Special Senses Flashcards
Describe the sensory pathway from receptor to brain.
A stimulus generates a receptor potential -> triggers an action potential in the sensory nerve -> Action potential travels to the brain where it is ”sensed”
How are receptor potentials different than action potentials?
The receptor potential triggers an action potential in the sensory nerve
Where are the special senses located?
Special senses are localized and
confined to the head region
What kind of papillae have taste buds?
Vallate (circumvallate) papillae, Fungiform papillae, Foliate papillae
Detail the pathway from receptor to cortex for gustation.
Taste receptors-> sensory nerve fibers in cranial nerves -> brainstem -> thalamus -> gustatory cortex (insula)
What contributes to the flavor of a substance?
Dissolved molecules in saliva enter taste pore -> Molecules bind to receptors on gustatory hair cells
What kind of receptor is involved with olfaction?
Chemoreceptors
What bone do the olfactory receptor cells pass through as they enter the brain?
Cribriform plate of ethmoid bone
Detail the paths from receptor to brain for olfaction.
filaments of olfactory nerve-> Enter CNS through cribriform plate of ethmoid bone -> Synapse with mitral cells in olfactory bulb at glomeruli ->Limbic system -> Primary olfactory cortex in temporal lobe
What are some disorders of smell?
Anosmia = absence of smell
Uncinate fits = olfactory hallucinations
Follow the flow of tears from production to drainage into the nose
Tears move across eye -> enter puncta -> Drain into lacrimal canaliculi -> Lacrimal sac -> Nasolacrimal duct -> Nasal cavity
What type of muscles help the eyeballs move?
Skeletal muscles
What is strabismus? What is amblyopia?
Strabismus = misaligned eyes (cross-eyed)
Amblyopia (reduced vision in the weaker eye “lazy eye”)
How does eye positioning influence 3D vision?
3D vision relies on both eyes working together to accurately focus on the same point in space. The brain is then able to interpret the image the each eye sees to create your perception of depth.
List from the outermost to the innermost layers (tunics) of the eye.
Fibrous tunic , Vascular tunic, Sensory tunic
What are the structures covered that make up the fibrous tunic?
Sclera, Cornea
What is a difference between the sclera and the cornea?
Sclera is the white opaque area surrounding the iris of the eye
The cornea is the clear covering of the eye over the iris
What are structures covered that make up the vascular tunic?
The structures of the eye that make up the vascular tunic is the Choroid and the Iris
How are blue and brown eyes different?
Darker colored eyes have more pigment in anterior region of iris. Light eyes have little to no pigment in the anterior region.
What makes up the ciliary body?
Ciliary muscle, Suspensory ligaments
What happens to the ciliary muscle and suspensory ligaments when looking at close objects? Distant objects?
Close objects: Ciliary muscle contracts, Suspensory ligaments slacken
Distant objects: Ciliary muscle relaxes, Suspensory ligaments become taut
What is the innermost tunic of the eye? What two layers make up this tunic?
Sensory tunic: Pigmented layer, Neural layer
Describe how the cells that make up the neural layer are oriented to each other. How does light entering the eyes travel through these layers? Which cells respond to light?
- Photoreceptor cells : Rods (Most numerous in periphery of retina) and cones (Concentrated in central part of retina)
- Bipolar cells : Activated by rods and cones
- Ganglion cells : Activated by bipolar cells
What cells form the optic nerve?
axons of ganglion cells
Compare rods and cones
Rods: Have most of these, Most sensitive to light, Sides of eye
Cones: Color, center of eye, works best in bright light
What is the blind spot?
The spot in your eye with no rods and cones since it is the entrance of the optic nerve
What is the optic disc? What kind of photoreceptors are found there?
Location at back of eye where axons of ganglion cells leave eye. No photoreceptors
What is glaucoma?
Condition where aqueous humor is drained slower than it is produced
What is another term for nearsightedness? What can cause this?
Myopic eye -> Eye may be too long, image focuses in front of retina
What is presbyopia?
Lens becomes less elastic with age—need bifocals
What happens with astigmatism?
Abnormal shape of corneal surface causes light rays to diffract differently
What is a cataract?
Lens becomes cloudy -> Most commonly due to age-related damage to the internal part of lens
What is the structure of the ear that is easily seen?
External ear
What are the glands that produce ear wax?
Ceruminous glands and sebaceous glands
The middle ear lies between what two structures?
The middle ear extends from the tympanic membrane to oval window
What are the ossicles, in order, as you move deep into the ear?
Malleus, Incus, Stapes
What connects the middle ear with the pharynx?
Pharyngotympanic tube
What are the muscles that dampen loud noises? What are they attached to?
Tensor tympani -> attaches to malleus
Stapedius -> attaches to stapes
What is a myringotomy?
A tube used to drain fluid in ears into throat
What are differences between the bony and membranous labyrinths?
Bony: Cavity in the petrous portion of temporal bone
Membranous: Continuous series of membrane-walled sacs
and ducts that fit loosely within bony labyrinth
What kind of fluid fills the membranous structures? The bony labyrinth?
Bony: perilymph
Membranous: endolymph
What are differences between inner hair cells and outer hair cells?
Inner hair cells: True receptors, transmit vibrations of basilar membrane to cochlear nerve
Outer hair cells: Tune and amplify signal (100X), Helps us hear faint signals, Can produce otoacoustic emissions, Used to test hearing in newborns
Where in the cochlea do high pitched sounds deflect the basilar membrane? Low pitched sounds?
- Low pitch (low frequency) sounds deflect deep into cochlea
- High pitch (high frequency) sounds deflect near entrance of cochlea
Which structure (utricle or saccule) is involved to vertical movements?
Saccule
What are otoliths and how are they involved with equilibrium?
Calcium carbonate crystals that add weight to membrane and cause more dramatic shift
What kind of stimuli do the semicircular canals respond to?
Are involved with rotational acceleration of the head
What structure in the semicircular canals has receptors?
crista ampullaris
What is vertigo and what can cause it?
feeling of motion when you aren’t moving
* Alcohol consumption changes viscosity of endolymph
* Infection (viral or bacterial)
* Otolith from maculae can become dislodged and eventually end up near crista ampullaris where they impact cupula function
What is the vomeronasal organ? What does it respond to?
Pheromone sense in nose
