Chapter 18 - General and Special Senses Flashcards
Two major types of sensory receptors
- Tonic receptor
- Phasic receptor
A specialized cell that sends sensations to CNS
Sensory receptor
Always sending signal to CNS
Tonic receptor
Becomes active only with changes in the conditions they monitor
Phasic receptor
Receptor that detect taste and smell
Chemoreceptor
Receptor that detects cell damage (mechanical, electrical, thermal)
Nociceptor
Receptor that detects thermal changes
Thermoreceptor
Receptor that detects hearing, stretching, and body position
Mechanoreceptor
Receptor that detects light
Photoreceptor
Area monitored by a single receptor
Receptor field
- Each receptor responds to a specific stimulus
Receptive field
Example of receptor specificity
Photoreceptor will not respond to a chemical stimulus
The sensory information arriving at the CNS
Sensation
Conscious awareness of sensation
Perception
How is perception the 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?
Occurs when sensory receptors are subjected to continuous stimulation
What does sensory adaptation results in?
Reduction of sensitivity
For sensory adaptation, at some point along the pathway, impulses are _____
Conducted at a decreased rate
When sensory receptors decrease their level of activity
Peripheral adaptation
- Sensory neurons are still active
- CNS causes reduced perception
Central adaptations
What are the sensory limitations?
- Sensory information from receptors is incomplete
How is sensory receptors incomplete?
- Do not have receptors for every stimulus (animals detecting infrared, uv, ultrasonic)
- Receptors have limited ranges
- Stimulation requires a neural event that is interpreted
Do not have specialized receptor cells or sensory organs
General senses
What are special senses?
- Can have specialized receptor cells separate from the sensory neuron
- Structurally more complex
- Receptors localized in sense organs
Three major groups of general sense with their meanings
Exteroceptors - relay info about external environment
Proprioceptors - depict body position in space
Interoceptors - monitor the internal environment
What are nociceptors?
- Sense tissue damage
- Perceived as pain
- Free nerve endings with large receptive field
Where are nociceptors found?
Found everywhere except brain
What function do nociceptors have?
- Provide a protective function
- Do not adapt well
Quick, inducing a reflex usually, end when stimulus ends (prickling)
Fast pain
Begin later; persist longer, ache (burning)
Slow pain
What is referred pain
- “brain-freeze”
- visceral pain that feels like it is coming from a more superficial region
- Due to superficial structure being innervated by the spinal nerves as the damaged viscera
What are thermoreceptors?
- Involve heat and cold (no differences in structure between the two)
- Free nerve endings in skin
- Quick to adapt
- Felt as pain if temp goes above 45C or below 10C
Sensitive to mechanical forces that cause tissues to be deformed
Mechanoreceptors
Types of mechanoreceptors with their meanings
Tactile - touch, pressure, vibration
Baroreceptors - pressure changes in walls of vessels
Proprioceptors - position of joints and muscles
Two types of tactile receptors
- Unencapsulated
- Encapsulated
Three different types of unencapsulated tactile receptors
Free nerve endings
Root hair
Tactile disc
- In papillary dermis
- General touch
Free nerve endings
Monitor distortions and movement across body surface
Root hair
Expanded nerve terminal that synapses with Merkel cell
- Sensitive to fine touch
Tactile disc
Three types of encapsulated cells
- Tactile (Meissner’s) corpuscles
- Lamellated (Pacinian) corpuscle
- Ruffini Corpuscle
Found where tactile sensitivities are very well developed
Tactile corpuscles
Respond to deep pressure
Lamellated corpuscle
- In dermis
- Detect pressure with little adaptation
Ruffini corpuscle
What are baroreceptors?
- Stretch receptors
- Monitor changes in pressure (detect stretching of tissue walls)
What do baroreceptors regulate?
Autonomic activities
- Digestive tract
- Bladder
- Carotid sinus
- Lung
- Colon
- Major arteries
What do proprioceptors do?
- Monitor position of joints, tension in tendons, state of muscle contraction
- No adaptation to stimulus
Types of proprioceptors with meanings
Muscle spindle - monitor length of muscle
Golgi tendon organ - monitor tension in a tendonduring contraction (degree in which tendon is stretched)
What are chemoreceptors?
- Respond to substances dissolved in surrounding fluids
- Monitor chemical composition of body fluids
Examples of chemoreceptors monitoring chemical composition of body fluids
Sensitive to pH, pCO2 changes
Where are chemoreceptors found?
- Inside CNS; medulla
- Aortic bodies
- Carotid bodies
Sense of smell
Olfaction
Where is the olfactory organ and what composes it?
- Located within the nasal cavity on either side of nasal septum
- Covers the CRIBRIFORM PLATE of ethmoid
- Made up of OLFACTORY EPITHELIUM
Olfactory epithelium consists of what?
Olfactory receptors - chemoreceptors
Supporting cells - surround the receptors
Basal cells - stem cells that grow new cells
- Covered in secretions from OLFACTORY GLANDS
What are olfactory receptors?
- Highly modified bipolar neurons
- Have cilia that extend into mucus secreted by olfactory glands
- Odorous particles dissolve into mucus and cause depolarization
Olfactory nerve pathway
- Impulses travel along AXONS of RECEPTOR CELLS
- pass through openings in the CRIBRIFORM PLATE
- Go to OLFACTORY BULB and CRANIAL NERVE 1
- Unique in that the impulses DO NOT go to the THALAMUS
- Travel along TRACTS to the LIMBIC SYSTEM
- Smells can trigger strong EMOTION
- Interpreted as SMELL in TEMPORAL LOBE and BASE OF FRONTAL
What is olfactory discrimination?
- No structural difference in receptor cells
- Olfactory can turn-over (reproduce) (numbers decrease with age)
- 50 primary smells (can distinguish thousands of smells)
- Adapt quickly
Taste = ?
Gustation
Chemoreceptors in structure called _____
- Gustation
Taste buds
Taste buds on superior surface of tongue in ____
Papillae
What are papillae?
- Epithelial projections
- Taste buds lie along papillae
Three types of papillae?
- Filiform
- Fungiform
- Circumvallate
- In taste buds
- Receptor clusters
- About 40 per bud
Gustatory cell
Replace receptors every 10-12 days in taste buds
Basal cells
Gustatory cells extend microvilli called a ____ in a ____
Taste hair into a taste pore
Gustatory Pathway
- Uses cranial nerve VII, IX, and X
- Afferent fibers synapse with NUCLEUS SOLITARIUS in medulla
- Goes to thalamus and cerebral cortex
Primary tastes
- Sour
- Sweet
- Salt
- Bitter
- Water
- Umami
what is Gustatory discrimination?
- Individual differences in taste
- Number and sensitivity decrease with age
Parts of the external ear
- Auricle
- External acoustic meatus
- Tympanic membrane
External structure supported elastic cartilage
Auricle
Canal to middle ear
External acoustic meatus
Makes wax (cerumen)
Ceruminous glands
What does the external acoustic meatus have?
- Hair
- Ceruminous glands
The external acoustic meatus ends where?
Tympanic membrane
Functions of the external ear?
- Protects middle and inner ear
- Limits microoganism growth
- Deny access to foreign objects
- Funnel vibrations
Components of the middle ear
- Tympanic cavity
- Tympanic membrane
- Auditory tube
- Ossicles
- Muscles
Air filled space between external and inner ear
Tympanic cavity
Thin, transparent connective tissue sheet
Tympanic membrane
When teh auditory tube is open…..
- Middle ear equalized to atm pressure
- Can be induced by chewing or yawning
- Allows for microbes to get in and cause and ear infection
- Tiny bones in middle ear
- Transfer vibrations from the tympanic membrane to inner ear
Ossicles
Three ossicles
- Malleus
- Incus
- Stapes
Two types of muscles with their meanings
Tensor tympani muscle - inserts on malleus
Stapedius muscle - inserts on stapes
A series of tubes and cavities in the ear
Inner ear
Two section so the inner ear
- Vestibule (balance)
2. Cochlea (hearing)
Inner ear consists of several layers
- Membranous labyrinth
2. Bony (osseous) labyrinth
What does the membranous labryinth contain?
Endolymph fluid
What does the bony labyrinth contain?
- Dense bone layer of temporal
- Contains perilymph fluid
What does the cochlea do?
- Converts vibrations to sound
- Contacts the stapes at the oval window
- Coiled tube with cochlear duct
The cochlea is divided into three ducts
- Vestibular duct - divided by the vestibular membrane
- Cochlear duct - divided by the basilar membrane
- Tympanic duct
Where is the organ of corti found?
On the basilar membrane
What is in the organ of corti with their meanings?
Hair cells - mechanoreceptors with stereocillia
Cranial nerve VIII - Cochlear branch contact hair cells
Tectorial membrane - positioned right above hair cell stereocilia
Path of Vibrations
- Auricle funnels vibrations into meatus
- Tympanic membrane vibrates
- Transmits to ossicles (malleus to incus to stapes)
- Stapes connected to oval window (transmits vibrations to inner ear)
- Oval window vibrates; perilymph moves
- Membranous labyrinth vibrates (cochlear duct vibrates within)
- Basilar membrane bounces (hair cell stereocilia contact tectorial membrane, become deformed and creates depolarization, transmits an action potential down CN VIII)
Pathway for auditory sensations
- Carried by cochlear branch of cranial nerve VIII
- Goes to cochlear nucleus of medulla
- Travel through thalamus
- Processed in AUDITORY CORTEX of temporal lobe
Vestibule consists of two parts
Semicircular canals
Utricle and saccule
- Three (anterior, lateral, and posterior)
- Surrounding semicircular ducts
Semicircular canals
At the base of semicircular canals
Ampulla at base
Each ampulla possess a _____ that attaches to a _____
Cristae, cupula
- Paired membranous sacs
- Conected by endolymphatic duct
Utricle and saccule
Saccule possess ___
Maculae
The cupula has ___
Hair cells
How does head rotation work?
- Causes fluid to move through canals
- Fluid moves cupula
- Hair cells stereocilia bends
- Depolarization occurs
The maculae consists of what?
- Hair cells
- Otolith
Small calcium carbonate crystals
- Gel like substance
Otolith
As head orientation changes
- Gravity pulls on crystals
- Moves otolith
- Deforms hair cell stereocillia
- Depolarization occurs
Pathway for balance sensation
Hair cells
- Activate neurons of vestibular branch of cranial nerve VIII
- Synapses with vestibular nuclei
Eye accessory structures
Eyelids or palpebrae
Tarsal glands
Conjunctiva
Function and location of palpebrae
- Protects and lubricates
- Epidermis, dermis, and CT
Function of tarsal glands
Oily secretions keep lids from sticking together
Thin protective mucus membrane on the eye
Conjunctiva
Two parts to the conjunctiva
Palpebral and bulbar
Where does the conjuntiva stop?
At the corneal edge
How are conjunctiva bloodshot?
Dilated blood vessels
- Produces tears
Lacrimal apparatus
Lacrimal apparatus consists of what?
Lacrimal glands - produce tears
Lacrimal punctum - drains tear into….
Lacrimal canaliculi - passageway that leads to the ….
Lacrimal sac - fills groove on lacrimal bone and connects to the …
Nasolacrimal duct - delivers tears to nasal cavity
Three layers of the eye
Fibrous tunic
Vascular tunic
Neural tunic
- Outer tunic
Fibrous tunic
Part of the fibrous tunic
Sclera - white of eye, dense irregular CT
Cornea - transparent layer
Parts of the vascular tunic
Iris - smooth muscles and pigments, controls the size of the pupil
Choroid - vascularized, pigmented layer
Lens - layered proteins, refracts light
Ciliary body
- Below the iris
- Has ciliary process
- Ciliary muscles change the lens shape (focus)
Ciliary body
- Attach to suspensory ligaments
- Attach to lens
Cilary processes
Functions of the vascular tunic
- Route for BVs
- Regulate amounts of light
- Secrete and absorb aqueous humor
- Control shape of lens
- Inner most layer
- Consists of Retina
- 5 groups of retinal neruons
Neural Tunic
Retinal neruons
Receptor cells
Bipolar neurons
Ganglion cells
Amacrine cells
Contains rods and cones
- Detect light
Receptor cells
Synapse with receptor cells
Bipolar neurons
Synape with biopolar neurons
Ganglion cells
Modulate communication between bipolar and ganglion cells
Amacrine cells
- Very light sensitive
- Do not discriminate color
- Requires less light
Rods
- Color vision
- Three types
- Give sharper images
Cones
Regions of the retina with meanings
Macula lutea - area of no rods
Fovea centralis - area of most cones (within macula)
Optic disc - beginning of optic nerve, “blind spot’
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 occipital lobe
Two cavities in the eye
- Posterior cavity - contains gelatinous vitreous body
2. Anterior cavity - contains clear aqueous humor
Patrick’s new watch looks very _______
nice
this species is 6”1’, 180 lbs., resides in its natural habitat of New York and commonly has blue eyes and curly hair
what is a Patrick Carbary
