Sensory System Flashcards
Mechanoreceptors
detect, stimuli related to touch, pressure,
vibration, proprioception
(information about body position
and movement), hearing,
equilibrium, and blood pressure
Thermoreceptors
detect changes in temperature
Photoreceptors
detect light on the retina of the eye
Nociceptors
detect pain,
usually as a result of physical or
chemical damage
to tissues
Chemoreceptors
have the ability to sense
chemicals, whether this is taste in the mouth, smell in
the nose, or chemicals in body fluids such as oxygen,
carbon dioxide, water and glucose
proprioceptors
a sensory receptor that responds to position and movement
cutaneous sensors
sensory receptor found in the dermis or epidermis
Hyposmia
reduced ability to smell, Free nerve endings of olfactory cells in nasal, mucosa are damaged over time
Outer Ear The auricle (pinna)
Shell-shaped Cartilage covered by thick skin. Collects and
transmits sound waves to middle ear, causing tympanic membrane to vibrate.
Outer Ear External auditory
canal
– Short, curved tube in temporal bone and filled with ceruminous glands Hairs and ear wax in external auditory canal prevent foreign materials entering ear
Outer Ear Tympanic membrane
(eardrum)
Thin connective tissue membrane that vibrates in response to sound. Transfers sound energy to the middle ear ossicles
Boundary between outer and middle ears.
Structure of the middle ear
Small, air-filled cavity in the temporal bone. Tympanic membrane separates middle ear from external ear Ov.al and round windows separate middle ear from inner ear.
Functions of the middle ear
- Transmit vibrations from tympanic membrane to fluid in the cochlea (inner ear) via vibration of ossicles.
- Equalizes pressures on both sides of tympanic.
-Middle ear provides protection from large vibrations.
Ear Ossicles
- The tympanic cavity contains three small bones: the malleus (hammer), incus (anvil), and stapes (stirrup)
- Transmit vibratory motion of the eardrum to the oval window
The inner ear structure
- Bony labyrinth
- Canals hollowed out of the
temporal bone - Contains 3 areas: the semicircular canals(equilibrium), the vestibule (equilibrium), and the cochlea (hearing)
- Filled with perilymph (similar to CSF)
The cochlea
- A spiral, conical, bony
chamber that:
– Extends from the anterior
vestibule
– Contains the cochlear duct,
which ends at the cochlear
apex
– Contains the organ of Corti
(hearing receptor)
Scala vestibuli
the scala vestibuli is a cochlear duct that runs along the length of the cochlea and is filled with endolymph. It is where sound vibrations from the oval window enter the cochlea and travel through the organ of Corti. It also contains the vestibular membrane which helps to regulate the pressure of the endolymph.
Scala media
the scala media is the longest cochlear duct and is filled with perilymph. It contains the organ of Corti, which is made up of sensory hair cells that detect sound vibrations and send signals to the brain. These signals are then translated into meaningful auditory information.
Scala tympani
the scala tympani is the shortest cochlear duct and is also filled with perilymph. It contains the basilar membrane which vibrates in response to sound waves, and this vibration helps to amplify the sound waves traveling through the duct. It also contains the tectorial membrane which helps to convert the sound waves into electrical signals. The electrical signals are then sent to the brain and are interpreted as sound.
Vestibular apparatus
equilibrium receptors in the
semicircular ducts and vestibule
Maintain our orientation and balance in space
Sclera
- Forms white of eye
- Tough fibrous coat
- Gives shape to eyeball
- Protects inner parts
– It is transparent and nonvascular, covers iris, It is the principal refractive medium of the eye
Choroid
- Choroid is pigmented and highly
vascularised - Nourishes retina
- Pigment absorbs light rays so they
do not bounce around in the eye - Posterior choroid continues
anteriorly - Anterior choroid – ciliary body and
iris
Iris
Colored part of eye.
Diaphragm between lens and
cornea
Alters pupil size
Retina
- Contains nervous tissue and
has pigment - Contains photoreceptors
- Role in image formation
- Macula lutea
– Small spot in the centre of the retina
– Contains a depression called the fovea
– Point of highest visual acuity
– High concentration of cone photoreceptors
Lens
- Transparent
- Located immediately posterior to iris
- Focuses light rays on retina for image formation
- Part of the refractory apparatus of the eye
- Enclosed by fibrous capsule
- Suspensory ligaments attach lens to ciliary body
Anterior cavity
– Filled with aqueous humor secreted from blood capillaries in the ciliary
body
– Maintains intraocular pressure
– Supplies nutrients to lens and cornea
Posterior cavity
– Filled with vitreous humor, jelly – like substance
– Contributes to intraocular pressure
– Holds retina flush against choroid
Conjunctiva
- Thin mucous membrane
- Lines eyelid and covers the front surface of the
eyeball, except the cornea - Produces lubricant and keeps front of eyeball moist
Describe the formation of an image on the retina.
Light enters the eye and passes through the cornea, aqueous humor, pupil, and lens. The light is then focused on the retina, a thin tissue layer at the back of the eye. The light is then converted into electrical signals by photoreceptor cells in the retina, which sends the signal to the brain where it is interpreted as an image.
Rod
- 20 times more numerous than
cones - Dim light, high sensitivity and
peripheral vision receptors - Does not provide sharp images
(low acuity)
Cones
- Less numerous than rods
- Operates in bright light, low
sensitivity, mostly central
receptors - Provides high clarity (high acuity)
and colour vision
Describe the pathway of the nervous impulses from the
photoreceptors of the retina to the brain
Photoreceptors in the retina transduce light into electrical signals, which are passed through the bipolar cells and then the ganglion cells. The axons of the ganglion cells pass through the optic nerve, then the optic chiasm, before continuing through the optic tract. The optic tract then enters the thalamus, before sending impulses to the visual cortex of the brain.
