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what are the 2 types of awareness
Conscious and unconscious
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sensory receptors respond to changes in what?
thier enviroment (stimulus)
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Activation of sensory receptors results in what?
graded potentials that trigger nerve impulses
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define sensation
awarness of stimulus
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define perception
interpretation of the meaning of the stimulus
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sensation and preception occur where?
the brain
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receptors are classified based on what 3 things?
- stimulus type
- location
- structural complexity
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what are the 5 stimulus "type" classifications?
- mechanoreceptors
- thermoreceptors
- photoreceptors
- chemoreceptors
- nocireceptors
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which receptor responds to touch,pressure, vibration?
mechanoreceptors
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which receptor responds to changes in temprature?
thermoreceptors
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which receptors respond to light energy?
photoreceptors
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Wich receptors respond the chemicals (like smell,taste and changes in blood chemistry)?
chemoreceptors
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Which receptors are sensitive to pain stimulus?
Nocireceptors
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what are the 3 stimulus "location" classifications?
- Exteroreceptors
- Interoceptors
- proprioreceptors
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exterorecptors respond to stimulus occuring where?
outside the body
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where are exteroreceptors found?
- skin (touch, pressure, pain, temp)
- most special senses organs
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what are the 2 classifications of receptors based on structural complexity?
- complex receptors
- simple receptors
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what does the complex receptors handle?
special sense organs (taste, vision, hearing, equlibrium, smell)
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what does the simple receptors handle?
- general senses
- tactile sensations
- encapsulated or unencapsulated (free) dendritic endings
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what 3 receptors are classified with unencapsulated dendritic endings
- Thermoreceptors - cold (10-40 C) / heat (32-48 C)
- Nocireceptors - respond to pinching, chemicals from damaged tissue, temps outside the range of thermoreceptors
- Light touch receptors - tactile (merkel) discs
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which receptor is the only to be classified with encapsulated dendritic ending?
mechanoreceptors -
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what are the encapsulated dendritic ending mechanoreceptors? (6)
- meissners (tactile) corpuscles
- pacinian (lamenatted) corpuscles
- ruffini endings
- muscle spindles
- golgi tendon organs
- joint kinesthetic receptors
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meissners corpuscle is responsable for what ?
descriminative touch (2 point descrimination)
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is meissners corpuscle shallow or deep?
shallow
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what is Pecinian corpuscles resonsable for?
deep pressure and vibration (think P for PRESSURE)
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is pecinian deep or shallow
deep
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Ruffini Endings sense what?
deep continous pressure
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muscle spindles respond to what
muscle stretch
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what do golgi tendon organs sense
stretch in tendons
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what do joint kinetic receptors sense
stretch in articular capsuls
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what is the adaptation of sensory receptors
adaptation is a change in sensitivity in the presence of a constant stimulus
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what happens in adaptation
- receptor membranes beacome less responsive
- receptor potentials decline or stop
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what does sensory adaptation allow the CNS to do?
concentrate on the important stimuli and ignore noncritical ones to maintain homeostasis
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which receptors adapt to continuing stimuli
light, touch, pressure, and smell
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which receptors do not adapt
pain, joint, and muscle monitoring receptors
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which percentage of sensory receptors are found in the eye?
70%
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most of the eye is protected by what ?
cusion of fat and boney orbit
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what do the assesory structures of the eye do?
protect the eye and aid in eye function
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what are the 5 accesory structures of the eye?
- eyebrows - sweat
- eyelids (palpebrae)
- conjunctiva
- lacrimal apparatus
- extrinsic eye muscles
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eyebrows - location, function
- overlie the superorbital margins
- funtions in shading the eyes and preventing persperation from reaching the eye
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eyelids are also known by what name
palpebrae
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what is the function of the eyelids
protect the eye anteriorly
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what are the two parts of the eyelid and thier funtions
- palpebral fissure - seperate the eyelids
- lacrimal - caruncle - the elevation at medial commisure contain oil and sweat glands
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eyelashes have nerve endings which initaite what
blinking
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conjuctiva -
transparent membrane over eye
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what are the two types of conjunctiva
- palpebral conjunctiva - lines the eyelid
- bulbar conjunctiva - covers the whites of the eyes
- produces lubricating mucus secreation
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what makes up the lacrimal apperatus?
Lacrimal gland and the ducts that connect to the nasal cavity
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what are lacrimal secretions (tears) made of
dilute saline solution containing mucus, antibodies, and lysozyme
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blinking spreads tears toward what structure?
medial commisure
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tears drain into what
nasolacrimal duct
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how many extrinsic eye muscles are there?
6
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where do the extrinsic eye muscles originate
from the boney orbit
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what are the functions of the extrinsic eye muscles
- enable eye to follow an object
- maintain the shape of the eye
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extrinsic eye muscle are made up of what to types of muscles
-
how many rectus muscles are there and where do they originate
- 4
- originate from the common tendonious ring
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how many oblique eye muscles are there and what is their function
- 2
- move the eye in a verticle plane and rotate the eyeball
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name the 4 rectus muscles of the eye
- lateral
- medial
- superior
- inferior
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what is the action of the lateral rectus muscle of the eye
moves the eye laterally
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what is the action of the medail rectus muscle of the eye
moves the eye medially
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what is the controlling cranial nerve of the lateral rectus muscle of the eye
VI abducens
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what is the controlling cranial nerve of the medial rectus muscle of the eye
III oculomotor
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what is the controlling cranial nerve of the superior rectus muscle of the eye?
III oculomotor
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what is the controlling cranial nerve of the inferior rectus of the eye?
III oculomotor
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what is the controlling cranial nerve of the inferior oblique muscle of the eye?
III oculomotor
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what is the controlling cranial nerve of the superior oblique muscle of the eye?
IV trochlear
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whats another name for a layer in the eye
tunic
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the wall of the eyeball contains 3 layers, name them.
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the internal cavity of the eye is filled with fluid called...
humors
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the lens seperates the internal cavity of the eye into what to cavities or chambers
- anterior chamber
- posterioir chamber
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what is the outermost layer of the eye?
fiberous
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the fiberous layer consists of ....
dense avascular connective tissue
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what are the two regions of the fiberous layer
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what is the sclera and its functions
- opaque posterior region
- protects the eye shape
- anchors extrinsic eye muscles
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what is the cornea and what are its functions
- transparent anterior 1/6 of fiberous layer
- bends light as it enters the eye
- numerous pain receptors contribute to blinking and tearing reflexes
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what are the 3 parts of the vascular layer or tunic of the eye
- choroid region
- ciliary body
- iris
-
what is the function of the choroid region
supplies blood to all layers of the eyeball
-
what is the ciliary body
ring of tissue surrounding the lens
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ciliary body is made up of two structures name them
- smooth muscle bundles (ciliary muscles)
- ciliary zonules (suspensory ligaments)
-
what is the function of the smooth muscle bundles of the ciliary body?
controls lens shape
-
what is the function of the ciliary zonules
holds lens in position
-
which part of the is the iris
colored part
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what is the central opening of the iris that controls the amount of light that enters the eye called?>
pupil
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what are the 2 muscles that make up the iris and control the size of the pupil
- sphincter pupallae
- dilator pupallae
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of the two muscles in the iris which would be sympathetic and which would be parasympathetic
- sphincter - parasympathetic
- dilator - sympathetic
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the retina is made up of
delicate two layer membrane
-
what are the 2 layers of the retina
- pigmented layer
- neural layer
-
what is the function of the pigmented layer of the retina
- absorbes light and prevents its scattering
- absorbs vitamen A
-
what is the functions of the neural layer of the retina
its the photoreceptor - transduces light energy
-
why is the optic disc a blind spot?
there are no photorecptors there
-
ganglion cell axons of the the retina are located where in the retina
run along the innersurface of the retina
-
what do the ganglion cell axons of the retina leave the eye as?
the optic nerve
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what is the optic disc
site where optic nerve leaves the eye
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what are the 2 types of photoreceptors
-
what condition do rods preform in and what type of vision do they provide
- operate in dim light
- provide indistinct, fuzzy, non color peripheral vision
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what conditions do cones operate in and what typoe of vision do they provide
- operate in bright light
- provide high acuity color vision
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what does the posterior segment of the eye contain
vitreous humor
-
what are the functions of the vitreous humor
- transmit light
- support the posterior surface of the lens
- hold the neural retina firmly against the pigmented layer
- contributes to interoccular pressure
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anterior segment consists of what two segments
- anterior chamber
- posterior chamber
-
what type of "humor" does the anterior segment hold
aqueous humor
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what are the properties of the lens
- biconvex
- transparent
- flexible
- elastic
- avascular
-
what does the lens allow?
precise focusing of light on the retina
-
what transparent protein are lens fibers filled with
crystallin
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what happens to the lens with age?
becomes denser, more convex, and less elestic
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what is the pathway of light entering the eye?
- cornea
- aqueous humor
- lens
- vitreous humor
- neural layer of retina
- photoreceptors
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the outer layer of both rods and cones contain visual pigments. what is a visual pigment?
molecules that change shape as they absorb light
-
what are the chemical senses
taste and smell
-
what is the origin of smell
olfsactory epithelium in the roof of the nasal cavity
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what are olfactory receptor cells
bipolor neurons with radiating olfasctory cilia
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what are the receptor organs of taste and where are they found
-
what are the 5 primary taste sensations
- salty
- sweet
- sour
- bitter
- umami
-
what is the gustatory pathway
- CN's VII and IX carry impulses from taste buds to solitary nucleus of the medulla
- impulses then travel to the thalamus from there fibers branch to the; gustatory cortex in the insula and then hypothalamus and limbic system
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what are the influence of other sensations on taste?
- taste is 80% smell
- thermoreceptors, mechanoreceptors, nocirecptors in mouth influence taste
- temp and texture enhance or detract from taste
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