/F: Rod cells in the retina are responsible for perception of black-and-white vision.

True.

T/F: The path for olfaction starts with olfactory receptors and ends at the temporal lobe.

True.

The ______ and the ______ detect static equilibrium and linear acceleration (ex: running).

Utricle and Saccule The utricle and saccule detect equilibrium and linear acceleration.

Which parts of the ear detects equilibrium and linear acceleration?

Utricle and saccule,

Which layer of the eye possesses the iris and pupil?

Vascular layer

Sensation of the ear involves:

Vestibulocochlear nerve (CN VIII): vestibular branch and cochlear branch.