Presentation on theme: "Senses Sense: ability to perceive stimuli Sensation:"— Presentation transcript:
1Senses Sense: ability to perceive stimuli Sensation: conscious awareness of stimuli received by sensory neuronsSensory receptors:sensory nerve endings that respond to stimuli by developing action potentials
2Types of Senses General senses: - 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 itchSpecial senses:smell, taste, sight, hearing, and balance
3Types of Receptors Mechanoreceptors: - detect movement - Ex. touch, pressure, vibrationChemoreceptors:- detect chemicals- Ex. OdorsPhotoreceptors:detect light
10Pain Control Local anesthesia: - action potentials suppressed from painreceptors in local areas- chemicals are injected near sensory nerveGeneral anesthesia:- loss of consciousness- chemicals affect reticular formation
11Referred Pain What is it? - originates in a region that is not source of painstimulus- felt when internal organs are damaged orinflamed- sensory neurons from superficial area andneurons of source pain converge onto sameascending neurons of spinal cord
13Olfaction What is it? - sense of smell - occurs in response to odorants- receptors are locatedin nasal cavity andhard palate- we can detected10,000 different smells
14How does olfaction work? Nasal cavity contains a thin film of mucous where odors become dissolved.Olfactory neurons are located in mucous. Dendrites of olfactory neurons are enlarged and contain cilia.3. Dendrites pick up odor, depolarize, and carry odorto axons in olfactory bulb (cranial nerve I).4. Frontal and temporal lobes process odor.
16Taste Taste buds: - sensory structures that detect taste - located on papillae on tongue, hard palate,throatInside each taste bud are 40 taste cellsEach taste cell has taste hairs that extend into taste pores
18How does taste work?Taste buds pick up taste and send it to taste cells.Taste cells send taste to taste hairs.Taste hairs contain receptors that initiate an action potential which is carried to parietal lobe.Brain processes taste.
19Types of Tastes Sweet Sour Salty Bitter Umami Certain taste buds are more sensitive to certaintastes.Taste is also linked to smell.
20Vision Accessory Structures Eyebrow: - protects from sweat - shade from sunEyelid/Eyelashes:- protects from foreign objects- lubricates by blinking
26Anatomy of Eye Hollow, fluid filled sphere Composed of 3 layers (tunics)Divided into chambers
27Fibrous Tunic Outermost layer Sclera: - firm, white outer part Cornea: - helps maintain eye shape, provides attachmentsites, protects internal structuresCornea:- transparent structure that covers iris and pupil- allows light to enter and focuses light
28Vascular Tunic Middle layer Contains blood supply Choroid: - black part (melanin)- delivers O2 and nutrients to retinaCiliary body:helps hold lens in placeSuspensory ligaments:help hold lens in place
29Lens:- flexible disk- focuses light onto retinaIris:- colored part- surrounds and regulates pupilPupil:- regulates amount of light entering- lots of light = constricted- little light = dilated
32Nervous Tunic Innermost tunic Retina: - covers posterior 5/6 of eye - contains 2 layersPigmented retina:- outer layer- keeps light from reflecting back in eye
33Sensory retina:- contains photoreceptors (rods and cones)- contains interneuronsRods:- photoreceptor sensitive to light- 20 times more rods than cones- can function in dim lightCones:- photoreceptor provide color vision- 3 types blue, green, red
36Rhodopsin:photosensitive pigment in rod cellsOpsin:colorless protein in rhodopsinRetinal:- yellow pigment in rhodopsin- requires vitamin A
37Effects of Light on Rhodopsin Light strikes rod cellRetinal changes shapeOpsin changes shapeRetinal dissociates from opsinChange rhodopsin shape stimulates response in rod cell which results in visionRetinal detaches from opsinATP required to reattach retinal to opsin and return rhodopsin to original shape
39Retina Structures Continued Rods and cones synapse with bipolar cells of sensory retinaHorizontal cells of retina modify output of rods and conesBipolar and horizontal cells synapse with ganglion cellsGanglion cells axons’ converge to form optic nerve
40Nervous Tunic (Retina) Innermost layer2 parts of retina: sensory and pigmentedKeeps light from reflecting back into eyeRods:photoreceptors that detect amount lightCones:- photoreceptors that detect colors- 3 types: red, blue, green
41Macula:small spot near center of retinaFovea centralis:- center of macula- where light is focused when looking directlyat an object- only cones- ability to discriminate fine images
42Optic disk:- white spot medial to macula- blood vessels enter eye and spread over retina- axons exit as optic nerve- no photoreceptors- called blindspot
44Chambers of Eye Anterior chamber: - located between cornea and lens - filled with aqueous humor (watery)- aqueous humor helps maintain pressure, refractslight, and provide nutrients to inner surface ofeyePosterior chamber:- located behind anterior chamber- contains aqueous humor
45Vitreous chamber:- located in retina region- filled with vitreous humor: jelly-like substance- vitreous humor helps maintain pressure, holdslens and retina in place, refracts light
46Functions of Eye Light Refraction Bending of light Focal point: - point where light rays converge- occurs anterior to retina- object is inverted
47Focusing Images on Retina Accommodation:- lens becomes less rounded and image can befocused on retina- enables eye to focus on images closer than20 feet
53Astigmatism:- irregular curvature of lens- glasses or contacts required to correctColorblindness:- absence or deficient cones- primarily in malesGlaucoma:- decreased pressure in eye- can lead to blindness
55Hearing and Balance External (Outer) Ear Extends from outside of head to eardrumAuricle:fleshy part on outsideExternal auditory meatus:canal that leads to eardrumTympanic membrane:- eardrum- thin membrane that separates external andmiddle ear
56Middle EarAir filled chamberMalleus (hammer):bone attached to tympanic membraneIncus (anvil):bone that connects malleus to stapesStapes (stirrup):bone located at base of oval window
57Oval window:separates middle and inner earEustachian or auditory tube:- opens into pharynx- equalizes air pressure between outside airand middle ear
65How do we hear?Sound travels in waves through air and is funneled into ear by auricle.Auricle through external auditory meatus to tympanic membrane.Tympanic membrane vibrates and sound is amplified by malleus, incus, stapes which transmit sound to oval window.Oval window produces waves in perilymph of cochlea.
665. 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.
68Balance (Equilibrium) Static equilibrium:- associated with vestibule- evaluates position of head relative to gravityDynamic equilibrium:- associated with semicircular canals- evaluates changes in direction and rate of headmovement
69Vestibule:- inner ear- contains utricle and sacculeMaculae:- specialized patches of epithelium in utricleand saccule surround by endolymph- contain hair cellsOtoliths:- gelatinous substance that moves in responseto gravity- attached to hair cell microvilli which initiate actionpotentials
72Semicircular canals:- dynamic equil.- sense movement if any directionAmpulla:base of semicircular canalCrista ampullaris:in ampullaCupula:- gelatinous mass- contains microvilli- float that is displaced by endolymph movement