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111 Cards in this Set
- Front
- Back
Special senses:
Taste |
Chemoreceptor (detects chemicals in air or mouth)
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Special senses:
Smell |
Chemoreceptor
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Special senses:
Hearing |
Mechanoreceptor (air movements)
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Special senses:
Equilibrium |
Mechanoreceptor (Balance fluid in head)
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Special senses:
Sight |
Photoreceptor
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Taste
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About 10,000 taste buds
Mostly found on projections of tongue. |
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Taste:
Papillae |
Projections on tongue, where taste buds are found
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Fungiform papillae
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Appears in long sections, like muschrooms - large top, small bottom
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Circumvallate papillae
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Large ones on back of tongue
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Folliate papillae
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Look like leaves
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Taste:
Taste buds |
Sensory receptor organs for taste, are located in the oral cavity with the majority located on the tongue.
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Taste sensations can be grouped into five basic qualities:
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Sweet, sour, bitter, salty, and umami.
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Taste:
Basal cells |
Produce the supporting and gustatory cells which are replaced every 10-14 days
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Taste:
Sensory nerves |
VII (facial)
IX (glossopharyngeal) X (vagus) |
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For a chemical to be tasted
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It must be dissolved in saliva, move into the taste pore, and contact the gustatory hairs.
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Each taste sensation appears
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To have its own special mechanism for transduction.
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Afferent fibers carrying taste information from the tongue are found
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primarily in the facial nerve and glossopharyngeal cranial nerves.
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Taste impulses from the few taste buds found
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On the epiglottis and the lower pharynx are conveyed via the vagus nerve.
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Taste is strongly influenced by
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Smell and stimulation of thermoreceptors, mechanoreceptors, and nociceptors
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Sweet tastes are elicited by
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Sugars, alcohols, and some amino acids.
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Sour taste is produced by
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Acids, specifically H+ ions
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Bitter taste is elicited by
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Alkaloids such as quinine, nicotine, cyanide.
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Umami is elicited by
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The amino acid glutamate, found in high amounts in meat
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Taste reactions are
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Partly genetic, partly learned
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Sweet + salty are
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Natural cravings
–most sweet things in nature are safe and nutritious –salt satisfies our need for electrolytes. |
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Bitter taste you
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Naturally avoid
Many naturally occurring toxins (like cyanide and many fungal toxins) have a bitter taste. Our receptors are most sensitive to bitter tastes. |
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Smell:
Olfactory epithelium is in |
Located in roof of nasal cavity
Contains olfactory receptor cells Recieves data by olfactory cilia |
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Smell:
To smell a particular odor it must be |
Volatile and it must be dissolved in the fluid coating the olfactory epithelium
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Smell:
Axons of the olfactory receptor cells synapse in the |
Olfactory bulbs sending impulses down the olfactory tracts to the thalamus, the hypothalamus, amygdala, and other members of the limbic system
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Olfactory receptor cells are
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Neurons which send fiber bundles of axons through the cribriform plate of the ethmoid
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Smell:
The receptor cells are replaced about every 60 days. (why?) |
Neurons rarely have a mitotic rate
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Smell:
Anosmias are |
Olfactory disorders resulting from head injuries that tear the olfactory nerves, nasal cavity inflammation, or aging
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Smell:
Uncinate fits are |
Olfactory hallucinations
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Sight:
Vision is our (humans) dominant sense with |
70% of our body’s sensory receptors are found in the eye
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Sight:
Nearly half of the cerebral cortex is involved |
In processing of visual information
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Sight:
Eyebrows are |
Short, coarse hairs overlying the supraorbital margins of the eye that shade the eyes and keep perspiration out
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Sight:
Eyelids (= palpebrae) are |
Thin skin-covered folds supported by connective tissue plates called tarsal plates
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Sight:
Meibomian glands produce |
Oils to lubricate the eyelids
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Sight:
Eyelashes secrete |
Oils from their associated sebaceous glands
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Sight:
Eyelids (palpebrae), eyelashes, and their associated glands help to |
Protect the eye from physical danger as well as from drying out.
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Sight:
Eyelid - Meibomian gland infection |
Creates a large cyst (chalazion)
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Sight:
Eyelid - oil gland infection |
Called a sty
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Sight:
Conjunctiva |
Transparent mucous membrane which lines the eyelids (the palpebral) and covers the anterior surface of the eye (the ocular conjunctiva).
It produces a lubricating mucus that prevents the eye from drying out |
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Sight:
Palpebral |
The eyelid
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Sight:
Ocular conjunctiva |
Covers anterior surface of eyeball
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Sight:
Conjuctiva - blood shot |
Has many tiny blood vessels which can get irritated
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Sight:
Conjuctivitis |
An inflammation of the conjunctiva
It can be caused by bacteria or viruses. |
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Vision:
Lacrimal glands |
Which secretes a dilute saline solution that cleanses and protects the eye as it moistens it, and ducts that drain excess fluid into the nasolacrimal duct.
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Lacrimals:
Tears contain |
water
salts mucus lysozyme Tear production declines with age, so the eyes become drier and more subject to infection. |
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Sight:
Extrinsic muscle |
Smallest motor unit of any muscle
Movement of each eyeball is controlled by six extrinsic eye muscles that are innervated by the abducens and trochlear nerves |
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Sight:
Eyeball - Fibrous tunix |
The outermost coat of eyeball is dense avascular connective tissue, has two regions: sclera and the cornea
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Sight:
Eyeball - Sclera |
Is tough, protective, white and opaque
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Sight:
Eyeball - Cornea |
Is transparent, forming a window that lets light enter the eye
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Sight:
Eyeball - Vascular tunic (=uvea) |
Is the middle layer and has three regions: the choroid, the ciliary body, and the iris
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Sight:
Vascular tunic - Choroid |
Supports blood vessels and absorbs light to prevent glare.
(In some animals, the choroid reflects light.) |
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Sight:
Vascular tunic - Ciliary body |
Is a thickened ring of tissue around the lens
Largely consists of smooth muscle called ciliary muscle which controls the shape of the lens. The muscles are attached to the lens via suspensory ligaments. |
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Sight:
Vascular tunic - Iris |
Is the visible colored part of the eye.
Lies between the cornea and the lens and is anchored to the ciliary body at its edges. It is made of smooth muscle which can control the size of its central opening, the pupil |
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Sight:
Iris - Pupil |
Centrally located circular muscles cause constriction of the pupil
Marginal radial muscles dilate the pupil |
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Sight:
Iris - Pigment |
The only pigment is melanin (brown)
The iris can display other colors if the amount of melanin is small and concentrated at the posterior surface of the iris. The refraction of light causes other colors (called structural colors) to appear. |
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Sight:
Iris - Structural colors |
The refraction of light causes other colors to appear
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Sight:
Sensory tunic or Retina |
The innermost tunic of the eye
It has 2 layers |
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Sight:
Retina - 1rst layer |
The outer pigmented layer abuts the choroid. It contains phagocytes and stores Vitamin
Outer pigmented layer absorbs light |
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Sight:
Retina - 2nd layer |
The inner neural layer contains the functional cells of the eye, the photoreceptors
the inner neural layer contains millions of photoreceptors (rods and cones) that transduce light energy. |
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Sight:
Retina - 3 major cell types |
Photoreceptors (rods and cones)
Bipolar cells Ganglion cells |
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Sight:
Retina - 3 major cell types - Ganglion cells |
The ganglion cell axons unite to form the optic nerve.
The point where the optic nerve exits is called the optic disk, or, blind spot. The spot lacks photoreceptors. |
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Sight:
Retina - 3 major cell types - Photo receptors |
The rods: dim-light and peripheral vision; they do not provide sharp images or color vision
The cones: high acuity color vision; they require bright light. Human eyes are adapted for acuity; we have a high proportion of cones, giving us good color vision, but relatively poor night vision. |
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Sight:
Retina - 3 major cell types - Ganglion cells (blind spots) |
Near the blind spot is an area called the macula lutea, with a central pit called the fovea centralis.
This area has mostly cones and provides high acuity in the center of the visual field. We move our eyes constantly to get everything in our field of view exposed to this area. |
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Sight:
Chambers + fluids - anterior segment |
The anterior segment lies between lens and cornea.
It contains aqueous humor, a fluid which diffuses out of blood capillaries. It provides nutrients to the lens and cornea. Constantly replaced, it drains into the scleral venous sinus. |
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Sight:
Chambers + fluids - anterior segment(aqueous humor) |
A fluid which diffuses out of blood capillaries
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Sight:
Chambers + fluids - posterior segment |
Lies between lens and retina.
Contains vitreous humor, a gel-like fluid with a network of collagenous fibers. Physically supports the eye. Formed during embryonic growth, it is not replaced. |
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Sight:
Chambers + fluids - posterior segment (vitreous humor) |
Gel-like fluid with a network of collagenous fibers.
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Physiology of light 1:
Wavelengths |
The wavelengths of light to which our photoreceptors respond is called the human visible spectrum.
Spectrum differs for different organisms; |
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Lens
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A flexible, transparent structure that can change shape to focus light on the retina.
Made of proteins called crystallins, the lens fibers are constantly replaced. The lens becomes thicker and less flexible with age. |
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Physiology of light 2:
Lens change shape |
The lens changes shape to focus light on the retina. When the ciliary muscles are relaxed, the eye is focused for distance
For close focusing, the muscles pull on the lens, causing it to bulge. As you age, the lens gets less flexible and the muscles get weaker - you lose the ability to focus on close objects. |
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Physiology of vision:
Emmetropic |
In normal eyes, the lens focuses light on the retina
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Physiology of vision:
Myopia |
(Nearsightedness), the lens, when relaxed (for distance vision), the lens focuses in front of the retina, making distant objects blurry.
It typically results from an eyeball which is too long. |
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Physiology of vision:
Hyperopia |
(Farsightedness), the lens cannot be flexed enough to focus on close objects.
It is the result of an eyeball which is too short or an inflexible lens. |
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Physiology of vision:
Visual pathway (retinal ganglion cells) |
Merge in the back of the eyeball to become
the optic nerve, which crosses at the optic chiasma to become the optic tracts. |
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Physiology of vision:
Visual pathway (optic tracts) |
Send their axons to neurons within the lateral geniculate body of the thalamus.
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Physiology of vision:
Visual pathway (Axons from the thalamus) |
Project through the internal capsule to form the optic radiation of fibers in the cerebral white matter.
These fibers project to the primary visual cortex in the occipital lobes. |
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Physiology of vision:
Visual pathway (visual processing) |
Occurs when the action of light on photoreceptors hyperpolarizes them, which causes the bipolar neurons from both the rods and cones to ultimately send signals to their ganglion cells.
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Physiology of vision:
Rods and cones contain photopigments which are |
chemically altered by light, exciting the cells and sending a nerve impulse to the brain.
The pigment in rods (rhodopsin) responds to all wavelengths of human visible light |
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Physiology of vision:
Rhodopsin |
Pigment in rods
formed and broken down within the rods. |
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Physiology of vision:
3 different cones |
(Green, blue, and red) which have different photopigments (iodopsins) responding to different wavelengths of light.
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Physiology of vision:
Stimulation of the Photoreceptors |
Is exposed to light which cause pigment breakdown, which hyperpolarizes the receptors inhibiting the release of neurotransmitter conveying the information.
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Physiology of vision:
Light adaptation |
Occurs when we move from darkness into bright light.
Retinal sensitivity decreases dramatically and the retinal neurons switch from the rod to the cone system. |
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Physiology of light:
Dark adaptation |
Occurs when we go from a well-lit area into a dark one.
The cones stop functioning and the rhodopsin starts to accumulate in the rods increasing retinal sensitivity. |
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Structure of ear
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The outer (external) ear consists of the auricle (pinna)
The external auditory canal, which is lined with skin bearing hairs, sebaceous glands, and ceruminous glands. |
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Structure of ear:
Auricle |
Directs sound into the canal.
The canal is lined with ceruminous (wax) glands. The tympanic membrane (eardrum) separates the outer ear from the middle ear. |
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Structure of ear:
The middle ear or tympanic cavity |
Is a small, air-filled, mucosa-lined cavity in the petrous portion of the temporal bone.
Contains the ear bones (ossicles): malleus, incus, and stapes. It is spanned by the auditory ossicles. |
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Structure of ear:
Ossicles |
The ossicles vibrate when sound waves hit the tympanum.
Vibrations are transferred malleus -> incus -> stapes to the oval window. The tensor tympani and stapedius muscles prevent excessive vibration of the ossicles. |
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Structure of ear:
Inner ear |
Contains the organ of hearing, the cochlea, and the organs of equilibrium, the vestibule and the semicircular canals.
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Hearing of ear
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Sound waves strike the tympanum
The ear ossicles vibrate, pushing on the oval window Fluid in the cochlea vibrates, pushing on hair cells within The hair cells cause excitation of sensory neurons of the cochlear nerve which sends signals to the brain |
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Hearing of ear:
Sound waves |
has a characteristic amplitude and frequency.
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Hearing of ear:
Sound waves - amplitude |
Height of the wave
It represents loudness |
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Hearing of ear:
Sound waves - frequency |
The frequency (or wavelength) is the pitch of the sound.
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Hearing process
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When a sound wave enters the ear, it is amplified in the middle ear, because the oval window is smaller than the tympanic membrane.
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Hearing process
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Fluid inside the scala vestibuli, the perilymph, starts to move.
The organ of Corti rests on the basilar membrane. It is composed of some 16,000 cochlear hair cells. The movement of the perilymph stimulates the hair cells, which causes depolarization of fibers of the auditory nerve (a branch of the vestibulocochlear, VIII). |
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Hearing of ear:
Different wavelengths of sound |
Different parts of the basilar membrane are stimulated by different wavelengths of sound. This gives us our perception of pitch
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Hearing disorders:
Conduction deafness |
Occurs when sounds do not get conducted to the inner ear. –blockage of the auditory canal
perforated eardrum otosclerosis, a growth of bone which fuses the stapes to the oval window |
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Hearing disorder:
Sensorineural deafness |
Results from damage to the inner ear or nervous tissues.
Exposure to loud noises (damages cilia) Degeneration of the cochlear nerve Brain damage in the auditory cortex |
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Equilibrium of ear
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Not only upon the organs in the inner ear, but also involves vision and information from proprioceptors.
The organs in the ear involved in equilibrium are the vestibule and the semicircular canals. |
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Equilibrium of ear:
Static equilibrium |
Refers to your sense of position (i.e., your sense of gravity).
This one is just about always turned on. |
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Equilibrium of ear:
Dynamic equilibrium |
Refers to the sense of change of momentum (acceleration or deceleration).
This one turns off if you are not moving or if you are moving at constant velocity |
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Static equilibrium:
Organs |
The organs of static equilibrium are located in the vestibule, which contains membranous sacs, the saccule and utricle.
Within these sacs are the maculae (sing., macula) |
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Static equilibrium:
Organs - Maculae |
A macula is a flat epithelial patch with supporting cells and hair cells.
Within each macula is a jellylike otolithic membrane. It is covered with CaCO3 crystals called otoliths. |
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Equilibrium:
When head moves |
When the head moves, the otolithic membrane falls to a different position, deforming hair cells.
The brain receives the information on the position of the membrane, and thus determines the position of the head |
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Equilibrium:
Macula give us a |
Sense of “up and down”, or, static equilibrium
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Equilibrium:
Semicircular canals |
Sense changes in momentum, or dynamic equilibrium (changes in velocity only, acceleration or deceleration)
Has 3 canals running in different directions to detect all kinds of movement. |
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Equilibrium:
Endolymph |
The fluid within the ampullae of the semicircular canals
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Equilibrium:
Crista ampullaris is a |
Small elevation which can be deformed by movements of the endolymph
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