Ch. 10 Senory Physiology

conscious–sensation; special senses, somatic senses, some proprioception receptors (joint)
unconscious–no sensation; viseral; some proprioception
What are the differences between conscious and unconscious sensory information?
something perceived
What is a sensation?
transduction (converting a chemical signal to an electrical signal)
What is the function of a receptor in the sensory system?
Sending signals along the sensory neurons from the primary sensory neuron (PNS) to the secondary and tertiary neurons in the CNS. It often goes from PNS to spinal cord/brainstem, to the brain
What is the function of transmission in the sensory system?
It takes signals to the brain, either the cerebral cortex, where it is conscous perceived, or other aras, where it subsonscious, not perceived (such as the cerebellum or the thalamus)
What is the function of integration in the sensory system?
Simple receptors are free nerve endings that are just dendrites on the end. The axon is unmyelinated. There is a cell body that sticks out and an axon leading away from the cell body. Its function is to feel pain, temperature, and olfaction.
Name the structure and function of simple receptors
Complex receptors have nerve endings enclosed in connective tissue capsules (think Pacinian corposcles) The axons are myelinated and the cell body sticks out. Its function is to feel touch, pressure, vibration
Name the structure and function of complex receptors
Most special senses receptors are cells that release neurtotransmitter onto sensory nuerons, initiating an action potential. For example, a hair cell found in the ear has a hair cell receptor. Other examples are in gustation, vision, hearing, and equilibrium.
Name the structure and function of specialized non-neural receptor cells
The somatic receptors are on the skin, joints, muscles, maybe tendons. There are also some viseral receptors. On the other hand, the specialized senses are in the head in their specialized organs.
Compare the distribution of sensory receptors of the somatic senses and the special senses.
both, both, special, somatic, somatic
Do these receptors types belong to the somatic senses or special senses or both?
chemoreceptors
mechanoreceptors
photoreceptors
thermoreceptors
nociceptors (pain)
external, organs and blood vessels, muscle spindles and joints and glogi tendon organ
Compare the following with regards to the origin of the stimuli:
exterocetors
interoceptors (visceroceptors)
proprioceptors
meaning “one’s own”, “individual” and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement. It is provided by proprioceptors in skeletal striated muscles and in joints. It is distinguished from exteroception, by which one perceives the outside world, and interoception, by which one perceives pain, hunger, etc., and the movement of internal organs. The brain integrates information from proprioception and from the vestibular system into its overall sense of body position, movement, and acceleration.
What is proprioception?
Receptor potentials from ionotrpic receptors and metatropic receptors may create an action potential because receptor potentials=graded potentials. There are even some speicialzed receptor cells that may lead to neurotransmitter secretion without an AP but from a receptor potential.
Identify and dicussion each of the following in the transduction of sensory information:
ionotropic receptors
metatropic receptors
Adequate stimulus: stimulus a receptor is more sensitive to (rods and cones sensitive to light)
Threshold stimulus: minimum stimulus required for transduction or activation
Identify and dicussion each of the following in the transduction of sensory information:
adequate stimulus
threshold stimulus
a graded potential. May produce an action potential in a neuron. Taste bud is an example. The receptor potential releases neurotransmitter.
What is a receptor potential?
is the particular part of the body surface in which a stimulus will trigger a firing of an individual sensory neuron
What is a receptive field?
Primary–area of tissue with a single primary receptor. They can overlap and be large or small. Secondary–area of tissue a single secondary receptor is responsible for. Can have a convergence of multiple primary neurons on one secondary sensory neuron.
What is the difference between a primary receptive field and a secondary receptive field?
the size of secondary receptive fields determines how sensitive a given area is to a stimulus. In some areas, many primary neurons converge on a single secondary neuron, so the secondary receptive field is very large. In contrast, more sensitive areas of skin have smaller receptive fields with as little to a 1:1 ratio of primary and secondary sensory neurons.
Discuss the impact of size of primary recepitve fields and secondary receptive fields
Receptive fields frequently overap with neighboring receptive fields. They are then on the same secondary receptive field and go to the same secondary neuron. This called convergence of pathways.
What is the impact of overlap of primary receptive fields?
Unconcious integration is in the spinal cord and brainstem. Conscious integration depends on the sense, but most go to the thalamus and are in the cerebrum.
What is the difference between unconscious and conscious integration?
olfactory cortex, limbic system, hypothalamic systems
Name the conscious sensory integration pathway for olfaction (an odd one)
midbrain, thalamus, visual cortex
Name the conscious sensory integration pathway for vision
medulla, thalamus, auditory and gustatory cortexes
Name the conscious sensory integration pathway for sound and taste
medulla, cerebellum, and thalamus to cerebral cortex
Name the conscious sensory integration pathway for eqilibrium
spinal cord, thalamus, somatic sensory cortex
Name the conscious sensory integration pathway for somatic senses
A threshold for perception of a stimulus. You can pick up the stimulus, send at action potential etc, but do not necessary perceive it. The CNS can modify the strength needed to perceive it. The CNS can also modulate, changing what you do with the message you got.
What is a perceptual threshold?
Habituation inhibits modulation and therefore decreases the liklihood of perception. It reduces suprathreshold stimulus to subthreshold stimulus.You might be ignoring it.
How does habituation impact the likelihood of perception?
All the info you’re obtaining through the message from your stimulus. What it is, how strong it is, where it is located, the instensity, the duration.
What is sensory coding?
Sensory modality: what is the stimulus? how am i perceiving it? Senses we recognize are modalities. Touch, taste, vision, pain, changes in temperature.
Submodality: Break down modalities a little more, like the types of taste: sweet, salty, sour, bitter.
What is sensory modality and submodality?
Think of it as wiring, electrical wires. From point A to point B. Receptor to perception. Direct line between sensory receptor to location of perception in the brain. Signal is interpreted based on where it goes.
What is labeled line coding?
Go to primary receptor field, this goes to specific spot in the brain. Areas with more receptrs are more sensitive and have a larger area in the brain (a lot of space for the face and the lips). Phantom limb pain–receptors and primary neurons not there, but secondary neurons stimulated. Still carries info to the same place in the brian and get a response. After amputation can still feel.
Explain how the brain is able to localize a stimulus. How is this illustrated in pantom limb pain?
Brain comprehends time difference between sound reaching one ear vs the other ear.
How does interaural time difference assist in localization of sounds?
Pathway closest to the stimulus inhibits its neighboring neurons through its axon to the neighboring axon. Then, the inhibition enhances the perception of the simulus from its initial location. Otherwise, it may seem from multiple places and more difficult to detect location.
How does lateral inhibition with axoaxonic inhibition assist in the localization of a stimulus?
Population coding is taking info from multiple primary receptive fields that provide comparative information about the stimulus. One field may be stronger and others weaker. The number of activated receptors increases the detected intensity of the stimulus. This could provide some info on where it’s coming from.
How does population coding assist in the localization of a stimulus?
Because an action potential is all or nothing. Can’t vary strenth of an action potential, but you can vary how many you send. You can then tell by frequency.
Explain why the strength of an action potential cannot be used to determine the strength of a stimulus.
The more receptor fields activated, the more intense.
How is population coding used to dermine intensity?
No, different receptors have different thresholds. Some have low thresholds and requires only a weak stimulus. Others have higher and require stronger stimulus. More receptors activated, whether weak or strong, a more intense stimulus is detected.
Do all sensory receptors respond to the same level of stimulus? How does this assist in population coding?
The stronger the graded potential, the higher the frequency, the more intensity. Intensity must be high enough to send the signal.
How is frequency coding used in the determination of stimulus intensity?
Key is being suprathreshold with graded potential.
What determines the duration of transduction of a stimulus?
Receptor adaptation: response can stop because of prolonged exposure to the stimulus and you adapt to it.
Tonic receptor slow adaptation: initial rapid firing followed by slower, constant rate firing, maintains a “tone” (equilibrium)
Phasic receptors: rapid adaptation. Ignore continuous stimulus. Initital rapid firing followed by no firing (temperature, smells, some touch) relates to afterimage–firing after stimulus removed
How does each of the following help to determine the duration of a stimulus?
receptor adaptation
Tonic receptor slow adaptation
Phasic receptor rapid adaptation
First: afferent neuron, PNS to CNS
Second: within the CNS, an interneuron. Decussates (at the medulla or spinal cord and then synapses with third neuron at thalamus or brainstem).
Third: in the CNS, an interneuron, goes to cerebal cortex (somatosensory cortex or pyamidal cells)
Where would you find a first order neuron? a second order neuron? a third order neuron?
It is a sensory pathway. Antierior and lateral are different but paths look same. Body to spinal cord, then cross over and go up to thalamus. From thalamus to somatosensory cortex. (decussates at secondary neuron when enters spinal cord)
What is the anterolateral spinothalamic pathway? Where is the first order neuron? Second? Third? Where does decussation occur?
Lateral: pain and temperature
Anterior: (think ants crawling on you) light and crude touch, itch, tickle
What somatic sensations are carried by the lateral spinothalamic pathway? By the anterior spinothalamic pathway?
A sensory pathway. Goes from the body and synapses and cross at the medulla (instead of the spinal cord). It then goes to the thalamus and then the somatosensory cortex.
What is the doral or posterior column pathway? Where is the first order neuron? Second? Third? Where does decussation occur?
Fine touch, vibration, precise pressure, proprioception
What somatic sensations are carried by the dorsal or posterior column pathway?
contralateral—decussation has already happened
Which side of the body would be affected by a lession in the anterolateral pathway right under the medulla? Contralateral or ipsilateral to lesion?
somatic senses: somatic sensory cortex
visual:
auditory: auditory cortex
vestibular:
gustation: gustatory cortex in insula
olfactory senses: cerebral cortex, limbic system (olfactory cortex)
What is the CNS destination for somatic senses? For special senses (visual, auditory, vestibular, gustation, olfactory senses?)
ipsilateral–because decussation not happened yet
Which side of the body would be affected a lesion in the doral column pathway if under the medulla? Contralateral or ipsilateral to the lesion?
skin, hypothalamus
thermoreceptors (free nerve endings)
nociceptors for pain (free nerve endings)
Identify location and receptors assocated with the somatic sense:
temperature
pain
Thermoreceptors are called polymodal because they respond to extreme temperatures and feel pain as well. Some thermreceptors also respond to chemical channels. The temperature activates cation channels. Add menthol and you feel cold. Add ethanol and you feel cool…even though activated warm receptors…its evaporating and evaporative cooling. Drink alcohl and its warm.
Why are some thermoreceptors consdiered polymodal? How can some thermoreceptors also respond to chemcials?
There is no actual stimulus for pain or itch. Pain is extremes of other sensations.
Why are pain and itch considered sensations and not true stimuli?
subtsance P or glutamate
What is the neurotransmitter of nociceptors?
Withdrawal reflex–very fast–to the spinal cord
Perceived pain has to ascend and go to the cerebral cortex in the brain
Explain how the withdrawl reflex associated with a painful stimulus differs from a perceived painful stimulus
Withdrawl reflex, spinal reflex
Large diameter, myelinated
Carries info to the brain
Fastest
A-beta pain fibers
What type of pain perception?
What is the physical structure?
How does it relate to the transmission of the AP associated with it?
fast pain: sharp and localized
small diameter, myelinated
rapid transmission
A-delta pain fibers
What type of pain perception?
What is the physical structure?
How does it relate to the transmission of the AP associated with it?
slow pain: dull and diffuse (ache)
small diameter, unmyelinated
slow transmission
C pain fibers
What type of pain perception?
What is the physical structure?
How does it relate to the transmission of the AP associated with it?
Itch only on the skin. Histamine stimulates it. Inflammatory response of immune system.
Why is itch associated with the immune system?
Placebo effect. Think with kids and changing your response. Rub it, it will feel better. Blow on it. Put ice on it.
How is it involved in the modulation of pain:
emotion, memory, and suggestion
It is an increased sensitivity to pain, which may be caused by damage to nociceptors or peripheral nerves. Increased sensitivy to the pain even after stimulus.
How is it involved in the modulation of pain:
hyperalgesia
a drug that removes the pain. Asperin. It is decreasing sensitivity.
How is it involved in the modulation of pain:
analgesia
From within, you make them yourselves. Runner’s high. Releases endogenous opioid. Endorphins can make you feel better. Inhibits C pain fibers (aches).
How is it involved in the modulation of pain:
endogenous opioid
Rub it. Activate touch and pressure to the area. Partially inhibit nociceptors.
How is it involved in the modulation of pain:
transcutaneous electrical nerve stimulation
The gate control theory of pain asserts that non-painful input closes the “gates” to painful input, which prevents pain sensation from traveling to the central nervous system. Therefore, stimulation by non-noxious input is able to suppress pain. Activate alpha beta pain fibers (which are involved in reflexes and fast)…activates inhibitory interneuron which inhibit the ascending pain pathway.
Explain the gate control theory of pain modulation.
inhibitory interneuron: tonically inhibits ascending pain pathway. Block pain normally.
C fiber: When really painful: inhibits interneuron neuron, pain pathway relseased from inhibition (now it can go through because usually doesn’t)
A-beta fiber: stimulate inhibitory interneurons so pain not sent to the brain.
How are these fibers involved in gate control theory of pain modulation?
inhibitory interneuron
C fiber
A-beta fiber
Excess potassium. (damaged muscles release potassium)
Which ion is associated with deep muscle pain?
is pain perceived at a location other than the site of the painful stimulus.
Define referred pain.
Viseral organs when damaged send signals and we recognize it as referred pain. When somatic sensory neurons and from organs share a common pathway with second order neuron, you can’t tell where the signal is coming from, skin or organ? You recognize it as the most common sensation you would experience.
How and why does referred somatic pain serve as an identifier for visceral pain?
Smells dectected by chemoreceptors (dendrites in olfactory epithelium). Transduction: olfactory neurons in olfactory epithelim–cranial nerve 1–olfactory bulb–olfactory tract–olfactory cortex. (not going through thalamus–will next go to limbic system)
How are odors dected and transduced? be able to trace the neural pathway of olfaction from the nasal epithelium to the olfactory cortex.
Combination of receptors. Add sensory messengers as it goes up. Memories. Emotion. Can activate sexual behavior, food, sympathetic system. Gender, age, smoking, colds/allergies, level of hunger, anosmia
What other factors can affect olfaction?
Specialized chemoreceptor cells in taste buds. Tastant must e dissolved in the saliva or mucus.
Transduction:
Type 1: sodium channel–sodium entry results in depolarization
Type 2: G protein coupled recepotors relase ATP
Type 3: hydrogen channel or receptor releases neurotransmitter serotonin (Think how sour is an acid)
How is taste (gestation) detected and transduced?
salty, sweet, bitter, umami, sour
What are the submodalities of taste?
Type 1–support cells; salt
Type 2–receptor cells; sweet, bitter, umami
Type 3–presynaptic cells; sour
Basal cell–potential stem cells
What are the 4 cell types of the taste buds? What are their functions?
texture, temperature, spicy (hot)
What are some of the other factors dected in the mouth but NOT actual taste?
Primary sensory neurons: facial, gloosopharyngeal and vagus cranial enrves (VII, IX, X)
Secondary neurons: medulla to thalamus
Tertiary: thalamus to gustatory cortex in insula
Be able to trace the neural pathway of gestation from the taste buds to the taste cortex.
Frequency is number of cycles per second, measured in Hz (hertz). The higher the frequency the higher the pitch. Pitch is determined in the cochlea. Oval window is high frequency. Helicotrema is low frequency.
Explain frequency and pitch
Measured as the amplitude of waves. Measured in decibels (which are like pH, 10 fold increases). This is the intensity. the cochlea determines loudness through frequency coding. the high the decibel, the more action potentials.
Explain loudness
They are mechanoreceptors. Sound waves alter them. Finger-like projections. Sterocilia–short ones. The last, tall one is the kinocilium. Both linked by protein-linked chains. Depending on how they bend, pull or shorten the linked chains.
Explain sterocilia and kinocilium
Outer: anything before the tympanic membrane; pinna, external ear canal

Middle:after the tympanic membrane, goes to oval window (malleus, incus, stapes, some muscles)

Inner: other side of the oval window; cholea, scala vestibuli, coclear duct, endolymph (high potassium), scala tympani, and round window. Vestibularcocholear canal (cranial nerve)

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now
Explain outer, middle, and inner ear
Truly the sensory organ in the cochlea. Vibration of basilar membrane, movement of hair cels, deformation of stereocilia.
Organ of corti
How does it impact detection.
How does it impact transduction.
How does it impact localization of sound?
Cilia are sitting on the basilar membrane. It vibrates.
Basilar memebrane
How does it impact detection.
How does it impact transduction.
How does it impact localization of sound?
Jelly like mass above the cilia. It vibrates from the cilia movement and pushes down on them. The deformation of the cilia.
Tectorial memebrane
How does it impact detection.
How does it impact transduction.
How does it impact localization of sound?
The hair cells deform. Stereocilia can be in neutral position, bend towards kinocilium, bend away from kinocilium.

Neutral: Tonic release of neurotransmitter 10% of ion channels open (constant low signal)
Sound waves come in, push down and release (modifies releases of neurotransmitter)

Bend towards kinocilium: pulls protein link channels further apart and stretches them. Physically opens ion channels. Potassium moves into cell, depolizes receptor cell. Voltage gated calcium channels open. Neurtotransmitter is glutamate (excitatory) Continues to afferent neuron (primary)

Bend away from kinocilium: proteins shorten, don’t open channels or close them, reduce signal being sent

Steriocilia and kinocilium
How does it impact detection.
How does it impact transduction.
How does it impact localization of sound?
The brain determines the location of the sound by noticing the difference in time between each ear.
Interaural time difference
How does it impact detection.
How does it impact transduction.
How does it impact localization of sound?
Primary sensory neuron: vestibulocochlear cranial nerve (CN VIII), choclear branch

Secondary sensory neuron: cochlear nuclei in medulla to thalamus (some decussate and some remain ipsilateral)

Tertiary sensoring neuron: thalamus to auditory cortex (collaterals to RAS and cerebellum)

Be able to trace the neural pathway of audition from the organ of corti to the auditory cortex.
conductive: bone conduction/air conduction (ossicles part of air). Cerumen (ear wax), otosclerosis (ossicles won’t vibrate, hardened), otitis media (middle ear inflammation), tympanic membrane (broken ear drum)

sensorineural: hair cells and cochlear portion of the nerve (not in the brain yet). Presbycusis–old age hearing loss. Can get hearing aides. Children have cochlear implants.

Central: is the brain. Anything in pathway in CNS proper. Auditory tracts or cortex.

What is conductive, sensorineural and central hearing loss?
feedfoward of GI tract (seeing food, thinking of food, smelling food), behavior responses for feeding (what we eat, how much we eat), also your sense of smell
What other factors can affect taste?
1. rotation, angular movement (don’t respond to gravity), spining mechanism. Respond to changes in head rotation. Canals have endolympth. Endolympth moves when you move, but with a delay. You are changing which side has more pressure.

2. Cupula moves as body moves. At rest, stereocilia are not bent, tonic release of neurotransmitter telling you you’re stationary. Same as with hearing…if bent towards release, bend away close.

3. Vestiblue or otolith organs. cceleration, deceleration, vertical forces, rising/dropping, otoliths move (crytals on jelly). Gravity. Sterocilia moves like in other examples.

Be able to explain the function when it comes to balance:
semicircular canals and endolympth
Cupula and sterocilia and kinocilium
Vestibule, otoliths, and sterocilia and kinocilium
Opposite effects on opposite sides of the head.
In equilibrium, how does the stimulation of semicircular canals one side of the head differ from the stimulation on the other side of the head?
Most primary sensory neurons goes straight to the cerebellum.
Primary: vestibulocochlear cranial nerve
Secondy: vesticular nuclei of medulla to thalamus
Tertiary: thalamus to auditory cortex (most going other places though becaue of balance etc)
How does the neural pathway of balance differ from the neural pathway of sound?
Involuntary eye movement. “eye dancing” Alcohol gaze nystagmus. Positional alcohol nystagmus (when a person lies down)
What is nystagmus?
Control eye muscles, rotational nystagmus and post rotational nystagmus eyes will move different ways
How is nystamus related to the reflexive control of extraocular eye muscles and the organs of equilbrium?
When a person lies down after alcohol consumption. When person noticies the impact on their balance.
What is positional alcohol nystagmus?
In positional alcohol nystagmus:
PAN 1 at the beginning. Person still getting alcohol into their system. The membrane of the vestibular apparatus picks up alcohol faster than the endolymph. Now the cupula is lighter than the endolymph and it pushes on the hair cells. Nystagmus towards undermost ear
PAN 2: clearing alcohol out of their system. Reverse. Clear alcohol out of the endolympth before the cupula. So endolympth lighter. Nystagmus towards uppermost ear.
What causes the difference between PAN I and PAN II?
Vertigo: can’t match up info with what is happening.
Motion sickness: unfamiliar movement.
Miniere’s diease: result of too much pressure in the ear of too much endolymph. Vertigo can happen and ringing of the ear and dizziness.
What are vertigo? motion sickness? Miniere’s disease?
bending of light (gets light into the eye to bend it to the pupil) Cornea does this first and responsible for the majority of refraction. Lens fine tune refraction.
Refraction
Fine tune refraction. Lenses is responsible for accomodation. Pinpoint the light on the retina. Ciliary muscles help change the shape and make a focal point.

Far accomodation: looking in the distance. sympathetic inhibition. To keep yourself safe, you want to see what’s out there. Scan the horizon. NE. Cilary muscle relaxed. Lens thin.

Near accomodation: looking up close. Parasympathetic stimulation. ACh muscarinic. Ciliary muscles contracts. Lens thickens. (the 4 Cs: close, contract, constrict, converge)

Accomodation
far and near
lens becomes opaque, not as much light can get through. Not bright, fuzzy.
Cataracts
Near sighted. Eye ball too long. Focuses in front of retina.
Myopia
far sighted. Eye ball too short. Focuses behind of the retina.
Hyperopia
Uneven cornea.
Astigmatism
degeneration of the optic nerve. Blind spot enlarges. Decrease amount of vision going through. Apoptosis–cell death “tunnel vision”
Glaucoma
loss of functional retina. Lose receptors.
macular degeneration
Linked recessive genetic disorder. mutation in genes for red and green opsins
red-green color blindness
Far: far, relax, thin lens. NE Sympathetic. Radial muscles. Dilate.

Near: close, constrict, contract, converge. thick lens. ACh. Parasympathetic. Sphincter muscles

iris: regulates amount of light entering the eye. Sphincter mucles Contract: less light, front visual field in focus, shallow depth of field, parasympathetic

Radial muscles contract: more light, full extent of vision in focus, sympathetic system, Dilation

Explain how the eye changes for far and for near accommodation. Explain how the size of the iris is regulated.
receptor cells (not neuron…ganglion are neural cells)
Photoreceptors
Rods: black and white, lower acuity
Cons: color, high acuity
What are the characteristics and function of rods? of cones?
All cells in the retina back to front

rods and cones: color and acuity (last ones in line)

Hoizontal cells: modulate communication between photoreceptors and bipolar cells

Bipolar cells: Bipolar cells in the retina are also unique as they do not fire impulses like the other cells found within the retina. Rather, bipolar cells have a receptive-field that surrounds them

Amacrine cells: modulate communication between bipolar and ganglion cells

Ganglion cells: is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: horizontal cells and amacrine cells. Retinal ganglion cells collectively transmit image-forming and non-image forming visual information from the retina in the form of action potential to several regions in the thalamus, hypothalamus, and mesencephalon, or midbrain.

Nerve fibers

How does each of the following impact the detection and transduction of light?
Rods and cones
Bipolar cells
Ganglion cells
Accessory horizontal and amacrine cells
Light ON pathway bipolar cells (on in the light)
Metabotropic glutamate receptors
Bipolar cells Activated in the light
less glutamate release, bipolar simulateion and depolizartion. release excitatory neurtransmitter. Inhibited in the dark. Basically, ON in the light because NOT inhibited by glutamate!!

OPPOSITE
OFF pathway bipolar cells (off in the light because glutamate excitatory)
Ionotropic glutamamte receiptors
Activated in the dark
Increase glutamate relases–bipolar simulation and depolarization
Releases excitatory neurotransmitter
Inihibited in the light

Both modulated by horizontal and amocrine cells.

Explain the on and off pathways of function of bipolar cells and their associated ganglion cells
binocular: what both eyes can see, deep of field
monocular: out to the side, temporal field, one eye
nasal fields: binocular vision
temporal fields: monocular vision
Be able to identify the various visual fields:
binocular
monocular
nasal fields
temporal fields
Senory neurons: ganglioin cells make up optic cranial nerves CN II in retina. Enter CNS at optic chiasma. Decussation. Optic tracts go to the thalamus. Synapse in lateral geniculate body. Collateral pathways carry info to midbrain. Synapse with motor neurons of CN III for control of pupillary reflexes. Integrated with smotosenory and eqiuilbrium info for balance and motion. Finally goes to occipital cortex.
be able to trace the neural pathway of vision from the retina to the visual cortex (occipital).
optic chiasma–fibers from temporal fields cross
light cross as well when it comes in–temporal goes medially, nasal goes laterally (ipsilateral)
Be able to determine the effect of vision due to a cut in each of the following locations:
optic nerve
optic chiasma
optic tract
semicircular canals
Which structure(s) contain(s) receptors that detect rotation of the head?
lens
Which of the following structures focuses light for clear vision?
The receptor hyperpolarizes, decreasing the amount of neurotransmitter it releases. (Photoreceptors do not produce action potentials at all)
Which of the following correctly describes how a photoreceptor responds to light?
1:1
Which primary-to-secondary neuron ratio would allow for the greatest receptive sensitivity?
duratoin
The CNS must distinguish four properties of a stimulus. These properties include location, intensity, modality, and which other property?
graded
A receptor potential is a type of ________ potential
They would lose fine touch from the right side and nociception from the left side below the site of the damage.
Trauma to the spinal cord can cause a loss of function. If the trauma is only to a portion of the spinal cord, several functions can be partially lost in surprising ways. If someone experienced localized trauma to only the right side of their spinal cord, how would that change the fine touch and nociceptive stimuli they receive in their cortex?
Somatosensory cortex
Where do all tertiary somatic sensory neurons terminate?
Changing sensitivity to pitch along the length of the basilar membrane
The ability to distinguish different pitches (frequencies) of sound results from which of the following?
There are no blood vessels or neurons covering the cones.
Vision is especially acute in the fovea and surrounding macula. This is due to a high density of cone cells and which other reason?
involve receptors that consist of a neuron with naked free nerve endings or ones with nerve endings encased in connective tissue capsules
The somatic senses ________.
small, unmyelinated C fibers
Slow pain, described as dull and diffuse, is carried by ________.

large, myelinated A-Beta fibers
small, unmyelinated C fibers
large, unmyelinated C fibers
small, myelinated A-delta fibers

changing shape: rounding up or flattening out
The lens focuses light on the photoreceptor cells by ________.

moving up and down
opening and closing
moving in and out
changing shape: rounding up or flattening out

transduction; adequate stimulus; threshold
The conversion of stimulus energy into information that can be processed by the nervous system is called __________. Each sensory receptor has a(n) __________, a particular form of energy to which it is most responsive. The minimum stimulus level required to activate a receptor is called the __________.
respond to chemical ligands that bind to a cell membrane receptor
Chemoreceptors ________.
where the optic nerve exits the eye
The blind spot of the eye is ________.
ON–On bipolar cells. Glutamate inhibited causes activated.
OFF–Off bipolar cells. Glutamate inhibited causes inhibition.
Which cells are ON during the light?
Which cells are OFF during the light (but activated during the dark)?
Explain what is activated or inhibited…
multiple photoreceptors
Bipolar cells receive info from….
one ganglion
_______ receives info from an area of bipolar cells
ON and OFF
Ganglion visual fields have an ____ area and an ____ area
Is a process by which light is converted into electrical signals in the rod cells, cone cells and photosensitive ganglion cells of the retina of the eye.
What is visual phototransduction?