PSYC 102 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS
Why is proprioceptive systems important?
Proprioceptive systems often have very high acuity, which is important for the day-to-
day, but also for inventing things that help compensate for deficits in the sensory
systems.
Skin
- Heaviest organ in the body
- Protects the organism by keeping damaging agents from penetrating the body
Epidermis
Outer layer of skin made of flat cells called:
- Squamous cells: outer layer
- Basal (round) cells: middle layer
- Melanocytes: bottom layer
Dermis
Below the epidermis and contains mechanoreceptors that respond to stimuli such as
pressure, stretching, and vibration
What is the first pass at sending movement on the skin?
Hair cells
What are the 4 types of mechanoreceptors?
,- Merkel
- Meissner corpuscles
- Pacinian corpuscle
- Ruffini cylinder
Merkel Receptors
Disk like receptors right at the surface, responsible for the ability to feel things in fine
detail
Meissner corpuscle
Stacked body of cells with an afferent nerve fiber running through them; at the surface
Pacinian corpuscle
Layered structure that go into an afferent nerve fiber in the middle of the cell
Ruffini cylinder
Branched fibers inside a cylindrical capsule (Bulbous corpuscle) or collagen
Temporal Response Properties
How quickly receptors adapt to pressure
Slow Adapting fibers
Slow to adapt to a stimulus; as long as stimulus is present, they will continue to fire
- Merkel (SA1) and Ruffni (SA2)
Rapidly Adapting Fibers
Will rapidly adapt to stimulus; will fire at the onset of the stimulation, and often again
when stimulus is removed
- RA1 (meissner corpuscle) and RA2 (Pacinian corpuscle)
Merkel Cells (SA1)
, Located in superficial layer, slowly adapting, specialized to pick up extracellular
potentials
- High acuity (found right at the surface of the skin)
- Pressure on the skin causes release of transmitters; when pressure is applied, ion
channels open, and positive ions flow in, and neurotransmitters are released
- As long as pressure is present, ion channels will stay open, which means the cell will
continue firing
Ruffini Cylinder (SA2)
Slowly adapting cells that respond to stretch, located in a deeper layer of tissue; useful
for detecting slippage and adjusting group aperture
- Embedded in collagen; as collagen is stretched, the cell is pulled apart, leading the
influx of positively charged ions, leading to firing of action potentials
- As long as cell is stretched, you will get continuous firing
Meissner Corpuscle (RA1)
Rapidly adapting cells close to the surface
- Made up of disks that are stacked on top of one another; these disks are innervated by
one afferent nerve
- Action potential is triggered when there is a "slippage" of disks
- Because it is RA, though, once the disk slips, the influx on positive ions will quickly
stabilize
- Won't fire another set of action potentials unless the disks "slip" into new positions
Pacinian Corpuscle (RA2)
COMPLETE SOLUTIONS
Why is proprioceptive systems important?
Proprioceptive systems often have very high acuity, which is important for the day-to-
day, but also for inventing things that help compensate for deficits in the sensory
systems.
Skin
- Heaviest organ in the body
- Protects the organism by keeping damaging agents from penetrating the body
Epidermis
Outer layer of skin made of flat cells called:
- Squamous cells: outer layer
- Basal (round) cells: middle layer
- Melanocytes: bottom layer
Dermis
Below the epidermis and contains mechanoreceptors that respond to stimuli such as
pressure, stretching, and vibration
What is the first pass at sending movement on the skin?
Hair cells
What are the 4 types of mechanoreceptors?
,- Merkel
- Meissner corpuscles
- Pacinian corpuscle
- Ruffini cylinder
Merkel Receptors
Disk like receptors right at the surface, responsible for the ability to feel things in fine
detail
Meissner corpuscle
Stacked body of cells with an afferent nerve fiber running through them; at the surface
Pacinian corpuscle
Layered structure that go into an afferent nerve fiber in the middle of the cell
Ruffini cylinder
Branched fibers inside a cylindrical capsule (Bulbous corpuscle) or collagen
Temporal Response Properties
How quickly receptors adapt to pressure
Slow Adapting fibers
Slow to adapt to a stimulus; as long as stimulus is present, they will continue to fire
- Merkel (SA1) and Ruffni (SA2)
Rapidly Adapting Fibers
Will rapidly adapt to stimulus; will fire at the onset of the stimulation, and often again
when stimulus is removed
- RA1 (meissner corpuscle) and RA2 (Pacinian corpuscle)
Merkel Cells (SA1)
, Located in superficial layer, slowly adapting, specialized to pick up extracellular
potentials
- High acuity (found right at the surface of the skin)
- Pressure on the skin causes release of transmitters; when pressure is applied, ion
channels open, and positive ions flow in, and neurotransmitters are released
- As long as pressure is present, ion channels will stay open, which means the cell will
continue firing
Ruffini Cylinder (SA2)
Slowly adapting cells that respond to stretch, located in a deeper layer of tissue; useful
for detecting slippage and adjusting group aperture
- Embedded in collagen; as collagen is stretched, the cell is pulled apart, leading the
influx of positively charged ions, leading to firing of action potentials
- As long as cell is stretched, you will get continuous firing
Meissner Corpuscle (RA1)
Rapidly adapting cells close to the surface
- Made up of disks that are stacked on top of one another; these disks are innervated by
one afferent nerve
- Action potential is triggered when there is a "slippage" of disks
- Because it is RA, though, once the disk slips, the influx on positive ions will quickly
stabilize
- Won't fire another set of action potentials unless the disks "slip" into new positions
Pacinian Corpuscle (RA2)
