Chapter 19 - Special Senses Flashcards
Stimuli
Sensory information that initiate action potentials and perception in our bodies
Sensation/Perception
our conscious awareness of stimuli
Sensory Receptors
detect stimuli
General Sense Receptors
sense temperature, pain, touch, stretch, and pressure
Special Sense Receptors
sense gustation, olfaction, vision, equilibrium, hearing
Transducers
change one form of energy into another ie. visual light receptors change light energy into electrical energy on the optic nerve
Olfaction
-sense of smells
-can recognize 10 000 different smells
-nose contains 10 million receptors
Olfactory Epithelium
consists of 3 types of cells
-receptors
-supporting
-basal
Olfactory Receptor Cells
Detect odour
Supporting Cells
-support, nourishment, insulation to receptor cells, odour-binding proteins
Basal Cells
replace worn out olfactory receptor cells
Olfactory (Bowman’s) Glands
mucous producing glands that moisten the epithelial surface and dissolve odorant molecules
The Olfactory Pathway
olfactory receptor-> olfactory (CN I) nerves-> olfactory bulbs-> olfactory tract-> cerebral cortex-> olfactory cortex (temporal lobe)
Gustation
-sense of taste
-receptors are located in adult taste buds
Sweet
sugars
Salty
Na+ and Cl-
Sour
acids (H+)
Bitter
alkaloids
Umami
amino acids
Taste Buds
-found in tongue, soft palate, epiglottis, pharynx
-3 types of papillae contain taste buds
Papillae
4 types - elevations on the tongue where taste buds are found
Filiform Papillae
-contain tactile receptors but NO TASTE BUDS
-increase friction between tongue and food so tongue can move food into oral cavity
Fungiform Papillae
-5 taste buds each
-mushroom shaped elevations scattered over entire surface of the tongue
Vallate (Circular) Papillae
-100-300 taste buds
-form an inverted V-shaped row at the back of the tongue
Foliate Papillae
-located on the lateral margins of the tongue
-most of their taste buds degenerate in early childhood
Gustatory Pathway
taste buds-> gustatory receptor-> CN VII (facial), IX (glossopharyngeal), X (vagus)-> gustatory nucleus (MO)-> thalamus-> Insula (cerebral cortex)-> primary gustatory cortex-> perception of taste
Accessory Structures
-prevent foreign objects from entering
-keep surface moist, clean, lubricated
Eyelid
-aka palpebrae
-anterior, moveable protective covering of the eye
Levator Palpebrae Superioris Muscle
weak twitch
Palpebral Fissure
space between eyelids
Lacrimal Caruncle
-contain sebaceous and sudoriferous glands
-pink bump containing ciliary glands that produce gritty secretion
Tarsal Plate
supports the eyelids
Tarsal Glands
-located in tarsal plates
-prevent tear overflow and sticking together of eyelids
-sebaceous glands
Chalazion
tumor or cyst in tarsal glands
Conjuctiva
lining over the anterior surface of the eye
Palpebral Conjuctiva
thin, protective mucous membrane
Eyebrows
-prevent sweat from dripping into the eye
Eyelashes
prevent foreign objects from entering eyes
Medial and Lateral Palpebral Commissures
corners of the eyes
Lacrimal Apparatus
-tears are produced in lacrimal gland
-dispersed across eye when we blink
-fluid enters the lacrimal puncta and drains into lacrimal canaliculi, collects in lacrimal sac
-drains through nasolacrimal duct
-enters nasal cavity
Orbital Fat
cushions the eye within the socket
Anterior Cavity
-in front of the lens
-contains circulating aqueous humor
Posterior Cavity
-behind the lens
-contains permanent vitreous humor
Aqueous Humor
-secreted by ciliary processes into the posterior chamber
-moves from posterior chamber, through the pupil, to the anterior chamber
-excess is reabsorbed by scleral venous sinus
Wall of the Eye
3 layers
Fibrous Tunic
-sclera
-cornea
-sclera venous sinus
Sclera
-support, protection, shape of the eye, muscle attachment
-the white of the eye
Cornea
-avascular collagenous tissue
-refracts light rays coming into the eye
Scleral Venous Sinus
-collects aqueous humor from the anterior chamber and delivers it to the bloodstream
Vascular Tunic
-choroid
-ciliary body
-iris
-pupil
-lens
Choroid
-vascular
-melanocytes (absorbs light)
-supplies nourishment to the retina
Ciliary Body
-melanocytes, aqueous humor
-smooth muscles and an inner secretory epithelium
-between choroid and iris
-secretes aqueous humor
-holds suspensory ligaments that change the shape of the lens
Iris
-coloured portion of the eyeball
-two smooth muscles that control pupil diameter
Pupil
-opening in the iris that regulates the amount of light that enters
Lens
changes shape to focus light on the retina
Inner Tunic
-macula lutea
-fovea centralis
-optic disc
-hyaloid canal
Retina
-converts light into impulses
-layer at the back of the eyeball
Pigmented Layer
-melanin helps absorb stray light rays
-provides vitamin A for photoreceptors
-passes on nutrients and oxygen
Neural Layer
-contains photoreceptors that convert light into impulses
-3 layers
Photoreceptor Cells
-outermost layer composed of rods and cones
Rods
-night vision
Cones
-precise and colour vision
Bipolar Cells
synapse with photoreceptors and ganglion cells
Horizontal Cells
some lie between photoreceptors and bipolar cells
Ganglion Cells
-innermost layer of the retina
-axons of these cells leave the retina and form the optic nerve (CN II)
Amacrine Cells
-between bipolar cells and ganglion cells
-help process and integrate visual info
Are there more rods or cones in human eyes?
20x more rods than cones
Optic Disc
-“blind spot”
-located on the retina
-lacks photoreceptors
-located where ganglion cells exit to form optic nerve
-also where blood vessels enter/exit retina
Fovea Centralis
-depression in the retina
-contains the highest amount of cones and almost no rods
-area of sharpest vision
Macula Lutea
-houses fovea
-yellow region
-sharp detailed vision
-located on retina
Visual Pathway
bipolar cells->optic nerve (CN II)->optic chiasm->optic tract->lateral geniculate nucleus-thalamus->primary visual cortex of the occipital lobe->superior colliculi (visual reflexes)->pretectal nuclei (accommodation of reflexes)
External Ear
collects sounds waves
Pinna (aka auricle)
-directs sound waves into the ear canal
External Auditory Canal
-funnels sound waves to the tympanic membrane
-bony tube
Ceruminous Glands
-produces a waxlike secretion called cerumen
-combines with dead skin cells to from ear wax
-helps reduce infection
Tympanic Membrane (aka eardrum)
-vibrates when hit with sound waves
-transmit sound energy into middle and inner ear
Umbo
-central point of maximum depression
-marks the end of the manubrium of the malleus
Middle Ear
-transmits sound waves to the oval window
-small, air-filled cavity in the temporal bone
Ossicles
-malleus, incus, stapes
-amplify the vibrations
-footplate of the stapes fits into the oval window
-initiate waves in the inner ear fluid
Tensor Tympani and Stapedius Muscle
restrict ossicle movement when loud noises occur (protect sensitive receptors in the ear)
Auditory Tube (aka eustachian tube)
-opens to the nasopharynx from the middle ear
-normally closed
-air movement when yawning, chewing, swallowing allows pressure in ear to equalize
Inner Ear
-receptors for hearing and equilibrium
-aka labyrinth
-2 divisons
-located in temporal bone
Bony Labyrinth
-outer part that encloses an inner membranous labyrinth
-3 areas: semicircular canals, vestibule, cochlea
Membranous Labyrinth
-membrane lines, fluid filled tubes
-houses receptors for equilibrium and hearing
Perilymph
-within bony labyrinth
-space between bony and membranous
-similar composition of ECF and CSF
-suspends, supports, protects membranous labyrinth from wall of the bony labyrinth
-in scala vestibuli and tympani
Endolymph
-in membranous labyrinth
-low Na+ high K+ conc. similar to ICF
-in scala media
Semicircular Canals
-contain membranous labyrinth structure called semicircular duct
-fluid filled tubes that help with balance associated with circular motion
Vestibule
-contain saccule and utricle which sense linear motion
-utricle: horizontal motion
-saccule: vertical motion
Cochlea
-houses cochlear duct (membranous labyrinth)
-hearing
Macula
-sensory receptor located along internal walls of saccule and utricle
-composed of hair cells and supporting cells
Hair Cells
-sensory receptors of the inner ear for hearing and equilibrium
-release NTs to sensory neurons
Stereocilia and Kinocilium
-line apical surface of each hair cell
-release NTs when bent certain directions
-embedded in gelatinous layer
Otoliths
-also in gel layer (otolithic membrane)
-calcium carbonate crystals
Modiolus
three turns of the cochlea around one bony core
Coclea Divisions
-divided into three channels (scala)
Scala Media
-aka cochlear duct
-roof: vestibular membrane
-floor: basilar membrane
-filled with endolymph
Scala Vestibuli
-adjacent to vestibular membrane
-perilymph
Scala Tympani
-adjacent to basilar membrane
-perilymph
Helicotremma
-interconnect scala vestibuli and tympani at the apex of the cochlea
Organ of Corti
-the sensory structure for hearing
-hair cells and supporting cells rest on basilar membrane
-single row of inner hair cells and three rows of outer hair cells (alter response to sound)
Tectorial Membrane
-stereocilia and kinocilium on apical hair cell surface housed in this gelatinous structure
Spiral Ganglion
-house cell bodies of sensory neurons
Auditory Pathway
spiral ganglia->cochlear nuclei (MO)-> lateral lemniscus->inferior colliculus-> superior olivary nucleus (pons)-> medial geniculate nucleus (thalamus)-> primary auditory area-> temporal lobe
Static (linear) Equilibrum
-maintain position of body relative to gravity
-receptors in saccule and utricle (macula)
Dynamic (rotational) Equilibrium
-maintain body position in relation to sudden movements
-receptors in semicircular canal (crista)
Semicircular Ducts
-ampulla
-crista
-capula
Ampulla
expanded region, farthest from utricle connection
Crista
-elevated region
-covered by hair and supporting cells
Cupula
-where crista embeds hair cells into this gelatinous dome
Equilibrium Pathway
vestibular ganglia-> vestibular branchof CN VIII-> vestibular nuclei-> inferior cerebral peduncles
Vestibular Nuclei
integrate info from vestibular, visual and proprioceptors and send commands
