ap chapter 15 sense organs

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ap chapter 15 sense organs

chemoreceptors

1. receptor responds to chemical, ex. smell, taste
2. also interior
3. one that adapts but it's not firing. one is the nose.
4. pain receptors never stop firing - don't adapt - you learn to deal with it b/c thalamus filters it out

photoreceptors

only in eye

External ear

1. Auricle or pinna (outside of ear) - traps sound waves
2. External auditory meatus: (carries sound down)
a. Ceruminous glands (protective ear wax)
3. Tympanic membrane (eardrum)
a. Thin membrane of two layers of epithelium with connective tissue between
b. Vibrate when sound waves travel down meatus
c. Border between external and middle ear

tympanic membrane

External ear (eardrum)
a. Thin membrane of two layers of epithelium with connective tissue between
b. Vibrate when sound waves travel down meatus
c. Border between external and middle ear

external auditory meatus

external ear
Ceruminous glands (protective ear wax)
carries sound down

middle ear

1. Auditory or eustachian tube (elastic cartilage)
a. Opens into pharynx, equalizes pressure
2. Ossicles: malleus, incus, stapes (separate bones)
a. Has to Transmit vibrations from eardrum (tympanic membrane) to oval window
3. Oval window (in vestibule)
4. Round window
*this is where the nerves are

Auditory or eustachian tube

Middle ear
Opens into pharynx, equalizes pressure

Ossicles: malleus, incus, stapes

Middle ear
Ossicles: malleus, incus, stapes (separate bones)
a. Has to TRANSMIT vibrations from eardrum (tympanic membrane) to oval window

Inner ear

In temporal, sense of balance & hearing
1. aka Labyrinths ("maze")
a. Bony (white in lab) labyrinth: chambers in the temporal bone
b. Membranous (gray in lab) labyrinth: ducts and chambers in the bony labyrinth
2. Fluids
a. Endolymph: in membranous labyrinth (inside) - more potassium
b. Perilymph: space between membranous labyrinth and periosteum of bony labyrinth

Inner ear - labyrinths

a. Bony (white in lab): chambers in the temporal bone
b. Membranous (gray in lab): ducts and chambers in the bony labyrinth

Inner ear - Fluids

a. Endolymph: in membranous labyrinth (inside) - more potassium
b. Perilymph: space between membranous labyrinth and periosteum of bony labyrinth

Cochlea

1. Oval window opens into vestibule
2. Scala vestibuli (above cochlear duct & organ of Corti) beginning of oval window. contains perilymph.
3. Scala tympani (below cochlear duct & organ of Corti) beginning of round window. contains perilymph

Cochlea

1.`Wall of scala vestibuli is vestibular membrane
2. Wall of scala tympani is basilar membrane
3. Cochlear duct : space between vestibular and basilar membranes. Filled with endolymph
4. High frequency sounds near oval window, low frequency near end of scala vestibuli

cochlea problems

1. problems with hair cells & they die, cause is sound beating hair cells
2. nerve damage - then possible cochlea implant

cochlea how it works

1. round window = doesn't allow the wave to go backwards
2. how do you know which direction its coming from? comes into one side of brain sooner than the other
3. stapes = sound waves changes to fluid around cochlea generating a nerve impulse. brain then interprets the nerve impulse.

organ of corti (spiral organ)

1. Nervous tissue
2. Hair cells
3. Tectorial membrane (has hair cells)
4. Afferent fibers form the cochlear nerve (leave ear as vestibulocochlear nerve)

Sense of hearing

1. Sound waves ---> fluid waves ---> action potential
2. Sound travels down external auditory meatus and causes vibration of tympanic membrane
3. Ossicles transmit vibration from tympanic membrane to oval window (causes fluid wave)
4. Sound wave converted to a fluid wave in scala vestibuli - causes displacement of basilar membrane
5. Fluid wave is dissipated at round window
6. Action potentials generated in organ of corti carried away by cochlear nerve (end up in brain to be interpreted)

Neuronal pathway of hearing

Vestibulocochlear nerve

Cochlear nuclei (pons)

Inferior colliculi (midbrain) - auditory reflex

Thalamus (relay system)

Primary auditory cortex (temporal lobe - interpretation in cerebrum, feelings etc.)

May also produce an auditory reflex (inferior colliculi) (head turning)

Equilibrium

1. Control of coordination and balance
2. Receptors in semicircular canals and vestibule (saccule & utricle)
a. semicircular ducts contain crista
b. saccule and utricle contain macula
3. Static equilibrium -Forward & backward motion of head
a. Utricle and saccule
b. Evaluates position of head relative to gravity
c. Detects linear acceleration and deceleration (as in a car)
4. Dynamic equilibrium Turning and at what speed.
a. Semicircular canals
b. Evaluates movement of the head in three dimensional space

Static equilibrium

Forward & backward motion of head
a. Utricle and saccule (contain macula)
b. Evaluates position of head relative to gravity
c. Detects linear acceleration and deceleration (as in a car your head snaps forward & head automatically snaps back)

Dynamic equilibrium

Turning and at what speed.
a. Semicircular canals
b. Evaluates movement of the head in three dimensional space
c. distorts hair cells

Neuronal pathways for balance

1. Vestibulocochlear nerve - this splits
2. Vestibular nucleus - (pons & medulla)
a. Receives input from motor sources - proprioception (determine where your body is, ex. laying on right or left side, tries to coordinate info from ear)
3. Send fibers to cerebellum (influences posture)
4. Sends fibers to oculomotor, trochear and abducens nerves (influences eye movement - skeletal muscles in eye)
5. Thalamus
6. Vestibular area of temporal lobe, b/c different info to interpret

anatomy of the eye

Three layers:
1. Sclera (hard white part) and cornea
2. Choroid, ciliary body, iris - becomes ciliary body & iris, comes all the way around
3. Retina (not complete circle)

Sclera

1. white outer layer, fibrous, continuous w/cornea
2. Maintains shape
3. Protects internal structures
4. Provides muscle attachment point (allows you to move the eye)

Cornea

1. Transparent anterior portion of sclera
2. Avascular
3. Allows light to enter eye
4. Bends and refracts (bends to a point) light.

Choroid layer

1. Contains most of the blood vessels of the eye
1. Iris: colored part of the eye.
a. Controls light entering the pupil.
b. Smooth muscle determines size of pupil.
3. Ciliary body (vascular): w/ridges, goes all the way around
a. Produces aqueous humor
4. Ciliary muscles/process
a. Control lens shape, changes shape of lens
b. Ciliary processes attached to suspensory ligaments of lens

Iris

choroid layer
a. Controls light entering the pupil.
b. Smooth muscle determines size of pupil.

Ciliary body

choroid layer
Produces aqueous humor
(vascular): w/ridges, goes all the way around

ciliary muscles

choroid layer
a. Control lens shape, changes shape of lens
b. Ciliary processes attached to suspensory ligaments of lens

Retina

Retina is nervous tissue - three types of nerves
Two layers
1. Pigmented retina:
a. Reduce light scattering/washing out
2. Sensory retina:
a. Inner layer of rod and cone cells sensitive to light.

Opthalmoscopic view of retina

1. Lens focuses light on macula lutea and fovea centralis
a. Macula lutea: small yellow spot (everything you see in front of you) peripheral is outside of macula lutea
b. Fovea centralis: area of greatest visual acuity (center of macula lutea)
2. Optic disc: blind spot.

macula lutea

small yellow spot (everything you see in front of you) peripheral is outside of macula lutea

fovea centralis

area of greatest visual acuity (center of macula lutea)
cones are densely located here

optic disc

aka blind spot b/c no rods or cones only nerve fibers

retina - nervous tissue (3)

1. Photoreceptors -visual receptors
a. Rods - black, white and shades of gray
b. Cones - red, green and blue
2. Bipolar neurons - pass on info to ganglionic neurons
3. Ganglionic neurons - collect info, but also act as photoreceptors

anterior cavity

Anterior cavity = lens to cornea and
Consists of:
1. Anterior chamber = iris to cornea
2. Posterior chamber = lens to iris
3. anterior cavity contains aqueous humor (made from blood by ciliary body) if you can't move aqueous humor btw chambers then glaucoma, lose peripheral vision, destroys retina from outside.

posterior cavity

posterior cavity = retina/posterior to lens
Contains vitreous humor

accessory structure of eye

1. Eyebrows and eyelashes - protective
2. Eyelids
a. Conjunctiva - shiny lining
3. Lacrimal apparatus = tears wash across & drain, eventually into the nose
4. Muscles
a. Intrinsic - smooth, change shape of lens or opening of iris
b. Extrinsic - skeletal. ex. rolling your eyes

conjunctiva

1. Mucous membrane lining each lid. it continues over surface of eyeball, where modified to give transparency.
2. Richly innervated and vascular

lacrimal apparatus

1. lacrimal glands =drains tears into conjuctiva
2. lacrimal ducts/canals
3. lacrimal sacs
4. nasolacrimal ducts.

formation of retinal image refraction #1

A. Refraction of light rays
a. Cornea - lasix changes
b. Lens
c. Humors
2. Problems
a. Myopia - nearsightedness, changes refraction. eye is longer and focuses in fron of retina
b. Hyperopia - farsightedness in kids. eye is shorter, focuses in back of retina
c. Astigmatism - ripple in cornea or lens - distorts, changes how it hits

formation of retinal image accommodation #2

1. Adaptation change in focus from near to far and vice versa
2. Lens - need to change shape
3. Ciliary muscles, changes shape of lens
4. Problem
a. Presbyopia - reading glasses, lose flexibility & elasticity

formation of retinal image constriction #3

1. Control of amount of light entering eye
2. Iris
3. can be light out and have "deer in headlights" b/c of sympathetic

formation of retinal image convergence #4

1. Overlap of visual fields
a. Both eyes focusing to form one image
2. Problem
a. Strabismus = cross eyed
b. double vision, 2 eyes aren't focusing on one thing. brain has 2 impage & can't tell what to do.

Photopigments - rods

1. Rods - black, white & shades of gray, dim light
a. Rhodopsin - pigment needs to be stimulated ("bleaching")
i. Contains retinol (vit A) & opsin
b. Low light vision
c. Noncolor vision
d. Mostly in periphery
Night blindness due to lack of vitamin A

Photopigments -cones

1. Visual pigment is iodopsin
2. Mostly in macula & fovea
3. Color vision and visual acuity, sharper
4. cones need more energy, stimulation and light (bright light)

neuronal pathway of eye

has a crossing over. actually see in brain. Eye is the action potential
1. Optic nerve - half of fibers cross over
2. Optic chiasma - white matter/fibers, cut=blind
3. Optic tract - goes out
4. Superior colliculi - visual relfex
5. Thalamus
6. Visual cortex (occipital lobe)

neuronal pathway of eye - damage (3)

1. if you cut one optic nerve they lose sight in one eye
2. if you cut optic chiasma they lose sight in both eyes
3. if you have damage to occipital lobe, you can be blind. no damage to the eye but brain can't interpret what you are seeing

red-green color blindness

..

macular degeneration

..

glaucoma (tunnel vision)

..

cataracts

..

laser surgery - myopia

..

4 openings in middle ear

1. tympanic membrane
2. auditory tube
3. oval window
4. round window

neuron structure in ear

bipolar

scala vestibuli

1. Scala vestibuli (above cochlear duct & organ of Corti) beginning of oval window
2. Wall of scala vestibuli is vestibular membrane

scala tympani

1. Scala tympani (below cochlear duct & organ of Corti) beginning of round window
2. Wall of scala tympani is basilar membrane

all neurons in ear are?

hair cells

Ear - general

the stimulation involves activation of hair cells
sound waves & fluid movement are the physical forces that act on hair cells to generate receptor potentials & then nerve impulses, which are perceived in brain as sound or balance

ear functions

hearing and balance/equilibrium

Inner ear - Endolymph fluid

a. Endolymph: in membranous labyrinth (inside) -potassium
rich

Inner ear - Perilymph fluid

Perilymph: space between membranous labyrinth and periosteum of bony labyrinth

Inner ear - bony labyrinth consists of 3 parts

1. vestibule
2. cochlea
3. semicircular canals

Inner ear - Membranous labyrinth consist of 3 parts

1. utricle & saccule inside the vestibule
2. cochlear duct inside the cochlea
3. membranous semicircular ducts inside the bony ones

Inner ear - 2 parts involved in balance

1. vestibule (containing utricle & saccule)
2. semicircular canals ( and membranous ducts)

Inner ear - 1 part involved in hearing

cochlea

tears

are protective - liquid, oil & mucous. keep sterile, keep cornea moist.

muscles of the eye (2)

1. Intrinsic - smooth/involuntary, change shape of lens or opening of iris
2. Extrinsic - skeletal/voluntary. ex. rolling your eyes

suspensory ligaments

hold the lens in place

what is structure of neurons in ear?

bipolar

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