Transcript 2320Lecture7.pptx

How do we Stay Balanced?
The Vestibular System
Vestibular System (Balance)
Vestibular System (Balance)
Vestibular System (Balance)
Vestibular System (Balance)
Head
accelerates
this way
Fluid goes
this way
Cupula gets
pushed
Vestibular System (Balance)
Fluid goes
this way
Head
accelerates
this way
Cupula gets
pushed
Vestibular System (Balance)
• movement of the cupula is detected by
hair cells
• hair cells in the vestibular system are
more sensitive than hair cells on the
basilar membrane!
Vestibular, Visual, and Proprioceptive
Systems Work Together
• Try standing on one foot with your eyes
closed!
Fun Facts about The Vestibular
System
• Seasickness arises when the vestibular
system and the visual system send conflicting
information
Fun Facts about The Vestibular
System
• Seasickness arises when the vestibular
system and the visual system send conflicting
information
• People can be knocked down by moving
walls!
Fun Facts about The Vestibular
System
• Seasickness arises when the vestibular
system and the visual system send conflicting
information
• People can be knocked down by moving
walls!
• Alcohol causes the spins by (among other
things) changing the density of the fluid in the
semicircular canals
Sensory Systems:
• Touch, temperature, taste, smell
There are a variety of touch
receptors
•
Touch receptors send signals
to the somatosensory cortex
via long axons in the spinal
cord
•
Signals are sent to the
opposite (contralateral) side of
the brain
The Homunculus
• Wilder Penfield Montreal
Neurological
Institue - 1940’s
• Found somatotopic
map by stimulating
brain during
surgery
Thermoception
• Two classes of thermoreceptors:
warm and cold
Taste (Gustation)
Taste buds
contain
chemical
receptors
Taste
What are the various “tastes”?
Taste
• Multi-dimensional scaling reveals
several “varieties” of tastes:
– sweet
– salt
– bitter
– sour
– umami (MSG) - possibly a protein
receptor
– there may also be a lipid (fat) receptor
Smell
• Olfactory bulb
receives input
from olfactory
receptors which
contact mucus
in nasal cavity
Smell
• There are thousands of different
receptors for different kinds of
molecules
Smell
•
Olfactory receptors use a “lock-and-key” mechanism - only specific
molecules will bind with a given receptor
Odor Molecules
Receptor
Smell
• Odor recognition is excellent in humans
• but odor identification (naming) is very
poor
• Women tend to be (slightly) better than
men at naming smells
Smell
• Smell is strongly influenced by “topdown” processes such as what you are
expecting to smell
Pheromones
• Pheromones are not smells
• Pheromones are chemical signals sent
from one animal to another
Pheromones
• Pheromones either induce a behavior in
another animal or cause some
physiological change
• Very common in insects...not so
common in mammals...unclear role in
humans
Fun Facts about Pheromones
• For example: Androstenone, found in
male pig saliva, causes a female pig to
allow the male to mate with her
Fun Facts about Pheromones
• androstenone is also found in the sweat
of human males!
• Does androstenone (or pheromones in
general) affect humans?
• Design an (ethical) experiment…
Fun Facts about Pheromones
• Kirk-Smith & Booth (1980) sprayed
some of the seats in a dentist’s waiting
room with androstenone
• Compared to a control condition, more
women used the androstenone seat
Fun Facts about Pheromones
• Fewer men used the androstenone seat
!
Pheromones
• Other possible ways in which
pheromones influence humans:
– synchronization of menstrual cycles
– mate selection - attraction to opposite
major histocompatibility complex
Pheromones
• Pheromones do not control behavior!
• Human behavior is largely under topdown influences, but may be affected
subtly by pheromones
• It is unclear whether molecules such as
androstenone even qualify as
pheromones - they may be just like
other odour molecules