how do we stay balanced?

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How do we Stay Balanced? The Vestibular System

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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. - PowerPoint PPT Presentation

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Page 1: How do we Stay Balanced?

How do we Stay Balanced?

The Vestibular System

Page 2: How do we Stay Balanced?

Vestibular System (Balance)

Page 3: How do we Stay Balanced?

Vestibular System (Balance)

Page 4: How do we Stay Balanced?

Vestibular System (Balance)

Page 5: How do we Stay Balanced?

Vestibular System (Balance)

Head accelerates this way

Cupula getspushed

Fluid goes this way

Page 6: How do we Stay Balanced?

Vestibular System (Balance)

Head accelerates this way

Cupula getspushed

Fluid goes this way

Page 7: How do we Stay Balanced?

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!

Page 8: How do we Stay Balanced?

Vestibular, Visual, and Proprioceptive Systems Work Together

• Try standing on one foot with your eyes closed!

Page 9: How do we Stay Balanced?

Fun Facts about The Vestibular System

• Seasickness arises when the vestibular system and the visual system send conflicting information

Page 10: How do we Stay Balanced?

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!

Page 11: How do we Stay Balanced?

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

Page 12: How do we Stay Balanced?

Sensory Systems:

• Touch, temperature, taste, smell

Page 13: How do we Stay Balanced?

There are a variety of touch receptors

Page 14: How do we Stay Balanced?

• 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

Page 15: How do we Stay Balanced?

• Wilder Penfield - Montreal Neurological Institue - 1940’s

• Found somatotopic map by stimulating brain during surgery

The Homunculus

Page 16: How do we Stay Balanced?

• Two classes of thermoreceptors: warm and cold

Thermoception

Page 17: How do we Stay Balanced?

Taste (Gustation)

Taste buds contain

chemical receptors

Page 18: How do we Stay Balanced?

Taste

What are the various “tastes”?

Page 19: How do we Stay Balanced?

• 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

Taste

Page 20: How do we Stay Balanced?

• Olfactory bulb receives input from olfactory receptors which contact mucus in nasal cavity

Smell

Page 21: How do we Stay Balanced?

• There are thousands of different receptors for different kinds of molecules

Smell

Page 22: How do we Stay Balanced?

• Olfactory receptors use a “lock-and-key” mechanism - only specific molecules will bind with a given receptor

Smell

Receptor

Odor Molecules

Page 23: How do we Stay Balanced?

• 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

Page 24: How do we Stay Balanced?

• Smell is strongly influenced by “top-down” processes such as what you are expecting to smell

Smell

Page 25: How do we Stay Balanced?

• Pheromones are not smells• Pheromones are chemical signals sent

from one animal to another

Pheromones

Page 26: How do we Stay Balanced?

• 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

Pheromones

Page 27: How do we Stay Balanced?

• For example: Androstenone, found in male pig saliva, causes a female pig to allow the male to mate with her

Fun Facts about Pheromones

Page 28: How do we Stay Balanced?

• 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

Page 29: How do we Stay Balanced?

• 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

Page 30: How do we Stay Balanced?

• Fewer men used the androstenone seat !

Fun Facts about Pheromones

Page 31: How do we Stay Balanced?

• Other possible ways in which pheromones influence humans:– synchronization of menstrual cycles– mate selection - attraction to opposite

major histocompatibility complex

Pheromones

Page 32: How do we Stay Balanced?

• Pheromones do not control behavior!• Human behavior is largely under top-

down 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

Pheromones