Sense Organs Flashcards
What two subcategories fall under conscious control ?
Special senses and somatic senses
What are the special senses(conscious) ?
vision, hearing, taste, smell, and equilibrium?
What are the somatic senses(conscious)?
Touch/pressure, temperature, pain, and proprioception.
What two subcategories fall under unconscious control?
Somatic stimuli and visceral stimuli
What is somatic stimuli(unconscious) ?
muscle length and tension
What are the visceral stimuli(unconscious)?
blood pressure, ph/oxygen content in blood , ph of CSF, lung inflation, osmolarity of body fluids, and blood glucose.
Describe a simple receptor
neurons with free nerve endings
Describe a complex neural receptor
nerve ending enclosed in connective tissue capsules
Describe special senses receptor
cells that release NT onto sensory neurons initiating an action potential
What are the three kinds of unencapsulated nerve endings? What do they do?
free nerve endings(warm cold, pain receptors) , tactile discs(associated with base if epidermis) , and hair receptors(monitor movement of hairs).
What are the four encapsulated nerve endings?
ruffini corpuscles, tactile (meissner) corpuscles ,krause end bulb, and lamellated (pacinian) corpuscles
True or false unencapsulated nerve endings are found as receptors for the general sense. Their Dendrites are not wrapped in connective tissue
True
What are ruffini corpuscles for ?
heavy touch, pressure, joint movements &; skin stretching
what are tactile (meissner) corpuscles for?
light touch &texture
what are krause end bulbs for?
tactile corpuscles in mucous membranes
what are lamellated (pacinian) corpuscles for?
deep pressure, stretch, tickle & vibration
True or false the Dendrites on encapsulated nerve endings are wrapped by glial cells or connective tissue
True
What are the 4 characteristics of receptors?
modality(type of stimulus), location of stimulus, intensity (frequency of firing), and duration.
What are phasic receptors
give burst of activity &quickly adapt
What are tonic receptors
adapt slowly & generate impulses continually
True or false all receptors are transducers
True, they convert one form of energy to another.
What are the 5 modality receptors?
chemoreceptors, thermoreceptors, nociceptors(pain), mechanoreceptors and photoreceptor
What are the 2 distribution receptors ? what do they do?
general (somesthetic) sense(widely distributed), special senses (limited to head)
What do exteroreceptors pick up ?
touch, pressure, pain, temperature, special senses
What are merklel’s discs?
free nerve with disc shaped ending deep in the dermis and are for light touch
What are meissner’s corpuscles ? Where are they found?
dermal papillae of hairless skin(lips,nipples, and finger tips) They respond to light pressure and discriminate touch .
What are krause’s end bulbs? Where are they found?
in the mucosa EX. mouth, conjuctiva, hairless skin near body openings. They detect the same as the meissner’s.
What are pacinian corpuscles? where are they found?
in hypothermis, respond to deep pressure and stretching . Respond only when pressure is first applied.
what are ruffini’s corpuscles? where are they found?
Found in deep dermis , hypodermis, and joint capsules. They detect the same as the pacinian
What are examples of interoreceptors and what do they detect?
free nerve endings and pacinian corpuscles , they detect pain ,discomfort, stretching tissue, and temperature.
When responding to internal stimuli in muscles and joints what 3 groups monitor the degree of stretch?
muscle spindles, golgi tendon organs, receptors in joint capsules.
What are 1st order neurons?
afferent neurons that are large, fast, and myelinated
What are 2nd order neurons ?
decussate, and synapse at the thalamus.
What are 3rd order neurons?
go from the thalamus to the post central gyrus (somesthetic cortex)
Describe a heat and cold neuron and where they decussates
small, slow, unmyleinated, decussate at entrance of spinal cord
Define adaptation
When the frequency of receptor firing declines after prolonged stimulus exposure.
Define Tonic receptors and give an example of one
adapt slowly and generate nerve impulses more steadily. proprioceptors are among the slowest to adapt cause they have to always take into account body position.
Define phasic receptors and give an example of one
generate a bunch of action potential when 1st stimulate, then quickly adapt, and sharply reduce, or halt signal transmission even if stimulus continues. smell receptors adapt quickly.
Define receptor field
The region within a tactile stimulus evokes a sensory response in the cell or its axon.
How can you measure receptor fields ?
two pint discrimination (poke person with compass and ask if it was two poke or one)
True or false temperature sensitivity is uniformly distributed
False it is NOT evenly distributed
True or false there are more cold receptors than warm receptors
True
True or false temperature receptors can adapt
True
Were does somatic pain arise ?
skin, muscles, and joints
Injured tissues release release what chemicals that stimulate pain fibers?
bradykinin, histamine, protaglandin
What is the projection pathway for neurons?
1st order cell bodies on dorsal root release chemicals (glutamate or substance P)
2nd order decussate up spinothalamic tract to thalamus
3rd order reaches post central gyrus
What is referred pain?
misinterpreted pain . Brain assumes pain is coming from the skin not the organ
What three parts of the spinal cord (transverse section) are part of the somatosensory pathways?
Posterior, anterolateral coulmmns on the spinal cord
The axon that ascend within the fasciculus gracilis and fasciculus cuneatus of posterior column relay information to the thalamus via what ? (somatic pathway in spinal cord) and what kind of information does it carry ?
medial lemniscus .Carries fine touch, pressure and proprioceptive sensations
Describe the anterolateral pathway . What kind of information does it carry ?
axons decussate in spinal cord and ascend within anterior and lateral spinothalmic tracts and head toward ventral nuclei of the thalamus. carries poorly localized sensations of touch pressure, pain, and temperature.
true or false, intensity of pain is affected by the state of mind
True
Where are pain receptor sites found in the spinal cord ?
Pain signals are found in the central gray of midbrain and the dorsal horn of the spinal cord
spinal ______ stops pain signals at dorsal horn
Gating
What are the three primary pain signals
primary somesthetic cortex, sometsthetic association area, hypothalamus and limbic system, and reticular formation .
what does the spinocerebellar pathway do ?
includes posterior and anterior spinocerecellar tracts and carries sensation to the cerebellum concerning position of muscles, tendons, and joints.
Gustation
sensation of taste resulting from the action of chemicals on the taste buds
how many kinds of lingual papillae are there ? What are their names.
filiform, foliate, fungiform, and circumvallate
What lingual papillae is the most abundant? What is its function? Do they have taste buds?
Filifiorm papillae look like tiny spikes without taste buds, appreciates texture of food.
What lingual papillae mostly degenerate by age 3 ? Do they have taste buds?
Foliate papillae , weakly developed in humans, forms parallel ridges in back of tongue. No taste buds
What lingual papillae is at the tip and sides of tongue?
fungiform papilae , theyre mushroom shaped
What lingual papillae has only 7-12 on your tongue but contains 250 taste buds each?
Circumvallate papillae. They are arranged ina v at the rear of the tongue
Describe hairy tongue and what causes it .
Tobacco staining in the filiform papillae from smoking or antibiotics. Only treatment is to stop smoking and brush tongue.
Describe geographic tongue and what causes it.
Loss of filiform papilae leaving atrophic tongue . Caused by life stress.
Describe furrowed tongue and what causes it
furrows get more prominant with old age and in the furrows bacteria can accumulate causing malodor . There is no treatment aside from brushing tongue.
Describe smooth tongue and what causes it
smooth, caused by vitamin B deficiency and anemia
What are the three kinds of cells in the taste bud structure ?
taste , supporting, and basal cells.
True or false taste buds synapse with sensory nerve fibers at their base
True
True or false taste buds are neurons that synapse with sensory neurons .
False , taste buds are epithelial cells.
What are taste hairs?
microvilli that serve as receptor surface for taste molecules in taste cells
what is a taste pore ?
a pit on the epithelial surface of the tongue
What is the purpose of supporting cells?
contain microvilli and secreare substances into lumen of taste bud
What is the purpose of basal cells?
replace degenerated taste cells every 7-10 days
To be tasted molecules must _____
dissolve in saliva
What re the 5 primary sensations?
salty, sweet, sour, bitter, and umami(taste of an amino acid )
Sweet tastes concentrated on what part of the tongue?
Tip of the tongue
salty tastes & sour are concentrated on what part of the tongue.
lateral margins of tongue
Bitter tastes are concentrated on what part of the tongue?
rear part
True or False sugars and umamI flavors bind to receptors and activate 2nd messenger systems
true
True or false sodium and acids penetrate cells and depolarize them
true
The facial nerve(VII)controls for what part of the tongue ?
anterior 2/3 of the tongue
The glossopharyngeal (IX) controls what part of the tongue?
posterior 1/3
What part of the mouth does the vagus nerve (X) control?
palate, pharynx, and epiglottis
Where do all the fibers project to?
solitary nucleus in the medulla
Where do CELLS project to for autonomic reflexes ?
thalamus and amygdala
Were do CELLS project to for sense of taste ?
thalamus and post central gyrus
what triggers the production of a second messenger in smell?
volatile molecules binding to an olfactory receptor
how are receptors able to quickly adapt in the olfactory bulbs?
Synaptic inhibition
where do the axons of the bulb cells of the olfactory tract lead to? what is it responsible for?
leads to temporal lobe, amygdala, & hypothalamus. They are responsible for cough, salivate, sneeze or vomit in response to odors. emotional responses to odors
For what does the cerebral cortex sends feedback to bulb cells
changing quality &; significance of odors when hungry
what are the olfactory projection pathways ?
Hippo campus (conscious perception), Amygdala (emotional response), Reticular formation (visceral response), olfactory cortex of temp. lobe (conscious perception )
True or false Receptor cells for olfaction form olfactory mucosa. What does the mucosa cover ?
True , superior concha and nasal septum
What are olfactory cilia called?What are they for?
olfactory hairs . The cilia are binding sites for odors (volatile molecules)
True or false Olfactory receptor cells are neurons with a modified dendrite
True
What kind of neurons are olfactory hairs? (polar)
They are bipolar neurons that transduce chemical sensations into neural signals
What nerves are the only kind to be directly exposed to the external environment?
olfactory hairs
What are the other cell types present in olfactory epithelium(in mucosa ).
supporting cell, basal cell, olfactory cell
What is the purpose for the supporting cell?
provides physical and nutritive support, its ciliated
What is the purpose for the basal cell?
glial element (glue) they also differentiate into new olfactory cells every 60 days.
Granule cells receive signals from the cortex and are ________ to the mitral cells (causing adaptation)
Inhibitory
The axons from what cells form bundles called the olfactory tract
the mitral and tuft cells
What is sound?
Any audible vibration of molecules
molecules in the air connect with what in the ear making it vibrate?
Tympanic membrane
True or false sounds grater than 90 decibles (dB) can cause damage
true
what gives us sense of pitch?
frequency of the ear vibrating
What is “loudness” ?
perception of sound intensity
How are waves categorized?
frequency and intensity
What is frequency?
greater the frequency the higher the pitch, measured in hertz (cycles per sec.)
What is intensity ?
directly related to amplitude of sound waves, measured in decibles.
What part of the ear directs vibrations down the auditor canal ?
Auricle/pinna (your whole outer ear)
What are the three regions of the ear?
Outer, middle, and inner.
What is the purpose of the outer and middle ear?
transmission of sound into inner ear.
What is the purpose of the inner ear?
converts sound into fluid motion and then to electrical impulses(action potential)
Why is the tympanic cavity thats filled with air connected to the nasopharynx?
to equalize air pressure on both sides of eardrums . Done by yawning and swallowing.
True or false the stapes is attached to the eardrum ?
True
True or false the incus and stapes is attached to the oval window
True
How is the cochlea protected ?
Tensor tympani pulls eardrum inward to reduce mobility of ear bones .
What is the smallest muscle in the skeletal body?
stapedius , connects to stapes and reduces its action . Contracts before speaking and chewing.
What CN innervates the stapedius muscle?
CN VII facial nerve
What CN innervates the Tensor Tympani muscle?
CN V Trigeminal , madndibular branch(V3)
What is a Myringotomy tube for?
Equalization of air behind the eardrum so it doesn’t build up with fluid and cause hearing disorders.
How is sound in the inner ear produced ?
vibrations of ossicles and basilar membrane under hair cells
What portion of the cochlea is responsible for the ascending fluid (perilymph)?
scala vestibuli
What portion of the cochlea is responsible for the descending fluid (perilymph)?
scala tympani
what structure is found inside the cochlear duct?
Organ of cordi
What is the name of the fluid inside the cochlear duct (cochlear duct is in between the scalas) ?
endolymph
How are stereocilia depolarized ?
Movement of the tectorial membrane moves the embedded cilia tips causing an influx of potassium which depolarizes and releases NT. stimulating sensory dendrites
What NT is released when stereocillia are depolarized ?
glutamate
What lobe is the site of conscious perception ?
Temporal
Define equilibrium
control of coordination and balance
Define static equilibrium
perception of head orientation perceived by macula
Define dynamic equilibrium
perception of motion or acceleration perceived by macula and crista
What does the vestibular apparatus maintain?
maintains body at equilibrium and stabilize the eyes relative to the environment .
What two structures does the vestibular apparatus have ?
otolithic organs(static) and semicircular canals(dynamic)
What structures does the macula consist of?
sensory hair cells and supporting cells (sustentaculare cells ) for keen vision and contains fovea
Define Utricle
irregular oblong membraneous sac on the medial wall of vestibule , most sensitive to horizontal acceleration.
What is the otolithic membrane and where does it sit?
gelatinous membrane, produced by sustenticular cells, that sits on top of sensory cells.
What are otoliths?
Crystals of calcium carbonate that are sensitive to horizontal movements
Define saccule
flattened membranous sac located in the medial wall of the bony vestibule. Most sensitive to vertical movement
What direction is the saccular macula most sensitive to?
Vertical, Up, down, forward, and back
Describe Crista Ampullaris
Hair cells buried in a mound of gelatinous membrane
True or Flase ?Hair cells of macula sacculi, macula utriculi & semicircular ducts synapse on vestibular nerve
True
What is vision (sight)?
Perception of light emitted or reflected from objects in the environment.
What do tarsal glands secrete?
Oil that reduces tear evaporation (white krusties in the morning)
True or False the conjunctiva is highly vascular
True
What are the three layers of the tunic (eyeball)?
Tunica Fibrosa, Tunica Vasculosa, Tunica Interna
What consists of the Tunica Fibrosa?
Scalera and cornea (avascular)
What consists of the Tunica Vasculosa?
Choroid, ciliary body and iris (Vascular)
What consists of the Tunica Interna?
Retina
what is aqueous humor?
serious fluid produced by ciliary body that flows from post. chamber through pupil to ant. chamber
what reabsorbs left over aqueous humor ?
Canal of schlemm (Sclera Venous sinus)
What is deep to the sclera and is highly vascular?
Choriod (vascular tunic)
The choroid continues to the anterior portion of the vascular tunic and becomes what structure?
Ciliary body
What secrets aqueous humor?
Ciliary processes in the ciliary body
What part of the ciliary body are the suspensory ligaments?
Zonular fibers
What is the function of the ciliary muscle?
Contracts and relaxes to alter the shape of the lens to adapt for near or far vision
What is the function of the iris ?
Regulates the amount of light entering the pupil (suspended between the cornea and lens)
Describe optic disc
Site where the optic nerve and retinal artery and vein enter and exit the eye (blind spot)
What does the neural apparatus include?
The retina and optic nerve
What is the function of melanin in the retina ?
Absorbs stray light and prevents reflection allowing for sharp images
What are the three layers of retinal neurons from superficial to deep?
Photoreceptor layer, Biopolar cell layer, and Ganglion cell layer
What are the two types of photoreceptors ?
Rods and cones
Explain rods
low light threshold, good for dim light, NO COLOR, and shades of gray
Explain cones
higher light threshold, color vision, difficult seeing in dim light
True or False? The loss of cones causes visual legal blindness
True
True or False? There are more rods than cones
True, 120 million rods to 6 million cones
Define Macula Lutea
Exact center of posterior retina
Define Central Fovea
Small depression in center of Macula Lutea that contain only cones.
True or False? the Macula Lutea contains ONLY cones
True
Where is the lens located?
Behind the pupil and iris
What divides the internal eye into Anterior and Posterior cavities?
The lens
What is the purpose of aqueous humor and where is it found?
Nourishes the lens, provides intraocular pressure and is found in the anterior cavity of the interior eye
What maintains the shape of the eyeball and prevents it from collapsing?
Intraocular pressure
What is the function of vitreous body ?
A jelly-like substance that contributes to intraocular pressure that holds the retina flush against the choroid
True or False? Vitreous body does not undergo constant replacement
True
Define hyaloid canal
narrow channel that was occupied by the hyaloid artery in the fetus
What type of cells remove debris from the vitreous body?
Phagocytic cells
Image formation involves what four things?
Refraction, accommodation, light control, and convergence
True or False? The cornea refracts more light than the lens
True
True or False? Lens shifts focus between near and distinct objects
True
What kind of vision is Emmetropia?
Normal distant vision
what is Myopia?
Nearsightedness, focus power to strong, or eyeball to long,
what is hyperopia ?
Farsightedeness, focus power to weak, or eyeball to short.
Define Astigmatism
Caused by an unevenly shaped eyeball, cornea, or lens
Define Presbyopia
At an old age the lens loses elasticity and its ability to accommodate
Define Cataracts
clouding of the normally clear lens of the eye
Define convergence
Both eyes looking at the same object
Describe the Photopupillary reflex
Both pupils constrict when one eye is illuminated (parasympathetic reflex)
What does the constriction of the pupil prevent ?
doesn’t allow peripheral light rays in and reduces aberrations(blurry edges)
How is the lens accommodated ?
Contraction of ciliary muscle relax the suspensory ligaments and allows the lens to relax into a convex shape allowing light to refract strongly onto the retina as needed.
What kind of lens do you need to correct hypertropia?
convex lenses
What kind of lens do you need to correct Myopia ?
concave lenses
Define photo-pigments, where are they found?
integral proteins in the plasma membrane of the outer segment
Define rhodopsin
photopigment in rods (outer segment)
Define photopsin or iodopsin
there are three types one for each type of cone
What two parts do all photopigments contain ?
opsin, and retinal
What does opsin do?
one for each color and one for rhodopsin , 4 all together. They absorb different wavelengths (different colors)
What wavelength is perceived as Red by opsin?
long wavelengths
What wavelength is perceived as Green by opsin?
middle wavelengths
What wavelength is perceived as Blue by opsin?
short wavelengths
What does retinal in a photopigment do? Why do they store vitamin A?
The part of the photopigment that absorbs light. Vitamin A is stored in photopigmented cells for regeneration in rods
Why do you feel pain when you turn on a bright light in the middle of the night ?
Your pupil was dilated at the time you were exposed to the bright light and over stimulated your retina.
In dark adaptation why cant you see well at first when the lights are turned off?
The rhodopsin was bleached (it was seeing white and when the lights turned off they were resting meaning you only saw pitch black until they recovered) but returns to it maximally possible sensitivity in the dark in 20-30 min.
Upon illumination what happens to the CNG channels?
The CNG channels close and the photoreceptor hyperpolarizes
In the dark what happens to the CNG channels?
The CNG(in the plasma membrane) channels are kept open by cGMP and the cell depolarizes.
What part of the photopigment is activated with bleaching.
Opsin
List the chain of events that causes the CNG channels to close when light enters the eye
The light enters and activates rhodponsin wich activates transducin, which activates phosphodiesterase which breaks down cGMP (keeps the gate open) into GMP which no longer can keep the gate open so therefore closes in the day
Bipolar cells synapse with what other 3 cells
rods, cones, and ganglion cells
What are the largest neurons of the retina?
Ganglion cells
What are horizontal and amacrine cells responsible for?
enhancing perception contrast, edges of objects, and changes in light intensity.
Describe the shape of rhodopsin when it is cis-retinal
the shape is bent
Describe the shape of rhodopsin when it is transretinal?
it is straight , becomes straight when bleached
What is the shape of rhodopsin when it is bleached?
It is straight, trans-retinal
How does a patient fail the webers test?
they fail to hear the tuning fork equally in both ears
If a person cant hear the tuning fork well in one ear meaning they have failed the webers test where can you place the tuning fork to where they can hear it ?
You can place the tuning fork on the mastoid process. If they do hear it when placed on the bone easier then when placed on the ear , they still failed the test, and something is wrong.
What do rods produce in the dark that causes no signal in the optic nerve?
a steady ion flow that causes a IPSP
What causes the dark current to cease ? (in the rods)
When the light hits the rods the dark current ceases and no longer inhibits EPSP.
Photorecpetors are derived from stem cells that produced what neuroglia?
ependymal cells
Bipolar are __ order neurons and Ganglion are __order neurons.
Bipolar 1st ganglion 2nd . Everything converges down to the ganglion neurons that make up the optic nerve.
What is the ratio of rods to bipolar cells? How does this ratio affect your vision?
600 rods to one bipolar cell. The convergence of all the rods onto one bipolar cells creates mixed messaged due to spatial summation resulting in low resolution.
Photopic is to ____ vision and Scotopic is to____ night vision.
Photopic is to day vision, Scotopic is to night vision.
True or false there is are rod cells in the fovea
False
True of false each foveal cone cell has its own private line to the brain
True, no neural convergence.
True or false foveal cones are less sensitive to light intensity.
True
Do nocturnal vertebrates have cones ?
No they only have rods
What is the perception of color?
perception of color is based off of a mixture of nerve signals.
True or false is color blindness hereditary?
Yes, males carry the gene and in general 8% has the recessive gene .
Where doe conscious visual sensation occur?
Visual cortex
Where are the 3rd order neurons for the eyes?
lateral geniculate nucleus of the thalamus
what does the association areas in parietal and temporal lobes process what types of visual data?
object location, motion, color, shape, boundaries, and store visual memories (recognize printed words).
Macular degeneration is most common in who?
old people and is the leading cause of blindness
What causes Macular degeneration?
degeneration of pigmented epithelium leading to leakage of fluid behind macula and fovea causing white spots.
Why cant ppl with macular degeneration read or see fine print?
The cones of the fovea die causing central visual loss.
what causes glaucoma
Anterior chamber of the eye cannot exchange fluid properly by the normal aqueous outflow. Pressure compromises the blood vessels of the optic nerve and eventually the axons of the ganglion cells so that these vital cells die.
What kind of treatment is essential for glaucoma ?
release of intraocular pressure
Describe Diabetic Retinopathy
side affect of diabetes that can cause blindness by blood vessels multiplying in uncontrollable ways.
What is the most common treatment of Diabetic Retinopathy ?
Laser treatment for stopping blood vessel proliferation and leakage of fluid into the retina
True or false Retinitis Pigmentosa is hereditary .
True
Why do patients with Retinitis Pigmentosa have tunnel vision?
The rods of the peripheral retina degenerate , causing night blindness, only the cones in the fovea are left resulting in the tunnel vision
What causes the rods to die in a patient with Retinitis Pigmentosa?
Thinned blood vessels at the optic nerve head (less blood supply causing atrophy of rods)
