Chapter 18 - General & Special Senses Flashcards
What are sensory receptors?
A specialized cell that sends sensations to CNS.
What are the types of sensory receptors?
Tonic and phasic.
What doe tonic receptors do?
Always sending signals to CNS.
What do phasic receptors do?
Becomes active only with changes in the conditions they monitor.
What are the types of receptors?
Chemoreceptors, nociceptors, thermoreceptors, mechanoreceptors, photoreceptors.
What is the function of chemoreceptors?
Taste and smell.
What is the function of nociceptors?
Cell damage (mechanical, electrical, thermal,).
What is the function of thermoreceptors?
Thermal.
What is the function of mechanorecepors?
Hearing, stretching, and body position.
What is the function of photoreceptors?
Light.
Receptor characteristics?
Receptive field and receptor specificity.
What are receptive fields?
Area monitored by a single receptor cell.
What is receptor specificity?
Each receptor responds to a specific stimulus (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.
Perception characteristics?
All nerve impulses are identical, brain interprets impulses, and feeling that occurs when sensory impulses are interpreted.
Sensory adaptation characteristics?
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, there are several types.
What are the types of sensory adaptations?
Peripheral adaptation and central adaptation.
What is peripheral adaptation?
When sensory receptors decrease their level of activity.
What is central adaptation?
Sensory neurons are still active and CNS causes reduced perception.
What are sensory limitations?
Information from receptors is incomplete, do not have receptors for every stimulus, receptors have limited range, and stimulation requires a neural event that is interpreted.
What are some animals can detect that humans cannot?
Infrared, ultraviolet, ultrasonic, and magnetism.
What are general senses?
Do not have specialized receptor cells or sensory organs.
What are special senses?
Can have specialized receptor cells separate from the sensory neuron, structurally more complex, and receptors are localized in sense organs.
What are the major groups of general senses?
Exteroceptors, proprioceptors, and interoceptors.
What are exteroceptors?
Relay info about external environment.
What are proprioceptors?
Depict body position in space.
What are interoceptors?
Monitor the internal environment.
What are nociceptors?
Sense tissue damage, perceived as pain, and free nerve endings with large receptive field.
Nociceptor characteristics?
Found everywhere except brain, provide a protective function, and do not adapt well.
What are the types of pain?
Fast pain (prickling), slow pain (burning), and referred pain.
What is fast pain?
Quick, inducing a reflex usually end when stimulus ends.
What is slow pain?
Begin later, persist longer, ache.
What is referred pain?
Visceral pain that feels like it is coming from a more superficial region.
What causes referred pain?
Superficial structures being innervated by the same spinal nerves as the damaged viscera.
Example of referred pain?
Brain freeze.
Thermoreceptor characteristics?
Involve heat & cold, free nerve endings in skin, quick to adapt, and felt as pain.
When do thermoreceptors feel pain?
If temp goes above 45 C or if temp goes below 10 C.
Mechanoreceptor characteristics?
Sensitive to mechanical forces that cause tissues to be deformed.
Types of mechanoreceptors?
Tactile, baroreceptors, and proprioceptors.
What do tactile receptors sense?
Touch, pressure, and vibration.
What do baroreceotors detect?
Pressure changes in walls of vessels, etc.
What do proprioceptors sense?
Position of joints & muscles.
How many types of tactile receptors are there?
6.
How many categories of tactile receptors are there?
2.
What are the categories of tactile receptors?
Unencapsulated and encapsulated.
What are the unencapsulated tactile receptors?
Free nerve endings, root hair, and tactile disc.
Where are free nerve endings and what do they detect?
In papillary of dermis. General touch.
What do root hair receptors detect?
Monitor distortions & movement across body surfaces.
Where are tactile discs and what do they detect?
Expanded nerve terminal that synapses with merkel cell. Sensitive to fine touch.
What are the encapsulated tactile receptors?
Tactile (meissner’s) corpuscles, lamellated (pacinian) corpuscles, and ruffini corpuscles.
Where are tactile corpuscles found?
Where tactile sensitivities are very well developed.
What do lamellated corpuscles respond to?
Deep pressure.
Where are ruffini corpuscles and what do they detect?
In the dermis. Detect pressure with little adaption.
What is another name for baroreceptors?
Stretch receptors.
What do baroreceptors regulate?
Autonomic activities such as… Digestive tract, bladder, carotid sinus, lung, colon, and major arteries.
What are the types of proprioceptors.
Muscle spindles and golgi tendon organ.
What do muscle spindle proprioceptors detect?
length of muscle.
What do golgi tendon organ proprioceptors detect?
tension in a tendon during contraction.
what do chemoreceptors respond to?
Substances dissolved in surrounding fluids
What do chemoreceptors do?
Monitor chemical composition of body fluids (pH, PCO2 changes).
Where are chemoreceptors found?
Inside CNS (medulla), aortic bodies, and carotid bodies.
What are general senses?
Do not have specialized receptor cells or sensory organs.
What are special senses?
Can have specialized receptor cells separate neuron, structurally more complex, and receptors localized in sense organs.
What is olfaction?
sense of smell.
Olfactory organ characteristics?
Locatd within the nasal cavity on either side of nasal septum, covers the cribiform plate of ethmoid, and made up of olfactory epithelium.
What does olfactory epithelium consist of?
Olfactory receptors, supporting cells, and basal cells.
What type of receptor are olfactory receptors?
Chemoreceptors.
What are supporting cells?
Surround the receptor.
What are basal cells?
Stem cells that crow new cells.
What is olfactory epithelium covered in?
Secretions from olfactory glands.
Olfactory receptor characteristics?
Highly modified bipolar neurons, have cilia that extend into mucus secreted by olfactory glands, and odorous particles dissolve into mucus and cause depolarization.
Olfactory nerve pathway?
- Impulses travel along axons of receptor cells.
- Pass through openings in cribiform plate.
- Go to olfactory bulb and cranial nerver I.
- Travel along tracts to limbic system.
- interpreted as smell in temporal lobe & base of frontal.
How is the olfactory nerve pathway unique?
The impulse does not go through the thalamus.
Smells can?
Trigger strong emotion.
What is olfactory discrimination?
Olfactory can turn over (decrease with age), adapt quickly, and no structural difference in receptor cells.
How many primary smells are there?
50.
What is gustation?
taste.
What are chemoreceptors of gustation called?
Taste buds.
Where are taste buds located?
On superior surface of tongue in papillae.
What is the papillae?
Epithelial projections and taste buds run along papillae.
What are the types of papillae?
Filiform, fungiform, and circumvallate.
How many gustatory cells (receptor) clusters are on a taste bud?
40 per.
How often do basal cells replace receptors?
10 - 12 days.
What are taste hairs made of?
Microvilli extended by gustatory cells into taste pore.
What is the gustatory pathway?
- Use cranial nerves VII, IX, and X.
- Afferent fibers synapse with nucleus solitarius in medulla.
- Goes to thalamus & cerebral cortex.
What are the primary tastes?
Sour, sweet, salt, bitter, water, umami.
Number and sensitivity to taste (increases or decreases) with age?
Decrease
External structure supported by elastic cartilage
Auricle
Canal to the middle of ear
External Acoustic Meatus
Type of gland that makes wax
Ceruminous Glands
Functions of the External Ear (4)
- Protect middle and inner ear
- Limits microorganism growth
- Deny access to foreign objects
- Funnel vibrations
Structure that when opened, middle ear equalized to atmospheric pressure
- This can be induced by chewing or yawning
- Allows for microbes to get in and cause ear infection
Auditory Tube
- Tiny bones in middle ear
- Transfer vibrations from the tympanic membrane to the inner ear
Ossicles
3 ossicles
- Malleus
- Incus
- Stapes
2 Muscles of the Inner Ear
- Tensor Tympani Muscle
2. Stapedius Muscle
Where does the tensor tympani muscle insert?
Malleus
Where does the stapedius muscle insert?
Stapes
The inner ear is split up into 2 sections…
- Vestibule (balance)
2. Cochlea (hearing)
The 2 layers of the inner ear…
- Membranous labyrinth
2. Bony Labyrinth
What does the membranous labyrinth contain?
Endolymph fluid
What does the bony labyrinth contain?
Perilymph fluid
Structure that converts vibrations to sound
-Contacts the stapes at the oval window
Cochlea
The cochlea is divided into what 3 ducts?
- Vestibular duct
- Cochlear Duct
- Tympanic duct
Where is the organ of corti found?
Basilar membrane
What does the organ of corti contain? (3)
- Hair cells
- Cranial Nerve 8
- Tectorial membrane
Mechanoreceptors with stereocillia
Hair cells
Cochlear branch contacts hair cells at…
Cranial Nerve 8
This structure is positioned right above hair cell stereocilia
Tectorial Membrane
Pathway of vibrations… (6)
- Auricle funnels vibrations into meatus
- Tympanic membrane vibrates
- Transmits to ossicles (malleus, incus then stapes)
- Stapes connected to oval window, that 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, transmits action potential to CN 8)
Pathway of Auditory Sensations (4)
- Carried by cochlear branch of Cranial Nerve 8
- Goes to cochlear nucleus of medulla
- Travels through thalamus
- Processed in auditory cortex of temporal lobe
What 3 structures does the vestibule contain?
- Semicircular canals
- Utricle
- Saccule
At base of the semicircular canals
Ampulla- each possesses cristae that attaches to the cupula
- Paired membranous sacs
- Connected by endolymphatic duct
Urticle and Saccule
What does the saccule possess?
Maculae
What happens during head rotation?
- Causes fluid to move through canals
- Fluid moves through the cupula
- Hair cell stereocilia bends
- Depolarization occurs
What does the maculae consist of? (2)
- Hair cells
2. Otolith
- Small calcium carbonate crystals
- Gel like substances
Otolith
What happens when head orientation changes? (4)
- Gravity pulls on crystals
- Moves otolith
- Deforms hair cell stereocilia
- Depolarization occurs
Structure that activates neurons of vestibular branch of cranial nerve 8
-Synapses with vestibular nuclei
Hair cells
- Structure that protects and lubricates
- Epidermis, dermis, CT
Eyelids or Palpebrae
Gland that is responsible for oily secretions that keep lids from sticking together
Tarsal Glands
Thin protective mucus membrane
- Palpebral and bulbar
- Stops at corneal edge
- Dilated BV= bloodshot
Conjunctiva
Gland that produces tears?
Lacrimal Gland
Where tears drain into
Lacrimal Punctum
Passageway that leads to the lacrimal sac
Lacrimal Canaliculi
Structure that fills the groove on the lacrimal bone
Lacrimal Sac
Delivers tears to the nasal cavity
Nasolacrimal Duct
The 3 layers of the eye
- Fibrous tunic
- Vascular Tunic
- Neutral Tunic
- White of eye
- Dense irregular connective tissue
Sclera
Transparent layer
Cornea
- Smooth muscle and pigments
- Controls the size of the pupils
Iris
Vascularized pigment layer
Choroid
Layered proteins
-Refracts light
Lens
- Structure in the vascular tunic
- Below the iris
- Has ciiliary processes
- Attach to suspensory ligaments
Ciliary Body
Ciliary muscles change the lens shape with changes the…
Focus
Functions of the vascular tunic (4)
- Route of BV’s
- Regulate amount of light
- Secrete and absorb aqueous humor
- Control shape of lens
5 Retinal Neurons Groups (only 4 listed)
- Receptor cells
- Bipolar neurons
- Ganglion cells
- Amacrine cells
Retinal neuron that… detects light, rods and cones
Receptor cells
Retinal Neuron that… synapse with receptor cells
Bipolar cells
Retinal Neuron that… synapses with bipolar neurons
Ganglion cells
Retinal Neuron that… modulate communication between bipolar and ganglion cells
Amacrine cells
Very light sensitive, do not discriminate color, requires less light
Rods
Color vision, 3 types, give sharper image
Cones
Regions of the Retina
- Macula Lutea
- Fovea Centralis
- Optic Disc
Area of no rods
Macula Lutea
Area of most cones, within macula
Fovea Centralis
Beginning of the optic nerve , blind spot
Optic Disc
The steps of the visual pathway
- Photoreceptors to…
- Bipolar cells to…
- Ganglion axons converge on optic disc into optic nerve (Cranial nerve 2)
- Optic tract to optic chiasm
- Relayed to lateral geniculate nucleus
- Onto visual cortex of occipital lobe
Cavities of the eye? (2)
- Posterior cavity
2. Anterior Cavity
What does the posterior cavity contain?
Vitreous Body
What does the anterior cavity contain?
Aqueous humor
