What are the special senses in humans?
How do special senses differ from general senses?
General:Scattered throughout the body, and relatively simple in structure
Special: are localized by their respective sensory organ.
What is the sequence of structures and fluids that light rays must pass through to reach the retina?
conjuctiva, cornea, anterior segment, margin of pupil, lens, ciliary body, ciliary process, ciliary zonule, posterior segment, retina.
Which of the eye structures does most of the refraction of light rays?
What is astigmatism?
a condition in which unequal curvatures in different parts of the cornea or lens of the eye lead to blurred vision.
How does the ANS control pupil diameter?
The parasympathetic controls constriction and the sympathetic controls dilation
How does the ANS control changes in lens shape during accommodation (how does the ciliary muscle change lens shape when viewing a near versus distant object)?
For near objects, the ciliary muscle relaxes and the lens flattens.
For distant objects, the ciliary muscle contracts and the lens bulges.
What are the layers of cells that constitute the retina?
horizontal, bipolar, amacrine, and ganglion cells
In which direction does light pass through these cell layers in the retina?
horizontal, bipolar, amacrine, and ganglion??
Which neurons of the retina form the optic nerve?
How do rods and cones differ anatomically?
Rods contain rhodopsin; they are for black and white.
Cones contain retinal; they are for colors.
What is the outer segment?
contains visual pigment molecules
What is photodissociation?
bleaching of visual pigments
What is rhodopsin?
visual pigment made of retinal and opsin
What is retinal?
protein derived from vitamin A
What is opsin?
protein that helps make up rhodopsin and is activated by light.
Why is vitamin A important for vision?
retinal comes from vitamin A
What vision problem occurs as a result of vitamin A deficiency?
What is responsible for dark adaptation?
How are action potentials (nerve impulses) generated in the optic nerve when light strikes the photoreceptors?
phototransduction closes the Na channels; no release of inhibitory neurotransmitter
What are the types of cones?
red, green, blue
How do the different types of cones differ?
Each type contains retinal attached to different types of opsin
red(560 nm), green(530 nm), blue(420 nm)
What anatomical features of the retina are responsible for producing high visual sensitivity?
What anatomical features of the retina are responsible for producing high visual acuity?
What are the relative distribution of rods and cones in the retina?
way more rods than cones
What is the extent of neuronal convergence from these photoreceptors to the ganglion cells?
Extensive neuronal convergence from rods; no neuronal convergence from cones.
What is myopia?
What is hyperopia?
What produces conditions of hyperopia?
the eye is too short
How do corrective lenses compensate for myopia?
How do corrective lenses compensate for hyperopia?
What is glaucoma?
inadequate drainage of aqueous humor
What produces glaucoma?
high intraocular pressure damages optic nerve
What is cataract?
inadequate delivery of nutrients to deeper lens fibers
What produces cataract?
clumping of crystallin proteins
What types of receptors are responsible for the sense of taste?
taste buds aka taste cells or taste hairs
What types of receptors are responsible for the sense of olfaction?
How are taste receptors stimulated?
dissolved molecules bind to protein receptors
How are olfaction receptors stimulated?
volatile molecules bind to protein receptors
How many different odors can humans distinguish?
more than 1 trillion
How many different tastes can humans distinguish?
What are the tastes that humans can distinguish?
salty, sweet, sour, bitter, savory
What structures are located in the outer ear region?
auditory canal, tympanic membrane
What structures are located in the middle ear region?
tympanic membrane, auditory tube, oval window
What structures are located in the inner ear region?
oval window, cochlea, auditory tube
What is the sequence of events that leads to generation of action potentials in cochlear nerve?
Sound waves vibrate tympanic membrane, the vibration moves ossicles, stapes move oval window, pressure waves created in fluid inside cochlea, pressure waves in cochlear fluid move the basilar membrane, hair cells in spiral organ are bent, bending of hair cells opens K+ channels of sterocilia, K+ inflow --> depolarization --> Ca influx --> release of glutamate --> APs in cochlear nerve fibers
What are the sensory receptor cells for hearing?
cochlear hair cells
Where are the sensory receptor cells for hearing located?
cochlea of the inner ear
How does transduction occur in hearing receptors?
outer modify responsiveness of inner
What is the reflex mechanism for preventing damage to hearing receptor cells when you are exposed to very loud sounds?
stapedius and tensor tympani limit movements from loud sounds
How does the ear detect differences in pitch of sound?
high pitch stimulates basilar membrane close to the oval window
low pitch stimulates basilar membrane farther from oval window
What types of problems can lead to conduction deafness?
auditory canal blockage, inflamed middle ear, abnormal bone growth near middle ear, damage to tympanic membrane
What types of problems can lead to sensorineural deafness?
loss of cochlear hair cells
Which structures of the inner ear are involved in sensory perception for balance?
hair cells in the inner ear
What are the sensory receptor cells for balance?
hair cells, visual receptors, somatic receptors(proprioceptors)
Where are the sensory receptor cells for balance located?
ear, eyes, neck, trunk, limbs
What are the stimuli for the balance (vestibular) receptors in these structures?
gravity and inertia
What are the motor responses for vestibular information?
reflexive eye movements, motion sickness