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52 Cards in this Set
- Front
- Back
Sense
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ability to perceive stimuli
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Sensation
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conscious awareness of stimuli received by sensory neurons
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Sensory receptors |
sensory nerve endings that respond to stimuli by developing action potentials |
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General senses
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- receptors over large part of body
- somatic provide info. about body and env’t - visceral provide info. about internal organs, pain, pressure - touch, pressure, pain, temp., and itch |
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Special senses |
smell, taste, sight, hearing, and balance (4/5 senses + balance) |
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Types of Receptors |
-Mechanoreceptors -Chemoreceptors -OdorsPhotoreceptors -Thermoreceptors -Nociceptors |
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Mechanoreceptor
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- detect movement
- Ex. touch, pressure, vibration- |
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Chemoreceptors
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- detect chemicals
- Ex. Odors |
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Photoreceptors |
detect light |
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Thermoreceptors
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detect temp. changes
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Nociceptors
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detect pain
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Types of Touch Receptors |
-Merkel’s disk -Hair follicle receptors -Meissner corpuscle -Ruffini corpuscle -Pacinian corpuscle
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Merkel’s disk
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detect light touch and pressure
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Meissner corpuscle
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- deep in epidermis
- localizing tactile sensations |
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Hair follicle receptors
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detect light touch
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Ruffini corpuscle
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- deep tactile receptors
- detects continuous pressure in skin |
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Pacinian corpuscle
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- deepest receptors - associated with tendons and joints
- detect deep pressure, vibration, position |
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Pain
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unpleasant perceptual and emotional experience
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Types of Pain
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-Localized
-Diffuse |
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Localized
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- sharp, pricking, cutting pain
- rapid action potential |
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Diffuse
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- burning, aching pain
- slower action potentials |
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Pain Control
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Local anesthesia: - action potentials suppressed from pain receptors in local areas - chemicals are injected near sensory nerve
General anesthesia: - loss of consciousness - chemicals affect reticular formation |
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Referred Pain
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- originates in a region that is not source of pain stimulus - felt when internal organs are damaged or inflamed
- sensory neurons from superficial area and neurons of source pain converge onto same ascending neurons of spinal cord |
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Olfaction
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- sense of smell - occurs in response to odorants - receptors are located in nasal cavity and hard palate - we can detected 10,000 different smells
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How does olfaction work?
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1. Nasal cavity contains a thin film of mucous where odors become dissolved.
2. Olfactory neurons are located in mucous. Dendrites of olfactory neurons are enlarged and contain cilia. 3. Dendrites pick up odor, depolarize, and carry odor to axons in olfactory bulb (cranial nerve I). 4. Frontal and temporal lobes process odor. |
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Taste
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Taste buds:
- sensory structures that detect taste - located on papillae on tongue, hard palate, throat - Inside each taste bud are 40 taste cells - Each taste cell has taste hairs that extend into taste pores |
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How does taste work?
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1. Taste buds pick up taste and send it to taste cells.
2. Taste cells send taste to taste hairs. 3. Taste hairs contain receptors that initiate an action potential which is carried to parietal lobe. 4. Brain processes taste. |
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Types of Tastes
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-Sweet
-Sour -Salty -Bitter -Umami -Certain taste buds are more sensitive to certain tastes. -Taste is also linked to smell. |
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Vision- Accessory Structures |
Eyebrow: - protects from sweat - shade from sun
Eyelid/Eyelashes: - protects from foreign objects - lubricates by blinking
Conjunctiva: thin membrane that covers inner surface of eyelid
Lacrimal apparatus: produces tears
Extrinsic eye muscles: help move eyeball
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Anatomy of Eye |
-Hollow, fluid filled sphere -Composed of 3 layers (Tunics: Fibrous, Vascular, & Nervous Tunics) -Divided into chambers |
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Fibrous Tunic
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-Outermost layer
Sclera: - firm, white outer part - helps maintain eye shape, provides attachment sites, protects internal structures
Cornea: - transparent structure that covers iris and pupil - allows light to enter and focuses light
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Vascular Tunic |
-Middle layer -Contains blood supply
Choroid: - black part (melanin) - delivers O2 and nutrients to retina
Ciliary body: helps hold lens in place
Suspensory ligaments: help hold lens in place
Lens: - flexible disk - focuses light onto retina
Iris: - colored part - - surrounds and regulates pupil
Pupil: - regulates amount of light entering
lots of light = dilated little light = constructed
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Nervous Tunic |
-Innermost tunic
Retina: - covers posterior 5/6 of eye - contains 2 layers
1. Pigmented retina: - outer layer - keeps light from reflecting back in eye ( dark/ black pigment makes it difficult for light to reflect back)
2. Sensory retina: - contains photoreceptors (rods and cones) - contains interneurons
Rods: - photoreceptor sensitive to light - 20 times more rods than cones - can function in dim light
Cones: - photoreceptor provide color vision - 3 types blue, green, red
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Nervous Tunic |
Rhodopsin: photosensitive pigment in rod cells
Opsin: colorless protein in rhodopsin
Retinal: - yellow pigment in rhodopsin - requires vitamin A |
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Effects of Light on Rhodopsin
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1. Light strikes rod cell
2. Retinal changes shape 3. Opsin changes shape 4. Retinal dissociates from opsin 5. Change rhodopsin shape stimulates response in rod cell which results in vision 6. Retinal detaches from opsin 7. ATP required to reattach retinal to opsin and return rhodopsin to original shape |
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Retina Structures |
-Rods and cones synapse with bipolar cells of sensory retina -Horizontal cells of retina modify output of rods and cones -Bipolar and horizontal cells synapse with ganglion cells -Ganglion cells axons’ converge to form optic nerve |
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Fovea centralis
Macula |
Macula: small spot near center of retina
Fovea centralis: - center of macula - where light is focused when looking directly at an object - only cones - ability to discriminate fine images
Optic disk: - white spot medial to macula - blood vessels enter eye and spread over retina - axons exit as optic nerve - no photoreceptors - called blindspot
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What are the three chambers of the eye? |
Anterior chamber: - located between cornea and lens - filled with aqueous humor (watery) - aqueous humor helps maintain pressure, refracts light, and provide nutrients to inner surface of eye
Posterior chamber: - located behind anterior chamber - contains aqueous humor
Vitreous chamber: - located in retina region - filled with vitreous humor: jelly-like substance -vitreous humor helps maintain pressure, holds lens and retina in place, refracts light
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Functions of Eye |
Light Refraction - bending of light
Focal point - point where light rays converge - occurs anterior to retina - object is inverted |
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Focusing Images on Retina
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Accommodation:
- lens becomes less rounded and image can be focused on retina - enables eye to focus on images closer than 20 feet |
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Neuronal Pathway for Vision
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Optic nerve:
leaves eye and exits orbit through optic foramen to enter cranial cavity Optic chiasm: where 2 optic nerves connect Optic tracts: route of ganglion axons |
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Eye Defects
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Myopia: - nearsightedness - image is in front of retina
Hyperopia: - farsightedness - image is behind retina Presbyopia: - lens becomes less elastic - reading glasses required Astigmatism: - irregular curvature of lens - glasses or contacts required to correct Colorblindness: - absence or deficient cones - primarily in males Glaucoma: - increased pressure in eye - can lead to blindness |
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Hearing and Balance |
External (Outer) Ear - Extends from outside of head to eardrum
Auricle: fleshy part on outside
External auditory meatus: canal that leads to eardrum
Tympanic membrane: - eardrum - thin membrane that separates external and middle ear |
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Middle Ear |
Air filled chamber (nothing but air)
Malleus (hammer): bone attached to tympanic membrane
Incus (anvil): bone that connects malleus to stapes
Stapes (stirrup): bone located at base of oval window
Oval window: separates middle and inner ear
Eustachian or auditory tube: - opens into pharynx - equalizes air pressure between outside air and middle ear
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Inner Ear |
Set of fluid filled chambers
Bony labyrinth: - tunnels filled with fluid
- 3 regions: cochlea (perilymph and ends lymph), vestibule, semicircular canals
Membranous labyrinth: - inside bony labyrinth - filled with endolymph
Endolymph: clear fluid in membranous labyrinth
Perilymph: fluid between membranous and bony labyrinth
Cochlea: - snail-shell shaped structure - where hearing takes place
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Inner Ear |
Scala vestibuli: - in cochlea - filled with perilymph
Scala tympani: - in cochlea - filled with perilymph
Cochlea duct: - in cochlea - filled with endolymph |
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Inner Ear |
Spiral organ: - in cochlear duct - contains hair cells
Tectorial membrane: - in cochlea - vibrates against hair cells
Hair cells: attached to sensory neurons that when bent produce an action potential |
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Inner Ear
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Vestibular membrane: wall of membranous labyrinth that lines scala vestibuli
Basilar membrane: wall of membranous labyrinth that lines scala tympani (hair) |
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How do we hear?
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1. Sound travels in waves through air and is funneled into ear by auricle. 2. Auricle through external auditory meatus to tympanic membrane. 3. Tympanic membrane vibrates and sound is amplified by malleus, incus, stapes which transmit sound to oval window. 4. Oval window produces waves in perilymph of cochlea. 5. Vibrations of perilymph cause vestibular membrane and endolymph to vibrate. 6. Endolymph cause displacement of basilar membrane. 7. Movement of basilar membrane is detected by hair hairs in spiral organ. 8. Hair cells become bent and cause action potential is created. |
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Balance (Equilibrium)
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Static equilibrium: - associated with vestibule - evaluates position of head relative to gravity
Dynamic equilibrium: - associated with semicircular canals - evaluates changes in direction and rate of head movement |
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Balance (Equilibrium) |
Vestibule: - inner ear - contains utricle and saccule
Maculae: - specialized patches of epithelium in utricle and saccule surround by endolymph - contain hair cells
Otoliths: - gelatinous substance that moves in response to gravity - attached to hair cell microvilli which initiate action potentials |
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Balance (Equilibrium) |
Semicircular canals: - dynamic equil. - sense movement if any direction
Ampulla: base of semicircular canal
Crista ampullaris: in ampulla
Cupula: - gelatinous mass - contains microvilli - float that is displaced by endolymph movement |