Nervous System Part 2 Flashcards
(page 8)
label parts a and b of the labyrinth.
A: semi circular canals
B: vesibule
(page 8)
label membrane sacks found inside part a and b shown at 1 and 2.
1: ampullae (three total)
2: saccule, utricle
(page 8)
what tiny organ is found within structure one? what term is used to describe its role in maintaining balance for the body?
each ampullae contains the crista ampularis which is responsible for dynamic equilibrium.
what tiny organ is found within the two structures? what term is used to describe its role in maintaining balance for the body?
the saccule and utricle both contain the macculae which is responsible for static equilibrium.
define the terms dynamic equilibrium and static equilibrium.
dynamic equilibrium (by the crista ampularis) informs the brain of rotational movements. static equilibrium (by the macculae) informs the brain of changes in the head position (head tilt) plus horozontal and vertical movements of the body (linear movements) which includes changes in speed.
when talking about balance perception, the term vestibular apparatus is used. what does this mean?
the vestibular apparatus is the five organs used for balance perception- two macculae and three crista ampularis.
in the labyrinth image on (page 8) label parts c and 3 and name the organ that is found inside 3.
c is the cochlea and 3 is the cochlear duct and inside three is the organ of corti.
the macculae, organ of corti, and crista ampularis are all nearly identical in structure. what do they all have in common? which of the three has something unique in its structure and why?
all contain hair cells and neurons with stereocilia that produce action potentials. all have a bottom layer of epithelia in which the hair cells are sitting in a gel like roof that the stereocilia are imbedded in. the macullae, however, has teeny calcium crystals in the cell like membrane “roof” called otolits that allow the macculae to respond to the pull of gravity- to literally flop backward or forward, left or right, so that the changes in head position and changes in linear movements can be accuaratley detected.
(page 9)
as sound waves enter the ear, vibrations of several structures lead to fluid vibrations in the cochlea. list the sequence of structures ending with the structure which begins the fluid vibrations.
sound waves (air vibrations) that enter the external auditory canal start vibrations in the tempantic membrane which then passes the vibrations > malleous > incus > stapes > oval window (of cochlea). the mallous, incus and stapes are tiny bones known as the ear ossicles.
the process in which sound waves are directed to the cochlea is called sound wave conduction. this process includes pressure amplification of sound waves. what does this mean.
because air vibrations are being turned into fluid vibrations the energy of the air vibration needs to be increased. this is because it takes more effort to move fluid than air.
how does pressure amplification of sound waves take place?
the energy of the sound (air vibrations) is increased by transferring the vibrations of the tempanic membrane into a much smaller structure, the oval window of the cochlea. the oval window of the cochlea is about 1/20th of the ear drum. which means the energy of the vibration is increased by 20 percent. this increase is necessary to start the fluid vibrations inside the cochlea.
there are three conditions which commonly cause conduction deafness. what is the overall cause of hearing loss in this type of hearing loss? what are the major causes?
the conduction deafness hearing loss occurs when sound vibrations are prevented from reaching the cochlea. the major causes are otitis media, otosclerosis, and a ruptured typantic membrane. the last two are often caused by ottits media but may occur for other reasons.
besides the sound wave conduction, what other important activity are the ear ossicles involved in?
the ear ossicles can reduce the volume of extreme sounds (to avoid damage) by a process called the sound attenuation reflex.
describe how the ear protects itself from loud noises. include what controls this process.
sound attenuation reflex: the trigeminal and facial cranial nerves are both connected to the ear ossicles by teeny muscles. these nerves cause the muscles to contract which pulls on the ossicles and slows their vibrations reducing the ear bones vibrations lowers the volume of the sound being transmitted in to the cochlea.
what are the shortcomings (limits) of the sound attenuation reflex?
the sound attenuation reflex cannot protect against sudden explosive noises OR substained noised of longer than ten minutes. it only protects against slowly building noises, that are brief in length.
(page 11)
name the fluid found in the three ducts or chambers.
vestibular duct = perilymph
cochlear duct = emdolymph
tympanic duct = perilymph
(page 11)
which chamber has fluid vibrations that are started by the stapes at the oval window? how do the fluid vibrations reach the organ of corti and eventually exit cochlea?
the stapes knocks against the oval window- opening in the top chamber, or vestibular duct, which begins perilymph vibrations inside. the fluid vibrations are passed downward as follows: perilymph and vestibular duct > endolymph in cochlear duct (organ of corti location) > perilymph in tympanic duct > exit cochlea through round window of tympanic duct.
(page 11)
label parts a through f
a: basilar membrane
b: outer hair cell
c: stereocilia
d: tectorial membrane
e: cochlear nerve
f: inner hair cell
when the endolymph surrounding the organ or corti vibrates, what happens that allows us to hear sounds?
when the endolymph vibrates, it causes the basilar membrane to vibrate. vibration of the basilar membrane causes the hair cells to dance up and down which bends the stereocilia of the hair cells. this causes the inner hair cells to produce action potentials. these action potentials flow down the cochlear nerve into the brain and the brain hears sound because of them.
what is the cochlear amplifier? how is it related to inner hair cells and outer hair cells?
the cochlear amplifier is made up of three rows of outer hair cells (OHCs). the OHCs do not make the AP’s that are sent to the brain for hearing- only the IHCs do that. instead the OHCs amplify/enhance the performance of the inner hair cells- they help the IHCs select which sounds to pay attention to and allow the IHCs to distinguish between a large number of pitches. certain antibiotics damage the OHCs causing permanent hearing loss- which shows the OHCs importance in the hearing process.
(page 12)
how does the height, or amplitude, of a sound wave affect sound.
the amplitude of the sound wave is what determines sound volume.
(page 12)
what kind of sound is the sound wave marked with?
a short sound wave is a low amplitude wave or a soft (low volume sound).
how do inner hair cells of the organ of corti tell the brain whether a sound is loud of soft?
in response to soft sounds, hair cells fire of a small number of AP’s. (this is called a low frequency of AP’s). in response to loud sounds, hair cells fire off a large number of AP’s. (a high frequency of AP’s).
complete the sentence:
the louder the sound, the _____ the amplitude or _____ of the sound wave.
taller; height.
the brain can tell the difference between a soft versus a loud sound based upon the _____ of AP’s the organ of corti produces.
number (frequency)
(page 13)
how does a low pitch sound differ from a high pitch sound?
a low pitch sound has a small number of waves per second. therefore, a low pitch sound is a low frequency sound wave. a high pitch sound has a large number of waves per second or is a high frequency sound wave.
(page 13)
in the image above, which sound wave is a high pitched sound?
B.
(page 13)
how does the organ of corti tell the brain what the pitch of the sound is?
the specific part of the basilar membrane that vibrates is what tells the brain about the pitch of a sound. this also means that the pitch is determined by how far the sound travels down the basilar membrane.
(page 13)
how does the thickness of the basilar membrane change as you go from the front (the base) to its end (the apex)?
the basilar membrane gets increasingly thinner from start to end. it begins narrow and stiff at the base and thins until it is wide and floppy at its end, the apex.
(page 13)
what types of sounds can vibrate from the beginning (base) of the basilar membrane?
sounds with large numbers of waves per second have maximal vibrations at the base. this means high pitched sounds vibrate at the base. (notice the image says 20,000 hZ at the base- this means 20,000 waves per second). high frequency sound wave = high pitch sound.
what types of sounds can vibrate the end (apex) of the basilar membrane?
sounds with a small number of waves per second (low frequency) or low pitched sounds. (notice that the lowest pitch we can hear is a 20 hZ or 20 waves per second.)
what is a major cause of sensorineural deafness?
the major cause of sensorineural deafness hearing loss is the gradual loss/dissapearence of hair cells that occur with aging. sensorineural deafness: permanent hearing loss caused by damage to any type of neuron in the hearing pathway such as neuron damage in the cochleal (hair cells) cochlear nerve, and the brain stem.
what causes high frequency hearing loss? what is happening in the cocheal?
the innability to hear high pitch sounds occurs as a result of prolonged exposure to loud noises or is often due to a single sudden explosive sound. excessivley loud sounds have air vibrations that are so violent that they tear the stereocilia off of hair cells which causes the hearing loss.
what is the rarest type of sensineural deafness?
hearing loss due to neuron damage in the brain- specificallly damage in the auditory cortex of the temporal lobe.
what is tennitus? what is one theory about this cause?
tennitus is ringing, buzzing or clicking in the ears in the absence of incoming sound of that type. it is a sign of damage and or irritation of inner ear structures often occuring after exposure to excessively loud sounds. one theory is it is caused when damaged hair cells spontaneuously make their own noises which are called otoacoustic emissions. the inner hair cells fire off AP’s into the brain even though they are not being stimulated by sound waves- so they are producing their own noises out of thin air.
controls the skeletal muscles of the face
facial nerve
main nerve used to move the eyeball
ocularmotor
has ophthalmic maxillary and mandibular
trigeminal nerve
allows for hearing and balance
vestibulocochlear
moves the eyeball laterally
abducens
moves the tongue for speech
hypoglossal
main nerve used for taste
facial
allows for vision
optic nerve
moves the eye out and down
trochlear
has important role in the regulation of blood pressure and breathing rate.
glossopharyngeal, vagus
controls mastication muscles
trigeminal
regulated parasympathetic actions of almost all organs
vagus
moves the tongue during swallowing
glossopharyngeal, hypoglossal
has a section that crosses through the middle ear over the ear drum
facial nerve
allows eyes to focus on nearby objects
oculomotor
controls contractions of the trapezius and sternocleidomastoid muscles
accessory
interprets taste and sensation for the tongue
glossopharyngeal
main nerve for speech (controls larynx)
vagus (accessory helps)
provides facial sensory information
trigeminal
gets its name because it assists function of the vagus
accessory
allows for smell
olfactory
has five branches
facial nerve
has only motor functions
oculomotor, trochlear, abducens, hypoglossal, accessory.
has mixed functions
glossopharyngeal, vagus, facial, trigeminal
involved in speech
hypoglossal (tongue), vagus, accessory (larynx)
controls the sound attenuation reflex
trigeminal and facial
contains the substantia nigra
midbrain (mesencphalon) (substania nigra makes dopamine)
areas of diencephalon
thalamus, hypothalamus, pineal gland
intermost mininge (directly touches the surface of the brain and spinal chord)
pia mater
structure that filters blood to form CSF
choroid plexus (found in brain ventricles)
area that controls basic consciousness
reticular formation
cerebral lobe for hearing
temporal lobe
controls eating and drinking behaviors.
hypothalamus (hunger thirst and satiety centers)
space above the arachnoid mater
subdural space
sends AP’s from the eye, ear, and mouth to specific cerebral lobes so they can be turned into visual, auditory, and taste information.
thalamus (sensory relay center)
another name for the midbrain.
cerebral peduncles
controls sleep/wake cycle
pineal gland (produces seratonin and melatonin)
meninge composed of two layers one of which is the periosteum
dura mater
controls the sympathetic and parasympathetic nerve effects on the body
hypothalamus (major autonomic control center)
cerebral lobe for vision
occipital
most important area for long term memory information
limbic system (specific part is the hippocampus)
meninge where the major BV that supply the brain are found
pia mater (highly vascularized)
two areas which control breathing
medulla and the pons
four areas of the brain stem
medulla, pons, cerebellum, reticular formation
overall emotional center of the brain
limbic system
meninge that controls the velle which delivers CSF to the dural sinus
arachnoid mater
controls the release of pituitary gland hormones.
hypothalamus (endocrine system control center)
cerebral lobe for taste and smell
parital lobe
cavity where CSF is found
subarachnoid space (space between arachnoid mater and pia mater in vertebral cavity in cranial cavity)
important pathway for AP’s controlling skeletal muscle movements
cerebral peduncles
controls body temperature
hypothalamus
allows us to select or ignore sensory information espicially sounds
reticular formation
controls heart rate and blood pressure
medulla, hypothalamus (the medulla is the most important, it contains the cardiac center and vasomotor center. hypotalamus also alters HR and BP as part of its automatic control center functions)
meninge made of aeriolar CT
pia mater
a bridge for AP’s moving from the cerebrum to the cerebellum
pons
meninge which forms septa or partitions that prevent excessive movement in the brain and skull
dura mater
cavity where anesthesia is injected
epidural space (space above dura mater in vertebral cavity and cranial cavity)
controls the water balance of body using ADH
hypothalamus (ADH helps save water when dehydrated by affecting the kidneys)
meninge made of dense CT
dura mater
produces seratonin and melatonin
pineal gland (controls the sleep/wake cycle)
contains vital reflex centers
medulla (the vital reflex centers control heart rate and BP. also causes breathing. cardiac respiratory vasomotor centers.)
where the learning and planning of complex movements occur, controls posture and balance.
the cerebellum (gross motor coordination is the overall name for what the cerebellum of what the cerebellum is in charge of)
when the eye focuses, what really is happening is that the light rays from an object entering the eye are bent _____ so that they come together _____ on a small pit on the retina.
refracted; converge
what two main structures are responsible for bending the light rays in this manner? which of these is the most important in this rule?
cornea; lens. the cornea is the most important for refraction and convergence of light rays. the cornea has a refractive power of 42 diopters compared to a refractive power of 12 diopters for the lens.
the small pit in the retina that light rays must fall on, the ______ is surrounded by a yellow area known as the _____.
fovea; macula lutea
what change in shape occurs to the lens when the eye focuses on a nearby object?
the lens takes on a rounder shape
what causes this shape change in the lens?
contraction of the cilliary muscles (which are connected to the lens by suspensory ligaments)
the changes in the eye that occur for near vision are called _____ and are caused by _____.
accomidation; the oculomotor nerve
besides the change in lens shape, what else happens when the eye focuses for near vision? (during accomodation)
constriction of the pupil and inward rotation of the eyes (which is also called convergence of the eyes)
what three important aspects of vision are the cones in the retina responsible for?
vision and bright light, color vision, vision acuity. (a sharply focused image)
what two important aspects of vision are the rods in the retina responsible for?
vision in dim light, black and white vision.
what happens to rhodopsin, the photo pigment found in rods when it is exposed to bright light?
it stops sending AP’s to the brain. it turns off. bright light causes it to break apart into its components. (retinal and opsin) and lose its purple color. this is known as bleaching.
why does it take a few seconds for you to be able to see when you leave a bright room and walk out into the night?
since you have been in bright light, your rhodpsin is inactive. literally, broken in half. it takes a few seconds for it to be remade so the rods can produce AP’s in dim light, allowing you to see.
what is the focal distance of the eye? how is focal distance connected to eye shape?
focal distance is the distance it takes light rays to focus after entering the eye. this means the distance at which the light rays come together (converge into a point) on the fovea. (the cornea and lens are what determine the focal distance. the human eye has a focal distance on average of 22 mm.) assuming the cornea has the perfect shape/curvature causing the focal distance to be 22 mm. the human eye needs to be the perfect size for vision to be sharp/crisp.
what is the clinical term for nearsidedness? how can eyeball shape cause this problem? where is the image focused?
myopia. (squint eye vision) the eyeball is too long causing light rays to focus in front of the fovea. the normal foval distance (22 mm) is too short to reach the fovea and needs to be increased.
what type of lens is used to correct nearsidedness? how does the shape of the lens correct the problem?
a concave lens, or one that is relatively flat on both sides. a concave lens causes light rays that pass through to diverge or spread out. the concave lens increases the focal distance- allowing the light rays to travel farther before they focus- so they reach the fovea.
what causes hyperopia? where is the image focused?
hyperopia is farsidedness. the eyeball is too short. this causes the light rays to focus behind the fovea. the normal focal distance (22 mm) is too long and needs to be shortened. (hyperopia means excessive major vision. the idea that the light rays go too far past the fovea)
what kind of corrective lens is used to correct hyperopia?
a convex lens that is round.
how is presbyopia, which is age related farsidedness, different from hyperopia or regular farsidedness?
presbyopia (old man vision) begins to develop in the mid 40’s because the lens has lost elesticity. as we age, the lens becomes less flexible because more crystallines are added to it. this means it can no longer take on the round shape it needs (during accomodation) to properly focus for near vision.
what two eye disorders can be caused by diabetes?
cataracts and retinal detachment (degeneration)
astigmatism occurs with myopia or hyperopia. it results in blurring of an image either vertically or horozontally. what causes this?
the cornea that is aspheric or asymmetric. this means it may be flattened on one side or that its overall curvature is more oval than round.
lens turns milky or opaque in color
cataracts
blurring of images caused by the eyeball being too short
hyperopia (farsidedness)
a hole that develops in the center of visual field.
maccular degeneration
caused by inadequite amount of aqueous humor
cataracts (lack of aqueous humor causes the lens to degenerate, turns cloudy, because it is the only nutrient supply for the lens)
loss of vision due to excess pressure which causes death of neurons in the retina of optic nerve
glaucoma
blurring of images caused by the eyeball being too long
myopia (nearsidedness)
leading cause of blindness in those over 50 years of age
macular degeneration
loss of vision that occurs due to shrinking of the vitrious humor with advanced age
retinal detachment
caused by too much aqueous humor
glaucoma (aqueous humor builds up because it fails to drain properly from the eye)
blurring of images caused by an aspheric or asymmetrical cornea
astigmatism
linked to high cholesterol, obesity, and smoking
macular degeneration
blurring of images caused by the age related accumulation of protein cristalines in the lens
presbyopia (age related farsidedness)
