senses

what are the 5 basic taste sensations on the tongue

sweet: organic compounds

salt: metal ions

sour: acids

bitter: alkaloids

umami: amino acid/meaty flavor

what part of the ear does this describe:

contains air-filled tympanic cavity

bony wall separates it from inner ear: oval and round window

contains auditory tube and auditory ossicles

middle ear

what does this describe:

passage extending from middle ear to nasopharynx

middle ear infections often result from infections spreading from throat through auditory tube

usually closed but yawning allows air movement through the tube; equalizes pressure on either side of tympanic membrane

auditory tube or eustachian tube

what does this describe:

three tiny bones in middle ear

amplify sound waves and transmit them to oval window

vibrate along with eardrum, so stapes moves in and out of oval window initiating pressure waves in inner ear fluid

two small muscles restrict movement during loud sounds

auditory ossicles

what does this describe:

attached to medial surface of tympanic membrane

resembles a hammer in shape

malleus

what does this describe:

middle ossicle resembling an anvil

incus

what does this describe:

resembles a stirrup of a saddle

has disclike footplate fitting into oval window

stapes

what two small muscles restrict ossicle movement during loud sounds and where do they attach

tensor tympany: attaches to malleus

stapedius: attaches to stapes

what does this describe:

spaces with petrous part of temporal bone

bony labyrnith

membranous labyrnith

choclea

vestibule

semicircular canal

inner ear

bony labyrinth

mazelike spaces in temporal bone

perilymph: interstitial fluid fills most of this space

membranous labyrinth

membrane-lined fluid filled tubes within bony labyrinth

contains receptors for hearing and equilibrium

contains endolymph: similar to intracellular fluid and rich in K+

cochlea

houses membranous choclear duct

snail shaped chamber of inner ear

vestibule

contains 2 saclike, membranous parts: utricle and saccule, that are interconnected and positioned at right angles

semicircular canal

contains membranous semicircular ducts

otitis media

infection of middle ear

young children

causitive agent from respiratory infection

fluid accumulation in ear

pressure, pain, reduced hearing, otoscope

may require myringotomy

what does this describe:

sensory structure for hearing

within cochlear duct

thick sensory epithelium consisting of hair cells and supporting cells on basilar membrane

hair cells: receptors that release neurotransmitter to sensory neurons

single row of inner hair cells; three rows of outer hair cells

may have stereocillia, and kincilium at apex

base of hair cells synapse with sensory neurons

spiral organ

what is the pathway from sound wave to nerve signal

sound waves vibrate tympanic membrane

ossicle vibrates and transmits waves to oval window

fluid pressure waves in scala vestibuli pusch vestibular membrane causing pressure waves in endolymph of cochlear duct

specific regions of basilar membrane move

hair cells distored, causing changes in neurotransmitter release

sensory neurons with axons in CN VIII are stimulated to fire

pressure is transmitted to scala tympani and absorbed by round window

describe cochlear hair cell stimulation

hair cells are bathed in K+ edolymph that is far more positive than the fluid inside the cell

deafness

two types

conductive deafness: interference of wave transmission in external or middle ear

sensorineural deafness: malfunction in inner ear or cochlear nerve

equilibrium

coordination, balance, and orientation in 3-d space

vestibular apparatus

responsible for sensing equilibrium

3 semicircular ducts: angular acceleration

vestibule: macula saccule and macula utricle; static equilibrium and linear acceleration

what do these general functions describe:

provide information about external and internal environements

respond to a stimulus

each type of receptor responds best to a type of stimulus

sensory receptors

transducers

convert stimulus energy into electrical energy

receptors have resting membrane potential

receptor membrane have modality gates channels that respond to their type of stimulus

action potentials are conveyed to CNS for interpretation

receptors covey signals to CNA by ______

sensory neurons

receptive field

the distribution area of the endings of a sensory neurons

smaller receptive fields allow more precise stimulus localization

sensation

a stimulus we are consciously aware of

to enter consciousness, signals must reach cerebral cortex

only a fraction of stimuli result in sensations

a lot of sensory input goes to other areas of the brain

receptors provide CNA information about stimulus ____,____,____, and _____

modality

location

intensity

duration

what does this describe:

receptor distribution

simple structures distributed throughout body

somatic sensory receptors

visceral sensory receptors

general sense receptor

somatic sensory receptors

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

visceral sensory receptors

found in walls of internal organs, they monitor stretch, chemical environment, temperature, pain

what does this describe:

receptor distribution

specialized reecptors in complex sense organs of the head

5 special senses: olfactions, gustation, vision, audition, equilibrium

special sense receptors

what does this describe:

stimulus orgin

detect stimuli from external environment

skin and mucus membranes; special sense receptors

exteroceptors

what does this describe:

stimulus origin

detect stimuli from internal organs

visceral sensory receptors monitoring internal environment

interoceptors

what does this describe:

stimulus origin

detect body and limb movements

somatosensory receptors of muscles, tendons, and joints

proprioceptors

what does this describe:

modality of stimulus

detect chemicals dissolved in fluid

include receptors for external environment or internal environment

chemoreceptors

what does this describe:

modality of stimulus

detect changes in temperature

include receptors in skin, hypothalamus

thermoreceptors

what does this describe:

modality of stimulus

detect changes in light intensity, color, movement

in the retina of eye

photoreceptors

what does this describe:

modality of stimulus

detect distortion of cell membrane

include touch, pressure, vibration, and stretch receptors

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

mechanoreceptors

what does this describe:

modality of stimulus

detect painful stimuli

somatic: detect chemical, heat or mechanical damage to body sruface or skeletal muslce

visceral: detect internal organ damage

nociceptors

tactile receptors

abundant mechanoreceptors of skin and mucous membranes

endings can be encapsulated or unencapsulated

what does this describe:

dendritic ends of sensory neurons with NO protective cover

free nerve endings

root hair plexuses

tactile discs

unencapsulated tactile receptors

free nerve endings

terminal ends of sensory neuron dendrites

simplest tactile receptors

reside close to skin surface and in muscous membranes

mainly for pain and temperature but also light tough and pressure

may be phasic or tonic

root hair plexuses

wrap around hair follicle

located in deeper layer of dermis

detect hair displacement

phasic receptor

tactile discs

flattened endings of sensory neurons extending to tactile cells (merkel cells)

tactile cells are specialized epithelial cells in basal layer of epidermis

respond to light to

what does this describe:

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

end (krause bulbs)

lamellated (pasinnian corpuscles)

bulbous corpuscles

tactile corpuscles

encapsulated tactile recptors

end bulbs (krause)

ensheathed in connective tissue

located in dermis and mucus membranes

detect pressure and low-frequency vibration

tonic recptors

lamellated corpuscles (pacinian)

wrapped in neurolemmocytes and concentric layers of connective tissue

located deep in dermis, hypodermis, some organ walls

detect deep pressure, coarse touch, high frequency vibration

phasic receptors

bulbous corpuscles (ruffini)

within dermis and subcutaneous layer

detect deep pressure and skin distortion

tonic receptors

tactile corpuscles (meissner)

are intertwined endings wrapped in modified neurolemmocytes, covered in connective tissue

in dermal papillae

discriminative light touch; allow. recognition of texture, shape

phasic receptors

reffered pain

inaccurate localization of sensory signals

signals from viscera perceived as originating from skin, muscle

many somatic and visceral sensory neurons send signals via the same ascending tracts within spinal cord

somatosensory cortex unale to determine true source

phantom pain

sensation associated with removed body part or limb

followed by amputation of limb

experience of pain from a removed part

stimulation of sensory neuron pathway on remaining portion

cell body of sensory neuron still alive

pain sometimes quite severe

olfaction

sense of smell

detect ordorants (chemcials in air)

adaptive

olfactory cells

receptor found in olfactory epithelium of nasal pasageways

neurons exposed to air

chemoreceptors

olfactory nerve goes directly to cerebral cortex

2000-4000 odors distinguished

gustation

sense of taste

detection of tastants

gustatory cells are cehmoreceptors within taste buds

what does this describe:

short and spiked

not taste buds/no role in gustation; help manipulate food

filiform papillae

what does this describe:

mushroom-shaped

each contains a few taste buds

located on tip and sides of tongue

fungiform papillae

what does this describe:

leaflike ridges

not well developed

house a few taste buds in early childhood

located on posterior lateral tongue

foliate papillae

what does this describe:

largest, least numerous

contain most of the taste buds

located in a row of 10-12 along posterior dorsal tongue surface

vallate (cirvumvallate) papillae

taste buds

onion shaped organs housing taste receptors

gustatory cells: receptor cells detect tastants (live 7-9 days)

supporting cells: sustain gustatory cells

basal cells: neural stem cells that replace gustatory cells

what 3 nerves have to do with taste

facial nerve (VII)

glossopharyngeal nerve (IX)

vagus nerve (X)

describe the pathway of gustation

sensory neurons connect to multiple gustatory cells in the tongue and project to the medulla

in anterior parts of tongue, sensory neurons are part of the facial nerve

posterior part of tongue, sensory neurons are glossopharyngeal

secondary medullary neurons project to thalamus

tertiary thalamic neurons project to primary gustatory cortex

for sweet bitter and umami the tastants are _____

molecules

for salt and sour the tastants are _______

ions

conjunctiva

transparent lining of eye and lid surfaces

specialized stratified columnar epithelium

contains numerous goblet cells to moisten eye, blood vessels to nourish sclera, and abundant nerve endings

does not cover cornea

lacrimal apparatus

produces, collects, drains fluid

lacrimal fluid: water Na+, antibodies, lysozyme

lubricates, cleanses and moistens eye

lacrimal glands produces fluid and secretes it through ducts

blinks wash fluid over eye

fluid drains into lacrimal puncta

sac drains to nasolacrimal duct to nasal cavity

excess lacrimal fluid produces tears

posterior cavity (behind lens)

contains permanent vitreous humor

anterior cavity (in front of lens)

contains circulating aqueous humor

fibrous tunic

sclera & cornea

tough outer layer

vascular tunic

iris

ciliary body

choroid

middle layer with many vessels, lymph vessels, intrinsic muscles

retina tunic

pigmented layer

neural layer

internal or neural tunic

sclera

white of the eye

desne irregular CT

eye shape

protects internal components

attachment site for extrinsic eye muscles

cornea

anterior convex tansparent window

inner layer is simple squamous epithelium, middle layer collagen, outer layer stratified squamous eputhelium

no blood vessels

limubs: conreneal scleral junction

refracts light

choroid

extensive, posterior region

many capillaries nourish retina

many melanocytes make melanin to absorb extraneous light

ciliary body

ciliary muscles and processes

located just anterior to choroid

muscles and processes

iris

gives eye color; most anterior region of uvea

contains smooth muscle, melanocytes, vesseks, neural structures

divides anterior segment into anterior and posteior chambers

pupil is opening in center of iris

pigmented layer of retina

attached to choroid

provides vitamin A for photoreceptors

absorbs stray light to prevents light scatter

neural layer of retina

houses photoreceptors and asociated neurons

receives light and converts it to nerve signals

ora serrata

jagged edge

boudary between parts of retina

path of light through the eye

cornea

through aqueous anterior chamber

through pupil

through lens

through vitreous posterior chamber

retina

photoreceptor cell layer

outermost nueral layer

contains rods and cones

contain pigment that reacts to light

bipolar cell layer

their dendrites receive synaptic input from rods and cones

ganglion cell layer

innermost neural layer

their axons gather at optic disc and form optic nerve

horizontal cells

regulate signals between phtoreceptors and bipolar cells

amacrine cells

regulate signals between bipolar and ganglion cells

optic disc

contains no photoreceptors- blind spot

where ganglion axons exit toward brain

macula lutea

rounded yellowish region lateral to optic disc

contain fovea centralis

peripheral retina

contain primarily rods

functions most effectively in low light

detatched retina

occurs when outer pigmented and inner neural layers seperate

result of head trauma

increased risk in diabetics and nearsighted individuals

nutrient deprivation in inner layer

floaters

flashes of light

decreased vision

pneumatic retinopexy and scleral buckle are treatments

macular degeneration

physcial deterioration of macula lutea

leading cause of blidness

may be associated with diabetes, infection, hypertension, eye trauma

loss of visual acuity in center of visual field

diminished color perception and floaters

lens

changes shape to focus light on retina

cells within it have lost organleeles and are filled with crystallin protein

lens enclosed by dense fibrous elastic capsule

shape determines light refraction

shape determined by ciliary muscle and suspensory ligaments

cataracts

small opacities within the lens

usually as a result of aging

difficulty focusing on close objects

reduced visual clarity and reduced color intensity

needs to be removed when interferes with normal activities

phacoemulsification new surgery

vitreous humor

transparent gelatinous fluid in posteiror cavity

permanent fluid first produced in embryonic development

helps maintain eye shape

supports retina

aqueous humor

transparent watery fluis in anterior cavity

continuously produced by ciliary processes

nourishes and oxygenates lens and inner cornea

production circulation and drainage

plasma filtered aross capillary walls

circulates throug pupil

drain from chamber via scleral venous sinus then to nearby veins

glaucoma

increased intraocular pressure

may cause compression of choriod layer, constrict lbood vessels

reduced field of vision, dim vision, halos around light

emmetropia

normal vision

parallel light rays focused on retina

hyperopia

far-sighted

trouble seeing up slose; eyeball too short

only convergent rays from distant points brought to focus

corrected with convex lens

myopia

near sighted

trouble seeing faraway objects; eyeball too long

only rays close to eye focus on retina

corrected with concave lens

astigmatism

unequal focusing

unequal curvatures in one or more refractive surfaces

presbyopia

are related change in vision

lens less able ot become spherical

reading close up is difficult

corrective convex lens

care be treated with surgery

describe light transmission to retina

•Light is refracted (bent) as it passes through the cornea and lens

•Image upside down and reversed

•Light passing through the center of the cornea is not bent

•Cornea refracts light more than lens does

–Lens merely fine-tunes image

–Lens can change shape and become rounder to increase refraction for near vision (accommodation)