Chapter 15 - Special Senses Flashcards
What do the special senses include?
Olfaction, Taste, Vision, Hearing, and Balance
What lobe is for taste?
Insula lobe
What lobe is for smell?
Temporal lobe
What lobe is for hearing?
Temporal lobe
What lobe is for equillibrium?
Medula Oblongata
What lobe is for vision?
Occipital lobe
What are the distinct receptors cells localized in the head region?
Special sensory receptors
How much percent of the body’s sensory receptors are in the eye?
70%
How much of the cerebral cortex is involved in visual processing?
Half
What is olfaction?
Sense of smell
What cranial nerve is it?
Cranial Nerve #1
Where are the olfactory receptors found?
Superior nasal cavity
How many olfactory neurons are there?
10 Million
What the olfactory hairs?
Cilia of olfactory neurons embedded in mucus
What dissolves in mucus?
Odorant molecules
What do we need for the olfactory hairs to bind, and what kind of receptor is it?
Molecules and chemical
How long do olfactory neurons replace?
Every 2 months
What do olfactory receptors respond to and how much does it provide of taste?
Chemicals dissolved in liquids and smell provides 75-80% of sense of taste
Olfactory organs are what kind of neurons?
Bi-polar neurons
What two sensories have bi-polar neurons?
Smell and sight
What is the pathway for smell?
Depolarize the receptor
Olfactory nerves synapsis with olfactory bulbs
Signal continues travels through olfactory tracts
Then through the Limbic system to olfactory cortex (for interpretation)
Olfactory bulbs begin to analyze sensory impulses
Ends/terminates in the Temporal lobe
What is smell associated with?
Memory
What is sensory adaptation?
Nose blindness
(Used as a protective mechanism and can drop 50% within 1 second)
What receptors are the only ones in direct contact with the enviroment?
Smell
What is the hypothesis on smells?
Each receptor contains only one type of binding protein (proteins can act as receptors) which can bind several types of odorants (molecules)
What does the brain interpret binding as?
Olfactory code
What is the Olfactory code?
A specific code that triggers the pattern for certain smells
What is gustation?
Sense of taste
Describe the taste bud?
The organs of taste gustatory hairs extending into taste pores
What are the four types of papillae?
Filiform, Vallate, Foliate, and Fungiform
What is the papillae that doesn’t have taste buds?
Filiform
Describe Filiform papillae.
Spikey in texture, filament shaped
What papillae is at the back of the tongue and forms a ‘V’, how many are there, and has taste buds?
Vallate and 8-12
What papillae is leaf or flower shaped on the side of the tongue and are the most sensitive?
Foliate (Flower) (Has taste buds)
What papillae is mushroom shaped?
Fungiform (Fungus)
(Small red dots interspersed among the Filiform)
What are the basic taste sensations?
Sweet, Sour, Salty, Bitter, and Umami
-Sweet - Sugar and alcohol
-Sour - Hydrogen ions (pH)
-Salty - Metal, sodium chloride
-Bitter - Opposite of sour (Alkaloid/low concentration of Hydrogen)
-Umami - Amino acids (make proteins/meat)
What does spicy food activate?
Pain receptors (Nociceptors)
What percent of smell does taste rely on?
80%
How many cranial nerves carry taste impulses from the tongue to the brain?
3
What are they and where are they located?
Facial Nerve (VII) - Tip of the tongue
Glossopharyngeal Nerve (IX) - Back of the tongue
Vagus Nerve (X) - Epiglottis/Pharynx (Throat)
Where does the cranial nerves conduct impulses to?
Medulla Oblongata (reflex/swallowing)
Where does it go after the Medulla Oblongata?
Thalamus
After the thalamus which lobe does it end in?
Insula (gustatory cortex)
What is the small sphere containing inner nerve layers?
Retina
What are the sensory receptors in the retina?
Photoreceptors (Deep inside)
What are the accessory structures?
Eyebrows - Shade; inhibit sweat
Eyelids - (Palpebrae) with conjunctiva, has tarsal glands that secrete oil onto eyelashes
Eyelashes - Double/triple row of hairs
Conjunctiva - Thin transplant mucus membrane
How many Extrinsic eye muscles are there?
Six
Where do the Extrinsic muscles originate and what do they attach to?
In the back and attach to the eye ball
What are the four rectus muscles?
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
What does the Superior rectus allow the eyeball to do?
Move the eyeball up
What does the Inferior rectus allow the eyeball to do?
Move the eyeball down
What does the Medial rectus allow the eyeball to do?
Move the eyeball to the middle
What does the Lateral rectus allow the eye to do?
Move the eyeball to the side
What two oblique muscles move the eye in a vertical plane and rotates?
Superior and Inferior oblique
Where are tears produced?
Lacrimal gland located superior and lateral to the eye.
Where to tears exit?
Lacrimal ducts
Where are the excess tears collected?
Lacrimal canaliculi
What does the lacrimal canaliculi open into?
Lacrimal sac
Tears flow from the _________ through the __________________ into the nasal cavity.
Lacrimal sac, Nasolacrimal duct
What is the antibacterial component of tears?
Lysozyme
What is the little hole that goes into the canaliculi?
Punctum
What is the division of the anterior and posterior chambers?
Iris (Color of your eye)
What two cavities does the lens separate the eye into?
Anterior (in front of the lens) and Posterior (behind the lens) cavities
What is the Vitrous chamber?
Contains thick vitrous fluid that pushes up against the 3 layers of the eye to keep it open
What is the outer most layer of the eye?
Fibrous tunica
What is the middle layer and what does it do for the eye?
Vascular tunica and supplies blood to the eye (Continuous with the optic nerve)
What is the inner most layer and what it is known as?
Nervous tunica and the Retina
What can be found behind the iris?
Aqueous fluid that is constantly being changed everyday
The lens provides ____ percent and the cornea provides ___ percent to see.
90, 10
What is the thick fibrous material that is continuous with the cornea?
Sclera
Describe the Cornea.
Most anterior part, Transparent, Helps to focus light, Transmits and refracts light
Describe the Sclera.
Most posterior part, White/opaque (keeps light out, Protects eyes/attaches muscles, Pierced by optic nerve and blood vessels.
What does the Vascular tunica consist of?
Choroid coat - provides blood supply
Iris - Controls light entering eye
Ciliary body - Changes lens shape for focusing
What type of cells is the lens made of?
Epithelial cells
What is Accommodation?
A change in the shape of the lens, to view close objects.
What happens when you are looking far away?
Your ciliary muscles are relaxed and pulls on the suspensory ligaments then flattens out the lens
What happens when you are looking up close?
The ciliary body contracts and the suspensory ligaments relaxes then your lens get thicker.
What is it called where the rays of light meet within the eye?
Focal point
What is refraction?
Bending of light rays
What is Visual acuity?
Ability to focus an image on the retina
What is Myopia?
Nearsightedness; focal point in front of the retina
(Not able to reach the retina)
Corrected by concave lens
What is Hyperopia?
Farsightedness; focal point behind the retina
Corrected by convex lens
What is Presbyopia?
Increase in near point of vision due to age
What is Astigmatism?
Elongated and not round, effecting the focal point.
What is the Nervous tunica?
Pigmented layer and Neural layer
What is the pigmented layer?
Single layer of cells
Filled with melanin
Reducing light scattering
What is the Neural layer?
Photoreceptors (rods and cones)
What is a rod?
Allows you to see in the dark
(Black and White)
Contains rhodopsin pigment
More sensitive than cones
What is a cone?
Allow you to see in the light (Color vision)
Visual pigment is iodopsin (Responds to blue, red, and green light)
______ helps you to see in the daytime and ______ help you see in the nighttime.
Cones, Rods
What does the lens focus light on?
Macula and fovea centralis
What is the Macula?
Small yellow spot
What is the Fovea centralis?
Photoreceptor cells (mostly cones) tightly packed
What is the optic disc?
Blind spot
Describe a blind spot.
Area through which blood vessels enter the eye and are found where nerve fibers from retina leave the eye to become the optic nerve (Fine vision)
What is the area that collects light?
Visual field
What two areas of the eye refract light and project to the opposite side of the retina, causing the image to be upside down and reversed from left to right which stimulates the photoreceptors?
Cornea and lens
What does the optic nerve connect to after exiting through the optic foramen?
Optic chiasm
Which hemisphere has axons from both sides of the retina project both to the same side hemispheres and opposite sides of the hemisphere?
Both hemispheres receiving visual input from both eyes.
Where do most optic tracts terminate?
Geniculate Nucleus of the Thalamus
Where do some axons separate from the tract and travel through?
Superior Colliculi
The fibers from the lateral geniculate form what?
Optic radiations
Where do the optic radiations project to and where?
Visual cortex and Occipital lobe
What is auditory?
Sense of hearing
What is the organ of hearing?
Ear
What are the three sections of the ear?
Outer/external ear, middle ear, inner/internal ear
Describe the outer ear
Auricle (Pinnacle) - funnel-shaped that collects sound waves
External Acoustic meatus
Tympanic membrane (eardrum)
Describe the middle ear
Auditory ossicles: malleus, incus, and stapes - amplify force of waves being transmitted
Oval window - opening in the wall of vestibule/stapes vibrates against it to move fluids in inner ear
What is the Auditory (Eustachian) tube?
Connects middle ear to throat
Help maintain equal pressure on both sides of tympanic membraine
The inner ear has what two types of labyrinths?
Osseous (bony) labyrinth (filled with perilymph fluid)
Membranous labyrinth (filled with endolymph fluid)
What are the three parts of labyrinths?
Cochlea - Functions in hearing
Semicircular canals - Function in dynamic equilibrium
Vestibule - Functions in static equilibrium
What is the Organ of Corti?
Organ for sense of hearing
What are hearing receptor cells called?
Hair cells
What do hair cells contain and what does it brush up against?
Stereocilia and tectorial membrane
What is the pathway for the sense of hearing?
-Cochlear nerve synapses with CNS neurons in the medulla oblongata
-Neurons project through reflex pathways to dampen loud sounds
-Ascending neurons synapse in the inferior colliculi and then project through the thalamus
-Neurons terminate in the auditory cortex
-Neurons from the inferior colliculus also project to the superior colliculus
-This is where reflexes that turn the head and eyes in response to loud sounds are initiated
What does the equilibrium rely on for balance?
Input from the inner ear, eyes, and stretch receptors
What is the static labyrinth?
Controlled by utricle and saccule of the vestibule, evaluates position of head relative to gravity, detects linear acceleration and deceleration
What is the dynamic labyrinth?
Controlled by crista ampullaris of the semicircular canals, evaluates movement of the head in three dimensional space
