Special Senses Flashcards
Olfactory receptor cells do what?
They detect odors
Supporting cells
sustain receptors
basal cells
Replace olfactory cells every 40-60 days
Lamina Propia
- Areolar connective tissue lay
- Houses Blood vessels, nerves and olfactory glands
Olfactory bowman glands
Help form mucous covering olfactory epithelium
Are olfactory receptor cells, Bipolar? Unipolar? or multipolar?
They are bipolar structure- single dendrite and unmyelinated axon
Where are chemoreceptors for a specific odorant housed
They are housed in the olfactory hairs- cilia projecting from receptor cell dendrite
What is the pathway of detecting smells
Mucous contains odorant-binding proteins——->odorant binds to protein——->protein stimulates receptor cells——>G-protein in receptor cell actiates adenylate cyclase & converts ATP to cAMP——-> cAMP leads to opening of ion channels for Na+, Ca2+ (depolarization)——> This triggers an action potential conducted to glomerulus
Secondary neurons carry signals of smell to what parts of the brain
- Cerebral cortex (perceive, and identify smell)
- Hypothalamus (visceral reaction to smell)
- amygdala (smell recognition, emotional reaction)
What is Gustation
The sense of taste
What are the four papillae of the tongue
- Filiform papillae
- Fungiform Papillae
- Vallate Papillae
- Foliate Papillae
short and spiked
No taste buds (no role in gustation); help manipulate food
Located on anterior two-thirds of tongue surface refers to what papillae of the tongue?
Filiform papillae
mushroom-shaped
Each contains a few taste buds
Located on tip and sides of tongue
Fungiform papillae
largest, least numerous
Contain most of the taste buds
Located in a row of 10–12 along posterior dorsal tongue surface
Vallate papillae
leaflike ridges
Not well developed
House a few taste buds in early childhood
Located on posterior lateral ton
Foliate papillae
How long do chemoreceptive receptor cells of taste buds usually live
7-9days
what are the 5 basic taste sensations
- Sweet
- salt
- sour
- bitter
- umani
What produces the “salt” taste
Produced by metal ions Na+ and K+
What produces the “Bitter” taste
Produced by alkaloids (unsweetened chocolate)
What produces the “umami” taste
This taste is related to amino acids producing meaty flavor
pathway for sweet, bitter and umami taste
- Tastant binds to specific cell membrane receptors
- G protein is activated causing formation of 2nd messenger
- Results in cell depolarization
Are the tastants for salt and sour molecules or ions?
Tastants for salt and sour are ions and depolarize the cell directly
What do depolarized gustatory cells release and what do they stimulate
- The release the neurotransmitter stimulating primary neuron in CN VII or CN IX
Two common defects of image formation
- Hyperopia- farsightedness
2. Myopia-near sightedness
What could be a result of weak extrinsic eye muscles
This can cause diplopia (double vision)
Extrinsic eye muscles are used in the convergence of the eyes
Describe the three actions involved in looking at objects of a distance greater than 20ft
- Eyes face forward (not converged)
- Lens is Flattened
- Pupil is relatively dilated
What are photopigments
These are light absorbing molecules
What are photopigments made of and do they all transduce the same wavelength?
They made of OPSIN protein and light absorbing retinal (made from vitamin A).
They do not transduce the same wavelength. Different pigment types have different opsins transducing different wavelengths
Do photoreceptors contain multiple photopigments or just one
- just one
Each photoreceptor has only one photopigment type
What do Rods contain?
Rods contain Rhodopsin
What are the three different types of cones and what kind of wavelength do they detect?
- Blue cones- Short wavelengths
- Green cones- intermediate wavelengths
- Red cones- best detect long wavelengths
Know the bleaching reaction and regeneration of rhodopsin
Refer to slides 23 and 24
Describe Dark adaptation
- Return of sensitivity to low light levels after bright light
- Bleached rods must regenerate rhodopsin
- May take 20 to 30 minutes to see well
Describe Light adaptation
- Process of adjusting from low light to bright conditions
- Pupils constrict, but cones initially overstimulated
- Takes about 5 to 10 minutes for full adjustment
Sound wave to never signal pathway
- Sound waves vibrate tympanic membrane
- Ossicles vibrate and transmit waves to oval window
- Fluid pressure waves in scala vestibuli push vestibular membrane causing pressure waves in endolymph of cochlear duct
- Specific regions of basilar membrane move (depending on sound wave frequency)
- Hair cells distorted, causing changes in neurotransmitter release
- Sensory neurons with axons in CN VIII are stimulated to fire
- Pressure is transmitted to scala tympani and absorbed by round window
Describe the stimulation pathway of the cochlear hair cell
- Inner hair cells contain ion channels at their tips and tip link proteins that connect them
- Hair cells are bathed in K+ endolymph that is far more positive than the fluid inside the cell
- When basilar membrane moves up, hair cells are pushed into tectorial membrane and their tips are tilted, pulling tip links
- Tip links pull open ion channel allowing K+ to diffuse into the hair cell and depolarize it
- Hair cell releases more neurotransmitter from its base, exciting the sensory neuron, which can fire action potentials
- When basilar membrane moves down, the process quickly reverses
What does loudness depend on?
Loudness depends on wave amplitude
- louder sounds create larger movements of basilar membrane
- the larger the movement the faster the nerve signal and larger number of stimulated cells
What creates the perception of sound
This is created by pressure waves vibrating objects
What is Pitch dependent on?
Dependent on the frequency of the vibrating object
-humans can hear 20-20,000 Hz
What do high frequency sounds excite? what do low frequency sounds excite?
High frequency excites cells in stiff basilar membrane
Low frequency sounds excite cells in flexible basilar membrane near apex
This creates variations in Pitch
What monitors our equilibrium
Equilibrium is monitored by vestibular apparatus: utricle, saccule, semicircular ducts
What do the Utricle and Saccule detect?
Static equilibrium and linear acceleration
What does the semi circular duct detect
angular acceleration
