Special Senses - AP exam 4

sensory receptors

info about internal and external environment

what is the job of sensory receptors? why is each receptor unique?

respond to stimulis; each receptor has a stimuli it responds best to

transducer

converts stimulis energy into electrical energy

generator potential

graded potential that occurs in sensory receptors when they are stimulated

what happens during a generator potential reaction

a stimulus activates. sensory receptor, ion channels in the receptor membrane open causing local depolarization; strong enough will be a action potential

Unipolar

neurons are the primary sensory neurons dor general senses. carry info into the brain

receptive field

the distribution area of a sensory neurons endings

what are the different types of receptive fields and what do they do

there is a small field which provides percice localization, and there is a large field which is more vague

sensation

a stimulus we are consciously aware of

what do stimuli need to do to reach consciousness

cross the cerebral cortex; only a fraction of stimuli result in sensation

what determins stimuli intensity

the frequency of nerve signals to the CNS

what is unique to stronger stimuli

they cause more sensitive neurons to fire more frequently

adaptation

decreases sensitivity to continuous stimulis

tonic receptors

respond continuously; limited adaptation

phasic receptors

adapt rapidly; only respond to new stimuli

general sensory receptors

simple structures distributed throughout the body

somatic receptors

tactile receptors of skin and mucous membranes; proprioceptors of joints, muscles and tendons

viceral receptors

found in the walls of organs, monitoring stretch, chemical environment, temperature and pain

special sense receptors

olfaction, gustation, vision, audition and equilibrium

exteroceptors

detect stimuli from external environment, skin and mucous membranes

interoceptors

detect stimuli from internal organs; visceral receptors monitor environment

proprioceptors

general sensory receptors - detect body and limb movements, somatosensory receptors of muscles, tendons and joints (all tonic receptors)

Chemoreceptors

detect stimuli dissolved in fluid (external - smell of food, internal - oxygen levels in blood)

thermoreceptors

detect change in temperature - receptors in skin (hypothalamus)

photoreceptors

detect changes in light intensity, color or movement - in retina of eye

Mechanoreceptors

detect distortion of cell membrane - touch, pressure, vibration and stretch

examples of mechanoreceptors

baroreceptors, proprioceptors, tactile receptors and specialized receptors in the inner ear

nocioceptors

detect painful stimuli - somatic (chemical or mechanical) and viceral (internal organ)

tactile receptors

abundant mechanoreceptors of skin and mucous membranes - endings unencapsulated or encapsulated

unencapsulated

Dedric ends of sensory neurons with o protective cover

free nerve endings

terminal ends of sensory neuron dendrites - simpilest tactile receptor (close to skins surface, in mucous membrane; for pain + temp, light and pressure

root hair plexuses

wrap around hair follicle - deeper layer of dermis, detect hair displacement

tactile discs

flattened endings of sensory neurons endings to tactile merkel cells - specalized epithelial cells in basal layer or epidermis, responds ot light touch

encapsulated tactile receptors

neuron endings wrapped in connective tissue or covered by tissue and glial cells

End (Krause) bulbs

Located in dermis and mucus membranes

Detect pressure and low-frequency vibration

Lamellated (Pacinian) corpuscles

wrapped in neurolemmocytes and concentric layers of connective tissue - deep dermis, hypodermis and some organ walls (deep pressure, course touch and high frequency vibration

Bulbous (Ruffini) corpuscles

wrapped in connective tissue - within dermis and subcutaneous alyer, detect deep pressure and skin distortion

Tactile (Meissner) corpuscles

intertwines ending wrapped in modified neurolemmocytes, covered in connective tissue - in demal papillae, allow recognition of texture and shape

Muscle Spindle

detect stretch in skeletal muscle

golgi tendon organ

detect stretch in tendon

join kinesthetic receptor

detect stretch in articular capsule (joint)

referred pain

inaccurate localization of sensory signals - signal from viscera percieved as originating form skin and muscle, many somatic and visceral sned signals down same tracts

phantom pain

pain from removed part due to stimulation of senspry neuron pathway - "lack of information"

Olfaction

smell - detection of odors; odorants

olfactory epithelium

olfactory receptors, supporting cells and basal cells

olfactory bowman glands

mucus production coats nerve endings and receptors

gustaiton

taste - detection of tastants; chemoreceptors within taste buds

Papilla

filiform, fungiform, foliate - minimal or no taste buds

vallate

largest, least numerous; most taste buds

tase senstaitons

sweet, salty, sour, bitter and umami

Eye accessories

eyebrows, eyelashes, eyelids, conjunctiva

eyebrow

keep sweat out of eyes + facial expressions (nonverbal communication)

eyelashes

keep away dust and debris

eyelid

protect eye and keep it lubricated - palpebral fissure (eyelid opening)

conjunctiva

vocers the scleras and inside eyelid, protective between eyelid and eyeball

lacrimal apparatus

produces collects and drains fluid - lubricates and moisturizes eye, lacrimal gland, lacrimal puncta and lacrimal canaliculus

chalazion

infection of tarsal gland, release oily secretion (blocks oil gland)

stye

infection of sebatious gland (true infection)

droopy eyelids

problems with muscles responsible for lifting eyelids

shape and size of eye

2.5cm in diameter, almost spherical

posterior cavity

permanent vitreous humor; thicker and more gelatinous

viterous humor

compresses retina, keeps eye shape, when fluid dries up can cause detached retina

anterior cavity

circulating aquaouss humor; thiner more watery

aquaous humor

nourishes and oxygenates lense and inner cornea - overproduction can lead to glaucoma (compression, reduced field of vision)

what does the iris seperate

the anterior and posterior chambers

what are the 3 tunics

fibrous (external), vascular (middle), retina (inner)

lense

changes shape to focus light on retina

how does the lense allow us to see

the pulling of suspensatory ligaments (threads) attached to the ciliary body

flat lense

allows us to see far away

rounded lense

allows us to see close up

what makes the fibrous tunic

the sclera and cornea

sclera

tough outer layer

Cornea

The clear tissue that covers the front of the eye - anterior convex

whate makes the vascular tunic

choroid, ciliary body, iris, pupil

choroid

extensive posterior region

cilliary body

muscles and processes - shape and secreting aqueous humor

iris

gives color - most anteirpor region of uvea, anteiro and posterior chamber

pupil

opening in center of iris connecting chambers - controls pupil diameter

what makes the retina tunic

photoreceptor cells, bipolar cells, ganglion cells

photoreceptor cell

rods (light) cones (color)

bipolar cell

dendrites receive synaptic later from rods and cones

ganglion cell

axons gather at optic disc and from optic nerve

optic nerve

carries all axons from each eyeball

optic chiasm

cross over even 1/2 of optic nerve tracts to each side of the brain

optic tracts

ganglion cell axons from both nerves

optic disk

blind spot; contains no photo receptors - brains good at compensating

maclula lutea

rounded, yellowish region lateral to optic disk - contains fovea centralis

what unique to the fovea centralis

it has the highest proportion of cones - sharpest vision

peripheral retin

primarily rods; functions most effective in low light

refraction of light

sharp vision required light rays to be bent, refraction results when light passes through, through curves surfaces such as the lense

focusing of light

object 20ft or further away; ciliary muscles relax, tensing suspensory ligaments and flattening the lense

phototransduction

converting light to electrical signals; photo receptor cells - outer segment extends into pigmented layer or retina

what are the types of photoreceptor cells

rods and cones

rods

long, narrow, more numerous - light sensitive

cones

contracted at fovea centralis - color sensitive

what are the parts of the ear?

external, middle and internal

what makes up the external ear

auricle, external acoustic meatus, and tympanic membrane

auricle

traps sound waved down ear cannal

external acoustic meatus

ear canal, extends to tympanic membrane

ear wax

dead skin and cerumen