Exam 2 Flashcards
Start of Sensory Information ;)
What are the 8 sensory receptors?
- Proprioception
- Touch
- Auditory
- Vestibular
- Vision
- Pain
- Taste
- Olfaction
What are and what do “sensory receptors” do?
Transduce a particular type of stimulus into electrical signals
stimulus –> electrical signals
Are all ‘sensory receptors’ “energy” receptors?
Yes
- ALL sensory receptors are converted into electrical signals because body can only understand electrical signals
‘Proprioception’ receptors are what kind of sensory receptors?
Mechanoreceptor
‘Touch’ receptors are what kind of sensory receptors?
Mechanoreceptor
‘Auditory’ receptors are what kind of sensory receptors?
Mechanoreceptors
‘Vestibular’ receptors are what kind of sensory receptors?
Mechanoreceptors
‘Vision’ receptors are what kind of sensory receptors?
Photoreceptors
‘Pain’ receptors are what kind of sensory receptors?
Chemoreceptors and Thermoreceptors
‘Taste’ receptors are what kind of sensory receptors?
Chemoreceptors
‘Olfaction’ receptors are what kind of sensory receptors?
Chemoreceptors
What are “Mechanoreceptors”?
Thy detect stimuli such as touch, pressure, vibration, and sound from the external and internal environments
What are “Photoreceptors” receptors?
They give us our color vision and night vision.
–> There are two types of photoreceptor cells: rods and cones.
–> They have/are special cells in the eye’s retina that are responsible for converting light into signals that are sent to the brain.
What are “Chemoreceptors” receptors?
They help detect changes in surrounding environment and such as smell and taste. (a sensory receptor)
What do olfactory hair cells respond to? What receptor?
They respond to concentration of chemical molecules in the air.
–> Chemoreceptor
What do rod and cone cells respond to? What receptor?
Rod and Cones are in the retina of the eye and respond to light.
–> Photoreceptor
What do ‘Meissner’s corpuscles’ respond to?
They respond to mechanical pressure.
What does “proprioception” mean?
Awareness of and about your body’s position in space.
- “Where is your my hand?”
What are ‘action potentials’, and what do they send information about?
They are ‘triggers’ that send long ranges or information in the nervous system such as info about light, touch, and heat.
What helps ‘AP’s’ move?
Myelin Sheaths
What are ‘receptor potentials’?
They are activated by sensory neurons by a stimulus like light, touch, and heat.
–> They receive a stimulus to create an AP.
The path of a external stimulus to the brain. (hierarchy of the nervous system)
External stimulus –> peripheral sensory receptor/axon –> spinal cord or medulla–> thalamus –> cerebral cortex
(sensory signals pass through many relay stations before gets to cerebral cortex)
What is the role of the ‘thalamus’?
The brain’s relay station.
What ‘sensory receptor’ does not go to the thalamus?
Olfactory
–> goes directly to the primary olfactory cortex
What is a ‘receptive field’ of a sensory neuron?
A region of space in which the presence of a stimulus will alter the firing behavior of the neuron.
–> Visual, somatosensory (tactile) and auditory system
Is the size of receptive field ‘inversely’ or ‘equally’ proportional to the density of the fibers supplying that area?
INVERSELY proportional
If the receptive filed is big/wide you get “better” or “weaker” resolution and/but “more” or “less” preciseness/acuity/resolution?
- BETTER
- LESS
If the receptive filed is smaller you get “better” or “weaker” resolution and/but “more” or “less” preciseness/acuity/resolution?
- WEAKER
- MORE
What are ‘neuronal receptive fields’?
The receptor area which when stimulated results in a response of a particular sensory neuron.
‘Neuronal receptive fields’ … firing “increases” or “decreases” when stimulated in the center of the receptive field?
INCREASES in the middle of receptive field
‘Neuronal receptive fields’ … firing “increases” or “decreases” when stimulated in the surrounding area of the receptive field?
DECREASES in the surrounding area of the receptive field
—> if you have bigger receptive fields its harder to tell the difference
TRUE or FALSE: NO effects of stimulation occur if outside of the receptive field.
True
TRUE or FALSE: Receptive fields determine how neuron responds to sensory stimuli.
True
Transduction is the first step in the conversion of sensory stimulus to action potentials.
TRUE —-> Sensory transduction is defined as energy transformation from the external world to the internal world.
Where are the somas (cell bodies) located that are involved in transduction?
Somas are outside the spinal cord in dorsal root ganglia
What type of neuron is involved in transduction?
‘Pseudounipolar’ which has 2 axon branches (peripheral and central)
Peripheral branch is the ____ receptor.
Sensory
What does the “central branch” do on the pseudounipolar neuron?
Terminates in spinal cord or medulla for cranial nerves
What are the two type of “tactile mechanoreceptors” in the skin? What do they detect?
- Superficial receptors - “feeling”, silk cloth on hand
- Deep receptors - “feeling pressure or something falling on you”
What are the two “superficial receptor” types?
- Meissner corpuscle - LIGHT touch and vibration
- Merkel discs - pressure
What are the two “deep receptor” types?
- Pacinian - HARD touch and vibration
- Ruffini corpuscles - stretch of the skin
What do “free nerve endings” detect what throughout the skin?
Course touch, tickle, and itch
“Nocieceptors” are a free nerve endings that have no complex sensory structures and that respond to …
Stimuli that damages or threatens tissues
–> these have different pathways compared to mechanoreceptors
More superficial receptors have “smaller” or “bigger” and “more” or “less” dense receptor fields. They are rapid and “fast” or “slow” adaptive?
- smaller
- dense
- slow
More deeper receptors have “smaller” or “bigger” and “more” or “less” dense receptor fields.
- bigger
- less
What are “muscle spindles”? What do they respond to?
- A sensory organ embedded in skeletal muscle.
- stretch of muscle
Muscle spindles consist of 1. intrafusal muscle fibers, 2. sensory endings, and 3. motor endings and DO NOT generate external force.
–> What are their functions?
- Intrafusal: provide sensation
- specialized sensory organs (proprioceptors) - Sensory: respond to stretch (changes in length and velocity of change) and transduce and transmit sensations to the brain
- Motor: axons that deliver motor signals and signal for movement and motor control
What are “intrafusal fibers” innervated by?
- motoneurons (tune sensitivity)
What are “extrafusal muscle fibers”?
Standard skeletal muscle fibers that are innervated by larger alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement.
What are “extrafusal fibers” innervated by?
- larger alpha motor neurons
What do “alpha motor neurons” do?
Innervate skeletal muscle and cause the muscle contractions that generate movement. Motor neurons release the neurotransmitter acetylcholine at a synapse called the neuromuscular junction.
Sensory endings have ‘large myelinate group 1a afferents’ and ‘medium myelinated group IIb secondary, fibers afferents’. What are their functions?
Large : respond to rapid adaptions in muscle length (Velocity and direction of limb movements)
Medium : respond to muscle stretch (Sustained responses to constant muscle length changes and info. about the static position of limbs)
Afferent
Take away
Efferent
Moves towards
What are “golgi tendon organs”?
Senses and relays info. about how much force/tension the muscle is exerting on tendons.
- If there is too much muscle tension GTO will inhibit the muscle from creating any force (via a reflex arc), thus protecting the you from injuring itself.
What are GTO’s innervated by?
Group Ib nerve endings woven among collagen strands of the tendon
In series with the extrafusal muscle fibers
What do “joint receptors” do?
Respond to mechanical deformation of joint capsules and ligaments
What 3 afferents are associated with joint receptors?
What do they sense?
- Ligament receptors - type Ib afferents
- Ruffini’s and Pacinian endings - type II afferents
- Free nerve endings - types III and IV afferents
–> help understand where joint is in space and time
Start of Visual Information :)
What is the “Cornea” of the eye?
At the front of the eye sclera
- Transforms into a transparent tissue that allows light rays to enter the eye
What is the “Lens” of the eye?
Transparent structure that focuses/adjusts light on the retina if we need to see closer or further away
What is the “Sclera”?
The fibrous outermost tissue layer
What is the “Retina”?
Receives light energy as photons and converts to –> electrical energy as AP’s
—> Has neurons that are sensitive to light and is in the back of the eye
—> Phototransduction occurs here
What is “Phototransduction”?
The process that occurs in the retina where light is converted into electrical signals that can be understood by the rest of the nervous system.
What is the “Foeva”?
Controls central sharp vision (highest visual acuity) like reading
- Gets excited by visual input right in front of the center of the eye
–> in the middle of the retina
What is the “Macula”?
has high visual acuity or resolution (clear, sharp)
What is the “Optic Disk” or papilla?
site of where the entry and exit of the ophthalmic artery =, vein, and nerve (retinal axons)
–> has NO photoreceptors = blind spot so doesn’t sense light and just act as a channel that allows info to just pass through
Pathway of light going into the Retina
- Cornea
- Aqueous humor
- Pupil
- Lens
- Venturous humor
- Retina
*What do the “Ciliary muscles” do?
Controls focus of the lens for looking at things far away clearly
*What do the “Iris” muscles do?
Control the amount of light entering the eye either by constriction by the sun or dilation by the night
*TRUE or FALSE : fluid in the anterior chambers is drained and replaces multiple times a day and prevents pressure and eye disorders
True
*Failure of the anterior chambers to drain fluid can lead to what disease? ..
Glaucoma which is a disorder that creates high pressure in the eye and damages retinal neurons
Light energy receptors are called…
Photoreceptors
Within the retina, AP’s travel to central targets via ‘what’, and to ‘where’?
What: Axons
Where: Optic Nerve
*What is “macular degeneration”?
The macula surrounds the foeva and it can create a blind spot on the eye if damaged
What is the “Direct pathway” of info flow from photoreceptors to the Optic nerve?
- Light
- Photoreceptors (rods and cones) on retina
- Bipolar cells
- Retinal ganglion cells
- Optic Nerve
- Brain
What is the “Indirect Pathway” to the optic nerve?
- Photoreceptors
- Horizontal Cells
–> this enables lateral interactions between photoreceptors and bipolar cells
–> maintains sensitivity for light contrast
What are the two types of ‘photoreceptors’?
- Rods
- Cones
What are “Rods” responsible for?
Rod bipolar cells?
Operating at low light levels (night time)
- have low acuity and low spatial resolution
- sensitive to light (even respond to a single photon) light info gets amplified (summed up) in dark conditions
- more indirect pathway connections
Rod biploar cell
- each receives info from 15-30 rods
- have high synaptic convergence
Rods have how many photopigments?
1
- What are “Cones” responsible for?
- Cone biploar cell?
- Operating at high visual acuity and color (brighter environments) in foeva
- have highest acuity area in retina, central vision
- have high spatial resolution
- insensitive to light (100 photons are required to produce a
comparable response)
- more direct pathway connections - Cone bipolar cell
- each receives input from a single cone
- love convergence
- high spatial resolution (detailed images)
Cones have how many photopigments?
3 which are all sensitive to different wavelengths
- Blue (short) 5-10%
- Green (medium) varies between individuals
- Red (long) varies between individuals
Do cones converge or do rods converge?
Rods, making system a better detector of light and decreases the spatial resolution of rods
Photoreceptors respond to the absence of stimulus which hyperpolarizes with light and releases less NT’s
*Rods outnumber cones by 20:1 but cones are in higher concentration in foreva.
What are “Ganglion cells”?
Respond to light stimulation on a small, circular patch of retina
What are the two types of “retinal ganglion cells”?
- On-Center cell
- Off-Center cell
–> main purpose of the system is to define borders and edges
“On- center cells” do what?
Fire AP’s when light is turned on in the center
–> cell Depolarizes when light is put on it and increase in transmitter (glutamate) release = firing
–> Retinal Circuit for on center cells = Bipolar cells have graded potentials (NOT AP’s)
–> During light increment, photoreceptors Hyperpolarize and decrease in release of NT’s
“On-Center bipolar cells” are sign inverting meaning they …
Change in membrane potential is opposite that of photoreceptor
- Glutamate hyperpolarizes on-center bipolar cells
- When glutamate release decreases on-center bipolar cells are freed from hyperpolarizing influence of photoreceptors and they depolarize thus on center firing increases
- Reduction in light have opposite effects
“Off-Center cells” do what?
Discharge rate is reduced when light is applied to the center
–> cell hyperpolarizes when light is put on = not firing
“Off-Center bipolar cells” are sign conserving meaning they …
Change in membrane potential is same as that of photoreceptor
–> Graded depolarization from dark leads to increase in glutamate release thus off-center firing increases (glutamate depolarizes off center bipolar cells)
On and Off center cells have different types of glutamate receptors which is why they respond to light and dark differently.
What are “Horizontal cells”?
Receive inputs from photoreceptors and are linked via ‘gap junctions with other cells
- they reflect illumination over a broad retinal area but during ill. their role is minimal
When the addition of surround illumination does the horizontal cells role get more prominent?
Yes, because they hyperpolarize terminals of photoreceptors decreasing their rate of neurotransmitter release/firing when less contrast in receptive field center + surround
In retina do photoreceptors exhibit action potentials?
No
What do photoreceptors respond to?
Absence of stimulus
Light activation causes graded change in membrane potential and a change in the rate of transmitter release on the POSTsynaptic neurons
In the dark, photoreceptors membrane potential is around … mv?
-40mV
During a flashed light it causes hyperpolarization or depolarization? Does this increase or decrease NT’s release onto post-synaptic terminal?
- Hyperpolarization of membrane to around -65mV
- decrease
Scotopic and Mesopic refer to …
Rods
- darkness
Photopic refers to …
Cones
- light
*Phototransduction cascade..
- Absorption of a single photon of rhodopsin (photopigment) results in the closure of approximately 200 ion channels
- Darkness causes = Ca2+ to open and depolarizes
- Light causes = Ca2+ channels to close, and K+ channels stay open and hyperpolarize
Start of Visual Pathway Information! ;)
TYPE UP ALL INFO
Start of the Auditory System! :)
What is “sound”?
The pressure waves generated by vibrating air molecules
What are the four major features of sound?
- waveform
- phase
- amplitude
- frequency = dull or sharp
What happens when air molecules are disturbed?
Change in density
Sound that we hear is composed of many ____ waves.
Sine = pure tone
Auditory system converts sound stimulus into electrical signals (AP’s)
Sound info is integrated with info. from other sensory systems.
True or False: Auditory cortex can be influenced by nonauditory information such as during speech.
True
Which statements are true about the primary visual pathway?
- Parvocellular can sense sustained light stimulation
- Magnocellular can sense to rapidly changing stimuli
The perception of depth, which arises from viewing objects from two eyes rather than one, is called….
Stereopsis
True or False: Retinal ganglion cells have center-surround receptive field (respond to spots of light), and visual cortex neurons have elongated receptive field ( respond to bar light of different orientations)
True
True or False: The sensory information is segregated in the thalamus but is organized somatotopically in the ventral posterior complex
True
