Neurology final DCOM
Terms
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Tactile Receptor
Corpuscles of Touch
Meissner corpuscles -
Capsule surrounds mass of dendrites in dermal papillae of hairless skin
Fine touch, pressure, and slow vibrations -
Tactile Receptors
Hair root plexuses -
Free nerve endings wrapped around hair follicles in skin
Touch -
Tactile Receptors
Type I cutaneous mechanoreceptors
(Tactile or Merkel disc) -
Saucer-shaped free nerve endings make contact with Merkel cells in epidermis
Touch and pressure -
Tactile Receptors
Type II cutaneous mechanoreceptors
(Ruffini corpuscles) -
Elongated capsule surrounds dendrites deep in dermis and in ligaments and tendons
Stretching of skin -
Tactile Receptors
Itch and tickle receptors -
Free nerve endings and lamellated corpuscles in skin and mucous membranes
Itching and tickling -
Thermoreceptors
Warm receptors and cold receptors -
Free nerve endings in skin and mucous membranes of mouth, vagina, and anus
Warmth or cold -
Pain Receptors
Nociceptors -
Free nerve endings in every tissue of the body except the brain
Pain -
Proprioceptors
Muscle spindles -
Sensory nerve endings wrap around central area of encapsulated intrafusal muscle fibers within most skeletal muscles.
Muscle length -
Proprioceptors
Tendon organs -
Capsule encloses collagen fibers and sensory nerve endings at junction of tendon and muscle
Muscle tension -
Proprioceptors
Joint kinesthetic receptors -
Lamellated corpuscles, Ruffini corpuscles, tendon organs, and free nerve endings
Joint position and movement -
Microscopic features of sensory receptors
Free nerve endings - Bare dendrites associated with pain, thermal, tickle, itch, and some touch sensations
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Microscopic features of sensory receptors
Encapsulated nerve endings - Dendrites enclosed in a connective tissue capsule, such as a corpuscle of touch
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Microscopic features of sensory receptors
Separate cells - Receptor cell synapses with first-order neurons; located in the retina of the eye (photoreceptors), inner ear (hair cells) and taste buds of the tongue (gustatory receptor cells)
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Receptor Location and Activating Stimuli
Exteroceptors - Located at or near body surface; sensitive to stimuli originating outside body; provide information about external environment; convey visual, smell, taste, touch, pressure, vibration, thermal, and pain sensations
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Receptor Location and Activating Stimuli
Interoceptors - Located in blood vessels, visceral organs, and nervous system;provide information about internal environment; impulses produced usually are not consciously perceived by occasionally may be felt as pain or pressure
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Receptor Location and Activating Stimuli
Proprioceptors - Located in muscles, tendons, joints, and inner ear; provide information about body position, muscle length and tension, position and motion of joints, and equilibrium (balance)
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Type of stimulus detected
Mechanoreceptors - Detect mechanical pressure;provide sensations of touch, pressure, vibrations, proprioception, and hearing and equilibrium; also monitor stretching of blood vessels and internal organs
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Type of stimulus detected
Thermoreceptors - Detect changes in temperature
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Type of stimulus detected
Nociceptors - Respond to stimuli resulting from physical or chemical damage to tissue
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Type of stimulus detected
Photoreceptors - Detect light that strikes the retina of the eye
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Type of stimulus detected
Chemoreceptors - Detect chemicals in mouth (taste), nose (smell), and body fluids
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Type of stimulus detected
Osmoreceptors - Sense the osmotic pressure of body fluids
- Process of sensation
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1. stimulation of sensory receptor
2. transduction of the stimulus
3. generation of impulse
4. integration of sensory input -
Somatic sensory pathways
1. first order neurons - conduct impulses from the somatic receptors into the brain stem or spinal cord. From the face, mouth, teeth, and eyes, somatic sensory impulses propagate along cranial nerves into the brain stem. From the neck, body, and posterior aspect of the head, somatic sensory impulses propogate along spinal nerves into the spinal cord
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Somatic Sensory pathways
2. Second-order neurons - conduct impulses from the brain stem and spinal cord to the thalamus. Axons decussate in the brain stem or spinal cord before ascending to the ventral posterior nucleus of the thalamus. Thus, all somatic sensory information from one side of the body reaches the thalamus on the opposite side.
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Somatic sensory pathways
3. Third-order neurons - conduct impulses from the thalamus to the primary somatosensory area of the cortex on the same side.
- stereognosis
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ability to recognize the size, shape, and texture of an object by feeling it
(reading Braille, identifying a paperclip by feeling it) - Proprioception
- awareness of the precise position of body parts, and kinesthesia is the awareness of directions of movement. Proprioceptors also allow weight descrimination, the ability to assess the weight of an object.
- Vibratory sensations
- arise when rapidly fluctuating touch stimuli are present
- circadian rhythm
- a cycle of active and nonactive periods in organisms determined by internal mechanisms and repeating about every 24 hours
- Reticular activating system (RAS)
- a portion o the reticular formation that has many ascending connections with the cerebral cortex; when this area of the bran stem is active, nerve impulses pass to the thalamus and widespread areas of the cerebral cortex, resulting in generalized alertness or arousal from sleep
- arousal
- awakening from sleep, a response due to stimulation of the reticular activating system (RAS)
- consciousness
- a state of wakefulness in which an individual is fully alert, aware, and oriented, partly a s a result of feedback between the cerebral cortex and reticular activating system
- Stage 1 sleep
- transition stage between wakefulness and sleep that normally lasts 1-7 minutes
- Stage 2 sleep
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light sleep
the first stage of true sleep
fragments of dreams,
eyes may slowly roll from side to side,
sleep spindles - Stage 3 sleep
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moderately deep sleep
body temp and BP decrease
sleep spindles and larger, lower frequency waves - Stage 4 sleep
- slow-wave sleep, deepest level of sleep
- REM sleep
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rapid eye movement
stage of sleep in which dreaming occurs, lasting for 5--10 minutes during the sleep cycle - vestibular branch of the vestibulocochlear nerve (cranial nerve VIII)
- ampullary, utricular, and saccular nerves
- vestibular ganglia
- where cell bodies of the sensory neurons are located
- cochlear duct
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the membranous cochlea consisting of a spirally arranged tube enclosed in the bony cochlea and lying along its outer wall
also called the scala media - spiral organ or organ or Corti
- the organ of hearing, consisting of supporting cells and hair cells that rest on the basilar membrane and extend into the endolymph of the cochlear duct
- semicircular ducts
- the portions of the membranous labyrinth that lie inside the bony semicircular canals, communicate with the utricle of vestibule
- ampulla
- the dilated portion of each semicircular duct
- crista
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a small elevation in the ampulla
contains a group of hair cells and supporting cells covered by a mass of gelatinous material called tha cupula - gustation
- sense of taste
- name the five primary taste sensations
- sour, sweet, bitter, salty, and umami (meaty or savory)
- olfaction
- sense of smell
- three types of epitheleal cells of the taste bud
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1. supporting cells
2. gustatory receptor cells
3. basal cells - vallate papillae
- for an inverted V-shaped row at the back of the tongue
- fungiform papillae
- mushroom shaped elevations scattered over the entire surface of the tongue that contain about five taste buds each
- Foliate papillae
- located in small trenches on the lateral margins of the tongue but most of their taste buds degenerate in early childhood
- filiform papillae
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over the entire surface of the tongue
pointed, threadlike structures contain tactile receptors but no taste buds - tastants
- chemicals that stimulate gustatory receptor cells
- sites of taste transduction
- plasma membrane of gustatory hair cells
- hyposmia
- reduced ability to smell
- external ear
- consists of auricle, external aurditory canal, and eardrum
- auricle
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Pinna
flap of elastic cartilage shaped like the flared end of a trumpet and covered by skin - lobule
- inferior portion of the auricle
- helix
- rim of the auricle
- external auditory canal
- a curved tube about 2.5 cm long that lies in the temporal bone and leads from the auricle to the eardrum.
- tympanic membrane
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eardrum
a thin, semitransparent partition between the external auditory canal and middle ear - ceruminous glands
- excrete ear wax
- cerumen
- ear wax
- middle ear
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auditory ossicles (malleus, incus, stapes)
oval window, round window, secondary tympanic membrane, Eustachean tube - auditory ossicles
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extend across middle ear and attached to it by ligaments
three smallest bones in the body
incus, malleus, stapes - oval window
- base of footplate of the stapes
- round window
- below the oval window, enclosed by a membrane called the secondary tympanic membrane
- secondary tympanic membrane
- membrane which encloses the round window
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Eustachean tube
(auditory tube) - connects the middle ear with the nasopharynx.
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Internal ear
(labyrinth) -
bony labyrinth, membranous labyrinth, perilymph, endolymph, vestibule,
utricle, semicircular canals, semicircular ducts - bony labyrinth
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series of cavities in the temporal bone divided into three areas
1) semicircular canals, 2) the vestibule, and 3) the cochlea - perilymph
- fluid which is chemically similar to cerebrospinal fluid and surrounds the membranous labyrinth
- membranous labyrinth
- a series of sacs and tubes inside the bony labyrinth and having the same general form
- endolymph
- extracellular fluid lining the membranous labyrinth
- vestibule
- oval central portion of the bony labyrinth which contains the utricle and saccule
- semicircular canals
- three bony canals projecting superiorly and posteriorly from the vestibule
- acoustic
- pertaining to sound or to the sense of hearing
- audiology
- a branch of science dealing with hearing, especially the therapy of individuals having impaired hearing
- conjunctiva
- mucous membrane which lines eyelids and coats the front portion of the eyeball
- equilibrium
- state of balance or rest; condition in which contending forces are equal
- hyperopia
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light rays come to a focus behind the retina
farsightedness - labyrinth
- intrcate communicating passages of the internal ear
- myopia
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light rays come to a focus in front of the retina
nearsightedness - ophthalmologist
- a physician who specializes in the medical and surgical treatment of disorders of the eye
- Ophthalmology
- the science dealing with the eye and its diseases
- Optician
- a person skilled in grinding lenses and fitting glasses
- Optometrist
- a person specially trained and licensed to examine the eyes for vision problems and to prescribe and adapt lenses to correct vision problems
- Otology
- the science dealing with the ear, its function, and its diseases
- Otorhinolaryngology
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the science dealing with the ear, nose, and larynx and their funcitons and diseases
otolaryngology - referred pain
- pain seeming to arise in an area other than its origin
- sense
- the general faculty by which conditions inside or outside the body are perceived
- somatic pain
- pain pertaining to structures of the body wall
- tactile
- perceptible to the touch
- turbinate
- one of three scroll-like bones which projects medially from the lateral wall of the nasal cavity; also called a nasal concha
- receptor
- specialized nerve ending which receives a stimulus
- sensory nerve
- the pathway which carries impulses from the receptor to the brain
- sensory center
- area of the brain which interprets the impulses as senses
- sclera
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outer layer of the eyeball
tough white fibrous protective layer
anterior portion is known as the cornea - cornea
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anterior portion of the sclera
lies over the colored part (iris) of the eye
is transparent
contains no blood vessels - choroid coat
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middle layer of the eye
contains blood vessels that supply the eye
anterior portion--Iris, ciliary body, suspensory ligament - Iris
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the colored part of the eye, donut-shaped sphincter muscle, which attaches to the ciliary body
regulates the size of the pupil and therefore the amount of light entering the eye - Ciliary body
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a flattened muscular ring that alters the shape of the iris
changes the focus of the lens and adjusts the eye for distant and close up vision - suspensory ligament
- the structure that hold the lens in place
- Retina
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the camera of the eye
innermost, incomplete coat of the eyeball
specialized nerve tissue for the reception of light
contains tin receptors-rod and cones-for vision - aqueous humor
- watery, transparent liquid that circulates through the anterior cavity of the eye
- vitreous humor
- clear jelly-like fluid in the posterior cavity of the eye which fills the vitreous body
- extrinsic eye muscles
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those that attach to the outside of the eyeball and to the bones of the orbit
voluntary
straight-superior rectus, inferior rectus, medial rectus, lateral rectus
oblique-superior oblique, inferior oblique - intrinsic eye muscles
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inside the eyeball itself
involuntary
iris and ciliary body - eyebrows and eyelashes
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give protection against foreign objects entering the eye;
small glands at the base of the eyelashes also secrete a lubricating fluid -
Eyelids
(palpebrae) -
blink as a result of sensory stimuli to keep out foreign objects
volutary musche and skin
lined with conjuntiva
openings between called papebral fissure
angles known as the canthus - lacrimal glands and ducts
- secrete tears which keeep the anterior surface of the eye moist and free; the size of small almonds and located in the upper, outer portion of each orbit; masolacrimal ducts are small tubees extending from the lacrimal sacs into the nose to drain tears from the ey into the nose
- Olfactory receptors are what type?
- first order, bi-polar neuron
- Where are the hearing receptors found?
- internal ear; cochlea
- what is the range of human hearing?
- 20-20,000 Hz
- List in correct order the parts through which light passes as it enters the eye
- cornea, pupil, lens, retina
- vascular tunic of the eye
- choroid, ciliary body, and iris
- Rod cells contain what pigment
- rhodopsin
- The auditory nerve pathways carry impulses to the auditory cortices in the ?
- temporal lobes
- Where are the auditory ossicle located?
- middle ear
- Olfactory receptors are best described as ?
- columnar epithelial cells
- meninges on the surface of the brain
- example of pain receptors
- the lens of the eye thickens when the ?
- suspensory ligament pulls on the lens capsule
- Blowing the nose improperly may cause an infection within the auditory tube to spread into where?
- internal ear
- What does the disorder gluacoma do to the eye?
- Increases intracellular pressure; results in blindness
- What is anosmia?
- lack of smell
- What would cause of form of conductive deafness?
- damage to auditory tubes
- Interference with vision and the feeling of numbness in the limbs experienced by a person with a migraine is probably caused by ?
- vasodialation of cerebral vessels
- Treatment for a cataract usually involves removal of the ?
- lens
- Where is the highest density of somatic receptors?
- tip of tongue, lips, and fingertips
- sensation
- the conscious or subconscious awareness of external or internal stimuli
- perception
- the conscious awareness and the interpretation of meaning to sensations