Anatomy Test 4: Pathways

stimuli

sensory information

sensation

conscious awareness of stimuli

transduction

stimuli converted to an impulse so it can be carried through the nervous system

perception

the brain assigning meaning to impulses

sensory receptors

detect stimuli around the body

general senses

distributed throughout skin and organs; sense temperature, pain, touch, stretch, and pressure

special senses

housed in complex organs in the head; sense gustation, olfaction, vision, equilibrium, and hearing

“classification by modality”

classification of stimulus depends on the stimulating agent

chemoreceptors

detect specific molecules dissolved in fluid; taste/ smell

thermoreceptors

detect changes in temperature; general/ all over the body

photoreceptors

detect changes in intensity, color, and position of light

mechanoreceptors

detect touch, pressure, vibration, and stretch; a lot in the inner ear

baroreceptors

detect pressure changes within body structures; ex. in cardiovascular system

nocireceptors

detect painful stimuli

phantom pain

sensation associated with a part of the body that has been removed

referred pain

impulses from certain viscera are percieved as originating not from the organ, but from the skin

tactile receptors

most numerous type; sense of touch; loacted in the dermis and subcutaneous layer

gustation

sense of taste

gustatory cells

taste receptors housed in taste buds; detect tastants

taste buds

special organs housing numerous gustatory cells; located on dorsal surface of tongue in papillae

papillae

epithelial and connective tissue elevations

tastants

molecules and ions in food giving it flavor

5 taste sensations

sweet, salty, sour, bitter, umami

olfaction

sense of smell

odorants

dissolved in mucus of nasal cavity and detected; not as sensitive in humans as in other animals

olfactory epithelium

lines superior nasal cavity

olfactory nerves

bundles of axons of olfactory receptor cells; extends into nasal cavity

olfactory bulbs

where axons from neurons foramina of cribiform plate enter

olfactory tracts

axon bundles running from within olfactory bulbs to olfactory complex of temporal lobe

extrinsic muscles

innervated outer muscles moving eyeball; accessory structure of eye

eyelids

flaps of skin protecting anterior surface of the eye; accessory structure of the eye

medial canthus

medial junction of the eyelids; inner corner of eye; accessory structure of the eye

lateral canthus

lateral junction of the eyelids; outer corner of eye; accessory structure of the eye

lacrimal caruncle

pink, fleshy area on medial eye; accessory structure of the eye

conjunctiva

a lining of the eyelids and over the anterior surface of the eye (besides cornea)

lacrimal apparatus

produces, collects, and drains lacrimal fluid from the eye

lacrimal fluid

tears; lubricate the anterior surface of the eye

lacrimal gland

produces and secretes tears; in the upper outer corner between eye and eyebrow

lacrimal canaliculi

where excess tears drain out of eye

lacrimal sac

collects excess tears to drain out through nose

nasolacrimal duct

how tears drain from the lacrimal sac out through the nose

anterior cavity

in front of the lens of the eye; contains circulating aqueous humor

aqueous humor

watery liquid/ fluid in the eye

posterior cavity

behind the lens of the eye; contains permanent vitreous humor

vitreous humor

gelatinous fluid maintaining the structure of the eye

3 layers of the eye wall

fibrous tunic, vascular tunic, retina

glaucoma

build up of pressure in the eye, usually due to too much aqueous humor

fibrous tunic (2 regions)

thick/ strong; cornea and sclera

cornea

transparent, anterior portion of eye

sclera

white of the eye; makes up most of fibrous tunic

vascular tunic (3 regions)

contains vessels in the eye; choroid, ciliary body, iris

choroid

contains vast network of capillaries supplying nutrients and oxygen to the retina

ciliary body

changes lens shape

iris

pigmented part of the anterior eye; defines the pupil

pupil

controls amount of light entering the eye

sphincter pupillae

decreases/ constricts the size of the pupil; circular muscle closest to pupil

radial dilator pupillae

contract to increase the size of pupil and let more light in; arranged like bike spokes

retina

internal layer of the eye

neural layer of retina

houses photoreceptors and associated neurons; receives light and converts energy into nerve impulses

3 layers of neural layer

photoreceptors cells, bipolar cells, ganglion cells

photoreceptor cells

outermost layer of neural layer composed of rods and cones

rods

important in dim light; more numerous than cones; low abillity to distinguish detail

cones

important for precise vision and color; concentrated in fovea; used in day vision; high ability to distinguish detail

bipolar cells

intermediate layer of neural layer; synapse with photoreceptors and ganglion cells

ganglion cells

deepest layer of neural layer/ retina; axons of these cells leave the retina and form the optic nerve

optic disc

blind spot on the retina lacking photoreceptors; located where optic nerve leaves eye

fovea centralis

depression in the retina containing the highest proportion of cones and almost no rods; area of sharpest vision; located within macula lutea

macula lutea

lateral to optic disc; contains fovea centralis

lens

transparent structure; suspensory ligaments attach to outer capsule; changes shape to focus on an image

optic chiasm

where axons from retina cross to the other side

optic tracts

extend laterally, posteriorly from chiasm

optic radiation

extends from thalamus to occipital lobe

visual acuity

the ability to distinguish fine detail

nearsightesness/ myopia

inability to focus on objects that are far away because the eyeball is too long; focal point ahead of retina

farsightedness/ hyperopia

inability to focus on objects that are close because the eyeball is too short; focal point behind retina

presbyopia

age related hyperopia

astigmatism

irregularity on cornea or lens; causes light to scatter

conjuctivitis

inflammation of the conjuctiva; pink eye; common in kids

cataracts

lens becomes cloudy; happens with age; corrected with surgery

diabetic retinopathy

small unstable blood vessels develop within the eye; prone to rupture which causes blind spots

strabismus

misalignment of eyes due to imbalance in strength of the extrinsic eye muscles; weaker eye lags behind in movement

3 distinct anatomic regions of the ear

external, middle, and inner

external ear parts (3)

auricle, external acoustic meatus, tympanic membrane (ear drum)

auricle

directs sound waves into external acoustic meatus; cone shaped

cerumen

waxlike secretion produced by glands deep within the external auditory meatus

middle ear parts (2)

auditory tube, auditory ossicles (malleus, incus, stapes)

auditory tube

connects middle ear to nasopharynx; when fluid is drained it reduces pressure

auditory ossicles

small bones; transmit sound waves to inner ear

3 auditory ossicles

malleus, incus, stapes

inner ear

within petrous portion of temporal bone; helps with equilibrium and hearing

equilibrium

the brain’s awareness of head position

vestibular apparatus parts (3)

sensory receptors helping with equilibrium; utricle, saccule, semicircular ducts

utricle and saccule

detect static equilibrium when head is stationary and linear acceleration

semicircular ducts

detect angular acceleration (rotational movements) of head

maculae

within utricle and saccule; contain hair cells

hair cells

bend and send electrical activity to the brain via vestibular nerve

otoliths

in gelatinous mass with hair cells of maculae; push on gelatin layer to bend hair cells

otolithic membrane

otoliths, gelatin layer, and hair cells together

3 semicircular canals

anterior, posterior, and lateral

ampulla

expanded region within each of the 3 semicircular canals