N261 Chapter 18: In-depth Exploration of General and Special Senses

a sensory receptor

specialized cell or cell process that monitors conditions in the body of the external environment

sensation

the sensory information arriving at the CNS

perception

conscious awareness of a sensation

general senses

-temperature, pain, touch, pressure, vibration, and proprioception

-receptors throughout the body

-somatosensory cortex

special senses

-smell, taste, balance, hearing, vision

-specialized receptor cells are structurally more complex than general

receptor specificity

each receptor responds to one type of stimulus

receptive field

the area that a receptor monitors

tonic receptors

always send signals, thus information is based of the frequency of action potentials

phasic receptors

send action potentials only if stimulated

peripheral adaptation

receptors may stop sending action potentials even if the stimulus is still present

central adaptation

CNS ignores an action potential from a receptor

exteroceptors

provide information about the external environment

proprioceptors

monitor body position

interoceptors

monitor conditions inside the body

noiceptors

tissue damage and pain

thermoreceptors

change in temperature

mechanoreceptors

physical distortion, contact, or pressure

chemoreceptors

chemical composition of body fluid

carotid and aortic sinus

provide information on blood pressure to cardiovascular and respiratory control centers

three types of papillae

-filiform

-fungiform

-circumvallate

four primary tastes:

-salty

-bitter

-sweet

-sour

cranial nerves involved in gustation

VII, IX, X

membranous labyrinth

filled with endolumph

bony labyrinth

filled with perilymph

cochlear duct

hearing

vestibular complex

equilibrium

semicircular ducts

rotation

utricle and saccule

detect linear acceleration and the effects of gravity

fibrous tunic

sclera and cornea

neural tunic

retina

vascular tunic

choroid, ciliary body, iris

anterior cavity of eye

aqueous humor

posterior cavity of eye

vitreous humor

photoreceptors

rods and cones

free nerve endings

-simplest receptors in the human body are the dendrites of sensory neurons

receptive field

area monitored by a single receptor cell

the larger the receptive field,

the harder it is to localize the stimulus

sensory information is sent to the CNS as an:

action potenial, which is an electrical event

sensory coding

provides information about the strength, duration, variation, and movement of the stimulus

tonic receptors

sensory neurons that are always active

ex: receptors of the eye and receptors monitoring body position

phasic receptors

normally inactive and become active whenever there is a change in the conditions they monitor

ex: touch and pressure receptors in the skin

adaptation

reduction in sensitivity in the presence of a constant stimulus

peripheral adaptation

when a receptor or sensory neuron alters its level of activity

phasic receptors

fast-adapting receptors

tonic receptors

slow-adapting

central adaption

-conscious awareness disappears

-involves nuclei along the sensory pathways within the CNS

eponyms

commemorative names

fast pain

-prickling pain

-produced by deep cuts or similar injuries

-

slow pain

-burning pain

-sensations begin later and persist longer

referred pain

pain originating in visceral organs but perceived as involving specific regions of the body surface innervated by the same spinal nerves

temperature sensations are conducted in the

spinothalamic tracts

-the same pathways carrying pain sensations

thermoreceptors are ___ receptors

phasic

tactile receptors

provide details information about exact location, shape, size, texture, and movement of the stimulation

-small receptive fields

Merkel cells

-stratum basale of the skin

-sensitive to fine touch and pressure

-tonically active

tactile corpuscles

-found where the sense of touch is well developed

-detect light touch, movement, and vibration

-phasic receptors

Bulbous corpuscles

-tonically active

-senstive to pressure and distortion of the skin

Lamellar corpuscles

-pulsing, vibratoin, deep pressure

-adapt rapidly

gustatory epithelial cells

taste receptors

-stimulated by dissolved food molecules

which cranial nerves carry gustatory information

VII, IX, X

the facial nerve innervates all the taste buds located on the ________ of the tounge

anterior two-thirds

the glossopharyngeal nerve innervates the vallate papillae and the _______ of the tongue

posterior one-third

external ear

-outer fleshy auricle

-surrounds external acoustic meatus

tympanic membrane

-eardrum

-thin, semitransparent connective tissue sheet separating the external ear from the middle ear

ceruminous glands

-line the external acoustic meatus

-cerumen= way secretions of glands slows growth of microorganisms

tympanic cavity

-air filled space in middle ear

-location of auditory ossicles

-communicates with nasopharynx

auditory ossicles

-ear bones

-connect the tympanic membrane with the receptor complex of the internal ear

-connected by synovial joints

-malleus, incus, stapes

malleus

-attached to tympanic membrane

incus

-middle ear bone

-connectes the medial surface of the malleus to the stapes

stapes

-base fills oval window

-causes vibrations int he fluid contents in the internal ear

vestibular complex

formed by vestibule and semicircular canals

cochlear duct

-elongated portion of the membranous labyrinth

round window

-separates the perilymph of the cochlear chambers from the middle ear

oval window

-superior of the 2 openings

-in the cochlear wall

-vibrations of the oval window are conducted to the perilymph of the internal ear

fibrous layer (eye)

-outermost later

-sclera and cornea

-provides mechanical support and physical protectoin for the eye

-attachment site for the extra-ocular muscles

-focusing muscles

sclera

-white of the eye

corneoscleral junction

-forms the junction between the cornea and the sclera

vascular layer (uvea)

-contains numerous blood vessels, lymphatics, and intrinsic eye muscles

-isis, ciliary body, and choroid

iris

Colored part of the eye

pupil

-opening of the center of the iris

sphincter pupillae

-constricts pupil

dilator pupillae

-enlarges/dilates pupil

ciliary body

-begins at junction of cornea and sclera and extends to the ora serrata

-ciliary muscle

-ciliary processes

-ciliary zonule

-hold the lens in place

choroid

-separates the fibrous layer and the inner layer

-delivers oxygen and nutrients to the retina

retina

-pigmented layer= outer layer

-neural layer= inner layer(contains visual receptors)

fovea centralis

site of sharpest color vision

superchiasmatic nucelus

-circadian rhythm

-metabolic rate

-endocrine function

-blood pressure

-digestive activities