Sensory System Flashcards
2 basic group of senses
General and Special Senses
This General Senses provides sensory information about the body and the environment.
Somatic senses
This General Senses provides information about various internal organs primarily involving pain and pressure.
Visceral senses
Special Senses
Smell (olfaction)
Taste
Vision
Hearing
Balance
sensory nerve endings or specialized cells capable
of responding to stimuli by developing action
potentials
Sensort Receptors
respond to mechanical stimuli, such as the bending or stretching of
receptors
Mechanoreceptors
respond to chemicals
Chemoreceptors
Example of Chemoreceptors
odor molecules bind to chemoreceptors, allowing us
to perceive smell
respond to light
Photoreceptors
respond to temperature changes
Thermoreceptors
respond to stimuli that result in the sensation of pain
Nociceptors
General Senses
Touch
Pressure
Pain
Temperature
Vibration
Itch
Proprioception
light touch and superficial pressure
Merkel disks
associated with hairs; involved in detecting light touch (not very discriminative)
Hair follicle receptors
- fine, discriminative touch and are located just deep to the epidermis
- very specific in localizing tactile sensations
Meissner corpuscles
continuous pressure in the skin
Ruffini corpuscles
- deepest receptors; associated with tendons and joints
- relay information concerning deep pressure, vibration, and body position (proprioception)
Pacinian corpuscles
Group of unpleasant perceptual and emotional
experiences
Pain
- Perceived to originate in a region of the body that is
not the source of the pain stimulus - Most commonly sensed when deeper structures,
such as internal organs, are damaged or inflamed
Referred Pain
Special Senses and its receptors
Smell (olfaction) - chemoreceptors
Taste - chemoreceptors
Vision - photoreceptors
Hearing - mechanoreceptors
Balance - mechanoreceptors
- Airborne odorants become dissolved in the mucus
on the surface of the epithelium - The binding of the odorant to the receptor initiates
action potentials
Olfaction
sensory structures that detect taste stimuli
Taste buds
Where is Taste buds located?
on the surface of the tongue (papillae)
5 Basic type of Taste sensation
Sour
Salty
Bitter
Sweet
Umami (savory)
Cranial nerve that is anterior two-thirds of the tongue.
Facial nerve
Cranial nerve that is posterior one-third
Glossopharyngeal nerve
Cranial nerve that is root of the tongue
Vagus nerve
Visual system includes the eyes, the accessory
structures, and sensory neurons.
Vision
Eyes are housed within bony cavities called? orbits
orbits
protect, lubricate, and move the eye
Accessory Structures of the Eye
List the Accessories Structures of the Eye
Eyebrows
Eyelids
Conjunctiva
Lacrimal apparatus
Extrinsic eye muscles
The __________ protect the eyes by preventing perspiration from running down the forehead and into
the eyes, causing irritation. They also help shade the
eyes from direct sunlight
eyebrows
- associated lashes, protect the eyes from foreign objects
- helps keep the eyes lubricated by spreading tears over the surfaces
Eyelids
- a thin, transparent mucous membrane covering the
inner surface of the eyelids and the anterior surface of
the eye - helps lubricate the surface of the eye
Conjunctiva
- situated in the superior lateral corner of the orbit
- produce tears
Lacrimal gland
Lacrimal Apparatus 2 parts
Lacrimal gland
Nasolacrimal duct
Responsible for the movement of each eyeball
Extrinsic Eye Muscles
Six extrinsic eye muscles attached to its?
surface
Four of these muscles attach to the four quadrants of
the eyeball. What are they?
superior, inferior, medial, and lateral rectus muscles
Two muscles are located at an angle to the long axis of
the eyeball. What are they?
superior and inferior oblique muscles
- hollow, fluid-filled sphere
- The wall of the eyeball is composed of three tissue
layers, or tunics
Eyeball
- Firm, white, outer connective tissue layer of the posterior
fibrous tunic - Maintains the shape of the eye
- Protects the internal structures, and provides attachment sites
for the extrinsic eye muscles.
Sclera
- Transparent anterior portion of the eye
- Permits light to enter
Cornea
Fibrous Tunic parts
Sclera
Cornea
- Middle layer of the eye
- Contains most of the blood vessels of the eye
Vascular Tunic
- The posterior portion of the vascular tunic
- Consists of a vascular network and many melanin-containing
pigment cells
Choroid
contains smooth muscles called ciliary muscles, which attach to
the perimeter of the lens by suspensory ligaments
Ciliary body
colored part of the eye; contractile structure consisting mainly of
smooth muscle surrounding an opening (pupil)
Iris
Innermost layer and consists of the retina
Nervous Tunic
covers the posterior five-sixths of the eye
Retina
Retina is composed of
two layers:
Outer pigmented retina
Inner sensory retina
With the choroid, keeps light from reflecting back into the
eye.
Outer pigmented retina
Contains photoreceptor cells and numerous interneurons.
Inner sensory retina
function in dim light because they are very sensitive; do not provide color vision
Rods
require much more light; provide color vision
Cones
What color is being provided by Cones?
blue, green, or red
small spot near the center of the posterior retina
Macula
- center of the macula
- part of the retina where light is most focused Optic disc
- contains only cone cell
Fovea centralis
- White spot just medial to the macula through which a
number of blood vessels enter the eye and spread over
the surface of the retina - “Blind spot of the eye”
Optic disc
Optic disc contains no photoreceptor cells and does not respond to?
light
Absence of perception of one or more of perception of one or more color.
Color blindness
Most forms of color blindness occur more frequently in?
males and are X-linked genetic traits
- Misalignment of the two eyes
- Results from weakness of the muscles moving the eyes
Diplopia/ double vision
The organs of hearing and balance are located in
the ears.
Hearing and Balance
part extending from the outside of the head to the tympanic membrane (eardrum) (areas of ear)
External ear
air-filled chamber medial to the tympanic membrane (areas of ear)
Middle ear
set of fluid-filled chambers medial to the middle ear (areas of ear)
Inner ear
External Ear parts
Auricle
The tympanic membrane
- fleshy part of the external ear on the outside of the head
- collects sound waves and directs them toward the external auditory canal
Auricle
- Eardrum, a thin membrane that separates the external ear from the middle ear
- Sound waves reaching the tympanic membrane cause it to vibrate
The tympanic membrane
- Medial to the tympanic membrane
- Air-filled cavity of the middle ear
Middle Ear
Middle Ear contains _____________________ forming a flexible, bony bridge that transmits vibrations from the tympanic membrane to the oval window
auditory ossicles (malleus, incus, stapes)
In the middle ear 2 muscles attached to the malleus help dampen vibrations
caused by loud noises, protecting the?
delicate inner ear structures
As a person changes altitude, sounds seem muffled and the person may experience?
ear pain
consists of interconnecting tunnels and chambers within
the temporal bone (bony labyrinth)
Inner Ear
Inside the bony labyrinth is a smaller set of membranous
tunnels and chambers called?
the membranous labyrinth
The membranous labyrinth is filled with a clear fluid
called?
endolymph
The space between the membranous and bony
labyrinths is filled with a fluid called?
perilymph
Bony labyrinth can be divided into three regions:
Cochlea - involved in hearing
Vestibule - balance
Semicircular canals - balance
Process of hearing involves two major steps:
- Conduction of sound waves
- Stimulation of hearing receptors
What happens in Conduction of sound waves?
involves structures of the outer, middle, and inner ears
What happens in Stimulation of hearing receptors?
occurs in the inner ear
The senses of hearing and balance are both transmitted by the vestibulocochlear nerve (VIII).
Neuronal Pathways for Hearing
associated with the vestibule; involved in evaluating the
position of the head relative to gravity
Static equilibrium
associated with the semicircular canals; involved in evaluating changes in the direction and rate of head movements
Dynamic equilibrium
Static equilibrium and Dynamic equilibrium are components of?
Balance
Type of conjunctivitis by Chlamydia; leading cause of infectious blindness in the world; transmitted by contact or flies.
Trachoma
Infection of eyelash hair follicle
Stye
Nearsightedness; caused when refractive power of cornea and lens is too great relative to length of eye.
Myopia
Farsightedness; caused when cornea is too flat or lens has too little refractive power relative to length of eye.
Hyperopia
Cornea or lens is not uniformly curved, so image is not sharply focused.
Astigmatism
One or both eyes are misdirected; can result from weak eye msucles.
Strabismus
Clauding of lens as a result of advancing age, infection, or trauma; most common cause of blindness in the world.
Cataract
Loss of sharp central vision, peripheral vision maintained; leading cause of legal blindness in older Americans; most causes not known.
Macular degeneration
Involves optic nerve degeneration, cataracts, retinal detachment; often caused by blood vessel degeneration and hemorrhage.
Diabetic retinopathy
Separation of sensory retina from pigmented retina; relatively common problem; may result in vision loss.
Retinal detachment
Phantom sound sensations, such as ringing in ears; common problem.
Tinnitus
Vertigo, hearing loss, tinnitus, and feeling of fullness in the affected ear; most common disease involving dizziness from inner ear; cause unknown but may involve a fluid abnormality in ears.
Meniere disease
