Chapter 18: General and Special Senses Flashcards
What is a sensory receptor?
A specialized cell that sends sensations to CNS
what are the 2 sensory receptors? describe them
tonic: always sending signals to the CNS
phasic: becomes active only with changes in the conditions they monitor
What are the five types of receptors? state what they are used to detect
- ) Chemoreceptors:
- smell
- taste - ) Nociceptors:
- Cell damage (mechanical, electrical, thermal) - ) Thermoreceptors
- thermal - ) Mechanoreceptors:
- hearing
- stretching
- body position - ) Photoreceptors
- light
What is the receptive field?
area monitored by a single receptor cell
What is receptor specificity?
each receptor responds to a specific stimulus
Example: photoreceptor will not respond to a chemical stimulus
What is sensation?
The sensory information arriving at the CNS
What is perception?
Conscious awareness of sensation
- All nerve impulses are identical (just action potentials)
- Brain interprets impulses
- “Feeling” that occurs when sensory impulses are interpreted
When does sensory adaptation occur?
what does it result in?
- Occurs when sensory receptors are subjected to continuous stimulation
- Results in a reduction of sensitivity
- At some point along the pathway, impulses are conducted at a decreased rate
What are the two types of sensory adaption?
peripheral adaptation:
when sensory receptors decrease their level of activity
central adaptation:
Sensory neurons are still active
CNS causes reduced perception
describe sensory limitations
Sensory information from receptors is incomplete.
-Do not have receptors for every stimulus
-Other animals can detect things we cannot:
(Infrared, ultraviolet, ultrasonic, magnetism, etc.)
Receptors have limited ranges
Stimulation requires a neural event that is interpreted
Compare General and Specialized senses
General senses:
-Do NOT have specialized receptor cells or sensory organs
Special senses:
- Can have specialized receptor cells separate from the sensory neuron
- Structurally more complex
- Receptors localized in sense organs
What are the three major general senses groups? briefly describe
Exteroceptors -Relay info about external environment Proprioceptors -Depict body position in space Interoceptors -Monitor the internal environment
describe nociceptors
Sense tissue damage perceived as pain free nerve endings with large receptive field -found everywhere except brain -Provide a protective function -do not adapt well
What are the three types of pain? (just names)
fast pain
slow pain
referred pain
describe fast pain
Prickling pain
Quick; inducing a reflex usually; end when stimulus ends
describe slow pain
Burning
Begin later; persist longer; ache
describe referred pain
- Visceral pain that feels like it is coming from a more superficial region
- Due to superficial structures being innervated by the same spinal nerves as the damaged viscera
- “Brain-freeze”
describe thermoreceptors
-involve heat & cold
(no difference in structure between the two)
-Free nerve endings in skin
-Quick to adapt
-Felt as pain
(if temp goes above 45 C or if temp goes below 10 C)
which receptor type is sensitive to mechanical forces that cause tissues to be deformed?
Mechanoreceptors
What are the three types of mechanoreceptors? state what they sense
Tactile -touch, pressure & vibration Baroreceptors -pressure changes in walls of vessels, etc Proprioceptors -position of joints & muscles
There are 6 types of tactile receptors in two categories. What are the two categories?
unencapsulated
encapsulated
what are the three unencapsulated tactile receptors?
describe them
- ) Free nerve endings
- in papillary of dermis
- general touch - ) Root hair
- monitor distortions & movement across body surface - ) Tactile disc
- expanded nerve terminal that synapses with Merkel cell
- sensitive to fine touch
what are the three encapsulated tactile receptors?
describe them
- ) Tactile (Meissner’s) corpuscles
- found where tactile sensitivities are very well developed - ) Lamellated (Pacinian) corpuscle
- respond to deep pressure - ) Ruffini corpuscle
- in dermis
- detect pressure with little adaptation
describe Baroreceptors
-Stretch Receptors
-Monitor changes in pressure
-Detect stretching of tissue walls
-Regulates autonomic activities
examples:
digestive tract
bladder
carotid sinus
lung
colon
major arteries
describe proprioceptors
- Monitor position of joints, tension in tendons, state of muscle contraction
- No adaptation to stimulus
name and describe the two types of proprioceptors
Muscle spindle: monitor length of muscle
Golgi tendon organ: monitor tension in a tendon during contraction
Chemoreceptors respond to _________________ and monitor___________________________________
substances dissolved in surrounding fluids;
chemical composition of body fluids (ie: sensitive to pH, pCO2 changes)
Where are Chemoreceptors found?
inside CNS; medulla
aortic bodies
carotid bodies
What is Olfaction?
sense of smell
describe the Olfactory organ (3)
- Located within the nasal cavity on either side of nasal septum
- Covers the cribiform plate of ethmoid
- Made up of olfactory epithelium
the Olfactory Epithelium consists of what? (3)
Olfactory receptors -chemoreceptors Supporting cells -surround the receptors Basal cells -stem cells that grow new cells
The olfactory cells are covered in excretions from_________
olfactory glands
describe the olfactory receptors (3)
- Highly modified bipolar neurons
- Have cilia that extend into mucus secreted by olfactory glands
- Odorous particles dissolve into mucus and cause depolarization
describe the olfactory pathway (6)
- impulses travel along axons of receptor cells
- Pass through openings in cribiform plate
- Go to olfactory bulb and cranial nerve I
- Unique in that the impulse does NOT go through the thalamus
- Travel along tracts to limbic system (smells can trigger strong emotion_
- Interpreted as smell in temporal lobe & base of frontal
How many primary smells do we have?
50
Refer to slide 26 for last information regarding Olfaction
What sense is Gustation?
Taste
chemoreceptors in gustation structures are called what?
taste buds
Taste buds on superior surface of tongue in __________
papillae
what are papillae?
Epithelial projections
what are the names of the three types of papillae?
Filiform
Fungiform
Circumvallate
slide 29
:)
The gustatory pathway uses which cranial nerves?
VII, IX &X
In the gustatory pathway, afferent fibers synapse with ________ in _________
nucleus solitarius, medulla
The gustatory pathway goes where?
thalamus & cerebral cortex
what are the primary tastes? (6)
Sour Sweet Salt Bitter Water Umami
true or false: Number & sensitivity decrease with age
true
what are the parts of the external ear? describe them
Auricle: external structure supported elastic cartilage
External acoustic meatus: canal to middle ear
Ceruminous glands
Make wax (cerumen)
Hairs
Ends at tympanic membrane
what are the functions of the external ear?
Protect middle and inner ear
Limits microorganism growth
Deny access to foreign objects
Funnel vibrations
what are the parts of the middle ear?
Tympanic cavity:
-Air filled space between external and inner ear
Tympanic membrane:
-Thin, transparent connective tissue sheet
-Auditory tube
-Ossicles
what does the auditory tube do when it is open?
- Middle ear equalized to atmospheric pressure
- Can be induced by chewing or yawning
- Allows for microbes to get in and cause an ‘ear infection’
describe the ossicles in the middle ear (not names)
- Tiny bones in middle ear
- Transfer vibrations from the tympanic membrane to inner ear
what are the three ossicles in the middle ear? (names)
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
what are the 2 muscles in the inner ear and where do they insert?
Tensor tympani muscle
-Inserts on malleus
Stapedius muscle
-Inserts on stapes
the inner ear is a series of _____ and _________
tubes and cavities
the inner ear is split into two sections. What are they? What are they responsible for?
cochlea (hearing) and vestibule (balance)
the inner ear consists of several layers. Name them and what they do
- ) membranous labyrinth
- Contains endolymph fluid - ) bony (osseous) labyrinth
- Dense bone layer of the temporal
- Contains perilymph fluid
describe the cochlea (3)
- Converts vibrations to ‘sound’
- Contacts the stapes at the oval window
- Coiled tube with cochlear duct
the cochlea is divided into 3 ducts. what are they? and what divides them?
Vestibular duct -Divided by vestibular membrane Cochlear duct -Divided by basilar membrane Tympanic duct
The organ of corti is found in the ________
basilar membrane
describe the organ of corti (3)
Hair cells (Mechanoreceptors with stereocilia) Cranial nerve VIII (Cochlear branch contacts hair cells) Tectorial membrane (Positioned right above hair cell stereocilia)
describe the steps in the path of vibrations
slide 40-41
describe the pathway for auditory sensations (4)
Carried by cochlear branch of cranial nerve VIII
Goes to cochlear nucleus of medulla
Travels through thalamus
Processed in auditory cortex of temporal lobe
what does the vestibular complex consist of?
- ) semicircular canals
2. ) utricle and saccule
what are the names of the three semicircular canals?
anterior, lateral, and posterior semicircular canals
what is located at the base of the semicircular canals?
what does each posses?
Ampulla; each posses cristae that attaches to a capula
the Utricle and Saccule are ___________________ connected by ___________________
paired membranous sacs; endolympthatic duct
what does the saccule posses?
maculae
in the semicircular canals, the _______ has ________
cupula; hair cells
describe what happens in the semicircular canals when your head rotates
- Causes fluid to move through canals
- Fluid moves cupula
- Hair cell stereocilia bends
- Depolarization occurs
the maculae of the saccule consists of what 2 things?
hair cells and otolith
what is otolith
small calcium carbonate crystals
gel like substance
in the utricle and saccule, head rotation changes what 4 things?
Gravity pulls on crystals
Moves otolith
Deforms hair cell stereocilia
Depolarization occurs
For the pathway for balance sensation the hair cells do what two things?
Activate neurons of vestibular branch of cranial nerve VIII
Synapses with vestibular nuclei
what are the names of the 4 eye accessory structures?
- ) Eyelids or Palpebrae
- ) Tarsal glands
- ) Conjunctiva
- ) lacrimal apparatus
what do the eyelids.palpebrae do? what is it made of?
protect & lubricate
epidermis, dermis, CT
what is the function of the tarsal glands?
oily secretions keep lids from sticking together
describe the conjunctiva (4)
Thin protective mucus membrane
palpebral & bulbar
stops at corneal edge
dilated BV–bloodshot
what does the lacrimal apparatus do?
produce tears
what does the lacrimal apparatus consist of? how are they connected?
- ) Lacrimal Gland
- produces tears - ) Lacrimal punctum
- drains tears into the Lacrimal Canaliculi - ) Lacrimal canaliculi
- passageway the leads to the lacrimal sac - ) Lacrimal sac
- fills grooves on lacrimal bone
- connects to the nasolacrimal duct - ) delivers tears to nasal cavity
What are the three layers of the eye?
Fibrous Tunic
Vascular Tunic
Neural Tunic
describe the fibrous tunic and what it consists of
outer Sclera -White of eye -Dense irregular CT Cornea -Transparent layer
what are the four parts of the vascular tunic? (names only)
iris
lens
choroid
ciliary body
what is the iris made up of and what does it control?
smooth muscles and pigments; controls the size of the pupil
what is the choroid of the eye?
vascularized, pigmented layer
the lens is made up of ________ and does what?
layered proteins; refracts light
describe the ciliary body of the eye
Below the iris Has ciliary processes -attach to suspensory ligaments -Attach to lens Ciliary muscles change the lens shape -focus
what are the functions of the vascular tunic? (4)
Route for BV’s
Regulate amount of light
Secrete & absorb aqueous humor
Control shape of lens
describe neural tunic briefly (3 things)
Inner most layer
Retina
5 groups of retinal neurons
name and describe the different retinal neurons in the neural tunic of the eye
- ) Receptor cells
- rods and cones
- detect light - ) Bipolar neurons
- synapse with above - ) Ganglion cells
- synapse with above - )Amacrine cells
- modulate communication between bipolar and ganglion cells
describe rods (3)
Very light sensitive
Do not discriminate color
Require less light
describe cones (3)
Color vision
Three types
Give sharper image
what are the three regions of the retina? describe them
- ) Macula lutea
- area of no rods - ) Fovea centralis
- area of most cones
- within macula - ) Optic disc
- beginning of optic nerve
- “blind spot”
describe the visual pathway
Photoreceptors to… bipolar cells to… ganglion axons converge on optic disc into optic nerve (cranial nerve II) Optic tract to optic chiasm Relayed to lateral geniculate nucleus On to visual cortex of occipital lobe (slide 59)
what are the two cavities of the eye?
What does each contain?
Posterior cavity
-contains gelatinous vitreous body
Anterior cavity
-contains clear aqueous humor
