Biol 373 Midterm #1 - Unit 3
Special senses - correct answer ✔✔Vision, hearing, taste, smell, equilibrium
Somatic senses - correct answer ✔✔Touch, temperature, pain, itch, proprioception
Proprioception - correct answer ✔✔Awareness of body movement + position in space, can be conscious
or unconscious. A somatic sense.
What is the function of the receptor in sensory systems? - correct answer ✔✔This sensory structure,
part of all sensory systems, is a transducer that converts the stimulus into an intracellular signal, usually
a change in membrane potential.
Where does stimuli have to reach to become "conscious"? - correct answer ✔✔Cerebral cortex
(association areas)
At each synapse along the way of a sensory system, the nervous system can... - correct answer
✔✔...modulate and shape the sensory information
What "type" are all somatic sensory neurons? - correct answer ✔✔Pseudounipolar...can be myelinated
or not
What makes special sense receptors "special"? - correct answer ✔✔Most special sense receptors are
CELLS (i.e. hair cells), not NEURONS. The cells release neurotransmitter onto neurons to initiate an AP.
What special sense uses a neuronal receptor instead of a cell receptor? - correct answer ✔✔Smell
What is the role of accessory structures? - correct answer ✔✔These structures enhance the info-
gathering capability of the sensory system.
,I.e. Lens and cornea of eye help focus incoming light onto photoreceptors
4 groups of receptors based on their preferred stimulus - correct answer ✔✔1. Chemoreceptors -
chemical ligands
2. Mechanoreceptors - mechanical energy/pressure
3. Thermoreceptors - temperature
4. Photoreceptors - light
Transduction - correct answer ✔✔The conversion of stimulus energy into info that can be processed by
the nervous system. Conversion of stimuli into graded potentials by stimulus opening or closing ion
channels.
Adequate stimulus - correct answer ✔✔Each sensory receptor has a particular form of energy to which it
is most responsive. I.e. Light is the adequate stimulus of photoreceptors.
"Adequate" = "Preferred"
Why do you "see light" when you push on your eye? - correct answer ✔✔The pressure on the eye
stimulates photoreceptors...although the adequate stimulus of photoreceptors is light, any stimulus
strong enough will stimulate any type of receptor.
Threshold stimulus - correct answer ✔✔Minimum stimulus req'd to initiate a receptor
Receptive field - correct answer ✔✔The area of surface monitored by a particular receptor.
Convergence - correct answer ✔✔Multiple pre-synaptic (primary) neurons synapse with a smaller
number of post-synaptic (secondary) neurons. Allows multiple simultaneous subthreshold stimuli to sum
at the post-synaptic neuron.
What happens to receptive fields when convergence occurs? - correct answer ✔✔When multiple
primary sensory neurons converge on a single secondary neuron, their individual receptive fields merge
into a single, large receptive field.
, What does the size of a receptive field tell us? - correct answer ✔✔The size of this field tells us how high
the "resolution" is in that area.
Smaller receptive field = higher resolution (i.e. fingertips)
Larger receptive field = lower resolution
When would a receptive field become "larger"? - correct answer ✔✔When there's a lot of
convergence...when multiple primary neurons synapse onto fewer secondary neurons, their receptive
fields merge into one.
What does high-convergence wiring result in (regarding senses)? - correct answer ✔✔HIGH SENSITIVITY
(increased chance of an AP due to summation) but LOW RESOLUTION (can't tell which primary neuron's
receptive field the info came from).
Two-Point Discrimination Test - Large Receptive Field - correct answer ✔✔High convergence rate so the
pinpricks are interpreted as a single pin. No two-point discrimination since the two pins fall within the
same receptive field resulting in only one signal being sent to the brain.
I.e. Arms and legs
Two-Point Discrimination Test - Small Receptive Field - correct answer ✔✔Low convergence rate (as little
as 1:1) so the pinpricks are interpreted as two distinct pricks. When fewer neurons converge, receptive
fields are much smaller. Now the 2 stimuli activate separate pathways to the brain, resulting in two-point
discrimination.
I.e. Fingertips
Where do unconscious sensory pathways usually terminate? - correct answer ✔✔Spinal cord or brain
stem
Where do most sensory pathways pass through in the brain? What's the exception? - correct answer
✔✔Thalamus...except olfactory/smell which skips the thalamus
Special senses - correct answer ✔✔Vision, hearing, taste, smell, equilibrium
Somatic senses - correct answer ✔✔Touch, temperature, pain, itch, proprioception
Proprioception - correct answer ✔✔Awareness of body movement + position in space, can be conscious
or unconscious. A somatic sense.
What is the function of the receptor in sensory systems? - correct answer ✔✔This sensory structure,
part of all sensory systems, is a transducer that converts the stimulus into an intracellular signal, usually
a change in membrane potential.
Where does stimuli have to reach to become "conscious"? - correct answer ✔✔Cerebral cortex
(association areas)
At each synapse along the way of a sensory system, the nervous system can... - correct answer
✔✔...modulate and shape the sensory information
What "type" are all somatic sensory neurons? - correct answer ✔✔Pseudounipolar...can be myelinated
or not
What makes special sense receptors "special"? - correct answer ✔✔Most special sense receptors are
CELLS (i.e. hair cells), not NEURONS. The cells release neurotransmitter onto neurons to initiate an AP.
What special sense uses a neuronal receptor instead of a cell receptor? - correct answer ✔✔Smell
What is the role of accessory structures? - correct answer ✔✔These structures enhance the info-
gathering capability of the sensory system.
,I.e. Lens and cornea of eye help focus incoming light onto photoreceptors
4 groups of receptors based on their preferred stimulus - correct answer ✔✔1. Chemoreceptors -
chemical ligands
2. Mechanoreceptors - mechanical energy/pressure
3. Thermoreceptors - temperature
4. Photoreceptors - light
Transduction - correct answer ✔✔The conversion of stimulus energy into info that can be processed by
the nervous system. Conversion of stimuli into graded potentials by stimulus opening or closing ion
channels.
Adequate stimulus - correct answer ✔✔Each sensory receptor has a particular form of energy to which it
is most responsive. I.e. Light is the adequate stimulus of photoreceptors.
"Adequate" = "Preferred"
Why do you "see light" when you push on your eye? - correct answer ✔✔The pressure on the eye
stimulates photoreceptors...although the adequate stimulus of photoreceptors is light, any stimulus
strong enough will stimulate any type of receptor.
Threshold stimulus - correct answer ✔✔Minimum stimulus req'd to initiate a receptor
Receptive field - correct answer ✔✔The area of surface monitored by a particular receptor.
Convergence - correct answer ✔✔Multiple pre-synaptic (primary) neurons synapse with a smaller
number of post-synaptic (secondary) neurons. Allows multiple simultaneous subthreshold stimuli to sum
at the post-synaptic neuron.
What happens to receptive fields when convergence occurs? - correct answer ✔✔When multiple
primary sensory neurons converge on a single secondary neuron, their individual receptive fields merge
into a single, large receptive field.
, What does the size of a receptive field tell us? - correct answer ✔✔The size of this field tells us how high
the "resolution" is in that area.
Smaller receptive field = higher resolution (i.e. fingertips)
Larger receptive field = lower resolution
When would a receptive field become "larger"? - correct answer ✔✔When there's a lot of
convergence...when multiple primary neurons synapse onto fewer secondary neurons, their receptive
fields merge into one.
What does high-convergence wiring result in (regarding senses)? - correct answer ✔✔HIGH SENSITIVITY
(increased chance of an AP due to summation) but LOW RESOLUTION (can't tell which primary neuron's
receptive field the info came from).
Two-Point Discrimination Test - Large Receptive Field - correct answer ✔✔High convergence rate so the
pinpricks are interpreted as a single pin. No two-point discrimination since the two pins fall within the
same receptive field resulting in only one signal being sent to the brain.
I.e. Arms and legs
Two-Point Discrimination Test - Small Receptive Field - correct answer ✔✔Low convergence rate (as little
as 1:1) so the pinpricks are interpreted as two distinct pricks. When fewer neurons converge, receptive
fields are much smaller. Now the 2 stimuli activate separate pathways to the brain, resulting in two-point
discrimination.
I.e. Fingertips
Where do unconscious sensory pathways usually terminate? - correct answer ✔✔Spinal cord or brain
stem
Where do most sensory pathways pass through in the brain? What's the exception? - correct answer
✔✔Thalamus...except olfactory/smell which skips the thalamus
