Special Senses And Nervous System Key Words Flashcards
Chemoreceptors
Respond to chemicals dissolved in solution
Nocioreceptors
help sense pain. Alerted by chemicals that indicate damage
Thermoreceptors
Respond to temperature changes
Mechanoreceptors
Modified dendrites that detect changes in pressure, flex or flexion
Photoreceptors
Specialized receptor cell that responds to light energy, rods and cones
Retina
Inner layer of eyeball,
Contains photoreceptors, rods and cones
Golgi receptor organs
Proprioceptors (sense organ that gets info from inside body) senses tension. If too much tension, will inhibit muscle from creating more force through a reflex arc. Will protect you from injuring yourself. Relax tendons
Muscle spindle fiber
Senses stretch and speed of stretch. Sends message to stop stretching when you reach the endpoint of spindle stretch. Protects you from overstretching or hurting yourself
Sensation
Perception of a stimulus through one of the special senses
Sensation
Awareness of internal and external stimuli
Perception
Conscious interpretation of internal and external stimuli
Sensory adaptation
Change in sensitivity and nerve impulse generation in response to a constant stimulus. For example, photoreceptors adapt to bright light
Sensory conflict (ex. Motion sickness)
Confusion of sensory inputs. Being in ship during storm. Visual input looks like stationary, but rough movement cause vestibular apparatus to detect motion sickness
Free nerve endings
Sense pain, cold and warmth.
Uncapsulated dendrite of a sensory neuron. Modified dendrites that collect information. Change information to stimulus
Most common nerve endings in skin
Free nerve endings,
Extend to middle of epidermis
Which nerve endings are less sensitive to to abrupt changes in stimulation?
Free nerve endings
Where are Meissner’s corpuscules found?
Papillary layer of dermis
Meissner’s corpuscules
Tactile corpuscules
Touch receptors
Light pressure receptors, at junction of dermis and epidermis
Sense textural differences
Pacinian corpuscules
Lamellar corpuscules
Deep pressure receptors in dermis and subcutaneous tissue. Respond only when pressure is first applied
Deep vibration
Visceral pain
Pain emanating from the internal organs ,
Vague, dull aching sensation can be caused by extreme stretching of tissue, irritating chemicals, muscle spasms
Causes of visceral pain
Extreme stretching of tissue,
Ischemia (low blood flow),
Irritating chemicals,
Muscle spasms
Ischemia
Low blood flow
Referred pain
Pain stimuli arising from one part of the body are perceived as coming from another part
Cause of referred pain?
Same segments of spinal cord innervate multiple parts. T1-T5 innervate heart and arm
Olfaction
Sense of smell
Olfactory receptor cells
Located in roof of nasal cavity under mucosa. Respond to chemicals dissolved in solution
In superior nasal cochae
Olfactory bulbs
Receive information from sensory neurons that are triggered by olfactory receptors.
Two small structures at front of brain above nasal cavity
Olfactory tracts
pair of nerve pathways that connect olfactory bulbs to brain. after the olfactory bulbs process the information about different smells, the olfactory tracts send this information to higher brain regions for further processing and interpretation. travel to brain and reach olfactory cortex which controls conscious awareness
Gustation
Sense of taste
Taste buds
Sensory receptor organs, house gustatory epithelial cells, respond to dissolved food chemicals
Where do you find taste buds?
Anterior and posterior of tongue and palate
Papillae
Hold some of the taste buds, small raised projections
Taste cells
Gustatory epithelial cells, receptor cells for taste
Taste pore
Holds gustatory hair
Gustatory hair
Sensitive portions of gustatory epithelial cells. Bathed in saliva to dissolve chemicals
Basal epithelial cells
Stem cells,
Divide and differentiate into new gustatory epithelial cells. Replaced every seven to 10 days
Causes of sweet taste
Sugar, saccharin, alcohols, aminoacids, lead salts
Sour taste causes
Acids H+ ions in solution
Salty taste causes
Metal ions (inorganic salts);NaCl tastes the saltiest
Bitter taste causes
Alkaloids, quinine, nicotine, caffeine,morphine, and non alkaloids like aspirin
Umami
Delicious
Beef taste of steak,
Auricle
Visible portion of outer ear.
Funnels sound waves into external acoustic meatus
External acoustic meatus
Short tube from auricle to eardrum. Lined with cerumenous glands to trap foreign bodies and repel insects. Guides sound to tympanic membrane
Middle ear parts
Ear drum
Ossicles
Eustachian tube
Auditory ossicles
Malleus, incus, stapes
Allow sound wave transmission. Connect tympanic membrane to inner ear
membrane covered opening that separates the middle ear from the inner ear. located at end of stapes.
Oval window
Round window
Inferior to oval window.
Equalizes pressure changes. Dissipate pressure created by sound waves entering the inner ear.
Tympanic reflex
protective mechanism in response to loud sounds. muscles in middle ear contract to dampen sound vibrations. the stapedius and tensor tympani muscles contract and stiffen the ossicles. Reduce transmission of sound vibrations to inner ear.
Auditory tube
Connects the middle ear an pharynx. Aka eustachian tube
Bony labyrinth
Makes up internal ear
Membranous labyrinth is suspended in this.
Membranous labyrinth
Continuous series of membranous sacs and ducts contained within the bony labyrinth more or less following its contours.
Perilymph
Fluid similar to CSF and continuous to CSF
Bony labyrinth parts
Vestibule, Semicircular canals and cochlea
Vestibule
Egg shaped cavity of bony labyrinth. Posterior to cochlea. Anterior to Semicircular canals flanks middle ear medially.
Perilymph
Fluid that helps transmit sound vibrations within cochlea
Endolymph
potassium rich fluid that helps transmit electrical signals related to hearing and balance within inner ear
Baroreceptors
Monitor changes in volume and pressure.
Important in cardiovascular system
Sensory nerve ending in wall of carotid sinus or aortic arch sensitive to vessel stretching.
General senses location
All over body
Special senses location
Mostly cephalic or found in the head
Free nerve endings are part of which kind of neuron
Unipolar sensory neurons
General flow of information in the nervous system
Sensory neurons connect to motor neurons or interneurons. Tracts take sensory and motor information up and down the spinal cord.
After sensory information enters the spinal cord it goes up to the brain for processing, integration and decision-making
Highly modified sensory neurons
Encapsulated nerve ending.
Mechanoreceptors, include tactile corpuscules, lamellar corpuscules, bulbous corpuscules and muscle spindles
Three levels of sensory integration
- Receptor (sensory receptors)
- Circuit (ascending pathway)
- Perceptual levels (cerebral cortex)
Transduction
Conversion of stimulus energy via receptor or generator potentials into action potentials.
Frequent stimuli are stronger or weaker?
Stronger
Adaptation
Decreased response to a continuous or unchanging stimulus
Adaptation occurs in
All general receptors except pain and proprioceptors
Modified epithelial cells
Act like sensory neurons
Send depolarization signal to a neuron> neuron sends along to nervous system
Example of modified epithelial cells
Taste buds
Modified epithelial cells that have microvilli
Taste buds
Provide information that gets interpreted as sense of taste
Taste buds
Rod
Photoreceptors found in retina.
Have continuous discs
Respond to dim light, night vision and peripheral vision
Respond to dim light, night vision and peripheral vision
Rods
Need bright light for activation
Cones , low sensitivity
Pigments in cones
One of three different pigments that create vividly colored view of world.
Pigment in rods
Single visual pigment. Only perceive grey tones
Converging pathway
Impulses from several neurons come together in one neuron
Wiring of rods
As many as 100 rods feed into each ganglion cell. Rod effects are summated and considered collectively.
Why is vision produced by rods fuzzy and indistinct.
Visual cortex doesn’t know which rods of the large number influencing a ganglion are activated
Proprioceptors
Give information about muscle position on the body. Info goes back to cerebellum.
Merkel discs
Respond to touch, in epidermal layer of skin
Connected to neurons
Krause end bulbs
Respond to touch
Root hair plexus
Responds to touch
Nerve fibers associated with hair follicle. Cause pain when pulling hair out
Ruffini endings
Detect pressure
Two examples of general sensors that help with proprioception or location of different muscles in the body
Golgi tendon organ
Muscle spindle
Reflex arc of muscle spindle
Stretch of muscle spindle causes reflex contraction. No interneuron
Golgi tendon organ reflex
Has interneuron
Which cranial nerves are involved with taste
Facial vii (anterior 2/3)
Glossopharyngeal IX (posterior 1/3 of tongue)
And vagus X (taste info around epiglottis)
Types of papilla on tongue
Fungiform,
Filiform,
Folliate
Circumvallate papilla
Fungiform papilla
Middle of tongue
Filiform papilla
Tip of tongue
Follate papilla
Side of tongue
Do all papillae hold taste buds?
No
Papilla with no taste buds
Filiform papilla
Which papilla have taste buds?
Foliate and circumvallate papilla
Special collections of modified epithelial cells behaving like sensory neurons. Detect flavor
Taste buds
Basal cell of taste buds
Stem cells that regenerate gustatory cells
Taste pore
Opening in papilla where gustatory cells are exposed
Function of gustatory hairs
Microvilli that grab onto molecules and dissolve them in saliva as you chew
Digestion starts in
Mouth
What does perception of taste cause?
Depolarization of taste cell in gustatory cell. Depolarization is going to transition into neurons that are plugged into the base of hair cells and will go back to one of the three cranial nerves, then to gustatory cortex
Why is taste important
Gives information on nutritional value of food being consumed. When something is sweet, it has carbs, source of energy
What does bitter taste indicate
Alkaloids, poisonous
Sour indicates
Acid content, vitamin c, citric acid, important coenzyme for collagen synthesis
Salty indicates
Electrolyte content
Umami indicates
Savory,
Content of aminoacids. Measure of protein concentration in food
Taste and smell are linked, tf?
True
Olfactory receptors
Bipolar neurons, flared out, grab onto molecules that are dissolved in mucus of nasal cavity
Olfactory epithelium
Epithelium that holds olfactory receptors,
Constantly produces mucus to prevent drying out
If you smell something your olfactory receptors are grabbing onto it t/f
True
Ends of cranial nerves 1
Olfactory bulbs
Sit in ethmoid bone
Olfactory foramina
In cribiform plate. Little holes that hold nerves associated with cranial nerve pair one .
Nerves associated with CN 1 go through
Olfactory foramina and into olfactory epithelium of superior nasal cavity
Nasal cochae
Hold olfactory receptors embedded in olfactory epithelium
What happens if you breathe in caustic materials
Olfactory receptors die. Can be regenerated if damage isn’t too severe. Has progenitor stem cells . Can be severely damaged by covid
Anosmia
Loss of sense of smell
Can happen with age. Can make eating not pleasureable
Types of equilibrium
Dynamic and static
Gross anatomy of ear
1.Auricle (pinna)
Satellite dish that helps sound waves enter ear.
2.Temporal bone
3. Ear canal
External auditory tube
Tunnel leading to tympanic membrane, lined with cerumenous glandsm
What kind of glans are cerumenous glands?
Apocrine
Secrete wax
Tympanic membrane function
Drum, receives sound waves
Ossicles in order
Malleus, incus, stapes
Function of ossicles
As sound wave beats tympanic membrane, ossicles vibrate. First malleus, incus then stapes. Take air pressure wave, turn to mechanical wave and amplify. Bones vibrate against oval window
Malleus
Hammer
Incus
Anvil
Stapes aka
Stirrup
Oval window location
Opening to inner ear
Foot of stapes sits on top of oval window
Has membrane covering it
Middle ear location
From tympanic membrane to oval window
Acts like plunger
Stapes.
Causes liquid pressure wave through moving back and forth in inner ear
What fills chambers of inner ear?
Endolymph and perilymph.
What is function of liquid pressure wave
Flex sensory receptors involved with hearing.
Moves through cochlea
Cochlea
Specialized organ of hearing
What happens after cochlea is done collecting sensory information from liquid wave?
Winds back out through separate chamber, if there’s any energy left in liquid pressure wave it goes to round window
What happens to round window as pressure wave hits?
Round window bulges out
Why is round window bulging important?
Would hear echo, round window dampens signal
Location of inner ear
Oval window and everything after it
Divisions of vestibulocochlear nerve
Vestibular division and cochlear division
Location of vestibulocochlear nerve
Connects to components of inner ear
Cochlear nerve function
Carries all sensory info from the spinal organ of corti that’s in cochlea.
Takes info from cochlea into auditory cortex of brain to process and turn into perception of sound
Vestibular nerve function
Carries sensory information related to static and dynamic equilibrium
Tympanic reflex
When you hear a loud noise, stapedius and tensor tympani contract to help stabilize and reduce the vibration of the malleus, incus and stapes
Smallest skeletal muscle
Stapedius
Small muscle on stapes
Tensor tympani muscle
Runs inside of eustachian tube
Why do we need the tympanic reflex?
Protects middle and inner ear by dampening noise. Prevents noise from moving freely
Problem with tympanic reflex
Some modern day equipment is faster than tympanic reflex. Gunshots and explosions can be too fast and can cause damage to hearing apparatus.
Types of deafness
Conductive deafness,
Sensorineural deafness
Conductive deafness
Anything from outside, all the way from external and middle ear. Can be temporary or permanent.
Something interferes with conduction of sound to inner ear
Sensorineural deafness
Problem with sensory receptors in cochlea or cochlear nerve going back to complex areas of cerebral cortex. Problem in inner ear
Cochlear implant
Directly stimulates cochlear nerve so that person who couldn’t hear can hear again. Microphone and electrode that winds around cochlea.
Hearing for the first time can sometimes be traumatic
Internal auditory tube, eustachian tube
Tube that connects right around nasopharynx. Posterior portion of superior nasal cavity
Eustachian tube drains into
Opening in superior nasal cavity, towards back of nasopharynx
Nasopharynx
Portion of throat at back of nasal cavity
Oropharynx
Portion of throat behind mouth
Laryngopharynx
Portion of throat down by larynx
Importance of eustachian tube
When you’re an adult, it has a downward slope to that region of the nasal cavity. Children have more horizontal eustachian tube, can have trouble with drainage
What happens if middle ear can’t drain like it’s supposed to?
Can cause ear infections and sinus infections. Some children get tube in ear to assist.
Coronal
Divides into dorsal and ventral
Petrus ridge
Part of temporal bone that holds bony and membranous labyrinth
Bony and membranous labyrinth
Hold Semicircular canals
Bony labyrinth
Snail shell, houses organ of corti,
Organ of corti
Sends hearing information back to cochlear division of vestibulocochlear nerve
Aka spiral organ
Cross section of bony labyrinth reveals
3 chambers from top to bottom:
1. Scala vestibuli
2. Cochlear duct
3. Scala tympani
First room is
Vestibule
First tube that liquid pressure wave travels down through
Scala vestibuli
Scala vestibuli
Filled with liquid.
Liquid wave travels first through here.
Has vestibular membrane in inferior portion.
Vestibular membrane flexes and pushes on liquid in cochlear duct
Cochlear duct
Scala media
Second chamber
Has tectorial membrane that wiggles modified cillia of epithelial cells that act as sensory neurons
Scala media
Cochlear duct
Stereocilia
Don’t move on their own. Flex in the membrane. Causes depolarization signal to travel down through connecting neuron. Back towards area of your brain associated with hearing.
All sensory info except for smell goes through
Thalamus
Helioctrema
End of spiral of cochlea
Remaining pressure goes out through opposite direction. Will hit Scala timpani which is bottom chamber.
Round window
End of cochlea away from inner spiral
Covered by membrane
Bulges out to dissipate energy of liquid wave
Hair cell
Modified epithelial cell
Has stereocilia on its top surface.
Connects to tectorial membrane by stereocilia
What happens as tectorial membrane moves?
Stereocilia attached move, causes depolarization signal to connecting neuron and sends information back to cranial nerve 8 (vestibulocochlear, to cochlear division)
What happens to stereocilia as you age?
They wear out, no longer function. People lose hearing if work in construction or lawn care
Need to know
Structures of inner ear and cochlea as they relate to hearing
Static equilibrium
Gives information about head hanging down or hanging back,
Very direct information
What controls static equilibrium
Vestibule?
Parts of vestibule
Macula,
Utricle,
Saccule
Macula
Think of jello with ball bearings on top
Has otoliths on top. As you lean forward, the weight of gravity pulls otoliths forward. Causes hair cells to bend because they extend into that gelatinous mass
Otoliths
Calcium carbonate crystals. Same thing seashells are made of
What do hair cells in macula do?
Send depolarization signal to neurons that connects to hair cells. Signal tells brain if head is hanging forward or facing back.
What is macula filled with?
Endolymph. Liquid where everything floats in.
What controls dynamic equilibrium
Semicircular canals
Positioning of Semicircular canals
At right angles from each other
Function of Semicircular canals
Judge spinning and rapid movements turning.
Gives three dimensional millisecond by millisecond position of head and body . Think turning, spinning, flipping
Similar to satellites that triangulate location
Semicircular canals
Otoliths location
On macula, part of static equilibrium. Can break free and move into Semicircular canals and stimulate organs of dynamic equilibrium in appropriately and cause instant vertigo
How are otoliths breaking off corrected
Through eppley maneuver
Think of square maze you move around to put ball in hole. Move head same way until crystal settles back in otolithic membrane (gelatinous mass)
What happens at base of Semicircular canals?
Information goes to vestibular division of vestibulocochlear nerve
Info from vestibule also goes together with info from Semicircular canals into vestibular nerve
Parts in organs in Semicircular canals
Cupula
Ampulla
Ampullary nerve
As the head rotates, the cupula
Bends in opposite direction of the rotation
Cupula
Mushroom shaped gelatinous mass.
Ampula
Holds the cupula
What happens to fluid in Semicircular canals when when you move?
Fluid moves, when fluid moves, cupula flexes, causes depolarization in hair cells. Hair cells send information to neurons
Sensory adaptation example
If you smell something really strongly often you become desensitized.
What causes sensory conflict example
Sitting down and feeling movement while seeing no movement. Seeing flat feet on ship but feeling movement of water.
Two different streams of sensory information that are in conflict with each other
How to get rid of motion sickness
If they look up at horizon, their dynamic equilibrium will match the movement of boat.
Lines up visual information with movement information.
Gross anatomy of vision
Majority of sensory neurons are
Photoreceptors in retina of eye
Tunics of eye
- Outer tunic
- Middle tunic
- Inner tunic
Skeletal muscles that control eye movement
6 skeletal muscles
Levator palpebrae superioris muscle
Open and close eyelids
Conjunctiva
Thin membrane inside of eyelids around the eye, surface of eye
Cornea
Same tissue as sclera, but clear. Does have neurons doesn’t have blood vessels.
Can be transplanted without fear of rejection
Cornea can be transplanted from cadaver yes or no
Yes
All eye muscles except which move back to common tendonous ring?
Inferior oblique
Function of recti
Superior rectus: up
Inferior rectus: down
Lateral rectus: laterally
Medial rectus: medially
Function of oblique muscles
Rotate eye in circular motion
Track motion in specific directions
Superior oblique controlled by
Trochlear IV
Superior oblique function
Moves eye down and medially
Inferior oblique function
Up and lateral
Abducens VI function
Controls lateral rectus
Optic disc
Blind spot in eye, where nerves and blood vessels enter.
No sensory receptors
What makes up sclera
Dense irregular connective tissue. Extremely tough
Posterior 3/4 of outer tunic
Sclera
Anterior 1/4 outer tunic
Cornea
Why is cornea clear?
Collagen fibers laid out in way that makes it clear
Middle choroid coat
Dark brown or colored because it contains a lot of melanin
Stops scattering of light in inside of eye
Ciliary body
Extension of choroid coat.
Iris
Smooth muscle that’s colored. Has radial layer
Iris gets bigger
Dilation event. Sympathetic nervous system
Suspensory ligaments
Small ligaments coming off ciliary body, made of smooth muscle. Connect to lens
Lens
Focuses light in back of eye, lets you see images
Function of suspensory ligaments
When ciliary bodies contract the suspensory ligaments get looser and lens gets narrower. Can see further
What happens when ciliary muscles relax?
Suspensory ligaments tighten, lets you read things more closely
Which two structures work together to improve shape of lens
Ciliary body and suspensory ligaments
Accomodation
Change in lens shape.
Gets harder with age
Lost when replaced lens with eye surgery
Ora serrata
Serrated junction between retina and ciliary body
Retina inner coat
Sensory layer on inner 2/3 of eye
Has rods, cones and bipolar neurons that sense light
Scleral venous sinus or canal of schlemm
Reabsorbs aqueous humor
How does cornea receive nutrients to stay alive?
Aqueous humor
Anterior cavity
Holds aqueous humor
+ Anterior and posterior chamber
Everything in front of ciliary body is bathed in
Aqueous humor
Humor
Body fluid
Aqueous humor is continuously
Produced and reabsorbed in canal of schlemm
Aqueous humor
Watery
Parts constantly bathed in aqueous humor
Lens and cornea
Vitreous humor
In posterior cavity
Holds lens in place
More viscous
Things to note:
-different layers of eye
-posterior vs anterior structure and function
Choroid coat of retina holds
Melatonin
Pathway of light through retina of eye
- Optic nerve axons
- Ganglion cells
- Bipolar cells
- Rods and cones
- Pigment epithelium
- Choroid
Pigment epithelium
Also filled with melanin
First part of retina
Any light that isn’t absorbed by rods or cones gets absorbed by pigmented epithelium
Any light that’s not absorbed by this gets absorbed by pigmented epithelium
Optic chiasma function
Sends information from right eye to left half of brain
Take info from left eye and send it to right eye of brain
Reason why both pupils constrict.
Sends signal to both eyes
Rods
Low energy light
Can’t sense color
100 connect to one or two bipolar cells and those bipolar cells form ganglia. Does not know which rod worked. Fuzzy vision. Not a sharp image.
One cone, one bipolar neuron, one ganglia.
Cones
Bind to one bipolar neuron.
Sharper image. Brighter light, more energetic light. Brain knows location of retina. Gives color vision and sharp vision
Fovea centralis
Pit where you have the highest concentration of photoreceptors in eye. Straight back from pupil.
Topographic mapping of retina on visual cortex
Each eye collects information from right and left visual fields.
Information crosses over at optic chiasma and gets processed. Heads back to occipital lobe towards visual cortex. Corrects orientation of visual information as it proceeds to areas of visual cortex.
Occipital lobe
Processes visual information
Ventral and dorsal streams
Dorsal: from occipital to parietal answers where is it?
Ventral stream: occipital lobe to temporal lobe requires multiple visual association areas to process that information and what it is
