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Ch. 9 Senses
Seeley's Essentials of Anatomy & Physiology
Terms in this set (126)
The ability to perceive stimuli
The conscious awareness of stimuli received by sensory receptors.
Receptors widely scattered throughout body which detect pressure, temperature, pain, vibration, itching and proprioception (position of limbs/muscle sense.
Provide sensory information about the body and the environment
Provide information about various internal organs, primarily involving pain and pressure.
Receptors housed in specialized organs (ear - hearing/equilibrium; eye - vision; tongue - taste; nose - olfaction).
Detect internal and external changes; specialized cells or sensory neurons (dentrites or dendritic processes)
Respond to mechanical stimuli, such as the bending or stretching of receptors. Detect changes in distortions of cell membranes, respond to mechanical stimuli such as stretching or bending of receptors, or movement (touch, pressure, hearing, equilibrium). Quickly adapts
Respond to chemicals, such as odor molecules
Respond to light
Respond to temperature changes
Respond to stimuli that result in the sensation of pain. Detect tissue damage
Respond to decreasing temperatures, stop responding at temp.'s below 12 Celcius
Respond to increasing temp.'s but stop responding at temp.'s above 47 Celcius.
Free Nerve endings
The simplest and most common receptors, relatively unspecialized neuronal branches similar to dendrites.
Nerve endings that transduce mechanical pressure into action potentials. Several different types.
Touch receptors. Small, superficial nerve endings involved in detecting light touch and superficial pressure.
Touch receptors. Located just deep to the epidermis, very specific receptors in localizing tactile sensations.
Touch receptors. Play an important role in detecting continous pressure in the skin.
Touch receptors. Deepest receptors associated with tendons and joints. Relay information concerning deep pressure, vibration, and position (proprioception).
Characterized by a group of unpleasant perceptual and emotional experiences. 2 types: localized, sharp, pricking or cutting pain (rapidly conducting AP) or diffuse/burning aching pain (AP propogated more slowly).
Gate Control Theory
Pain sensations can be influenced by inherent control systems., Peripheral nerve fibers can have their input modified at the spinal cord level before transmission to the brain. This is the basis of many pain intervention strategies, especially non-pharmacologic interventions.
Perceived to originate in a region of the body that is not the source of the pain stimulus. We most commonly sense BLANK when deeper strutcures ( eg. internal organs) are damaged/inflamed.
The sense of smell. The only major sensation that is relayed directly to the cerebral cortex without first passing through the thalamus.
airborne chemicals that are detected as odors
bipolar neurons with the olfactory epithelium lining the superior part of the nasal cavity
A mucous membrane at the top of the nasal cavity; contains the olfactory receptor neurons that respond to airborne molecules called odorants.
Nerve endings that act as the receptors for the sense of smell. Unlike most other receptor in the body, each olfactory receptor can bind multiple types of odorants.
Axons from olfactory nerves (cranial nerve I) pass through foramina of the cribriform plate and enter the olfactory bulb. There they synapse with interneurons that relay action potentials to the bran through the olfactory tracts
Carries AP brought by interneurons from the olfactory bulb and each olfactory tract terminates in an area of the brain called the olfactory cortex.
Located within the temporal and frontal lobes.
W/in the olfactory bulb/olfactory cortex are feedback loops that inhibit transmission of action potentials resulting from prolonged exposure to a given odorant.
The sensory structures that detect taste stimuli. Barral-shaped, contains taste cells and supportive cells (specialized epithelium).
Enlargements on the surface of the tongue
Gustatory (taste) cells on tongue that contain taste hairs > Taste hairs containg receptors extend into small opening called a taste pore. The sensory receptor cells for gustation located in the taste buds.
Hairs contained in taste cells. Microvilli that protrude from taste cells; the sensitive parts of taste cells
A tiny opening in the surrounding stratified epithelium.
Protect the eyes by preventing perspiration from running down the forehead and into the eyes, causing irritation. Also help shade the eyes from direct sunlight.
Protect the eyes from foreign objects. (blink reflex), normally occurs about 20 times/min.
A thin, transparent mucous membrane covering the inner surface of the eyelids and the anterior surface of the eye.
Consists of a lacrimal gland situated in the superior lateral corner of the orbit and a nasolacrimal duct and associated structues in teh inferior medial corner of the orbit.
This gland produces tears which pass over the anterior surface of the eye.
Excess tears are collected in teh medial angle of the eyes by theses small ducts (or canals).
Lacrimal canaliculi open into this sac, an enlargement of the nasolacrimal duct, which opends in the nasal cavity.
Lubricate and cleasne the eye, also contain an enzyme that helps combat eye infections.
Extrinsic Eye Muscles
Six muscles which attach to the outer surface of the eye and produce eye movements
(4 muscles) move eye up, down, left, & right --innervated by crainal nerves 3,4,and 6
Two muscles up front of eye
Three layers of the wall of the eye.
Outer layer of the eye wall. Consists of the sclera and cornea.
Middle layer of the eye wall. Consists of the choroid, ciliary body, and iris. Contains most of the blood vessels of the eye.
Inner layer of the eye wall. Consists of the retina
The firm, white, outer connective tissue layer of the fibrous tunic. Helps maintain the shape of the eye, protects the internal structures and provides attachment sites for the extrinsic eye muscles. (5/6 of fibrous tunic)
Transparent anterior 1/6 of eye which permits light to enter. As part of the focusing system of the fibrous tunic, it also powerfully focuses light entering eye (bends light). Primary focusing structure
The posterior section of the vascuclar tunic, associated with the sclera. Iridescent, dark tissue layer. Delivers Oxygen and nutrients to neural tunic. (melanin keeps interior of eye dark by absorbing excess light)
Continous with the anterior margin of the choroid.
..., Muscular tissue attached to the lens that is used to control the lens's shape.
a fibrous membrane that holds the lens of the eye in place
A flexible, biconvex, transparent disc
The colored part of the eye, attached to the anterior margin of the ciliary body, anterior to the lens. A contractile structure consisting mainly of smooth muscle surrounding an opening called the pupil.
Adjustable opening in the center of the eye through which light enters
Several layers of neurons and photoreceptors
With the choroid, keeps light from reflecting back into the eye.
Contains phtoreceptors cells which respond to light (rods and cones)
For night vision, very light sensitive. Requires less light so function in dim light. Only 1 type of photopigment, consequently do not detect color.
For daylight and color vision; sharp, clear vision, but requires more light. 3 types of cones (red, blue, green): various colors seen due to stimulations of different combinations of these cones.
Rod cells contain this photosensitive pigment, made up of the colorless protein opsin in loose chemical combination with a rellow pigment (retinal).
The separations of the sensory retina from the pigmented retina.
The bipolar and horizontal cells synapse with ganglion cells, whose axons conerge at the posterior of the eye to form the optic nerve.
Small spot near the center of posterior retina. Highest concentration of cones
Center of macula, site center of color and sharpest vision.
Circular white spot just medial to fovea and anterior to optic nerve. Contains no photoreceptos and doesn't respond to light (blind spot! - no rods or cones)
Area behind the cornea and in front of the lens and iris. It contains aqueous humor. Part of anterior cavity
The space between the iris and the front of the lens filled with Aqueous Humor. Part of anterior cavity
Posterior to the lens, filled w/ vitreous humor
Watery fluid which helps maintain pressure w/in eye, refracts light, and provides nutrients to the inner surface of the eye.
Helps maintain pressure w/in the eye and holds the lens and the retina in place. Also refracts light. However, unlike aqueous humor, doesn't circulate.
Focal Point (FP)
The crossing point of the light rays
causing the light to converge
(physiology) the automatic adjustment in focal length of the lens of the eye.
The two optic nerves connect to each other at the blank.
Carries visual information. Most of optic nerve terminates in thalamus.
the axons of the optic tracts that terminate in the visual cortex
Area of the brain responsible for the initial conscious registration of visual information; the designation of electric (nerve) impulses from the retina
The image seen by each eye
The fleshy part of the external ear on the outside of the head. Collects sound waves and dierects them toward the external auditory canal
External Auditory Canal
A passageway that leads to the eardrum. transmits soundwaves to the tympanic membrane
Found only in the external ear canal, where their secretion combines with sebum and dead epidermal cells to form a modified sebum: cerumen (earwax).
Eardrum, a thin membrane that separates the external ear from the middle ear; consists of a thin layer of connective tissue sandwiched between two epithelial layers. Sound waves reaching eardrum cause it to vibrate.
Membrane that covers the opening between the middle ear and inner ear. Displaced by stapes vibrations & moves inner ear fluid
A membrane-covered opening in the inner wall of the middle ear. Displaced as fluids move, removes excess sound waves
3 smallest bones in the body: Malleus, Incus, and Stapes.
They transmit the sound vibrations from the eardrum to the oval window and the round window which connect to the middle and inner ear.
Air passage (tube) between the middle ear and throat that equalizes air pressure on either side of the eardrum; also called the Eustachian tube
Interconnecting tunnels and chambers within the temporal bone. Three regions: choclea, vestible, and 3 semicircular canals.
Smaller set of membranous tunnels and chambers inside the bony labyrinth.
The clear fluid filling the membranous labyrinth.
The fluid filling the space between the membranous and bony labyrinths.
Coiled (snail-shaped), contains membranous labyrinth called cochlear duct (contains mechanoreceptors for hearing)
Cochlea (cochlear duct) contains hearing receptors (Organ of Corti) and are stimulated as fluid (endolymph) & membranes move.
Movement of stapes at the oval window transmits vibrations that pass through various fluids and structures. Vibrations then enter the endolymph of the cochlear duct and different frequencies of vibrations stimulate different sets of receptor cells
located Inside cochlear duct, contains specialized sensory cells (hair cells) which ahve hairlike microvilli, often referred to as stereocilia on their surfaces which are stiffened by actin filaments.
Acellular gelatinous shelf attached to spiral lamina where hair tips are embedded.
Hair cells have no axons of their own, but each hair cell is associated w/ axon terminals of sensory neurons, the cell bodies of which are located w/in the cochlear ganglion.
Vestibulocochlear Nerve (VIII)
The Cochlear Nerve joins the vestibular Nerve to form this nerve, which carries action potentials to the brain.
high or low sounds
function of sound wave amplitude, which causes basilar membrane to distort more intensely and the hair cells to be stimulated more strongly.
Hearing loss resulting from mechanical deficiencies
Sensorineural hearing loss
caused by deficiencies in the spiral organ or nerves (ex. loud sounds can damage the delicate microvilli of the hair cells leading to destruction of the spiral organ).
Associated w/ the vestibule and involved in evaluating position of head relative to gravity
Associated w/ the semicircular canals and is involved in evaulating changes in the direction and rate of head movements
Has membranous sacs called the saccule and the utricle which house mechanoreceptors for equilibrium (balance).
Specialized patches of epithelium called the maculae which are surrounded by endolymph. Like the spiral organ, contains hair cells, the tips of the microvilli of these cells are embedded in a gelatinous mass (oft. called otolithic membrane)
Ear stones in the otolithic membrane composed of protein and calcium carbanate. The weighted mass of the otolithic membrane moves in response to gravity, bending the ahir cell microvilli and initiating AP in the associated neurons.
An enlargement in each semicircular canal that contains the receptor structure (the crista ampullaris).
A specialized receptor located within the semicircular canals that detects head movements
Consists of a ridge of epithelium with a curved, gelatinous mass suspended over the crest.
The lens in an older adult loses elasticity and becomes hard and glasslike; this decreases the lens's ability to change shape to accommodate for near vision.
The number of hair cells in the cochlea decreases, which results in age-related sensorineural hearing loss.
Special Senses: Smell
Smell tied in with taste (much of what is considered taste, actually due to olfaction), For any chmical to be deteced, it must be partially water soluble.
Olfaction the only major sensation that is relayed directly to the cerebral cortex without first passing through the thalamus.
When light strikes a rod cell, retinal changes shape, which causes opsin to change shape, and retinal dissociates from the opsin molecules. The change in rhodpsin's shape then stimulates a response in the rod cell, resulting in vision. Retinal then completely detaches from opsin. Energy (ATP) is required to reatach retinal to opsin and, at the same time, to return rhodopsin to the shape it had before being stimulated by light.
Rods and Cones addit. info
Notice that the rod and cone cells do not have axons and, therefore, do not generate action potentials. However, they do generate receptor potentials that cause the release of an inhibitory neurotransmitter (this is important) from their synaptic ending. - Dr. Schmidt.
Special senses: hearing
Functions: hearing and equilibrium
Mechanoreceptors housed in ear (cochlear duct), hair cells in organ of Corti.
3 semicircular canals
house mechanoreceptors for equilibrium, placed at nearly right angles to one another, enabling person to detect movements in essentially any direction.
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