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Flashcards in senses Deck (76)

Function of baroreceptors

a type of mechanoreceptor, senses change in blood pressure


Function of chemoreceptors

respond to changes in the concentration of chemicals - detect changes in blood concetration of oxygen, hydrogen ions, glucose, and other chemicals.


Function of mechanoreceptors

sense mechanical forces by detecting changes that deform the receptors (proprioceptors, baroreceptors, stretch receptors)


Function of nociceptors

pain receptors, respond to tissue damage. Triggering stimuli include excess mechanical, electrical, thermal, or chemical energy.


Function of photoreceptors

in eyes, respond to light energy of sufficient intensity


Function of proprioceptors

type of mechanoreceptor, sense changes in tensions of muscles and tendons.


Function of stretch receptors

type of mechanoreceptor, sense degree of inflation in lungs


Function of thermoreceptors

sensitive to temperature change


Define sensation and explain how it occurs

Sensation is the raw form in which sensory receptors send information to the brain. A sensation occurs when the brain becomes aware of sensory impulses.


Explain sensory adaptation

Ability to ignore unimportant stimuli. Sensory impulses become less frequent until they may cease. Impulses are only triggered if the strength of the stimulus changes.


List and define 3 groups of somatic senses

1. Exteroreceptive senses _ changes at the body surface _ touch, pressure, temp, pain.
2. Visceroreceptive (interoceptive) senses _ changes in viscera (blood pressure, ingested meal stimulating pH receptors in small intestine, etc)
3. Proprioceptive senses _ Chagnes in muscles and tendons in body position.


List & describe the 3 kinds of touch & pressure receptors

1. Free nerve endings _ simplest, common in epithelial tissue, lies between epithelial cells. Responsible for itch.
2. Tactile (meissner_s) corpuscles _ oval masses in flattened connective tissue cells in connective tissue sheaths. Abundant in hairless portions of the skin, such as the lips, fingertips, palms, soles, nipples, and ext genital organs. Responsible for fine touch, such as distinguishing two points on the skin where an object touches, to judge its texture.
3. Lamellated (pacinian) corpuscles _ large, ellipsoidal structures composed of connective tissue fibers & cells. Common in deeper dermal tissue fibers and cells of hands, feet, penis, clitoris, urethra, breasts, etc. Responsible for heavier pressure and stretch, and vibrations in tissue


Identify the two types of free nerve endings located in the skin that function as temperature receptors

_ Warm receptors _ sensitive to temperatures above 77F, and become unresponsive above 113F. at 113F+, pain receptors are triggered, producing a burning sensation
_ Cold receptors _ sensitive to temps between 50F and 68F. Below 50F, pain receptors are stimulated, and the person feels a freezing sensation


Describe the receptors associated with the sense of pain.

_ Receptors are free nerve endings, widely distributed throughout the skin and internal tissue, except in nervous tissue of the brain.
_ They protect because they are stimulated when tissues are damaged _ unpleasant feeling, signaling that action be taken to remove the source of stimulation.


Explain pain nerve pathways and their regulation

o Two Types:
_ Acute pain fiber (a-delta) _ thin, myelinated fibers that conduct nerve impulses rapidly. Associated with sharp pain, which originates in a local area of the skin. This type of pain seldom continues after the pain-producing stimulus stops.
_ Chronic pain fibers (c fibers) _ thin, UNmyelinated fibers, conduct slowly, causes dull, aching pain sensations that may be widespread and difficult to pinpoint.


Explain referred pain.

o Referred pain: Pain in viscera may feel as though it_s coming from some part of the body other than what is being stimulated.
_ EX: pain in heart may hurt in the left shoulder. Pain in esophagus or stomach or small intestine may seem to come from epigastric region of the abdomen (upper central).


Discuss 2 types of stretch receptors, explain how they function.

_ Stretch receptors which provide the condition of muscles and tendons, two types:
o Muscle spindles _ skeletal muscles near their junctions with tendons _ stimulated when muscle is relaxed, and they initiate a reflex that contracts the muscle
o Golgi tendon organs _ in tendons close to their attachments to muscles _ each is connected to a set of skeletal muscle fibers and is innervated by sensory neurons. Stimulated by increased tension and stimulate a reflex with an effect opposite that a stretch reflex. Protects muscle attachments from being pulled away from their insertions by excessive tension.


Discuss the sense of smell.

o Organ: olfactory organs
o Olfactory receptors _ used to sense odors, similar to taste receptors in that they are chemoreceptors sensitive to chemicals dissolved in liquids.


Discuss the sense of taste.

o Organ: taste buds _ orange sections and associate on the surface of the tongue with tiny elevations called papillae. Also scattered in the roof of the mouth, lining of cheeks, walls of pharynx.
o Taste Receptors: taste buds consist of receptor cells & supporting cells. Taste cells have hairs sensitive to particular chemicals dissolved in saliva, and taste hair surfaces have receptor sites to which chemicals combine and trigger impulses to the brain.


Identify the locations of the four primary taste sensations.

_ Sweet receptors _ stimulus peaks at the tip of the tongue, stimulated by carbs
_ Sour receptors _ margins of tongue _ stimulated by acids
_ Bitter receptors _ back of tongue _ stimulated by many organic compounds, like Mg and Ca, alkaloids
_ Salt receptors _ errywhere. _ stimulated by ionized inorganic salts


Ear anatomy: auricle

EXT EAR: outer shell of skin and cartilage that is attached to the ear (what we call _ears_)


Ear anatomy: ear drum

EXT EAR: membrane at the deep end of the external auditory meatus


Ear anatomy: external auditory meatus

EXT EAR: canal that extends from the auricle into the head through the temporal bone; terminates at the tympanic membrane


Ear anatomy: eustachian tube

MID EAR: auditory tube, duct that extends inferiorly and medially from middle ear to the nasopharynx, and allows for the pressure of the air in the middle ear to be equalized with the outside.


Ear anatomy: ossicles

MID EAR: 3 bones united to form lever system - malleus, incus, stapes.


Ear anatomy: incus

MID EAR: middle ossicle that is anvil shaped


Ear anatomy: malleus

MID EAR: outermost ossicle that is attached to the tympanic membrane and shaped like a hammer.


Ear anatomy: stapes

MID EAR: innermost ossicle that is stirrup-shaped


Ear anatomy: Vestibulocochlear nerve - aka auditory, statoacoustic, vestibulocochlear

INNER EAR: 8th cranial nerve, responsible for hearing & equilibrium


Ear anatomy: cochlea

INNER EAR: branches of osseous labyrinth and is shaped like a snail's shell


Ear anatomy: cochlear nerve



Ear anatomy: endolymph

INNER EAR: fluid secreted inside membranous labyrinth


Ear anatomy: membranous labyrinth

INNER EAR: fluid located within the membraneous labyrinth that acts as a conduction medium for the forces involved in hearing and maintenance of equilibrium


Ear anatomy: organ of corti



Ear anatomy: osseous labyrinth

INNER EAR: outer bony canal


Ear anatomy: semicircular canals

INNER EAR: branch of osseous labyrinth off the vestibule, vestibular nerve originates here


Ear anatomy: vestibular nerve



Ear anatomy: vestibule

INNER EAR: has the oval window on its side into which the stapes fits


steps in the generation of sensory impulses from the ear

_ Sound waves enter external acoustic meatus (canal)
_ Waves of changing pressure cause the tympanic membrane to reproduce the vibrations coming from the sound-wave source.
_ Auditory ossicles amplify and transmit vibrations to the end of the stapes.
_ Movement of the stapes at the oval window transmits vibrations to the perilymph in the scala vestibuli.
_ Vibrations pass through the vestibular membrane and enter the endolymph of the cochlear duct.
_ Different frequencies of the vibrations in endolymph move specific regions of the basilar membrane, stimulating specific sets of receptor cells.
_ A receptor cell depolarizes; its membrane becomes more permeable to calcium ions.
_ In the presence of calcium ions, vesicles at the base of the receptor cells release neurotransmitter.
_ Neurotransmitter stimulates the ends of nearby sensory neurons.
_ Sensory impulses are triggered on fibers of the cochlear branch of the vestibulocochlear nerve.
_ The auditory cortex of the temporal lobe interprets the sensory impulse.


Two senses associated w/ equilibrium, location of structures

o Static equilibrium _ organs are in the vestibule, sense the position of the head, maintain stability when the head and the body are still.
o Dynamic equilibrium _ organs are in the semicircular canals, sense motion, maintain balance when the head and body suddenly move or rotate.


External anatomy of eye: conjunctiva

a thin membrane that lines eyelids and covers the exposed surface of the eyeball


External anatomy of eye: eyelids

protects the eyes


External anatomy of eye: superior & inferior canaliculi

two short ducts in the medial corner of the eye through which tear fluid flows


External anatomy of eye: lacrimal gland

between eyebrow and eyeball, and produces secretion that moistens the conjunctiva


External anatomy of eye: lacrimal sac

located near the medial aspect of the eye and receives tear fluid from the superior and inferior canalculi


External anatomy of eye: nasolacrimal duct

conveys tear fluid from the lacrimal sac into the nasal cavity through the nasal bone


Extrinsic eye muscles - action: inferior oblique

rotates eye upward and away from the midline


Extrinsic eye muscles - action: inferior rectus

rotates eye downward and toward the midline


Extrinsic eye muscles - action: lateral rectus

lateral surface of the eye, rotates the eye away from midline


Extrinsic eye muscles - action: levator palpebrae superioris

extends into the upper eyelid and raises it, opposes by the action of the orbicularis oculi


Extrinsic eye muscles - action: medial rectus

medial surface of the eye, rotates the eye toward the midline


Extrinsic eye muscles - action: superior oblique

rotates eye downward and away from the midline


Extrinsic eye muscles - action: superior rectus

rotates eye upward and toward midline


visual nerve pathway

_ Nerve fibers from the retina receptor cells form the optic nerves.
_ Some fibers cross over in the optic chiasma
_ Most of the fibers enter the thalamus and synapse with neurons whose fibers reach the visual cortex of occipital lobes
_ Other impulses pass into the brain stem and function in various visual reflexes.


Internal anatomy of eye: anterior cavity

space between cornea and lens that contains a watery fluid, aqueous humor, that is secreted by the ciliary body and is divided into two areas:
_ Anterior chamber _ space between cornea & iris
_ Posterior chamber _ space between iris & lens


Internal anatomy of eye: anterior chamber

Anterior chamber _ space between cornea & iris


Internal anatomy of eye: posterior chamber

space between iris & lens


Internal anatomy of eye: aqueous humor

transparent, gelatinous fluid similar to plasma, but containing low-protein concentrations. Located in anterior of the eye, space between the lens & the cornea.


Internal anatomy of eye: macula lutea

located in the center of the retina surrounding the fovea centralis; contains only cones and is the area where all critical vision occurs.


Internal anatomy of eye: optic nerve

contains fibers that lead from rods and cones of the retina to the brain


Internal anatomy of eye: posterior cavity

space between the lens and retina filled w/ a jellylike fluid called vitreous humor


Internal anatomy of eye: blind spot/optic disc

area of retina where optic nerve enters


Internal anatomy of eye: choroid

middle layer of eyeball wall


Internal anatomy of eye: ciliary body

attached to the suspensory ligament and changes the shape of the lens for focusing at different distances


Internal anatomy of eye: cornea

clear transp structure that covers the anterior portion of the eye


Internal anatomy of eye: eyelashes

hairs on edge of eyelid, protect from debris & perform like cat whiskers (sensitive to touch, providing warning that objects are near eye and should be closed).


Internal anatomy of eye: fovea centralis

pit to the right of the blindspot which is the center of a yellow spot, the macula lutea


Internal anatomy of eye: iris

circular colored portion of the eye that contains muscle fibers that change the size of the pupil and regulate the amount of light entering the eye


Internal anatomy of eye: lens

elliptical crystalline clear structure that focuses light on the retina


Internal anatomy of eye: pupil

opening in the center of the iris


Internal anatomy of eye: retina (rods & cones)

innermost layer of the eyeball wall
_ Rods _ processes of retinal receptor cells responsible for black/white vision and general outline of objects
_ Cones _ processes of retinal receptor cells that detect colors and images.


Internal anatomy of eye: sclera

outermost layer of the eyeball wall


Internal anatomy of eye: suspended ligament

suspends the lens in the eye


Internal anatomy of eye: tarsal glands

gland at rim of eyelid responsible for the supply of meibum, an oily substance that prevents evaporation of the eye's tear film.


Internal anatomy of eye: tendon of levator palpebrae superioris

muscle in orbit that elevates the superior (upper) eyelid


Internal anatomy of eye: vitreous humor

transparent, jelly like fluid inside posterior cavity