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Sensory Receptor & Sense
Organs
Any structure specialized to detect a stimulus.2. Structure
composed of nervous tissue alog with other tissues that
enhance its response to stimuli.
TERM 2
Receptor and Transduction
DEFINITION 2
The purpose of any sensory receptor is trans. which is the
conversiono f one form of energy to another (light, sound,
heat, touch vibration, or other forms of stimulus energy into
nerve signals.)
TERM 3
Sensory Receptors transmit 4 kinds of info:
MODALITY (1 OF 4)
DEFINITION 3
1. Refers to the type of stiumulus or the sesntion produced,
ex:vision, hearing, and taste.-Labeled nerve pathway/labeled
line code: As if each nerve pathway from sensory cells to the
brain is "labeled" to identify its origin and the brain employs
these labels to interpret what modality the nerve signal rep.
pain or tickle, sweet or bitter...ect.
TERM 4
LOCATION (2 OF 4) Receptive field
DEFINITION 4 -Tells which nerve fibers are issuing signals to the brain.-stimuli sensed within an area innervated by a specific nerve is called its receptive field-EX: A neuron with a large receptive field, such as in the skin of the back when touched in 2 close togethere places within this receptive field, the brain senses it as only one point of conact. But in places such as the fingers, there are neurons with small receptive fields which can stimulate 2 diff neurons...detect two close together points TERM 5
LOCATION CNTD. (Sensory Projection)
DEFINITION 5
It is the abiliy of the brain to identify the site of stimuation,
including very small and specific areas within a receptor such
as the retina.The pathway followed by sensory signals to
their ultimate destinations in the CNS are called projection
pathways.
INTENSITY (3 OF 4)
Refers to whether a sound is lous or soft, a light is bright or di, a pain is mild or excruciating...ect.It is encoded in 3 ways:1.As stimulus intensity increases, firing frequencies increase2.Intense stimuli recruit a larger number of nerver fibers to fire3.Weak stimuli activate only the most sensitive nerve fibers whereas strong stimuli can activate a less sensitive group of fibers with higher thresholds...thus the brain can distinguish intensities based on which fibers are sending it signals, how many fibers and how fast TERM 7
DURATION (4 OF 4)
DEFINITION 7
How long a stimulus lasts...is encoded by changes in the
firing frequency of a nerve fiber with the passage of
time.Sensory Adaptation: if the stimulus is prolonged, the
firing of the neuron gets slower over time, and with it, we
become less aware of the stimulus.
TERM 8
Phasic and Tonic Receptors (DURATION)
DEFINITION 8
- Generate a burst of action potentials when first stimulated, then quickly adapt and sharply reduce or stop signaling even if the stimulus continues. 1st stimulation is quick, but also quick to adapt. Inclues smell, hair movement, and cutaneous pressure2. Adapt more slowly and generate nerve signals more steadily. Proprioreceptors are among the most slowly adapting tonic receptors because the brain must always be aware of body position, muscle tension, and joint motion. TERM 9
Classification of Receptors- Thermoreceptors
(1 OF 5) Photoreceptos (2 OF 5)
DEFINITION 9
1. Respond to heat and cold2. The eyes, respond to light
TERM 10
Nociceptors (3 OF 5) Chemoreceptors (4 OF 5)
DEFINITION 10
3. Pain receptors, they respond to tissue injury or situations
that threaten to damage a tissue4.Respond to chemicals,
including odors, tastes, and body fluid composition
Special Senses (2 OF 2)
Related to head and neck, cranial nerves. Innervated by the
cranial nerves and employ relatively complex sense organs.
The special senses are vision, hearing, equilibrium, taste, and
smell.
TERM 17
General Senses-unencapsulated/encapsulated
DEFINITION 17
Sensory dendrites (nerve endings) that are NOT wrapped in
connective tissue.encap: erve fibers wrapped in glial cells
(supportive nervous tissue cells) or connective tissue
TERM 18
Unencapsulated
cntd.
DEFINITION 18
- Free Nerve Endings : Include warm and cold receptors for temp. and nociceptors for detecting pain(locate:skin/mucous membranes)2. Tactive (Merkel) discs : tonic receptors for light touch, senses texture, edges, and shapes. In basal layer of epidermis.3. Hair Receptors (peritrichial endings) : Monitor the movement of hairs. Respond to light touch that bends the hair but adapt quickly. TERM 19
Encapsulated
cntd.
DEFINITION 19
1. Tactile (Meissner) corpuscles : phasic recptors for light
touch and texture. Concentrated in hairless area: eyelids,
palms, fingertips, lips, tongue, nipples, genetalia2. End
bulbs (Krause) : Found in mucous membranes of the lips
and tongue, conjuctiva, epineriumof large nerves. Function
similar to corpuscles.
TERM 20
Encapsulated cnts (2)
DEFINITION 20
- Lamellar(pacinian) corpuscles : Phasic receptors for deep pressure, stretch, tickle, and vibration. Look like onion slice. Located in dermis, joint capsules, periosteum, breasts, genitals, viscera.4. Bulbous (Ruffini) corpuscles : Tonic receptors for heavy touch, pressure, stretching of the skin, and joint movements. Located in dermis, subcutaneous tissue, and joint capsules.Look at page 587 for chart
TASTE AKA...
Gustation: a sensation that results from the action of
chemicals on the taste buds (most are on tongue, but also
inside cheecks and soft palate, pharynx and epiglottis)-The
tongue exhibits 4 types of surface protusions called lingual
papillae.
TERM 22
Lingual papillae (1 of 4)
DEFINITION 22
Filiform :Most abundant papillae. No taste buds! Resposible
forr the rough feel of a cat's tongue and gromming fur..in
humans it is to sense the texture of food.
TERM 23
Lingual papillae (2 of 4)
DEFINITION 23
Foliate: Form parallel ridges on lateral aspect of tongue.
Taste buds located here degenerate by age 2-3 years. May
be why children reject foods that adults enjoy
TERM 24
Lingual papillae (3 of 4)
DEFINITION 24
Fungiform: Named for appereance (mushrooms). 3 taste
buds per papillae, maily located on apex. These papillae are
widely spread, but concentrated at the tip and sides of
tnogue.
TERM 25
Lingual Papillae (4 of 4)
DEFINITION 25
Vallate (circumvallate) : Lare in size, arranged in a "V" at
the rear of the tongue. only 7-12 of them but contain up to
1/2 of all taste buds.
Pitch
Our sense of whether a sound is high or low. It is determine by the frequency at which the sound source, eardrum, and other parts of the ear vibrate. One movement of a vibrating object back and forth is a CYCLE, and the # of cycles per sec is called frequency (aka Hertz). The INFRASONIC frequencies are not detected by the ear but we sense them through vibrations. ULTRASONIC are the inaudible vibrations that are high. The most sensitive ears can hear from 20-20,000Hz. TERM 32
Loudness
DEFINITION 32
The perception of soud energy, intensity, or the AMPLITUDE
of vibration. Expressed in decibels(dB) Normal hearing is
10dB, exposure to sounds greater than 90dB can cause
permanent loss of hearing.
TERM 33
Outer
Ear
DEFINITION 33 A funnel for conducting airborne vibrations to the tympanic membrane (eardrum).-Begins with the auricle (pinna) shaped by cartilage.-Audiroty canal: passing leading through the temporal bone o the tympanic membrane, beginning at the external acoustic meatus. It is lined w/ skin and then by temporal bone. It contains guard hairs. The canal has ceruminous and sebaceous glands whose secretions mix with dead skin cells to form cerumen (earwax). TERM 34
Cerumen
DEFINITION 34
Coats the guardhairs, making them more effective in
blocking foreign particles from the auditory canal. It precents
insects, ticks, other pests from entering. Contains lysozyme
and has a low pH, inhibiting bacterial growth. Waterproofs
the canal and protects its skin and tympanic membrane from
getting water, also keeps is flexible.
TERM 35
Middle
Ear
DEFINITION 35 Located in tympanic cavity of temporal bone. Contains tympanic membrane (eardrum)-It is innervated by sensory branches of the vagus and trigeminal nerves and is sensitive to pain.-Auditory (eustachian/pharyngotympanic) TUBE: passageway to the nasopharynx. It equalizes pressure between middle ear & the outside, yawning helps open it up and vibrate freely. This tube sadly allows throat infections to spread to the middle ear.
Auditory Ossicles
Small bones that connect the tympanic membrane to the inner ear.1. Malleus: Has an elongated hadle attatched to the inner surface of the tympanic membrane, it has a short process which articulates with the 2.Incus: Triangular body that articulates with malleus, long limb that articulates w/ stapes and short limb. 3.Stapes: shaped like stirrup, its head articulates w/ incus. The base is held by OVAL WINDOW-Where inner ear begins. TERM 37
Otitis Media
DEFINITION 37
Inflammation/ infection of middle ear. Common in children.-
Tympanostomy: Tubes are placed in tympanic membrane
whihc releases pressure and causes the liquid that has
accumulated to drain.
TERM 38
Inner
Ear
DEFINITION 38 Housed in Bony labyrinth: temporal bone passageway. which is lined by fleshy tubes called membranous labyrinth. BT the bone and membranous labyrinth is a cushion of fluid, the PERYLIMPH. Within membranous laby is endolymph: fluid supporting and cover certain hair cells and send signals to brain to give you sense of hearing. Forming a tube within a tube structure TERM 39
More Inner
Ear
DEFINITION 39 Vestibule: Chamber where labyrinth begins, .-Cochlea: organ of hearing, a coiled tube that arised from the anterior side of the vestibule. It has 3 fluid filled chambers seperated by membranes. VESTIBULI: SUperioir chamber and inferioir is SCALA TYMPANI. These are filled w/ perilymph and com w/ each other through narrow channel. The middle chamber is the CHOCLEAR DUCT (scala media) seperated by vestibular membrane. Its filled with endolymph and seperates endo from peri and helps mantain chemical diff bt them TERM 40
More Inner Ear
DEFINITION 40 Spiral organ/organ of corti: within cochlear duct- a thick epithelium of sensory and supporting cells ans associated membranes. This is what converts vibrations into nerve impulses. It has an epithelium composed of HAIR CELLS and SUPPORTING CELLS. Hair are named for the long stiff microvilli called streocilia (false cilia-dont move on their own). Resting on top of the stereocilia is a gelatinous tectorial membrane IHC: Where all our hearing comes from-Supply 95% of sensory fibers of the cochlear nerve. OHC: Adjusts the reponse of the cochlea to diff frequencies and enable the IHCs to work w/ greater precision. HC=synapse w/ nerve fibers @ base.
General Acoustin Startle Reflex & Auditory
Palpebral Reflex
1: Hear a noise that you are't prepared for2: WHen you blink
TERM 47
Conductive Deafness (2 types)
DEFINITION 47 1: Results from any condition that interferes w/ the tranmission of vibrations to the inner ear. Such as any damage to tympanic membrane, otitis media, blockage of auditory canal, osteclorosis. Non-nervous issue(otosclerosis) is fusion of the auditory ossicles to teach other, or fusion of the stapes to the oval window. (either way, it prevents bones from vibrating freely). 2: Sensorineural (nerve deafness) results from the death of hair cells or any of the nervous elements concerned with hearing. Common to people who have frequent exposure to loud noises. TERM 48
Tinnitus
DEFINITION 48
Constant noise/ringing in ear. Never goes away but there is
treatment to help cope with it.
TERM 49
Equilibrium
DEFINITION 49
Original function of the ear in evolution...which means
coordination, balance and orientation in 3D space. The
receptors for eq. is made up of the VESTIBULAR APPARATUS
which consists of 3 semicircular ducts and 2 chambers-an
anterior saccule and posterior utricle.
TERM 50
Eq. cntd
DEFINITION 50 The sense of eq. is div. into static eq.-which is the perception of the orientation of the head when the body is stationay and the dynamic eq.- which is the perception of motion or acceleration. There are 2 kinds of acceleartion. linear (chang in velocity in a straight line like when riding a car or elevator) and angular acc (change in rate of rotation like in turning a corner) SACCULE AND UTRICLE are responsible for static eq. and the sense of linear acceleraion; the semicircular ducts detect onlly angular acceleration.
