Module 5 (Nervous System Senses)

Organize the Pathway from sound wave to nerve signal steps listed below. -Sound waves vibrate tympanic membrane -Hair cells distorted, causing changes in neurotransmitter release -Pressure is transmitted to scala tympani and absorbed by round window -Fluid pressure waves in scala vestibuli push vestibular membrane causing pressure waves in endolymph of cochlear duct -Specific regions of basilar membrane move (depending on sound wave frequency) -Ossicles vibrate and transmit waves to oval window -Sensory neurons with axons in CN VIII are stimulated to fire

-Sound waves vibrate tympanic membrane -Ossicles vibrate and transmit waves to oval window -Fluid pressure waves in scala vestibuli push vestibular membrane causing pressure waves in endolymph of cochlear duct -Specific regions of basilar membrane move (depending on sound wave frequency) -Hair cells distorted, causing changes in neurotransmitter release -Sensory neurons with axons in CN VIII are stimulated to fire -Pressure is transmitted to scala tympani and absorbed by round window

1. Define Tactile Receptors 2. Define Unencapsulated tactile receptors 3. What are the free endings, root hair plexuses, and tactile discs in an Unencapsulated tactile receptors?

1. Abundant mechanoreceptors of skin and mucous membranes (can be capsulated or not encapsulated) 2. Dendritic ends of sensory neurons with no protective cover 3a. Free endings (simplest tactile receptor and close to the surface)- terminal ends of sensory neuron dendrites ***Used for pain and temperature but also light touch and pressure 3b. Root hair plexuses (deeper layer of dermis)- wrap around hair follicle. ***Detects hair displacement 3c. Tactile discs (basal layer of epidermis)—flattened endings of sensory neurons extending to tactile cells (Merkel cells) ***Respond to light touch

1. What is the function of the auditory ossicles? 2. What are the 2 small muscles that restrict ossicle movement during loud sounds?

1. Amplify sound waves and transmit them to oval window ***Vibrate along with eardrum, so stapes moves in and out of oval window initiating pressure waves in inner ear fluid 2a. Tensor tympani attaches to malleus 2b. Stapedius attaches to stapes

Deafness is any hearing loss and there are 2 types of Deafness. Explain the difference b/w Conductive deafness and Sensorineural deafness

1. Conductive deafness: interference of wave transmission in external or MIDDLE EAR 2. Sensorineural deafness: malfunction in INNER EAR or cochlear nerve

1. The left and right eyes have overlapping visual fields which allows for stereoscopic vision (_____________ perception). 2. What is the difference b/w Superior colliculi and Pretectal nuclei

1. Dept 2a. Superior colliculi coordinate reflexive eye movements 2b. Pretectal nuclei coordinate pupillary reflex and lens accommodation reflex

1. Define Equilibrium. Awareness and monitoring of head position 2. Which ear structures contribute to your equilibrium? 3. What do the Utricle and Saccule detect? 4. Which duct detects angular acceleration

1. Equilibrium: Awareness and monitoring of head position 2. Monitored by vestibular apparatus: utricle, saccule, semicircular ducts 3. Utricle and saccule detect static equilibrium and linear acceleration 4. Semicircular ducts

The tongue has 4 types of Papillae which are listed below. Explain the functions and characteristics of each.

1. Filiform papillae: short and spiked (no tastebuds) Function: helps manipulate food 2. Fungiform papillae: mushroom-shaped ***Each contains a few tastebuds 3. Foliate papillae: leaflike ridges (not well developed) ***House a few taste buds in early childhood Vallate (circumvallate) papillae: largest, least numerous ****Contain most of the taste buds

Where does the lacrimal apparatus fluid drain into?

1. Fluid drains into lacrimal puncta (holes by lacrimal caruncle) which drains into a "lacrimal sac". 2. The sac then drains into nasolacrimal duct to nasal cavity ***Fluid then mixes with mucus and is swallowed ***Excess lacrimal fluid produces tears

1. ________________ = sense of taste; detection of tastants 2. Gustatory cells are ______________________ (mechanoreceptors/chemoreceptors) within taste buds

1. Gustation 2. Chemoreceptors

1. Gustatory cells are neuroepithelial chemoreceptive cells of taste buds. Gustatory __________________ (taste hair) forms dendritic ending. This structure often extends through taste pore, to tongue surface 2. Explain the gustatory pathway

1. Gustatory microvillus 2a. Sensory neurons connect to multiple gustatory cells in the tongue and project to the medulla 2b. Secondary medullary neurons project to thalamus 2c. Tertiary thalamic neurons project to primary gustatory cortex in insula

Explain the cochlear hair stimulation process

1. Inner hair cells contain ion channels at their tips and tip link proteins that connect them 2. Hair cells are bathed in K+ endolymph that is far more positive than the fluid inside the cell 3. When basilar membrane moves up, hair cells are pushed into tectorial membrane and their tips are tilted, pulling tip links 4. Tip links pull open ion channel allowing K+ to diffuse into the hair cell and depolarize it 5. Hair cell releases more neurotransmitter from its base, exciting the sensory neuron, which can fire action potentials 6. When basilar membrane moves down, the process quickly reverses

1. What is the purpose of the lens? 2. Why does the lens shape have so much significance on its function? 3. How is the shape determined

1. Lens: changes shape to focus light on retina 2. Shape determines degree of light refraction 3. Shape is determined by ciliary muscle and suspensory ligaments

1. Proprioceptors are general sensory receptors located in __________ , ___________ , and ______________ 2. Proprioceptors are all ______________ (tonic/phasic) receptors (adapt slowly) 3. The 3 types of proprioceptors are listed below. Explain each of their function.

1. Muscles, tendons, and joints 2. Tonic 3a. Muscle spindle - detect stretch in skeletal muscle 3b. Golgi tendon organ - detect stretch in tendon 3c. Joint kinesthetic receptor - detect stretch in articular capsule

1. Define Encapsulated tactile receptors 2. Define the parts of the Encapsulated tactile receptors such as End (Krause) bulbs, Lamellated (Pacinian) corpuscles, Bulbous (Ruffini) corpuscles, Tactile (Meissner) corpuscles

1. Neuron endings wrapped by connective tissue or covered by connective tissue and glial cells (neurolemmocytes) 2a. End (Krause) bulbs (in dermis and mucus membrane) Are ensheathed in connective tissue ***Detect pressure and low-frequency vibration 2b. Lamellated (Pacinian) corpuscles (deep dermis, hypodermis, some organ walls)- are wrapped in neurolemmocytes and concentric layers of connective tissue ***Detect deep pressure, course touch, high-frequency vibration 2c. Bulbous (Ruffini) corpuscles (dermis & subcut. layer) Are wrapped in CT ***Detect deep pressure and skin distortion 2d. Tactile (Meissner) (dermal papillae) corpuscles are intertwined endings wrapped in modified neurolemmocytes, covered in connective tissue ***Discriminative light touch—allow recognition of texture, shape

1. Define Olfaction 2. Define Odorants 3. What is an Olfactory epithelium 4. ______________ receptor cells detect odorants 5. Explain the 2 structures that compose the Olfactory epithelium listed below -Lamina propria -Olfactory (Bowman) glands

1. Olfaction—detection of odorants dissolved in the air 2. Odorants (volatile molecules) dissolved in nasal mucus are detected by chemoreceptors 3. Olfactory epithelium—sensory receptor organ 4. Olfactory 5a. Lamina propria- Areolar connective tissue layer internal to olfactory epithelium ***Houses blood vessels, nerves, and olfactory glands 5b. Olfactory (Bowman) glands- Help form mucus covering olfactory epithelium

1. The eye is surrounded by what type of tissue to serve as a cushion? 2. The interior if the eye contains 2 cavities. List those cavities and what type of "humor" they contain What 3 tunics is the wall of the eye made of? (hint: external, middle, and inner)

1. Orbital fat 2a. Posterior cavity (behind lens) contains permanent vitreous humor 2b. Anterior cavity (in front of lens) contains circulating aqueous humor 3. Fibrous (external), Vascular (middle), Retina (inner)

1. The inner ear contain ___________ (interstitial fluid) fills most of this space which is housed in the ___________ labyrinth: mazelike spaces in temporal bone 2. The ____________labyrinth: membrane-lined fluid-filled tubes within bony labyrinth. It contains ____________, similar to intracellular fluid, rich in K+. It also contains receptors for hearing and equilibrium

1. Perilymph; Bony 2. Membranous; endolymph

1. Define a Photopigment 2. Where are they found? 3. What 2 products are they made of?

1. Photopigments: light-absorbing molecules 2. Found within membranes of outer segments of rods and cones 3. Made of opsin protein and light-absorbing retinal (made from Vitamin A)

1. Olfactory receptor cells are _______________ (primary/secondary) neurons in sensory pathway for smell 2. Olfactory receptors contain ______________ (unipolar/bipolar/multipolar) structure: a single dendrite and unmyelinated axon 3. What are Olfactory hairs? 4. What are Olfactory nerves made of?

1. Primary 2. Bipolar 3. Olfactory hairs: cilia projecting from receptor cell dendrite (houses chemoreceptors for odorant detection) 4. Bundles of olfactory cell axons

Explain the Gustatory pathway in 3 steps

1. Primary neuron in cranial nerve brings signal to nucleus solitarius within medulla 2. Signal is relayed to thalamus 3. Then relayed to primary gustatory cortex for conscious taste

1. During Refraction of light, sharp vision requires light rays to be bent (______________) as they pass toward retina 2. Refraction results when ___________ passes. 3. _____________ index: a number that represents its comparative density

1. Refracted 2. light 3. Refractive

1. A ____________ is a stimulus we are consciously aware of. To enter consciousness, signals must reach cerebral cortex. 2. Receptors provide _________ (CNS/PNS) information about stimulus modality, location, intensity, and duration 3. ___________ is a type of stimulus based on "labeled line". For example, brain interprets optic nerve signals to occipital lobe as visual, cochlear nerve signals as to temporal lobe as auditory 4. Location of stimulus determined by which receptive field is ___________ (active/inactive) 5. Intensity of stimulus determined by _____________ (frequency/amplitude) of nerve signals to CNS

1. Sensation 2. CNS 3. Modality 4. active 5. frequency

Explain the equilibrium pathway

1. Signals from maculae or crista ampullaris are conveyed by the vestibular branch of CN VIII 2a. These axons terminate in vestibular nuclei or cerebellum 2b. Vestibular nuclei (in superior medulla) help control reflexive eye movements and balance 3. Cerebellum helps coordinate balance and muscle tone 4. Vestibular nuclei and cerebellum send signals to thalamus 5. Thalamus relays information to cerebral cortex for awareness of body position

The Iris controls pupil diameter. Explain the 3 muscles listed below that help control pupil diameter change. 1. Sphincter pupillae muscles 2. Dilator pupillae muscle 3. Pupillary reflex

1. Sphincter pupillae muscles: concentrically circular fibers constrict pupil with parasympathetic nervous system activity (CN III) 2. Dilator pupillae muscle: radially organized smooth muscle dilates pupil with sympathetic nervous system activity 3. Pupillary reflex alters pupil size in RESPONSE TO LIGHT (increased brightness leads to constriction)

1. Sensory receptors provide information about external and internal environments. Sensory receptors respond to a _________________. 2. ____________________ convert stimulus energy into electrical energy. 3. Receptor membranes have _____________ gated channels that respond to their type of stimulus. 4. Receptors convey signals to CNS by ___________ neurons (sensory/motor). 5. _______________ field—the distribution area of the endings of a sensory neuron. Smaller ____________ fields allow more precise stimulus localization

1. Stimulus 2. Transducers 3. Modality 4. Sensory 5. Receptive; receptive

Receptor ADAPTATION helps determine stimulus duration. 1. ______________ (Phasic/Tonic) receptors show limited adaptation: respond continuously. For example, head position receptors in inner ear; all pain r 2. ____________ (Phasic/Tonic) receptors adapt rapidly: only respond to new stimuli For example, pressure receptors

1. Tonic 2. Phasic

1. The base of each semicircular canal has region called the ___________. 2. What ear structures help detect ANGULAR ACCELERATION

1. ampulla 2. When head rotates endolymph pushes against cupula -Cupula bends stereocilia and changes hair cell voltage

Phototransduction: light converted to electrical signal 1. In the dark, rhodopsin contains __________ -retinal (cis/trans). 2. Light causes reconfiguration to ___________ -retinal (cis/trans), which dissociates from opsin (bleaching reaction)

1. cis-retinal 2. trans-retinal Basically, the REPEATING cycle is... 1. cis-retinal converts to trans-retinal 2. trans-retinal is then converted back to cis-retinal so that rhodopsin can be formed again.

1. The ear detects sound and ___________ movement. 2. Explain the function of the 3 structures of the External ear listed below.

1. head movement 2a. Auricle- Protects ear entryway and directs sound waves inward 2b. External acoustic (auditory) meatus ***Ceruminous glands produce cerumen ***Ear wax impedes microorganism growth 2c. Tympanic membrane: (eardrum) ***Vibrates when sound waves hit it

1. Regarding the Olfactory nerves, the mucus contains _________________-binding proteins. This helps with detecting smells 2. Olfactory sensations begin when odorant binds to protein and protein stimulates _____________ cell (rapidly adapting receptor)

1. odorant 2. receptor

1. Taste buds: onion-shaped organs housing _______________ receptors. 2. Gustatory cells: receptor cells detect _____________. 3. Supporting cells _____________ (replace/sustain) gustatory cells while basal cells are neural stem cells that ______________ (replace/sustain) gustatory cells

1. taste 2. tastants 3. sustain; replace

1. Sound is the perception of pressure waves established from _________objects 2. Pitch depends on the ______________ of the vibrating object. 3. _______________ depends on wave amplitude

1. vibrating 2. Frequency 3. Loudness

Explain the characteristics of the 3 main regions that the Inner ear is composed of?

Cochlea- Houses membranous cochlear duct Vestibule- Contains two saclike, membranous parts: utricle and saccule, interconnected and positioned at right angles Semicircular canals- Contains membranous semicircular ducts

Explain the specific structures that are used for hearing (which are listed below) Cochlea Modiolus Cochlear duct Scala vestibuli Scala tympani Helicotrema Spiral organ

Cochlea-snail-shaped chamber of inner ear Modiolus- bony axis of the spiral Cochlear duct- membranous labyrinth in cochlea (HAS HAIR CELL receptors that release neurotransmitter to sensory neurons) Scala vestibuli- chamber of bony labyrinth adjacent to vestibular membrane Scala tympani- chamber of bony labyrinth adjacent to basilar membrane Helicotrema- small channel connecting scala vestibuli and scala tympani Spiral organ: sensory structure for hearing

Define a conjunctiva? What is the difference b/w an Ocular conjunctiva, Palpebral conjunctiva, and Conjunctival fornix

Conjunctiva (specialized stratified columnar epithelium) - transparent lining of eye and lid surfaces ***Ocular conjunctiva covers anterior sclera (white of eye) ***Palpebral conjunctiva covers internal surface of eyelid ***Conjunctival fornix: junction of ocular and palpebral conjunctiva

Explain the difference b/w Dark Adaptation and Light Adaptation. (below is a list of questions you should focus on) 1. Is it adjusting from low light to bright light? Or vice versa? 2. Are the cones or rods involved? 3. How many minutes does it take to adjust?

Dark adaptation 1. Return of sensitivity to low light levels after bright light 2. Bleached rods must regenerate rhodopsin 3. May take 20 to 30 minutes to see well Light adaptation 1. Process of adjusting from low light to bright conditions 2. Pupils constrict, but cones initially overstimulated 3. Takes about 5 to 10 minutes for full adjustment

Sensory receptors are classified by receptor distribution, stimulus origin, and stimulus modality. Explain the types of stimulus origins listed below. Exteroceptors Interoceptors Proprioceptors

Exteroceptors- detect stimuli from external environment. Ex: Skin and mucus membranes; special sense receptors Interoceptors: detect stimuli from internal organs. Ex: Visceral sensory receptors monitoring internal environment Proprioceptors- detect body and limb movements Ex: Somatosensory receptors of muscles, tendons, and joints

What is the purpose of eyebrows and eyelashes? 1. The upper eyelid is raised by _____________ palpebrae superioris muscle

Eyebrows- prevents sweat from coming into the eye Eyelashes- Prevent objects coming into contact with eye; can initiate blink reflex 1. levator

Explain the differences in the eyes when you are looking at an object 20+ feet away versus looking at an object less than 20 feet away. (Below should be the focus of your answers) Are the ciliary muscles relaxed or contracted? Are the pupils dilated or constricted?

For objects 20 feet away and further: **Ciliary muscles= relaxed ***Pupils= dilated (Dilator pupillae of iris contracts) For objects closer than 20 feet (near response): ***Ciliary muscles= contract ***Pupils= constrict (Sphincter pupillae contract)

Sensory receptors are classified by receptor distribution, stimulus origin, and stimulus modality. Explain the types of receptor distributions listed below. General sense receptors -Visceral sensory receptors -Somatic sensory receptors Special sense receptors

General sense receptors- Simple structures distributed throughout the body ***Visceral sensory receptors- found in WALLS of internal organs, they monitor stretch, chemical environment, temperature, pain ***Somatic sensory receptors: tactile receptors of SKIN and mucous membranes; proprioceptors of joints, muscles, and tendons Special sense receptors- Specialized receptors in complex sense organs of the head ***5 special senses: olfaction, gustation, vision, audition, equilibrium

Explain the Aqueous Humor: Secretion and Resorption process. 3 Steps. How does this relate to Glaucoma?

Glaucoma is the increased intraocular pressure

What is the purpose of the Lacrimal apparatus? What is a lacrimal gland?

Lacrimal apparatus: produces, collects, drains fluid ****Lacrimal fluid: water, Na+, antibodies, lysozyme (antibacterial enzyme) ***Lubricates, cleanses and moistens eye, reduces eyelid friction, defends against microbes, oxygenates and nourishes cornea Lacrimal gland: produces fluid and secretes it through ducts (Blinking (15 to 20 per minute) washes fluid over eye)

Name the 3 Auditory ossicles of the middle ear. Know the order/location of them.

Malleus- Resembles a hammer in shape Incus- Middle ossicle resembling an anvil Stapes- Resembles a stirrup of a saddle

Explain the function and characteristics of the Middle ear and the Auditory tube.

Middle ear: Contains air-filled tympanic cavity ***Bony wall separates it from inner ear Auditory tube (Eustachian tube): Passage extending from middle ear to nasopharynx (upper throat) ***(Middle ear infections often result from infections spreading from throat through auditory tube) ***Usually closed, but yawning allows air movement through the tube

Sensory receptors are classified by receptor distribution, stimulus origin, and stimulus modality. Explain the types of modality of stimulus (stimulating agent) listed below. ***There are 5 types Nociceptors (include somatic and visceral nociceptors) Chemoreceptors Photoreceptors Mechanoreceptors Thermoreceptors

Nociceptors-detect painful stimuli ***Somatic nociceptors detect chemical, heat or mechanical damage to the body surface or skeletal muscles ***Visceral nociceptors detect internal organ damage Chemoreceptors- detect chemicals dissolved in fluid (includes external AND internal receptors) Photoreceptors- detect changes in light intensity, color, movement. (In the retina of the eye) Mechanoreceptors- detect distortion of cell membrane Include touch, pressure, vibration, and stretch receptors (Function as baroreceptors, proprioceptors, tactile receptors, and specialized receptors in the inner ear) Thermoreceptors- detect changes in temperature (Include receptors in skin, hypothalamus)

What is the difference b/w Olfactory bulbs (pair) and Olfactory tracts (pair)

Olfactory bulbs (pair)- Ends of olfactory tracts located under brain's frontal lobes ***Connections form olfactory glomeruli Olfactory tracts (pair)- Axon bundles of mitral and tufted cells on inferior frontal lobe surface ***Project directly to primary olfactory cortex (in temporal lobe), hypothalamus, amygdala, and other regions NOTE: It Does not project through thalamus like other sensory pathways

Explain the 3 components of the retina that are listed below along with their functions. 1. Optic disc 2. Macula lutea 3. Peripheral retina

Optic disc: Contains no photoreceptors—blind spot ***Where ganglion axons exit toward brain Macula lutea: Rounded, yellowish region lateral to optic disc. Contains FOVEA centralis (central pit) ***Highest proportion of cones (hardly any rods) ***Area of sharpest vision Peripheral retina- Contains primarily rods ***Functions most effectively in low light

What is the pathway of light in the retina when we are talking about the ganglion cells, photoreceptors, and bipolar cells? What is the difference b/w Optic nerves and Optic tracts?

Pathway light in retina ***Photoreceptors → bipolar cells → ganglion cells Optic nerves: Exit backs of eyes and converge at optic chiasm Optic tracts: Optic tracts (ganglion cell axons from both eyes)

The Retina: cells of the neural layer form 3 sublayers. List the 3 sublayers along with their functions. Explain the other 2 retinal interneurons as well

Photoreceptor cell layer: outermost neural layer Contains rods and cones Contain pigments that react to light Bipolar cell layer- Their dendrites receive synaptic input from rods and cones Ganglion cell layer: innermost neural layer ***Their axons gather at optic disc and form optic nerve Capable of action potentials Other retinal interneurons: ***Horizontal cells regulate signals sent between photoreceptors and bipolar cells ***Amacrine cells regulate signals between bipolar and ganglion cells Capable of action potentials

The retina is made up of 3 types of neural tunic layers listed below. Provide each of their function and characteristics 1. Pigmented layer 2. Neural layer 3. Ora serrata

Pigmented layer- Attached to choroid (internal to it) ***Provides vitamin A for photoreceptors ***Absorbs stray light to prevent light scatter Neural layer Houses photoreceptors and associated neurons Receives light and converts it to nerve signals Ora serrata - jagged edge Boundary between photosensitive and nonphotosensitive parts of retina

Define Referred pain. Explain how this happens with respect to somatic and visceral sensory neurons. Give an example of a stroke regarding referred pain

Referred pain—inaccurate localization of sensory signals ***Signals from viscera perceived as originating from skin, muscle ***Many somatic and visceral sensory neurons send signals via the same ascending tracts within spinal cord ***Somatosensory cortex unable to determine true source Ex: Patient could be saying they have pain in their arm or chest when really they might be having a heart attack

Explain the difference b/w rods and cones. Where are both of them located in the eye? How does colorblindness relate to this?

Rods- Rods are longer and narrower than cones; more numerous (USED FOR LIGHT) Location: The periphery of the retina Cones- USED FOR COLOR. Cones are concentrated at fovea centralis Colorblindness= X-linked recessive condition where absence of one type of cone is not produced

Which 2 structures of the eye does the Fibrous tunic cover? Explain each eye structures functions.

Sclera: white of the eye (dense irregular CT) ***Provides eye shape ***Protects internal components ***Attachment site for extrinsic eye muscles Cornea: anterior convex transparent "window" ***Refracts light

Explain the Transduction in gustatory cells for sweet, bitter, and umami tastes. What about for salt and sour?

Sweet, Bitter, and Umami Taste Transduction 1. Tastant binds to specific cell membrane receptor 2. G PROTEIN is activated causing formation of 2nd messenger 3. Results in cell depolarization Salt and Sour The tastant depolarizes the cell directly

Explain the 5 basic taste sensations spread over broad regions of the tongue

Sweet- Produced by organic compounds, for example, sugar or artificial sweeteners Salt-Produced by metal ions, for example, Na+ and K+ Sour- Associated with acids, for example, vinegar Bitter- Produced by alkaloids, for example, unsweetened chocolate Umami- Taste related to amino acids producing savory or meaty flavor

The vestibule is composed of a layer of hair cells and supporting cells. The hair cells have stereocilia and one kinocilium projecting into gelatinous OTOLITHIC MEMBRANE. What is the purpose of the otolithic membrane?

The membrane serves to determine if the body or the head is tilted, in addition to the linear acceleration of the body.

Which 3 structures of the eye does the Vascular tunic (uvea)cover? Explain each eye structures functions.

Vascular tunic (uvea): middle layer with many vessels Choroid: Many capillaries nourish retina ****Many melanocytes make melanin to absorb extraneous light Ciliary body: ciliary muscles and processes ***Processes= capillaries that secrete aqueous humor ***Muscles= contraction alters lens shape Iris: (gives eye color); most anterior region of uvea ***Contains smooth muscle, melanocytes, vessels, neural structures ***Pupil is opening in center of iris connecting the two chambers

What is the difference b/w Vitreous humor (vitreous body) and Aqueous humor? Explain their functions and composition.

Vitreous humor (vitreous body)- Transparent GELATINOUS fluid in posterior cavity (behind lens) ***Helps eye maintain shape ***Supports retina—keeps it flush against back of eye Aqueous humor- Transparent watery fluid in anterior cavity (in front of lens). Production circulation and drainage ***Nourishes and oxygenates lens and inner cornea ***Aqueous humor circulates through pupil into anterior chamber

Define Phototransduction. 1. Phototransduction is performed by ________________ cells (rods and cones). The photoreceptor has 3 parts to it listed below. Explain each of their functions Outer segment Inner segment Cell body Synaptic terminals

converting light to electrical signals 1. photoreceptor Outer segment extends into pigmented layer of retina ***Hundreds of photopigment-containing discs that absorb light. Discs are continually replaced Inner segment contains cell organelles Cell body contains nucleus Synaptic terminals contain vesicles storing glutamate neurotransmitter