Item 7 Flashcards
Whereas some of the sensory receptors detect stimuli in the external environment, others, called _ receptors, detect stimuli that arise within the body.
visceral
_receptors monitor O2, CO2, and H+ levels in the blood
chemo-
_receptors in certain blood vessels monitor blood pressure
baro-
_receptors in the gastrointestinal tract monitor the degree of stretch or distention
mechano-
Are we consciously aware of the various visceral receptors?
no, despite the brain receiving info from these receptors and utilizing that info for regulatory purposes
The _ system is necessary for perception of sensations associated with receptors in the skin (i.e., somesthetic sensations)
somatosensory
T or F: proprioception depends on general proprioceptors in muscles and joints and on more specific receptors in the skin
false! the opposite - specific for muscles and joints, general for the skin
The ENERGY form of a stimulus is called its _
modality
e.g., light or sound waves, pressure, temperature, chemicals
e.g., the modality for sight is light
The law of specific nerve energies states that a given sensory receptor is specific …, responding best to an ADEQUATE stimulus
for a particular modality
The two mechanoreceptors are the
pacinian corpuscle - vibration
_ cells - sound and balance and equilibrium
HAIR!
_ potentials are graded, caused by the opening or closing of ion channels. The stronger the sensory stimulus, the greater the change in membrane potential that occurs
receptor
In some cases, a sensory receptor is as specialized structure at the CENTRAL/PERIPHERAL end of an afferent neuron. In other cases, the sensory receptor is a separate cell that communicates through a chemical synapse with an associated afferent neuron
peripheral
In most instances, if the afferent neuron is depolarized to threshold, then an action potential is generated and transmitted by that cell to the _
CNS
T or F: Slowly adapting or tonic receptors show little adaptation and, therefore, can function in signaling the intensity of a prolonged stim- ulus
true
Rapidly adapting or _ic receptors adapt quickly, and thus function best in detecting changes in stimulus intensity. Some can even have a second, smaller response, called the “off response”
phasic
having an “off response” is important for olfactory receptors (smelling stopped?) and Pacinian corpuscles (vibration in the skin - detecting earthquake? incoming prey?)
_ _ are specific neural pathways that transmit info pertaining to a particular modality. Their activation causes perception, regardless of what caused it
Labeled lines
e.g., labeled lines would be a boxer perceiving light when being punched in the eye
Labeled lines phenomenon explains that if you press on your eyeball (or preferably your eyelid on top of your eyeball), you will perceive _
a bright light, despite it just being pressure
A sensory FIELD/UNIT comprises a single afferent neuron and all the receptors associated with it, and the area over which an adequate stimulus can produce a response is called the receptive FIELD/UNIT
unit;
field
Receptive fields are specific to :
sense of vibration
_ [special sense]
vision
T or F: interneurons can receive Input from only one first-order neuron
false - they may receive that input from several first-order neurons
Afferent neurons that relay to the thalamus/diencephalon are considered…, The thalamus then relays info to - neurons
second-order;
third-order
The vestibular cortex lies on the underside of the _ cortex in the parietal lobe
somatosensory
The _ cortex lies on the internal side of the temporal lobe
auditory
The olfactory cortex is on the inferior surface of the _ lobe
temporal
- receptors respond with a change in receptor potential that persists for the duration of the stimulus, - receptors respond with a change in receptor potential at the onset of a stimulus, but then adapt
Slowly adapting/tonic - slow and steady wins the race
rapidly adapting/phasic - fast and inconsistent
_ is an example of a pathway being inappropriate activated and a sense being perceived due to the pathway being activated
synesthesia
Is there a ‘wetness’’ receptor?
no. instead it’s a combo of thermoreceptors and touch receptors that combine for te brain’s interpretation of wetness
Stimulus intensity is coded by how often action potentials occur (frequency/population coding) and the number of receptors activated (frequency/population coding).
frequency;
population
The precision with which the location of a stimulus is per- ceived is called _
acuity
Acuity depends on a variety of factors for sensations associated with the [body part]:
size and number of receptive fields
amount of overlap between receptive fields
lateral inhibition - a stimulus that strongly excites recep- tors in a given location inhibits activity in the afferent pathways of other receptors
skin
_ _ increases acuity because it increases the contrast of signals in the nervous system — that is, it allows the transmission of strong signals in some neurons while suppress- ing the transmission of weaker signals arising in nearby neurons
Lateral inhibition
T of R: it is thought that normal individuals develop sensory pathways from auditory to visual processing centres, but the pathways undergo apoptosis (programmed cell death), whereas in people with synesthesia, the pathways persist
true
One measure of tactile acuity is two -point discrimination; the ability of a person to perceive two fine points pressed against the skin as two distinct points. The minimum distance that must exist between two points for them to be perceived as separate is termed the two-point discrimination threshold; points that are closer to- gether than this distance are perceived as a single point. Two -point discrimination occurs only if the two points are applied to the _ _ of two different afferent neurons
re- ceptive fields
These two areas have a smaller distance for te two-point discrimination phenomenon due to their sensitivity:
- fingertips
_
lips
Olfactory and auditory systems code for the quality and intensity of their respective senses using _ rather than distance of sensation
time; different in the time of arrival of action potentials determines the intensity of the stimuli (whether quality and strength of smell or pitch and loudness for hearing)
OF all the sensory systems, the _ system has the widest variety of receptor types
somatosensory
proprio-, mechano-, thermo-, and noci-
When receptor types lack identifiable specialized structures, they are therefore called free _ _
nerve endings
Perception is the un/conscious interpretation of the world based on sensory systems, memory and other neural processes
conscious
The external environment is the sensory environment, whereas the internal environment involves the _ afferent environment
visceral (in/near the body vs. distal - environment)
Sensory systems include the special senses, and the somatosensory system, which includes:
- the _ (sensations of the skin)
- proprioception, perception of limb and body positions
somatic (soma is body - skin!)
The special senses include:
- vision
- hearing
- …
- taste
- smell
balance and equilibrium
(equilibrioception)
Sensory receptors are specialized nerve endings or…
a separate cell that detects a sensory stimulus
T or F: sensory neurons only receive info from the external environment
true
they would not receive info from other sensory neurons. They could detect light, pain, etc.
T or F: sensory receptors are similar to ionoreceptors and metaboreceptors in that they detect a specific form of energy in an environment, and can vary according to modalities
true
sensory receptors can detect light, sound, pressure, temperature and chemicals
Law of specific nerve energies; a given sensory receptor…
is specific for each modality
_ stimulus is the required amount of energy that sensory receptors are most responsive to
adequate
thermoreceptors are most receptive to temperature, but they can be started from pressure
Photoreceptors detect _ of light
photons
Sensory transduction means the conversion of stimulus energy into _ energy
electrical
The receptor potentials are a.k.a.
generator potentials
Receptor/generator potentials are similar to _ potentials, and are both graded
post-synaptic potentials (whether inhibitory or excitatory)
both are graded, and involve opening or closing of ion channels
Instead of the pre-synaptic neuron releasing neurotransmitters that are picked up by the post-synaptic neuron binding to neurotransmitters to have an effect, either in the form of EPSP or IPSP, receptor/generator potentials are triggered by…
sensory stimuli
such as light, pressure, a smell, etc.
Think: you can’t have neurotransmitters being perceived in the air to sense something (apart from chemicals in the air or mouth), but it is the perception of touch, light, etc and the conversion to electrical energy that gets signals perceived
If a generator potential…, it can generate an action potential
exceeds threshold
it’s still a graded potential, so it requires the same degree of stimuli to influence an action potential (if the depolarization exceeds threshold)
Sensory receptors transmit action potentials to the _NS
CNS
e.g., pressure would be sensed by mechanoreceptors, and enough of it will incur it will open an ion channel in the membrane and influence a current. Summation would reach threshold and trigger an action potential, signalling along the axon to the CNS
Do you need to create an action potential if a sensory/generator receptor can release neurotransmitters?
no
sending neurotransmitters from a sensory receptor cell to another afferent neuron that would pick it up would then likely act as the post-synaptic neuron. The receptor/generator neuron would release calcium into the cell which would be received by a receptor protein for transmission to an afferent neuron which would likely generate an action potential and the signal would be sent to the CNS
All _ceptors are neurons
mechanoreceptors
Mechanoreceptors take place in the skin and the _
viscera
_ adapting mechanoreceptors change _ [same word] in stimulation, but ceases to be stimulated when the action potentials are constant
rapidly (phasic)
_ adapting mechanoreceptors change _ [same word], given a constant stimulus, they keep reporting it for a long time
slowly (tonic)
_ corpuscle is a sensory receptor in the skin that is sensitive to light, touch, and stroking
Meissener’s
it is shaped like a sperm with a long tail at the very top of the dermis, touching the epidermis (a thick layer in itself)
Top to bottom skin layers:
hairy or glabrous skin
epidermis
dermis
hypodermis
Top to bottom skin layers:
hairy or _ skin
epidermis
dermis
hypodermis
glabrous
grab gloss (glab gross - glabrous)
The _ disk senses steady pressure and texture
Merkel’s
Angela Merkel, previous German Chancellor, provided a STEADY pressure/presence during post-9/11 through to covid; as a woman, she gave the landscape of mostly male legal world leaders a more interesting TEXTURE
The _ corpuscle senses vibration (pressure-sensitive receptors)
Pacinian
think of Pacino in Scarface with a AK-47 that VIBRATES as he shoots others
it is shaped like a sperm with a long tail at the bottom of the dermis/into the hypodermis; is larger than Meissner’s corpuscle or Ruffini’s ending
The _ endings sense skin STRETCH and their free nerve endings at the root sense HAIR MOVEMENT as well
Ruffini’s
think of Raffi’s incessant stretch and hair movement (free nerve endings)
Thermoreceptors detect temperature at the nerve endings and surrounding tissue, all over the body’s surface on the subcutaneous layer of the skin, with a receptive feel of about _ across
1 mm
Warm receptors:
- are/not free nerve endings
- respond to temperatures in the range of 30 - 43 degrees Celsius
- have increased frequency with increase in temperature
ARE free nerve endings
Cold receptors:
- possible free nerve endings
- respond to temps in the range of _ - _ degrees Celsius
- increased frequency with decrease in temperature
35 - 20
more frequent when temperatures decrease
Thermoreceptor responses are (line-)graphed with skin temperature in Celsius on the _-axis and frequency of action potentials (Hz) on the _-axis
x-axis;
y-axis
When thermoreceptor responses are shown on a line graph, the _ receptors are shown creating an inverted U-shape from 5 to 35-36 degrees (at a low incline) and another at and exponentially rising from 45 degrees onward. The _ receptors are shown from approx 30 - 46 in a steep inverted U-shape
cold;
warm
the lower cold and the higher warm makes sense, but what’s with the 45 degrees and above cold receptors? it appears to be a phenomenon called a ‘paradoxical cold’, when one’s body is so hot that it can feel cold. Strange, but true
There are markedly more _ thermoreceptors than _ thermoreceptors
cold;
warm
_ceptors are free nerve endings that respond to various noxious stimuli.
nociceptors
Mechanical nociceptors trigger action potentials when…
you drop a laptop on your toe
mechanics need steel-toed boots to prevent pain from injuring their toes
Thermal nociceptors respond to heat higher than _ degrees Celsius
44
_ nociceptors respond to a variety of stimuli, not including temperature or mechanical pressure, etc.
polymodal
many types of stimuli, therefore polymodal
Somatosensory is _ically organized
topographically
Columnar organization of the somatosensory cortex suggests that the vertical columns are organized with one column for one _
modality
e.g., 1 for temperature, 1 for pressure, etc. for the thumb
Two main pathways occur for signals to be sent to the CNS by somatosensory pathways:
- dorsal column-_al _al pathway
- …
dorsal column-MEDIAL LEMNISCAL pathway
The dorsal column-MEDIAL LEMNISCAL pathway is associated with _ sensations, such as:
- touch and pressure
- proprioception
SOMESTHETIC
The dorsal column-MEDIAL LEMNISCAL pathway project to the _ in the brain carrying sensory info, crossing to the other side BEFORE getting to the _ [repeat word]
thalamus
For the medial lemniscal pathway:
1. mechano- or _-ceptors receive stimuli
proprioceptors
it’s about touch, pressure or proprioception
For the medial lemniscal pathway:
1. mechano- or proprioceptors receive stimuli
2. the stimuli is picked up by an afferent _-order neuron on the dorsal horn of the spinal cord
first-order neuron
For the medial lemniscal pathway:
1. mechano- or proprioceptors receive stimuli
2. the stimuli is picked up by an afferent first-order neuron on the dorsal horn of the spinal cord [it remains on the dorsal-side before moving up]
3. the afferent neuron _-laterally continues to the medulla oblongata where it synapses with a second-order neuron [in the dorsal column nuclei] which moves ventrally to through the
_ of the medial lemniscus, before moving
_-laterally upward
ipsilaterally;
decussation
contralaterally
stays on the same side to the medulla oblongata (brainstem) where it then moves to the opposite side at the medial lemniscus
For the medial lemniscal pathway:
1. mechano- or proprioceptors receive stimuli
2. the stimuli is picked up by an afferent first-order neuron on the dorsal horn of the spinal cord [it remains on the dorsal-side before moving up]
3. the afferent neuron ipsilaterally continues to the medulla oblongata where it synapses with a second-order neuron [in the dorsal column nuclei] which moves ventrally to through the decussation of the medial lemniscus, before moving contralaterally upward
4. the axon then reaches the thalamus where it [the second-order neuron] synapses with a _-order neuron, which then projects _-laterally to the primary somatosensory cortex
third;
ipsilaterally
it wouldn’t move contralaterally again since it’s already done so in the medulla oblongata – why else would it be named the medial lemniscal pathway [the area in the medulla oblongata where it travels]
Nociceptors travel up the _ tract involving pain, while thermoreceptors follow the same path for determining temperature.
spinothalamic
Nociceptors moving up the spinothalamic tract capture:
- _ touch
- nociception.
Thermoreceptors also move up the same tract for temperature-detection.
coarse
For moving up the spinothalamic tract:
1. nociceptors or thermoreceptors pick up stimuli on the skin, carried by the _-order neuron to the spinal cord
first-order
For moving up the spinothalamic tract:
1. nociceptors or thermoreceptors pick up stimuli on the skin, carried by the first-order neuron to the spinal cord
2.the neuron then synapses with the second-order neuron [dorsal-side] which ) to the anterolateral quadrant [ventral side], thereby moving up )
decussates (thereby contralaterally moves up from the spinal cord;
contralaterally
it crosses in the spinal cord, NOT the medulla oblongata or the thalamus. In this way it seems to bypass any real changes within the medulla, although it technically goes through it.
For moving up the spinothalamic tract:
1. nociceptors or thermoreceptors pick up stimuli on the skin, carried by the first-order neuron to the spinal cord
2. the neuron then synapses with the second-order neuron [dorsal-side] which decussates to the anterolateral quadrant [ventral side], thereby moving up contralaterally
3. the second-order neuron moves upward through the ventral part of the medulla oblongata _laterally to the dorsal part of it, before moving upwards
ipsi-laterally
For moving up the spinothalamic tract:
1. nociceptors or thermoreceptors pick up stimuli on the skin, carried by the first-order neuron to the spinal cord
2. the neuron then synapses with the second-order neuron [dorsal-side] which decussates to the anterolateral quadrant [ventral side], thereby moving up contralaterally
3. the second-order neuron moves upward through the ventral part of the medulla oblongata ipsilaterally to the dorsal part of it, before moving upwards
4. the second-order neuron continues to the thalamus where it then synapses with a third-order neuron before moving towards the _ _ cortex
primary somatosensory cortex
The pain response is the sensation produced by any stimulus that damages or potentially damages the tissue.
It elicits _ responses
e.g.:
- increased blood pressure
- sweating
autonomic
The pain response is the sensation produced by any stimulus that damages or potentially damages the tissue.
Pain elicits _ responses (e.g., fear, anxiety)
emotional
T or F: pain perception depends on past experiences
true!
Chemicals that activate nociceptors:
- potassium
- histamine
- prostaglandins
- _
- serotonin
Bradykinin!
I don’t know why Brady would do me dirty like that, but I guess he activates my pain because I am away from him
_ _ inhibits prostaglandins, decreases inflammation, and slows the transmission of pain signals
Acetylsalicylic acid
i.e., aspirin
Opioids (e.g., codeine, morphine) block the pain perception by decreasing transmitter release from the first-order sensory neuron and by POST/PRE-synaptically inhibiting second-order sensory neurons
POST-
Runner’s high is an example of the body’s built-in pain response (in this instance, endorphins). The others are _-ins and dynorphins
enkephal-ins
Two types of pain are:
_
_
They are transmitted through different types of afferent neurons that experience pain differently.
fast;
slow
Nociceptors are perceived as pain or _
itch
Fast pain receptors:
- have A-delta fibers
- may include a sharp, pricking sensation, and are
- _ localized
EASILY
_ pain receptors:
- have C fibers
- may include a dull aching sensation, and are
- poorly localized
SLOW
3 MAIN CLASSES OF _ fibers:
A-beta fibers- large myelinated - mechanical
A-delta fibers - small, myelinated fibres - fast pain, cold and mechanical at 12 - 30 m/s
C fibers- small, unmyelinated fibres - slow pain, heat, cold, and mechanical at .5 - 2 m/s
somatosensory
Pain in the skeletal muscle can be experienced as _ _ pain
deep, somatic
T or F: pain and itch oppose one another
true - if you scratch an itch, it creates a mild pain which helps relieve the itch
Opioids block pain but may cause _
itch
because they oppose each other, so blocked pain may inspire itch
T or F: Pain is limited to the body’s surface
false - stomach, muscles, etc.
Visceral pain originates in internal organs and its sensation can be _ to the body’s surface
referred
Pain can be felt in the skeletal muscle as a burning sensation with the onset of anaerobic metabolism, and may be caused by accumulation of _ in the blood stream and muscle interstitium
potassium
During exercise, potassium is released from the intracellular to the extracellular space of human skeletal muscle and further into the blood stream. Accumulation of potassium in the muscle interstitium has been suggested to cause fatigue during intense exercise due to impaired membrane excitability (Fitts, 1994)
Muscle pain can also result in ischemia, i.e., …
low oxygen due to poor blood oxygen supply
Pain signals invoke responses from the _NS
CNS
Quick reactions due to pain (e.g., moving one’s hand away from a hot stove) is a _ reflex, and does/not involve the brain
spinal;
DOES NOT
Pain pathways can send branches to the _ system, specifically the _ [specific organ], causing one or more of the following:
- emotional distress
- nausea
- vomiting
- sweating
limbic system;
hypothalamus
The _scending pathways through the thalamus can block nociceptor cells in the spinal cord
descending;
helps survive when ignoring the pain is helpful
Somatic signals of non-painful sores can _hibit signals of pain
inhibit
e.g., rubbing a bumped knee helps the feeling of pain
Inhibiting pain by way of somatic signals of non-painful mechanical movement/sores (i.e.,g rubbing a toe to relieve pain from dropping a laptop on it) activates large mechanoreceptors that terminate on the dorsal horn, activating inhibitory interneurons that _-synaptically inhibit pain signals, and reduce the sensation of pain
pre-synaptically
so if you drop a laptop on your toe, pain is perceived and somatic signals are sent to the brain; by rubbing the toe, you create a mild pain which independently activates INHIBITORY interneurons (you want the pain to stop, right? and the interneurons go between neurons…), pre-synaptically inhibiting pains by stopping it before neurotransmitters can even be released in the synaptic cleft, etc./ion channels become opened from receptor (graded) potentials
The gate-control theory is defined as a method of…
pain modulation
e.g., inhibiting pain from somatic signals of non-painful sores (i.e., rubbing a stubbed toe to relieve its pain); it’s controlled before the neurotransmitters/etc. even leave the gate (or leave the synapse, so pre-synaptic)
In pain perception and modulation, the nociceptors (via C fibers) and mechanoreceptors (via A beta fibers) are stimulated in the PNS, and before/after they reach second-order neurons or interneurons, they enter into the CNS
BEFORE
imagine a continuing line from the nociceptor along the C fiber to an inhibitory neuron or a second-order neuron, with the dividing line from PNS to CNS before reaching either types of neuron
note that mechanoreceptors (A beta fibers) are only involved when simultaneously putting pressure that moves to an inhibitory neuron (thereby blocking excitatory pain from the nociceptor) AND movement up the dorsal column
The light enters through the hole in the pupil, and behind it the _ focuses the beam of light at the retina which contains photoreceptor cells
lens
Eyes have _ layers
3
Eyes have 3 layers (outermost to innermost):
1. sclera (tough connective tissue), which also includes the _, which takes place at the front - transparent to allow light to enter the eye)
cornea
Eyes have 3 layers (outermost to innermost):
1. sclera (tough connective tissue), which also includes the cornea
2. _, ciliary body (which contains ciliary muscle) which attaches to the lens by zonular fibres, and the lens
choroid
- 2nd layer of eye
how does it compare to the choroid plexus which produces CSF in the brain and spinal cord? plexus = intricate network of tissues - I guess the choroid makes sense, with the ‘plexus’ part of it being the number of mechanisms that take place in that second/middle layer of the eye
_ muscle changes the shape of the lens, enabling the eye to focus
ciliary
Eyes have 3 layers (outermost to innermost):
1. sclera (tough connective tissue), which also includes the cornea
2. choroid, ciliary body (which contains ciliary muscle) which attaches to the lens by zonular fibers, and the lens
3. retina, where the _s sit (similar to camera’s film)
photoreceptors
An _ enables one to see the interior anatomy of the eye
ophthalmoscope
I had to see an ophthalmologist to see more clearly the interior anatomy of my eye to get to the back of it to see retinal tears that persisted
When taking a photo, a red flash is captured, which is actually a replication of the eye’s _ in a photo
retina
red retina.
The _ is a region that is sensitive. Layers are pulled away to expose photoreceptors at the retina. Blood vessels encircle and DO NOT cross the _ [same word]
if blood vessels blocked the _ [same word], then vision would be negatively impacted
fovea;
DO NOT
The _ is the source of the best acuity for fine sight perception
fovea
if blood vessels blocked the fovea, then vision would negatively impacted
The optic disk (i.e., _ _) is the region where blood vessels and axons enter and exit the eye. There ARE/NOT photoreceptors here
blind spot;
ARE NOT
The optic disk/blind spot is off-center, away from the _
fovea
Blood vessels and axon bundles that form the optic nerve that travel through the _ layer to the CNS, like a service duct
retinal
Why is there no perceived hole in the visual field (i.e., considering the blind spot exists)?
different spots in the visual field are focused on each eye, therefore with binocular fusion takes place, the missing info from one eye is supplied to the other
The _ fills in the missing spot in monocular vision (likely through Gestalt perceptive qualities)
cortex
the ‘bigger picture’ is enabled by the brain which creates a ‘bigger picture’
De/increased lens curvature enables the eye to focus on near objects
INCREASED
magnifying glasses have increased curvature/concave glass to see items more closely
The following are mechanisms for visual accommodation:
- under para/sympathetic control
The following are mechanisms for visual accommodation:
- under PARAympathetic control
Light needs to focus on the retina, focusing di/convergent beams of light with the lens, focusing the image
DIVERGENT
For distant/near objects, the light ray entering the eye is quite parallel (many straight lines), not requiring much lens refraction (i.e., can be as thin as possible)
DISTANT
For distant/near objects, the light ray entering the eye is quite diverging (many varying, differently positioned light beams), requiring much lens refraction (i.e., needs to be as round as necessary)
NEAR!
you need a thick magnifying glass that can detect a small object, which appears rounded from the thickness of the glass
T or F: The lens can refract itself.
FALSE - it needs ciliary muscles and zonular fibers to change its positioning
T or F: The zonular fibers encircle the circumference of the lens, and the ciliary muscle is the circle muscle around the lens and zonular fibers
true
When there IS/NO force at the edge of a lens, the ciliary body is quite thick, which is good for NEAR vision
is NO
When the ciliary muscle is relaxed and the zonular fibers are tight, the lens is well situated for FAR/NEAR vision of distant objects
FAR
