Special senses Flashcards
Special senses
Separate cell structural classification of receptor
- smell
- taste
- hearing
- balance
- vision
Sense of smell
- odor dissolves in mucus surrounding the olfactory cilia (in contact with epithelium in the nasal cavity)
- receptor potential is passed to the olfactory nerves in the olfactory bulb
- impulse passes through olfactory tract into the thalamus and olfactory centers of the brain
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Sense of taste
- receptor potential in taste buds (from chemo receptors called gustatory cells)
- propagation of action potential
- transmits to the brain
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Hearing and balance
- external, middle, and inner ear
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External ear
- Auricle or pinna: visible portion
- External auditory canal: tube leading to the temporal bone and tympanic membrane
- Tympanic membrane
Middle ear
Tympanic cavity
- tiny epithelial lined cavity hollowed out of the temporal bone
- contains 3 auditory ossicles
1. Malleus - hammer - attached to inner surface of tympanic membrane
2. Incus - anvil - attached to malleus and stapes
3. Stapes - stirrup - attached to the incus
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Inner ear
Labyrinth
- consist of two main parts: a bony labyrinth and inside a membranous labyrinth
- the bony labyrinth consists of 3 parts
1. Vestibule
2. Cochlea
3. Semicircular canals
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Inner ear
Membranous labyrinth is inside the bony labyrinth and contains
- the utricle and saccule (inside vestibule)
- the cochlear duct inside cochlea
- the membranous semicircular ducts inside
- the bony semicircular canals
Vestibule and semicircular canals
Involved with balance
Cochlea
Involved in hearing
Endolymph
Fluid filling the membranous labyrinth
Perilymph
Fluid that suspends the membranous
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Sense of hearing
Sound is created by vibration
- the ability to hear sound waves is depend on volume, pitch, and other acoustic properties
- to be hear, sound must travel though air, bone, and fluid
Sense of balance
- the sense organs involved in the sense of balance, or equilibrium, are found in the vestibule and semicircular canals
- the sense organs located in the vestibule: utricle and saccule function in static equilibrium
- the sense organs associated with the semicircular ducts function in dynamic equilibrium
Static equilibrium: otoliths organs
Utricle and saccule
- walls of both organs contain a small thickened region called the macula
- the tow macula are perpendicular to each other and provide information for static equilibrium
- 2 kinds of cells in the macula (hair and otolithic membrane)
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Dynamic equilibrium: semicircular canals
Semicircular canals lie at right angles to one another in 3 planes
- 2 verticle ducts (anterior and posterior)
- 1 horizontal duct (lateral)
- sensory organ: crista. Located in ampulla and contains hair cells and supporting cellls
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Sense of vision
Light converts stored photochemical energy into nervous impulses that are interpreted by the brain as sight
- external structures include: eyebrows, eyelashes, eyelids, lacrimal apparatus, muscles (intrinsic and extrinsic)
Layers of the eyeball
- Fibrous layer
- sclera - cornea - Vascular layer
- choroid - iris - ciliary body - Inner layer
- retina - optic nerve - retinal blood vessels
Fibrous layer
Outer coat of eyeball
- cornea: the transparent anterior portion of the fibrous layer
- sclera: white opaque outer portion of the eye (white secondary to collagen and elastin bundles)
Vascular layer
- choroid: highly pigmented area
- ciliary body: formed by a thickening of the choroid and contains the ciliary muscle
- iris: colored part of the eye that attaches to the ciliary body which controls the diameter of the pupil
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Inner layer
Retina
- mostly made up of nervous tissue
- 3 layers of neurons
1. Photoreceptors cells: rods and cones
2. Bipolar cells: receive impulses from rods and cones
3. Ganglio cells: receive info from rods, conoces, and bipolar cells and send the information to the optic nerve via the optic disk
