McGraw Hill ch. 16 Senses

Describe the general function of sensory receptors as transducers. (What is "transduction"?)

respond to stimulus give info of internal/external environment giving info to brain

transduction: converts sensory signal to electrical signal processed in specialized area in brain

Describe the general structure of a sensory receptor, and explain the significance of a receptive field.

convey signals to CNS by sensory neurons

receptive field: distribution area of the endings of a sensory neuron

(area a receptor gathers information)

Define a sensation

a stimulus we are constantly aware of

consciousness signal must reach cerebral cortex

Explain the various characteristics of a stimulus that sensory receptors provide to the CNS.

modality: sensory receptor relaying sensory input along designated sensory neurons to specific regions of the CNS

location: sensory information is relayed either from different regions of a sensory receptor or from different locations

intensity: change in number of nerve signals that are arriving along a designated nerve

duration: decrease in sensitivity to a continuous stimulus is called adaptation

Distinguish between tonic and phasic receptors

tonic receptors: limited adaptation respond continuously head position receptors in inner ear all pain receptors

phasic receptors: undergo adaptation adapt rapidly only respond to a new stimuli pressure receptors

Identify and describe the three criteria used to classify receptors

distribution: general sense receptors

visceral and somatic sensory and special senses

modality: chemoreceptors, thermoreceptors, photoreceptors, mechanoreceptors, nocioceptors

taste smell temperature vision distortion pain

origin: exteroceptors, interoceptors, proprioceptors

cutaneous, in smooth muscle, found in joints

Classify the various types of sensory receptors based upon each of the three criteria.

somatic sensory: skin joints touch receptor

visceral sensory: blood vessels stretch receptor in stomach wall

special senses: head 5 senses

exteroceptors: external environment skin

interoceptors: detect stimuli in skin 5 senses

proprioceptors: detect stimuli in joints muscle spindles

chemoreceptors: detect chemicals taste receptors

thermoreceptors: temp change in skin hypothalamus

photoreceptors: change in light intensity color in retina

mechanoreceptors: deformation of plasma membrane skin

nociceptors: detect painful stimuli pain receptors

Compare and contrast unencapsulated and encapsulated tactile receptors.

unencapsulated tactile receptors: dendrite endings sensory neuron no protective covering

FREE NERVE ENDING/ ROOT HAIR PLEXUS/ TACTILE DISC

encapsulated tactile receptors: neuron ending wrapped in ct covered by glial cells and neurolemmocytes

END BULB/ LAMELLATED CORPUSCLES/ BULBOUS CORPUSCLES

Define referred pain, and explain its significance in diagnosis

inaccurate localization of sensory signals

region of pain isnt for where the medical problem is

heart attack pain in arm for men

back pain for liver failure

Briefly discuss how pain perception is moderated in 3 ways

stop pain message from being formed lidocaine numb mouth

block pathway of pain message nerve block procedure

alter CNS processing like narcotics

Which "sense" information does NOT pass through the thalamus?

smelling olfactory tracts

Name the components of the olfactory receptors, and discuss their mode of action.

Olfactory Epithelium- epithelium tissue inside nasal cavity olfactory, supporting and basal cells responsible for detecting odors

Olfactory Tract-bundle of axons connecting to mitral and tuffted cells of olfactory bulb to target regions of brain (amygdala, piriform & entorhinal cortex)

Olfactory bulb-structure brain receives neural input from nasal cavity sense of smell.

Olfactory nerve- bipolar neurons congregate to form olfactory nerve receptors in the mucosa of the nasal cavity relays info to the brain

Describe the path of a nervous impulse from your olfactory receptors to the cerebrum - which part? Is there just one path/one final destination?

olfactory never project through skull cribriform plate enter olfactory bulb

1)olfactory sensations start odorant binds to protein stimulate receptor cell

2) g-protein activate leading to depolarization of ion channels

3)action potential triggered on axon

4)secondary neuron conducts signals to CNS area

5)olfactory receptors adapt quickly bc synaptic inhibition in olfactory bulb

Describe the structure and function of papillae of the tongue 4 types

Fungiform: mushroom shaped, present at tip. Innervated by facial nerve.

Filliform: thin, long papillae "V" shaped and most numerous. However, not involved with gustation

Foliate: ridges & grooves towards posterior roof of mouth innervated by facial nerve and glossopharyngeal nerve

Circumvallate: only about 10-14 on most people. Present at the back of tongue arranged in a circular row. Innervated by glossopharyngeal nerve

Discuss the structure and location of gustatory receptors

receptors that detect various specific tastes, like sweet, salty, bitter, sour, and umami spread across the tongue

Describe the five types of tastes, and explain the association of smell with taste.

Sweet: Produced by organic compounds sugar or artificial sweeteners

Salt: Produced by metal ions Na+ & K+

Sour: Associated w/ acids vinegar

Bitter: Produced by alkaloids unsweetened chocolate

Umami: Taste related to amino acids producing meaty flavor

80% OF TASTE IS SMELL

Describe the path of a nervous impulse from your gustatory receptors to the cerebrum - which part? Which nerves carry this information?

Sensory neuron connect to gustatory cells in tongue project to medulla

sensory medulla neurons project to thalamus

tertiary thalamic neurons project to primary gustatory cortex in insula

Describe the accessory structures of the eye, and list their functions

Eyebrow, Eyelash, Eyelids: are to protect the eye from any potential irritant

Conjuctiva: thin-transparent membrane that covers the sclera. Helps lubricate the eye by producing mucous and tears

Which way do tears flow across your eye? What do tears do?

lacrimal gland above eye in bone produces tears

lacrimal apparatus collects/drains fluids

secretes through ducts in superolateral orbit

tears moisten eye and cleans, reduces eyelid friction

Describe the extrinsic eye muscles

superior inferior medial lateral rectus move eye up down laterally medially

superior inferior obliques move eye to or away from nose

Describe the structures of the eye

Retina-recieve light and convert the light into neural signals that are sent to the brain for visual recognition

Ciliary Body- focuses

Ciliary muscles-smooth muscle connected to lens

Lens-changes shape to focus on objects at various distances

Sclera-white of eye

Suspensory ligaments- controls lens

Iris- controls pupil diameter sphincter constrict pupil dilator dilate pupil

Describe refraction of light

when light passes b/w media of different densities like air and cornea through curved surfaces such as the lens

Discuss how light is focused on the retina

Light passes through the front of the eye (cornea) to the lens

The cornea and the lens help to focus the light rays onto the back of the eye (retina)

The cells in the retina absorb and convert the light to electrochemical impulses which are transferred along the optic nerve and then to the brain

Explain what a "blind spot" is

the optic disc is called the blind spot bc no photoreceptors are there

Explain how light gets from outside your eye to your photoreceptors...listing all the structures and fluids it passes through on the way

light passes through cornea

through aqueous humor

through the pupil hole

through the lens

through the vitreous humor

through the ganglion cells

through bipolar cells

hits rods and cones photoreceptors

Describe the location and function of the lens. What is myopia, hyperopia, emmetropia, and presbyopia?

emmetropia- normal vision

presbyopia-age related change in vision need convex lenses

hyperopia- farsighted

myopia- nearsighted

Why will everyone need glasses at some point in their lives?

presbyopia age related change in vision lens get stiffer less stable becomes more spherical get convex lenses

Define phototransduction

converting light to electrical signals by photoreceptors of rods and cones

Compare and contrast the two general types of photoreceptors, including their photopigments

rods long narrow in dim light

cones see color activated in high intensity light

Where is the highest concentration of cones located?

concentrated in fovea centralis

Why can you see better at night out of the corner of your eye than looking directly at something?

because your lens does not have to focus and change shape

in dim light your eyes do not need to adjust as much as in bright light

rods are present at the extremes of the eye

What is color blindness?

resessive condition in males absence in one type of cone cell for red and green most common

Explain the bleaching reaction and how it relates to dark adaptation and light adaptation

light causes reconfiguration to trans-retinal which dissociates from opsin (bleaching retraction)

dark adaptation bleached rods make rhodopsin

light adaptation processing from low to bright light rods work better in dim light take time to adjust

Describe the visual pathway from the photoreceptors to the brain

from rods and cones

goes to bipolar cells

then ganglion cells

goes to optic nerve

then optic chiasm

then optic tract

through thalamus

optic radiations occurs

primary visual center in occipital lobe gets the signal

Explain how stereoscopic vision provides depth perception

Stereopsis is depth that arises as a consequence of having two eyes have overlapping visual fields

What happens to the number of action potentials generated in light versus dark? Why?

Rod cells are hyperpolarized in the light and depolarized in the dark

During hyperpolarization, an action potential cannot be generated

so in the dark more action potentials are generated

Describe the structures of the outer, middle, and inner ear

external ear has auricle and external acoustic meatus

middle ear has air filled tympanic cavity and auditory tube and ossicles malleus incus stapes

inner ear has cochlea, vestibulae and semicircular vestibule-respond to change in position of head Semicircular ducts-maintain balance, detects motion Vestibulochochlear nerve

Round Window-"sound exit"

Name the auditory ossicles, and explain how they function in hearing

malleus incus stapes all transmit sound waves to inner ear to amplify sound

compare and contrast the bony labyrinth and the membranous labyrinth

bone labyrinth: maze in temporal bone has perilymph interstitial fluid fills most of space

membranous labyrinth: tubes has endolymph intracellular fluid with lots of potassium

Explain the components of the cochlea and how they function in the sense of hearing

cochlea receives sound in the form of vibrations, which cause the stereocilia to move in spinal sensory part

The stereocilia then convert these vibrations into nerve impulses which are taken up to the brain to be interpreted

Explain how moving air (which is what sound waves are) gets converted to a nervous signal. And how that nervous signal gets to the processing area in your brain

soundwaves collected by auricle travels down external acoustic meatus

vibrate tympanic membrane moving ossicles and make them vibrate

stapes vibrates moving oval window moving endolymph

endolymph moves basilar membrane moving into ear

hair cells in basilar membrane pushed against tectorial membrane

hair cells bend making depolarization release neurotransmitter

makes action potential in cochlear nerve

goes through vestibulocochlear nerve

moving to medulla oblongata

signal from pons can go to midbrain

nerve signal is now passed to thalamus

relayed to primary auditory cortex to be interpreted

now sound is perceived in temporal lobe of cerebrum

Distinguish between frequency (pitch) and intensity (loudness) of sound.

pitch is frequency of the vibrating object

frequency is rate of vibration

intensity is depends on wave amplitude

Describe the structures of the inner ear involved in equilibrium

vestibule and semicircular ducts-angular acceleration

responsible for balance and equilibrium

utricle and saccule

Explain how the utricle and saccule detect static equilibrium and linear movements of the head, and explain how the semicircular ducts function to detect rotational movements of the head

utricle and saccule detect static equilibrium and linear acceleration from the head bc hair cells have otoliths and when you tilt your head they move with macula knowing up and down

semicircular ducts detect angular acceleration and motion of the head info sent to brain to keep balance

Summarize the nerve pathways involved in equilibrium

signals from macula or ampulla conveyed by 8th CN

axons terminate in vestibular nuclei- medulla control reflexive eye movements and balance

cerebellum-coordinates balance and muscle tone

these send signals to thalamus

thalamus relays info to cerebral cortex of awareness

Clinical view: phantom pain

sensation associated with removed body part bc stimulation still happens to the sensory neurons

Clinical view: detached retina

happens when nearsighted

from outer pigmented and inner neural layers separate

see floaters in affected eye

Clinical View: Macular Degeneration

physical deterioration of macula lutea

cause of blindness associated w/ diabetes ocular infection eye trauma

Clinical View: Cataracts

small opacities in lens result from aging

risk factor of diabetes smoking uv light sunglasses

cant focus on close objects can be removed

Clinical view: glaucoma

increased intraocular pressure

Aqueous humor drainage being blocked is cause

makes reduced field of vision dim vision give halos around light

Clinical view: functional visual impairments

astigmatism: unequal focusing and unequal curvatures in one or more refractive surfaces

rest mentioned already on other card

Clinical view: otitis media

infection in middle ear in children common bc of short horizontal auditory tubes

cause from respiratory infection can spread from pharynx

Clinical view: deafness

any hearing loss

conductive interference of wave in external/middle ear

sensorineural malfunction in inner ear