taste smell vision hearing balance respond to chemicals in an aqueous solution food dissolved in...
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TasteSmellVision
HearingBalance
respond to chemicals in an aqueous solutionfood dissolved in salivaairborne chemicals dissolved in mucous membrane
Taste and smell are involved with specific receptor cells called chemoreceptors
The Tongue
Taste BudsTaste Buds
Circumvallate Papilla
Filiformpapilla
Fungiformpapilla
Connective tissue Tongue epithelium
Salty- metallic ions
Sweet- sugarSweet- sugar
Sour- HSour- H++
Bitter- alkaloidBitter- alkaloid
Why are they important?
Umami- savory/meatyUmami- savory/meaty
Dry tongue with a paper towel and Dry tongue with a paper towel and place a little sugar on surface.place a little sugar on surface.What do you taste?What do you taste?
Facial nerve (afferent) 2/3 anterior portion of tongueGlossophyngeal posterior 1/3 of tongueVagus nerve- few taste buds on epiglottis an pharynxThese afferent fibers synapse in medullathalamus gustatory cortex in parietal lobes and fibers to hypothalamus in limbic system
Taste triggers reflex involved in digestion; causes an increase of saliva in mouth (amylase) and gastric juice in stomach
acids cause strong salivary reflexbad tasting food causes gagging or reflexive vomiting
taste can change over time
taste is 80% smell
Mouth also contains: Thermoreceptors
Mechanoreceptors
Nociceptors- sensitive nerve fibers that are aware of painful stimuli
Smell not as good as animals; however, some people are wine tasters, perfumers
If you smell a particular odor all day, you won’t recognize its presence, you become accustomed, ex. garbage men
Old people lose sense of smell- lots of perfume
Humans can distinguish 10,000 or so chemicals
What we really smell is pain: ex. chili, ammonia, menthol (cold)Specific chemicals cause specific patterns of neurons to fire
Figure 15.21a
Olfactory tract
Olfactory bulb
(a)
Nasalconchae
Route ofinhaled air
Olfactoryepithelium
Figure 15.21a
Mitral cell (output cell)
Olfactorygland
Olfactorytract
Olfactoryepithelium
Filaments of olfactory nerve
Cribriform plate of ethmoid bone
Lamina propria connective tissue
Basal cell
Supporting cell
Dendrite
Olfactory cilia
Olfactory bulbGlomeruli
Axon
Olfactory receptor cell
Mucus
Route of inhaled aircontaining odor molecules(b)
Cortical Regions Associated with Olfactory Information
Olfactory auras- prior to epileptic attack
May be genetic or a cold (mucus), allergy, zinc deficiency
loss of sense of smell
Lose sense of smelllose taste
Uncinate- olfactory hallucinations; may be psychological ex. rotting meat smell
sclera
irispupil
teardrainage canal
cornea
Medial commisure
lateral commisure
palpabre
palpabre
Lacrimal caruncle
bright light normal light dim light
FLOW OF TEARSLacrimal gland
Lacrimal ducts
Sup. or inf. lacrimal canal
Lacrimal sac
Nasolacrimal duct
Nasal cavity
optic nerve
Superior rectus
Inferior oblique Lateral rectus
Inferior rectus
Medial rectus
Superior oblique
Fibrous tunic- sclera and cornea (outer most layer)
Composed of dense avascular connective tissue
Vascular tunic- uvea: choroid, cilliary body, iris, pupil (middle layer)
Choroid- rich vascular nutritive layer; contains a dark pigment
that prevents light scattering within the eye
Cilliary body- lens is attached; contains muscles that change the
lenses shape
Iris- pigmented ring of muscular tissue composed of circular
and radial muscles
• reflex contraction of circular muscle in bright light (small dia of pupil)
• reflex contraction of radial muscle in dim light (large dia of pupil)
Pupil- central hole in iris
Sensory tunic- retina (inner most layer)
Photoreceptors:
• rods (dim light, contains pigment rhodopsin) and
• Cones (color vision, not evenly distributed, concentrated in fovea)
Optic disc- blind spot because its where optic nerve leaves the eyeball (no rods or cones)
Macula lutea- yellow spot, area of high cone
Fovea centralis- in center of macula lutea, contains only cones, area of greatest visual acuity
Vitreous humor- behind lens, gel-like substance with fine collagenic fibrils imbedded in as viscous ground substance- binds with water
• transmits light• supports the posterior surface of the lens and
holds the neural retina firmly against pigmented layer
• contributes to intraoccular pressure, helping to counter act the pulling force of the extrinsic eye muscles
Aqueous humor- in front of lens, anterior segment, watery fluid
• Supplies cornea and lens with nutrients• Helps to maintain the shape of the eye• Produced and renewed every 4 hrs by the
cilliary body
Lens- transparent biconvex structure, flexible• Attached by suspensory ligaments to ciliary
body• focuses image onto retina• changes lens thickness to allow light to be
properly focused onto retina
Coarse Fixed FocusingCoarse Fixed Focusing• Cornea ShapeCornea Shape
AccommodationAccommodation- adjust configuration of- adjust configuration of • Lens ShapeLens Shape• Pupil SizePupil Size
refraction
Focusing on a Near Object
Focusing on a Far Object
• Emmetropia- normal 20:20• Hyperopia- farsighted• Myopia-near sighted• Presbyopia- mature eyes• Astigmatism
20 ft:20 ftYou see Normal vision
20/10
What condition does this person have?
What condition does this person have?
Clouding of lens (hardening or thickening
causes: diabetes mellitus, smoking, UV damage
blind spot macula
The RetinaThe Retina
lightlight
photoreceptive cells
ChoroidSchlera
Ganglion
Amacrine
Bipolar neuron
Horizontal cells
photoreceptors Rod cell membrane
Binocular vision
Geometrical illusions
Successive contrast : afterimages ...
what do you see?
fixate the black dot in the center for 60 seconds ...
… and then look at a the black dot in the right panel !
Outer ear- pinna (auricle), lobule, external auditory canal; elastic cartilage
External auditory canal has: ceruminous glands- wax secreting glands- protects delicate lining of meatus and helps prevent microorganisms from entering the ear
Tympanic membrane- membrane that vibrates in response to sound waves
Middle ear- Includes 3 small bones (ossicles)- hammer (mallus), anvil (incus), stirup (stapes)
Pharyngeotympanic auditory tube (Eustachian tube)- equalizes pressure; connects middle ear to pharynx. Oval window- found on cochlea; stirrup presses against cochleaRound window- pressure window on cochleaOtis media- inflammation of the middle ear; due to bacteria or allergies, common in children whose auditory tubes are short and horizontal
external auditory canal
tympanic membrane
Auditory tube
malleusincus stapes
round window
oval window
Inner ear- bony labyrinth filled with perilymph fluid (similar to CFS) and membranous labyrinth filled with endolymph fluid (similar to K+ rich intracellular fluid); these fluids conduct sound vibrations Bony labyrinth (includes vestibule, semicircular canal, and cochlea)Vestibule- posterior to cochlea and anterior to the semicircular canalsPerilymph fluid suspends 2 membranous sacs: utricle and sacule-- they house equilibrium receptors called maculae that respond to the pull of gravity
Semicircular canal- contains endolymph fluid; anterior, posterior, and lateral canal; contains equilibrium receptors (ampulla)
Cochlea- filled with perilymph fluid
Organ of Corti- rests a top basilar membrane; has long row of hair cells
Biology 100Biology 100Human BiologyHuman Biology
cochlea
saccule
utricle
semicircular canals
vestibulochoclear nerve
Properties of sound:Sound travels at 331 m/secIt's a pressure disturbance originating from the
vibrationFrequency- cycles/sec (hertz); Reflects sound
intensityHuman hearing- 20 to 20,000 htz
Pitch- different frequency's; high vs low; pure tone is a single frequency
Quality- sound mixture with several frequencies
Intensity- corresponds to amplitude of height; loudness measured in decibels
Transmission of sound:Airborne soundexternal auditory canaltympanic membranehammer, anvil, stirrupoval windowvestubularcochlear nervecochlear nuclei in medulla superior oliveup the lateral leminiscusinferior colliculusprimary auditory cortex in the temporal lobe
Scala tympani
Cochlear duct
Basilarmembrane
Malleus Incus
Auditory ossicles
Stapes
Ovalwindow
Scala vestibuli
Helicotrema
Cochlear nerve
32
1
Roundwindow
Tympanicmembrane
(a) Route of sound waves through the ear
Fibers of basilar membrane
(b) Different sound frequencies cross the basilar membrane at different locations.
Medium-frequency sounds displacethe basilar membrane near the middle.
Low-frequency sounds displace thebasilar membrane near the apex.
Base(short,stifffibers)
Frequency (Hz)
Apex(long,floppyfibers)
Basilar membrane
High-frequency sounds displacethe basilar membrane near the base.
Static Balance – utricle and sacule
Dynamic Balance- semicircular canals
(semicircular canal)
cupula
hair cells
Endolymph fluid
Vestibular nerve fibers
(semicircular canal)
The effect of gravitational pull on the macula receptor cell in the utricle
The effect of gravitational pull on the macula receptor cell in the utricle
Hearing loss- due to disease (ex. meningitus), damage, or age related
Conduction deafness- prevention or blocking sounds from entering inner ear.
Ex. ear wax, ruptured ear drum, middle ear inflammation (otis media), and otosclerosis (hardening of the ossicles of the ear)
Sensoneural deafness- damage to the neural structures from any point from the cochlear hair cells to and including the auditory cortical cells• Partial or complete deafness, or gradual loss
over time
Tinnitus- ringing or clicking sound in the absence of auditory stimuli; 1st symptom of cochlear nerve degeneration
• may result from inflammation of the inner or middle ear
• side effect from medicine such as aspirin
• Symptoms- vertigo, nausea, hearing loss
Meniere's Syndrome- labyrinth disorder; effects both semicircular canals and cochlea
IDENTIFY
Hearing Animation:http://health.howstuffworks.com/adam-200010.htmhttp://www.youtube.com/watch?v=dyenMluFaUw
INQUIRY
1. What type of stimulus triggers a response in nociceptors?
2. Two senses that detect chemical concentrations are____.
3. A person with defective otolith sensory receptors may have difficulty ______.
4. Which eye muscle moves the eye to look medially?5. Name the three bones in the middle ear.6. What is the blind spot in the eye called?7. Where are the highest concentration of cones
located?