Special Senses Flashcards
Explain the function of the eyelid, eyelashes, eyebrows , lacrimal caruncle and conjunctiva of the eye
Eyelid: protect from light, foreign objects, and assist in lubrication of the eye
Eyelashes: protect from foreign objects, sweat and light (can initiate blinking)
Eyebrows: protect from foreign objects, sweat and light
Lacrimal caruncle: protects underlying lacrimal tissue
Conjunctiva: ensures lubrication of the eye and inner eyelid
Name the three structures of the fibrous tunic
Cornea
Sclera
Canal of Schlemm
Name the three structures of the Vascular tunic
Choroid
Ciliary body
Iris
Name the four structures of the Retina
Photoreceptors
Macula lutea
Fovea centralis
Optic disc
What are the internal structures found in the eye
Anterior cavity
Posterior cavity
Lens
Name the structures and order involved in the pathway of light through the eye
- Ganglion cells
- Bipolar cells
- Photoreceptors (rods and cones)
- Pigment epithelium
What is accommodation?
Accommodation is the ability of the eye to change its focus distant to near objects (vis-versa). This is achieved by the lens changing its shape
What is the difference between rods and cones
Rods
- Most numerous
- operate in dim light
- do not discriminate colour
-many rods feed into single ganglion cell
Cones
- Less numerous
- Operate in bright light
- Discriminate colour (red,blue,green)
- One cone feeds into single ganglion cell
-Mostly found in fovea centralis
Name the 3 parts of the external ear
Auricle
External auditory canal
Tympanic membrane
Name the six parts of the middle ear
malleus
Incus
Stapes
Oval window
Round window
Auditory canal
Name the five parts of the inner ear
Bony labyrinth
Membranous labyrinth
Semicircular canals
Vestibule
Cochlea
What two structures house the receptors for equilibrium?
The vestibule and semicircular canals
Static equilibrium is monitored by?
The vestibule (utricle and saccule)
Dynamic equilibrium is monitored by?
semicircular canals
What does frequency and amplitude measure
frequency measures the pitch of sound
amplitude measures the loudness of sound
List the steps in order of stimulation of auditory receptors in the right ear
- Sound waves directed into external auditory canal via auricle
- Sound waves strike tympanic membrane causing vibrations
- Vibrations transmitted from tympanic membrane through ossicles
- Vibration of stapes at oval window causes movement of perilymph in scala vestibuli
- Movement of perilymph continues to scala tympani, pushing against round window
- Movement of perilymph in scala vestibuli causes vibration of vestibular membrane
- Vibration of vestibular membrane causes movement of endolymph in cochlear duct
- Movement of endolymph in cochlea duct causes vibration of basilar membrane
- Vibration of basilar membrane bends hair cells against tectorial membrane
Bending of hair cells generates receptor potential
What are the 4 functions of taste buds?
- Chemicals that stimulate gustatory receptor cells are called tastants
- Na+ ions in salty food enter receptor cells via Na+ channels in membrane
- H+ ions in sour foods enter receptor cells via H+ channels in membrane
- Sweet, sour and umami activate G proteins and second messengers
What cells provide the sense of taste?
Gustatory cells
Explain the functions of olfactory receptors?
- Odorant must be dissolved in mucous to bind to olfactory cilia
- Binding of odorant to olfactory cilia activates G protein
- Activation of G protein activates an enzyme which produces cAMP
- cAMP opens sodium channels on cilia and triggers depolarisation
What receptors are responsible for sense of smell?
Olfactory receptors
