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
T or F: Parasympathetic stimulation is needed for near vision of distant objects
true
para for near, none for far (it would be easier if it was none for near, but life isn’t like that)
When the ciliary muscle is contracted, the lens is free to form a spherical shape, i.e., thick, which is good for FAR/NEAR vision. The ciliary muscle can be adjusted for changing the thickness of the lens for whatever focus is required
NEAR
Near-sightedness if _opia
myopia
T or F: emmetropia is normal vision
true
Emma, a girl I worked with, had good vision, and didn’t require glasses
_-opia is hardening of the lens, whereas cataracts are _ of the lens
PRESBY-opia - hardening (you need to be hard to be a president);
discolouration - cats’ eyes get discoloured when they have cataracts
Glaucoma involves increased volume of _ _, signalling cancer
aqueous humor - and yet, it ain’t no joke
Astigmatism involves irregularities of the lens or _
cornea - dealing with stigma is by no means corny. need to take a serious lens on it
In _-pia, near and distant objects are nicely focused on the retina.
emmetropia
In emmetropia, near and distant objects are nicely focused on the retina. In myopia, however, we can see that in _ objects there is no focusing on the retina, whereas for _ objects there is.
distant;
near
my vision is myopic, since I cannot see distant objects clearly, but I can see near objects fairly well
T or F: Myopia involves a lens of the eye that is too weak for the length of the eyeball
false - the lens is too strong for the length, creating a converging not on the retina but more in the middle of the eye
Myopia is corrected with a conCAVE/VEX, which decreases overall refractive power (i.e., too much refraction is going on)
concave - that’s why my lenses on my red glasses wrap around my eye, creating a concave shape, not a convex one
Most of the refraction of a light beam is done by the _, at the front of the eyeball, before the light enters the pupil. Its clarity helps to refract for the eye. Its thickness can be reduced with Lasik surgery, by being shaved off, equivalent to making the lens being thinner
cornea
The _ is like the aperture of a camera; regulates the amount of light entering the eye
pupil
The iris consists of two layers of _ muscle
smooth
The iris consists of two layers of smooth muscle (with the hole opening in the center being the pupil):
inner circular muscle: constrict/dilator
outer radial muscle: constrict/dilator
constrictor;
dilator
imagine a black pupil surrounded by round inner circular muscle, which is then radiated out by outer radial muscle
Individual circular fibers of the rounder inner circular muscle of the iris [which constricts the iris, when needed] is called a _
sphincter
The sphincter fibers of the round circular muscle of the iris is stimulated by para/sympathetic stimulation, creating pupillary constriction (MAKING IT SMALLER)
PARAsympathetic
Radial muscles of the iris contract/constrict due to para/sympathetic stimulation enabling the pupil to dilate
SYMPATHETIC
if someone is chasing you, your sympathetic nervous system is activated, and also serves to dilate the pupils
Optical neural tissue that is composed of 3 layers:
1. outer - contains …
photoreceptors - cones and rods
Optical neural tissue that is composed of 3 layers:
1. outer - photoreceptors
2. middle - horizontal, bipolar, and _ cells
amacrine
Montreal (middle Canada) are the Habs - horizontal, amacrine, bipolar
Optical neural tissue that is composed of 3 layers:
1. outer - photoreceptors
2. middle - horizontal, bipolar, and amacrine cells
3. inner - _ cells
ganglion
Once an image is focused on the retina, it is transduced to neural signals and action potentials to the CNS. The photoreceptors are furthest from the light, requiring travel through the layers to get to them. These rods and cones communicate with the _ cells
bipolar cells -
rods and cones stimulate the axons of the BIPOLAR cells which transmit information to the next layer of retina called the inner plexiform layer, and horizontal cells, whose lateral processes interconnect photoreceptors and bipolar cells. these leave the eye to stimulate the optic nerve at the most inner layer on the ganglion cells
The retinal pigment epithelium is inky black with melanin because…
being dark enables little to no interference with the light refraction that is already occurring in the eye
The axons that leave the eye to the optic nerve (which is where the afferent neurons go to be recognized by the brain) occur at the _ layer of the retina, i.e., _ cells
inner, i.e., ganglion cells
Phototransduction is done by the _: rods and cones
photoreceptors
_ are more sensitive to light, being large, concentrated in the peripheral retina, away from the fovea. A single photon can be picked up by it, which cannot be done by the other types of photoreceptors
rods
rods are the awkward kids that hang away from the centre of the action, and tend to be sensitive and function in light-filled situations
Cones are small, DO/NOT function well in dim conditions, and are concentrated in the interior of the retina, near the fovea retina.
do not
cones hate being alone (stay close to the fovea/centre), and hate the dark
You focus your fovea and CONES/RODS for vision, therefore if you look at a star directly the start disappears. This is because they occur in a dark environment, which only stimulates CONES/RODS. Tilting your head helps incorporate the CONES/RODS [2nd word], allowing you to more easily see the star
CONES;
RODS
fovea and cones are focused on it, which means the star disappears. Tilting your head helps incorporate the rods for this
The synaptic vessels of the rods and cones are located at the bottom/innermost part of the eye, whereas the DISKS/NUCLEI is in the inner segment (technically the middle) and the DISKS/NUCLEI are in the outer segment (that which is not connected to other mechanisms but is surrounded by aqueous humor)
nuclei (inner segment);
disks (outer segment)
Phototransduction occurs by light-absorption _polarizing the membrane and reduces release of vesicles. Therefore, to get an action potential, darkness induces photoreceptor depolarization which opens Ca2+ channels and their entry triggers neurotransmitter secretion which then acts on the amacrine/bipolar/horizontal cells
HYPER-polarizes;
BIPOLAR
darkness creates outlines to see, creating greater contrast
Mapping colour is considered absorbance spectra for different photorespectors involves _ sizes of cones
3 - small, medium, large
The small cones deduce blue, whereas medium and large are green/red and green/red, respectively
green;
red
There is greater overlap for M and L cones, i.e., blue/green/red and blue/green/red, enables more different tones of colours are available
green and red
_ do not absorb the longest wavelength; red does
Rods (signified as black on an absorbance spectra for different photoreceptors line graph)
When in the dark, if you have green light instead of red light, you are using your cones/rods not your cones/rods, creating a problem
cones;
rods
T or F: Everyone has the same wavelength of colours.
false - they differ, suggesting that an individual won’t necessarily see the same colour I do; rather, they vary as they are on a spectrum
Photoreceptors (rods and cones) synapse on bipolar cells which are unexcitable; rather, they are _
graded potentials, therefore can be inhibitory or excitatory
Bipolars synapse with _ cells (moving from inner to outer part of retina), which become the first cell in the pathway to generate action potentials [remember, photoreceptors and bipolar cells do not feature action potentials]
ganglion
The axons of ganglion cells move to cranial nerve _ [].
cranial nerve II - optic nerve!
The axons of ganglion cells move to cranial nerve II [optic nerve]. Their convergence of excitation and inhibition gives complex receptive fields, called _ inhibition
lateral
Lateral inhibition of ganglion cells have receptive fields that are differentiated in two parts, the center and the surround. The surround involves input from the horizontal cells, which are _atory interneurons, whereas the central part involves input from the _ cells which are _atory interneurons.
inhibitory;
excitatory
to see, you need light in the centre and off in the surround, oppositely stimulated
if the center is on and the surround is on, then the effect of light is cancelled
Neural pathway for vision:
1. _ cells from the hemifields of the left and the right visual fields
ganglionic
Neural pathway for vision:
1. ganglionic cells from the hemifields of the left and the right visual fields synapse at the optic nerve
2. each HALF of the afferent’s action potentials move up the neuron to the _ _ where the neuron crosses (moves contralateral) to the optic tract on the other side
optic chiasm
Neural pathway for vision:
1. ganglionic cells from the hemifields of the left and the right visual fields synapse at the optic nerve
2. each HALF of the afferent’s action potentials move up the neuron to the optic chiasm where the neuron crosses (moves contralateral) to the optic tract on the other side; the other half of the afferent (2 halves per visual field) remains on the ipsilateral side
3. the neurons reach the _, and through the optic radiations and move to the visual cortex synapses
thalamus
Neural pathway for vision:
1. ganglionic cells from the hemifields of the left and the right visual fields synapse at the optic nerve
2. each HALF of the afferent’s action potentials move up the neuron to the optic chiasm where the neuron crosses (moves contralateral) to the optic tract on the other side; the other half of the afferent (2 halves per visual field) remains on the ipsilateral side
3. the neurons reach the thalamus, and through the optic radiations and moves to the visual cortex synapses
4. from here, both halves of the right visual field moves to the _ cortex of the primary visual cortex, and vice-versa
left
note it only crosses at the optic chiasm before the thalamus; it doesn’t cross more than once…which would be impractical
look at it this way: in the right visual field, the left part of the eye relays that field, whereas the right part of the eye features the left visual field. So it’s not the case of one eye vs another eye; it’s visual field, which uses both eyes to make the left visual field, and the same to make the right visual field.
Kill me now
Pre-thalamic nerves in the neural pathway for vision are considered optic nerves/tracts, whereas post-thalamic nerves are considered optic nerves/tracts
nerves;
tracts
The ear is composed of the outer ear, which is composed of the _ and the external auditory meatus i.e., _ _, which then follows down to the tympanic membrane (eardrum)
pinna;
ear canal
The middle ear is composed of the ear _:
- malleus-
- incus
- stapes
ossicles
Hearing is sound that moves to the eardrum which amplifies the soundwave by its vibration. The vibrations oscillate the ossicles, _ the soundwaves into vibrations and amplify them to be conveyed to the inner ear
transducing
sounds are amplified twice
If you have a cold, one’s swollen nasal cavities negatively impacts the vibration of the _ _, dampening sound to make it quieter
tympanic membrane / eardrum
The inner ear contain sensors, including the cochlea and the oval window (which connects to the ossicles), which translates wave energy activating _ cells [receptors for sound]
cochlear hair cells
Stereo cilia are hair cell ‘fingers’ (oriented from short to tall) that have endolymph that create waves. The response of the hair cells at rest in the membrane is being partially _
depolarized (10% of channels being open)
During an action potential, the membrane of cornea hair cells is depolarized, the stereocilia’s protein bridge is moved due to stress, either opening or closing mechanically/ligand/voltage-gated calcium/potassium/sodium channels
MECHANICALLY-GATED POTASSIUM channels
During an action potential, the membrane of cornea hair cells is depolarized, the stereocilia’s protein bridge is moved due to stress, either opening or closing mechanically-gated potassium channels.
Then, the channels allow potassium to move in/out, where potassium is in low/high concentration
IN;
high concentration (in the endolymph)
During an action potential, the membrane of cornea hair cells is depolarized, the stereocilia’s protein bridge is moved due to stress, either opening or closing mechanically-gated potassium channels.
Then, the channels allow potassium to move in, where potassium is in high concentration. By doing so, the membrane is depolarized, particularly when the bend is from short/tall to short/tall stereocilia
short to tall
In sound transduction, increased depolarization results in the opening of calcium channels which triggers neurotransmitter release and an increase in action potential-firing frequency, increasing in response to depolarization due to _ of hair cells.
MOVEMENT
If the stereocilia bend towards the shortest of the ‘fingers’ (i.e., moving towards the shortest, or tallest to shortest), then this leads to DE/HYPER-polarization, since potassium channels will close, meaning less potassium comes in and the frequency of action potentials are reduced
HYPERpolarization
Loudness of sound is coded by DE/INcreased bending of hair cells, with larger amounts of neurotransmitters (i.e., loudness intensity or decibels)
INCREASED
The loudness intensity of sound or its decibel quotient is _, meaning that 10 decibels equals to 10 times the sound loudness. Anything above 80 can damage your hearing, whereas a conversation is about 60
logirithmic
Anything above _ decibels can damage your hearing, whereas a conversation is about _
80;
60
The LOUDNESS/PITCH of the sound is coded by which of the hair cells along the cochlea are activated (i.e., frequency)
pitch (Hz)
Hearing can be from 20 - _ Hz
2,000
Neural pathways for sound occur by the receptor or modified neurons, another name for the _ _
hair cells
Action potentials in the hair cell (becoming a cochlear nerve) synapse with a second-order neuron in the _
brainstem
Action potentials in the hair cell (becoming a cochlear nerve) synapse with a second-order neuron in the brainstem.
The second-order neuron moves to the thalamus where it synapses with a third-order neuron which then travels to the _ cortex for processing
auditory
There are 3 kinds of hearing loss:
1. _ deafness - inadequate conduction of soundwaves through external and/or middle ear
conductive (near the outer or middle ear, therefore near the ear drum which conducts the initial sound waves)
There are 3 kinds of hearing loss:
1. conductive deafness - inadequate conduction of soundwaves through external and/or middle ear
2. _ deafness - inadequate transduction of soundwaves to electrical signals in INNER ear
sensorineural - action potentials occur at the hair cells, so any electrical signal problem would be found in the sensory neuron
There are 3 kinds of hearing loss:
1. conductive deafness - inadequate conduction of soundwaves through external and/or middle ear
2. sensorineural deafness - inadequate transduction of soundwaves to electrical signals in INNER ear
3. _ deafness - damage to the neural pathway for sound
central - the neural pathway in general is a central part of the process
90% hearing loss in the elderly is _ deafness
sensorineural
T or F: Birds can replace dead hair cells, but humans can’t [I’m referring to birds’ hearing systems replacing them on their own, not by surgical or other methods]
true!
If you have issues with the nerve from the cochlea to the thalamus to the cortex or some place in between, what issue do you have (diagnosable)?
central deafness
The vestibular apparatus detects the motion of the _ and its tilt relative to gravity
head
What is the source of equilibrium?
there are more than one, but a big one is the vestibular apparatus, although vision occurs, on top of other ones soon to be divulged
The 3 semicircular canals of the vestibular apparatus occur on the x-, y-, and z- axis, enabling effective _ detection:
stabilization
The 3 semicircular canals of the vestibular apparatus occur on the x-, y-, and z- axis, enabling effective head movement detection:
anterior (up or down head movement
lateral (…)
posterior (head up and down to the side
side-to-side
All of the receptor cells of the semicircular canals are _ cells
hair
The utricle and saccule are bulges between the semicircular canals and the _, which detect linear acceleration
cochlea
The utricle and saccule are bulges between the semicircular canals and the cochlea, which detect linear acceleration. The utricle detects … motion and the saccule …motion
forward and backward;
up and down
it would be nice if the utricle was up and down, but it’s not
Taste depends on chemicals in food binding to chemoreceptors, with more than _ taste buds
10,000
Taste depends on chemicals in food binding to chemoreceptors, with more than 10,000 taste buds occurring on the:
tongue
…
pharynx
roof of mouth
Pores exposed to saliva in the mouth are a.k.a. …
taste buds
There are 50 - 150 taste reecptors cells per _ _
taste bud
note that those with more are considered ‘super tasters’
Taste receptor cells are modified _ cells that respond to tastants which are flanked by support cells
epithelial
Taste receptor cell Type 1 detects salt, Type 2 detects sweet, bitter and Type 3 detects …
sourness
T or F: every taste receptor detects one type of sense of taste (i.e., salty or sweet/bitter or sour)
true
The afferent fibers that transduct action potentials associated with taste to the brain are the _ neurons
gustatory
The pores of a taste bud (one pore but several receptor cells flanked by support cells, like a tulip shape) are connected by _.
microvilli
The pores of a taste bud (one pore but several receptor cells flanked by support cells, like a tulip shape) are connected by microvilli.
The receptor cells synapse to _ _s, which are part of gustatory neurons which bring the stimuli to the brain
taste afferents
Action potentials along the taste afferents of the gustatory neurons travel to the thalamus and then onto the _ cortex for processing
gustatory
Every sense of taste has a different frequency of action potentials in the taste afferent. The following senses of taste stimulate for the following;
1. sweet - organic molecules sim to _
sucrose
Every sense of taste has a different frequency of action potentials in the taste afferent. The following senses of taste stimulate for the following;
1. sweet - organic molecules sim to sucrose
2. salty - _ ions
sodium
Every sense of taste has a different frequency of action potentials in the taste afferent. The following senses of taste stimulate for the following;
1. sweet - organic molecules sim to sucrose
2. salty - sodium ions
3. sour - presence of _ ions/acids
hydrogen
Every sense of taste has a different frequency of action potentials in the taste afferent. The following senses of taste stimulate for the following;
1. sweet - organic molecules sim to sucrose
2. salty - sodium ions
3. sour - presence of hydrogen ions/acids
4. bitter - …
potential toxins
The highest to lowest frequency of action potentials in taste afferent (i.e., coding of taste) is from the following:
bitter
salty
sour
sweet
- sweet
- salty
- sour
- bitter
Olfaction depends on chemical in air that bind to chemoreceptors in the olfactory _
epithelium
Olfactory signal transduction is similar to gustatory in that chemoreceptors capture chemicals, with both chemicals having to be…
dissolved in liquid (i.e., mucus in olfaction and saliva in gestation)
The olfactory bulb (which is exterior to the olfactory epithelium of the nasal cavity) is actually an extension of the _ lobe (forebrain)
frontal
In the olfactory epithelium there are 3 types of cells for olfaction:
1. _ cell (has cilia that pick up signals along the mucus layer of the nasal cavity - respond to olfactory stimuli)
receptor
In the olfactory epithelium there are 3 types of cells for olfaction:
1. receptor cell (has cilia that pick up signals along the mucus layer of the nasal cavity - respond to olfactory stimuli)
2. sustentacular cell (provide … and …)
structural support and maintain the extracellular environment
sustentacular - structural!
In the olfactory epithelium there are 3 types of cells for olfaction:
1. receptor cell (has cilia that pick up signals along the mucus layer of the nasal cavity - respond to olfactory stimuli)
2. sustentacular cell (structural support and maintain the extracellular environment)
3. _ cell (precursor cells which continuously replace olfactory receptor cells)
basal
Receptor cells respond to olfactory stimuli and transduces chemical stimuli into action potentials, travelling along the axon of the olfactory nerve located in the olfactory _ where it synapses with a second-order neuron
bulb
T or F: The second-order neuron in the olfactory bulb bypasses the thalamus and goes to the cortex and amygdala directly
true
Basal cells that become receptor cells/new neurons must …to make the connection with second-order neurons for olfactory perception
travel to the olfactory bulb
The cilia of receptor cells have chemoreceptors which bind to odorants and transports them to receptor cells with the signal carried to the brain through the _ _, a hold in the skull to allow olfaction to send axons directly to the brain
cribriform plate
T or F: breaking your nose can lead to a loss of sense of smell
true - due to issues with your cribriform plate which is a hole that allows olfactory nerve signals to go straight to the brain
For olfactory signal transduction to occur:
1. Olfactory binding _ deliver olfactants to receptors which then activate the G-protein
proteins - this differs because it’s called an olfactory G-protein
For olfactory signal transduction to occur:
1. Olfactory binding protein deliver olfactants to receptors which then activate the G-protein
2. the olfactory G-protein activates adenylate cyclase which produces _…
cyclicAMP
For olfactory signal transduction to occur:
1. Olfactory binding protein deliver olfactants to receptors which then activate the G-protein
2. the olfactory G-protein activates adenylate cyclase which produces _, secondary messengers
cAMP (cyclic AMP)
For olfactory signal transduction to occur:
1. Olfactory binding protein deliver olfactants to receptors which then activate the G-protein
2. the olfactory G-protein activates adenylate cyclase which produces _, secondary messengers
3. cAMP directly binds _ channels [i.e., sodium and _], opening them
CATION;
CALCIUM (not potassium - we are trying to create a depolarization with sodium here!)
For olfactory signal transduction to occur:
1. Olfactory binding protein deliver olfactants to receptors which then activate the G-protein
2. the olfactory G-protein activates adenylate cyclase which produces _, secondary messengers
3. cAMP directly binds cation channels, opening them
4. Na+ and _ enter cell, creating a depolarization
Ca2+
Olfaction works by enabling specificity of binding, i.e., specific olfactory receptor cells existing for…
each type of odorant-binding protein
All cells with the same kind of receptor _verge on a few secondary neurons in the olfactory bulb. The brain then deciphers hundreds of secondary neurons to distinguish particular smells
converge
In rodents, romeronasal organ (VMO) is involved in the behavioural responses to sex pheromones. For humans, there is…
no equivalent, but there may be compounds that act as human pheromones
What is the term for perception of the position of the body and the limbs?
a. proprioception
b. spinothalamic perception
c. somesthetic perception
d. somesthetic sensation
a. proprioception
What results in hair cells sending a signal?
a. mechanically gated K+ channels letting K+ rush in
b. mechanically gated K+ channels letting K+ rush out
c. mechanically gated Na+ channels letting Na+ rush out
d. mechanically gated Na+ channels letting Na+ rush in
a. mechanically gated K+ channels letting K+ rush in
When you spin while sitting in a swivel chair with your eyes closed, you can sense this movement by means of your ________.
a. semicircular ducts
b. cochlea
c. utricle
d. malleus
a. semicircular ducts
Which of the following occurs during accommodation for near vision?
a. Ciliary muscles contract, causing zonular fibers to become slack, and the lens becomes rounder.
b. Ciliary muscles relax, causing zonular fibers to become slack, and the lens becomes rounder.
c. Ciliary muscles contract, causing zonular fibers to become tight, flattening the lens.
d. Ciliary muscles contract, causing zonular fibers to become tight, and the lens becomes rounder.
a. Ciliary muscles contract, causing zonular fibers to become slack, and the lens becomes rounder.
Which part of the basilar membrane transduces high-frequency sounds?
a. narrow and stiff part near the oval window
b. wide and flexible part near the oval window
c. wide and flexible part near the helicotrema
d. narrow and stiff part near the helicotrema
a. narrow and stiff part near the oval window
Which one of the following statements about the sensory system is FALSE?
a. it provides info for conscious interpretation of the world
b. it sends info from the periphery to the CNS
c. it senses only the external environment
d. it is an afferent branch of the PNS
c. it senses only the external environment
Which of the following is a modality detected by the sensory receptors?
a. chemicals
b. pressure
c. temperature
d. all are true
d. all are true
You enter your home and you can smell a delicious meal being prepared. After a few minutes, you no longer notice this smell. What property of the sensory receptors does this represent?
a. proprioception
b. labeled lines
c. receptor adaptation
d. coding for stimulus intensity
c. receptor adaptation
Which one of the following is NOT involved in the eye’s accommodation to focus on near objects?
a. activation of the parasympathetic nervous system
b. contraction of the ciliary muscles
c. the lens becomes flatter
d. decreased tension on the zonular fibers
c. the lens becomes flatter
The different sides of the retina that incorporate the different fields of vision are the _ and _ retinas.
nasal
temporal
The nasal retina is found on _terior side of the eye, whereas the temporal retina is found on the _terior side
interior;
exterior
Vision shows up on the left and right vision fields of the retinas, then moves to the optic nerve leading to crossing from the _ retina part of the vision (the _ retina part of the vision remains on the ipsilateral side), moving up to the lateral geniculate body of the thalamus and then moving in optic radiations to various cortex (including primary visual)
nasal;
temporal
Damage to the right optic nerve would cause loss of vision from the right eye. Because the left eye perceives part of the right visual field, only the right temporal visual field would be lost. However, with no bilateral input going to the brain, _ _ would be decreased.
depth perception
Damage to the right optic tract would cause loss of input from the left nasal retina and right temporal retina, thereby resulting in loss of the _ visual field.
left
Damage to the right primary visual cortex would also result in loss of perception of the _ visual field
left
Damage to the spinothalamic tract affects the somatic sensations of temperature and _.
pain
Because spinothalamic tract pathway crosses to the contralateral spinal cord with a couple of segments at the level of input to the spinal cord, damage to the left spinal cord causes lack of sensation on the _ side of the body.
right
Because input from the arms is above any damage to the _ tract (cervical spinal cord versus thoracic damage), only the legs are affected.
spinothalamic
Damage to the left thoracic spinothalamic tract of the spinal cord causes a lack of temperature and pain sensation from the _ legs.
right
Damage of the dorsal columns affects the somatic sensations of touch, pressure, and _.
proprioception
Because the dorsal column pathway is _ until it reaches the brainstem, damage to the left spinal cord causes a lack of sensation on the left side of the body.
ipsilateral
Because input from the arms is above the level of damage to the _ _ (cervical spi- nal cord versus thoracic damage), only the legs are affected.
dorsal columns
Thus damage to the _ thoracic dorsal columns of the spinal cord causes a lack of touch, pressure, and proprioception from the left legs
left
When a flash picture is taken with a camera that corrects for “red eye,” the initial flash of light causes pupillary . When the next flash occurs in sync with taking the picture, the now- pupil allows less light to enter the eye and be reflected back to the camera, thereby minimizing the “red eye” phenomenon
constriction;
constricted
Because the membranous labyrinth is a functional part of both the cochlea and the vestibular apparatus, _’s disease can result in problems with hearing and equilibrium, often involving an excess of neural activity. Symptoms include tinnitus (ringing in the ears) and dizziness
Meniere’s
Red-green colour blindness occurs by a genetic defect in the photopigments of red or green cones. The genes that code for the red and green photopigments are _ive on the X chromosome; because males have only one X chromosome, they are more likely to inherit this _ [same word] trait
recessive
Ishihara tests are used, with numbers hidden within a pattern of dots to test for _ _
colour blindness (the dots are coloured)
_ frequency sounds cause deflections near the oval window, whereas _ frequency sounds cause deflections near the helicotrema (i.e., the frequency of vibration changes at different regions of the basilar membrane)
high (oval window)
low (helicotrema)
Stereocilia are composed of which type of protein filament?
microtubules
When you move your head to the _, pressure from the endolymph moves closer to the kinocilium (the tallest of the sterocilia), whereas if you move your head to the _, pressure from the endolymph moves furthest from the kinocilium
left; close to kinocilium (on its left side, shown on the right with the stereocilia at 6 o’clock in a diagram with it being surrounded by a tube that connects from one side to the other, like a ring);
right - farther from the kinocilium (on its right side)
The strength of a stimulus is coded by
a) The size of the receptor potential.
b) The size of the action potentials.
c) The frequency of action potentials.
d) Both a and c.
e) All of the above.
d) Both a and c.
action potentials don’t change in size; they change in frequency
The mechanism by which a receptor converts a stimulus into an electrical signal is called
a) Conduction.
b) Convection.
c) Transduction.
d) Modulation.
e) Propagation
c) Transduction.
In lateral inhibition,
a) The nervous system produces contrast to emphasize more-important information over less-important information.
b) Afferent neurons with neighboring receptive fields inhibit each other’s communication to second- order neurons.
c) The ability to locate the site of a stimulus is enhanced.
d) Both a and c.
e) All of the above
e) All of the above
Which of the following observations best illustrates the concept of the labeled line?
a) When a boxer gets punched in the eye, he perceives light.
b) Rotation of the head stimulates certain receptors in the vestibular system but not those in the visual system.
c) Information from different photore- ceptors converges on a single ganglion cell that projects to the lateral genicu- late nucleus.
d) Hair cells in the cochlea are stimulated by sound vibrations over a wide range of frequencies.
a) When a boxer gets punched in the eye, he perceives light.
Which of the following best illustrates the concept of an adequate stimulus?
a) When a boxer gets punched in the eye, he perceives light.
b) Rotation of the head stimulates certain receptors in the vestibular system but not those in the visual system.
c) Information from different photore- ceptors converges on a single ganglion cell that projects to the lateral genicu- late nucleus.
d) Hair cells in the cochlea are stimulated by sound vibrations over a wide range of frequencies.
b) Rotation of the head stimulates certain receptors in the vestibular system but not those in the visual system.
Rubbing a sore area can decrease the sen- sation of pain by
a) Activating the endogenous analgesia systems.
b) Referring the pain to another area of the body.
c) Activating larger- diameter afferents, which activate an inhibitory interneu- ron, which inhibits the second- order neurons for pain.
d) Decreasing the number of action po- tentials in nociceptor afferents.
e) Presynaptic inhibition of substance P release
c) Activating larger- diameter afferents, which activate an inhibitory interneu- ron, which inhibits the second- order neurons for pain.
In the dorsal column-medial lemniscal pathway,
a) Proprioception information is trans- mitted to the brain.
b) The first-order neuron communicates to the second-order neuron in the dor- sal horn of the spinal cord.
c) The pathway crosses to the contralat- eral side in the spinal cord.
d) Both a and c.
e) All of the above
a) Proprioception information is trans- mitted to the brain.
Which of the following is the correct name of the pathway from the retina to the optic chiasm?
a) Optic tract
b) Optic radiations
c) Optic nerve
d) Optic disk
c) Optic nerve
Which of the following is the correct name of the pathway from the lateral geniculate nucleus of the thalamus to the visual cortex?
a) Optic tract
b) Optic radiations
c) Optic nerve
d) Optic chiasm
e) Optic disk
b) Optic radiations
Where would you expect to find the ascending tracts for somatosensory information?
a) In the white matter of the spinal cord
b) In a spinal nerve
c) In the gray matter of the spinal cord
d) None of the above
a) In the white matter of the spinal cord
The ability to perceive different frequen- cies in sound vibrations is based on the fact that
a) The stereocilia of any given hair cell respond to only one frequency.
b) Different areas of the basilar membrane resonate at different frequencies, such that sound of a particular frequency causes only a certain region of the membrane to vibrate.
c) The frequency of action potentials in the cochlear nerve varies in pro- portion to the frequency of a sound stimulus
b) Different areas of the basilar membrane resonate at different frequencies, such that sound of a particular frequency causes only a certain region of the membrane to vibrate.
The stereocilia for hearing are exposed to
a) Endolymph in the scala vestibuli.
b) Perilymph in the scala vestibuli.
c) Endolymph in the scala media.
d) Perilymph in the scala media.
e) Endolymph in the scala tympani.
c) Endolymph in the scala media.
The parasympathetic nervous system causes
a) Contraction of the radial muscle of the iris.
b) Contraction of the ciliary muscle.
c) Pupillary dilation.
d) Both a and c.
e) All of the above
b) Contraction of the ciliary muscle.
The two types of thermoreceptors are _ and _
warm;
cold
Receptors are most sensitive to energy from the _ stimulus
adequate
A phasic receptor adapts (quickly/ slowly) to a constant stimulus.
quickly
The three types of nociceptors are:
- mechanical
- thermal
- _
polymodal
Information about touch detected on the left side of the body is transmitted to the brain in the dorsal columns on the _ side of the spinal cord
left
When a photopigment absorbs light, cGMP levels (increase/decrease).
decrease
The first neurons that support production of action potentials in the visual pathway are (photoreceptors/bipolar cells/gan- glion cells)
ganglion
The pitch of sound vibration reflects its (amplitude/frequency)
frequency
T or F: A hair cell in the cochlea can be excited by sounds of different frequencies
false
The process by which the lens becomes stronger for close-up vision is called _
accommodation
Rods and cones differ with regard to the type of (retinal/opsin) they contain
opsin
T or F: A single ganglion cell will either be ex- cited or inhibited by light applied to its visual field
false
T or F: The visual cortex on the left side of the brain receives information from the right eye only
true
T or F: Odorant molecules must be dissolved in mucus if they are to bind to olfactory re- ceptors
true
T or F: A given taste receptor cell responds to only one of the four primary tastes
false
3 MAIN CLASSES OF somatosensory fibers:
A-_ 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
beta
3 MAIN CLASSES OF somatosensory fibers exist, of which
A-beta fibers- large myelinated - TYPE OF RECEPTOR?
mechanical
3 MAIN CLASSES OF somatosensory fibres exist, of which
A-delta fibres - small, myelinated fibres - FAST/SLOW pain, COLD, HOT AND/OR BOTH and mechanical at 12 - 30 m/s
fast;
cold only
3 MAIN CLASSES OF somatosensory fibers exist, of which
C fibers- small, unmyelinated fibres - FAST/SLOW pain, COLD, HEAT AND/OR BOTH, and mechanical at .5 - 2 m/s
slow;
hot and cold
The following are mechanisms for visual accommodation:
- ciliary muscle CONTRACTS/RELAXES
- DECREASED tension on zonular fibers
- lens becomes ROUNDER (refractive index increases)
CONTRACTS
The following are mechanisms for visual accommodation:
- DE/INCREASED tension on zonular fibers
- DECREASED tension on zonular fibers
The following are mechanisms for visual accommodation:
- lens becomes FLATTER/ROUNDER (refractive index increases)
ROUNDER
BALANCE AND EQUILIBRIUM IN THE EAR: Within the _ at the base of each semicircular canal is the cupula, a gelatinous area separated from the endolymph by a membrane
ampulla
(the globular part of the semicircular canals - there are 3 of them, so 3 ampullae and 3 cupula within it)
Hair cells - the receptor cells for acceleration - have steriocilia that extend into the gelatinous _
cupula
When the head is still or moving at a constant rate of motion, _ net force is acting on the cupula, and the stereocilia are upright
NO
nothing’s happening, so no force would be acting on the cupula, and the stereocilia (smaller hairs within the ‘tulip’-shaped part of the cupula) move according to the direction the person is moving/accelerating
The hair cells are partially depolarized, releasing some chemical transmitter and causing a low frequency of action potentials in the afferent neuron when …[type of motion]
the head is still, or moving at a constant rate of motion
During acceleration of the head in the normal direction (moving forward), inertia of the fluid causes it to lag behind the motion of the head. As it does so, it pushes against the cupula in the direction OPPOSITE/SIMILAR that of rotation, causing the stereocilia to bend
OPPOSITE
similar stereocilia would be too easy, so opposite stereocilia it is
When the stereocilia bend away from the kinocilium, the hair cell is DE/HYPER-polarized, and the frequency of action potentials in the afferent neuron DE/IN-creases. This occurs during acceleration of the head in the normal direction moving forward
HYPER-polarized
decreases
i.e., the body assumes it is moving forward, so it doesn’t bother wasting precious action potentials on that movement. On the other hand, if one goes backwards…
During acceleration of the head in the opposite direction (i.e., going backwards), the stereocilia bend AWAY FROM/TOWARD the kinocilium, the hair cells are depolarized, and the frequency of action potentials in the afferent neuron increases
toward - to the kino/highest mini hair cell, creating an action potential
it’s more significant for the body to be going backwards than forwards (i.e., it is more novel, and likely more dangerous), so action potentials are more likely to occur, much as action potentials in the rods when there is more dimness than light
The SACCULE/UTRICLE detects forward and backward linear acceleration, whereas the SACCULE/UTRICLE detects up and down acceleration
utricle - hair cells are in horizontal rows, with the stereocilia extending up vertically (forward or backward)
saccule - hair cells are in verticle rows in the head, with stereocilia oriented horizontally (up or down)
A scientist identifies a synapse that allows for bi-directional communication. Following some additional investigations, the scientist correctly concludes that this is an electrical synapse. What evidence supports the scientist’s conclusion?
a. Voltage-gated Ca2+ channels are found in the presynaptic axon terminal
b. Neurotransmitter-containing vesicles are found in the presynaptic axon terminal
c. The synaptic cleft is found to be 30 - 50 nm wide
d. Connexin proteins are found in the synapse
d. Connexin proteins are found in the synapse
A new pharmaceutical drug is shown to effectively block Protein Kinase A, resulting in inhibition of slow exciting post synaptic potentials. Why is this drug effective?
a. It blocks the binding of neurotransmitter to its receptor
b. It blocks the adenylate cyclase enzyme
c. It blocks the phosphorylation of K+ channels
d. It blocks the production of cAMP
c. It blocks the phosphorylation of K+ channels (I noted it as ‘d’)
Which one of the following statements about the myofilaments is true?
a. Actin contains an ATP binding site
b. Myosin is a thin filament and actin is a thick filament
c. The myosin head contains an actin-binding site
d. Actin has a head and tail portion
c. The myosin head contains an actin-binding site
A new drug blocks all voltage-gated ion channels in neurons. What would not be affected?
a. The initiation of the action potential
b. The release of neurotransmitter
c. The after-hyperpolarization phase
d. Resting membrane potential
d. Resting membrane potential (I noted it as ‘c’)
Imagine 2 hypothetical axons, axon A and axon B. Axon A is myelinated while axon B is unmyelinated. Both axons are stimulated with the same intensity of signal. Which statement about these axons is false?
a. In axon B, potential is lost due to resistance in the cell membrane
b. In axon A, myelin provides insulation against the loss in potential difference
c. In axon B, the potential difference at the start is greater than the potential difference at the end
d. The potential difference at the end of axon A is less than the potential difference at the end of axon B
d. The potential difference at the end of axon A is less than the potential difference at the end of axon B
What would happen to glucose transport if you increased the concentration gradient between the outside of the cell and the inside of the cell, but you kept the number of glucose transporters the same?
a. The rate of glucose transport would increased at first and then slow closer to the transport maximum
b. At equilibrium, the overall amount of glucose that had been transported would be less
c. The rate of glucose transport would decrease until a transport maximum was reached
d. At equilibrium, the overall amount of glucose that had been transported would be the same
a. The rate of glucose transport would increased at first and then slow closer to the transport maximum
Which statement about coding for stimulus intensity is false?
a. As the stimulus strength increases, more graded potentials achieve threshold
b. As the stimulus strength increases, the frequency of action potentials increases
c. As the stimulus strength increases, the receptor potential stays constant
d. As the stimulus strength increases, there is still receptor adaptation
c. As the stimulus strength increases, the receptor potential stays constant
You discover a new cellular transport protein that transports potassium. You create an artificial membrane that is similar to the lipid protein of the plasma membrane but only contains your newly discovered protein and no other proteins. You place the membrane between two chambers. Chamber A has a solution of 1 M potassium and Chamber B has a solution of 0.5 M potassium. Predict what would happen if you had discovered an ungated potassium channel.
a. There would be a net movement of potassium from A to B
b. Potassium would only move from B to A in the presence of ATP
c. Potassium would only move from A to B in the presence of sodium
d. There would be a net movement of potassium from B to A
a. There would be a net movement of potassium from A to B (I said ‘b’)
Which statement about the neurological control of sleep is correct?
a As you sleep more deeply, the EEG waveforms become more erratic
b. The sleep centre is activated by the circadian clock and sleep debt
c. Sleep requires high levels of orexin
d. Sleep requires low levels of melatonin
b. The sleep centre is activated by the circadian clock and sleep debt
Sensory info in the skin travels via the _ to the _ and then to the _ in the spinal cord
a. efferent axon, ventral root, dorsal horn
b. efferent axon, ventral root, ventral horn
c. afferent axon, dorsal horn, dorsal root
d. afferent axon, dorsal root, dorsal horn
d. afferent axon, dorsal root, dorsal horn
In a nerve cell that is only permeable to potassium, the _ is -94 mV, the _ is inward and the _ is outward
a. electrical force; equilibrium potential; chemical force
b. action potential; chemical force; resistance
c. membrane potential; chemical force; electrical force
d. equilibrium potential; electrical force; chemical force
d. equilibrium potential; electrical force; chemical force
A new drug is created that blocks nicotinic cholinergic receptors. What is the likely effect of this drug?
a. It blocks signalling in both the sympathetic and parasympathetic nervous system
b. It does not block signalling in the nervous system
c. It blocks signalling in the parasympathetic nervous system
d. It blocks signalling in the sympathetic nervous system
a. It blocks signalling in both the sympathetic and parasympathetic nervous system
Which of the following is an example of negative feedback?
a. A rise in blood pressure stimulates the elimination of water in the urine, which reduces blood pressure
b. Hormone A stimulates the release of hormone B which then stimulates release of hormone A
c. During labour, contractions of the uterus cause the release of oxytocin which stimulates uterine contractions
d. The formation of a blood clotting factor called thrombin stimulates the formation of a blood clotting factor that stimulates the formation of more thrombin
a. A rise in blood pressure stimulates the elimination of water in the urine, which reduces blood pressure
Which statement about vision in the dark is false?
a. The parasympathetic nervous system is activated
b. Rods are depolarized
c. Neurotransmitters act on bipolar cells
d. Ca2+ channels are opened
a. The parasympathetic nervous system is activated (I said ‘d’)
Imagine 2 hypothetical nerve cells. Cell A is permeable only to Na+ and cell B is permeable only to K+. Which of the following parameters are different between these cells?
a. The equilibrium potential
b. The direction of the chemical force
c. The direction of the electrical force
d. All of these parameters are different
d. All of these parameters are different
A new anaesthetic has been created that blocks skin sensation. Which one of the following would not be a potential mechanism of this drug?
a. Blocker of neurotransmitter production
b. Activator of voltage-gated Ca2+ channels on the sensory cell
c. Blockade of the receptor protein for the neurotransmitter
d. Activator of neurotransmitter degrading enzymes
b. Activator of voltage-gated Ca2+ channels on the sensory cell
You have a cell with an intracellular osmolarity of 300 mOsm due to impermeant solutes. What would happen to the cell if you placed it in a beaker containing 400 mOsm impermeant solutes?
a. Water would move into the cell and the cell would swell
b. Some of the solutes would move into the cell and the cell would swell
c. Some of the solutes would move out of the cell and the cel would shrink
d. Water would move out of the cell and the cell would shrink
d. Water would move out of the cell and the cell would shrink
(I said ‘a’)
In the human body, _ are found in the CNS and _ are found in the PNS
a. neurons; microglial cells
b. astrocytes; schwann cells
c. axons; ependymal cells
d. oligodendrocytes; neurons
b. astrocytes; schwann cells
What event allows for the power stroke in the crossbridge cycle of muscle contraction?
a. Binding of ATP to myosin
b. Release of inorganic phosphate
c. ATP hydrolysis
d. Release of ADP
b. Release of inorganic phosphate (I said ‘a’)
Which one of the following statements about the action potential is false?
a. K+ channels open before Na+ channels open
b. The hyperpolarization phase is due to increased permeability to K+
c. The repolarization phase is due to increased permeability to K+ and decreased permeability to Na+
d. The depolarization phase coincides with an increase in permeability to Na+
a. K+ channels open before Na+ channels open
An injury completely disrupts a person’s autonomic nervous system. What is the consequence of this injury?
a. The loss of body movement
b. The loss of pain sensation
c. The loss of control of heart rate
d. The loss of the sense of sight
c. The loss of control of heart rate
A patient suffers from a stroke and loses her ability to form words. Which area of her brain is most likely damaged?
a. The primary auditory cortex
b. Broca’s area
c. The premotor cortex
d. Wernicke’s area
b. Broca’s area
Place in the correct order the structures that a sound wave passes as it enters the ear:
I) tympanic membrane
II) pinna
III) cochlea
IV) external auditory meatus
a. I, II, III, IV
b. IV, III, II, I
c. II, IV, I, III
d. I, III, II, IV
c. II, IV, I, III
Which one of the following statements about graded potentials is correct?
A)Graded potentials occur in one nerve at a time
B)Graded potentials always lead to action potentials
C)Graded potentials at high enough frequency can achieve threshold
D)Graded potentials are always depolarizing
C)Graded potentials at high enough frequency can achieve threshold
