Transcript Unit 2: Nervous System

Unit 2: Nervous System
Taste & Smell & Touch
(1) Smell
• Smell = chemicals binding to receptors
– “chemicals” = organic molecules
• Inside of your nose is lined with olfactory
receptors…
– Air flows in carrying organic molecules
– Organic molecules dissolve in mucus lining
– Organic molecules bind to receptors
– Impulse sent through Olfactory Nerve
(2) Smell Memory
• Smell strongly connected to emotion:
– We have very detailed memories of smells
• Each individual perceives smell differently…
– Connected to emotional memory
– Connected to receptor sensitivity
– Connected to lack of memory
• More often you smell it  Less often you smell
it! (WHAT?! )
(3) Taste
• Taste = chemicals binding to receptors
– “chemicals” = organic molecules
– “receptors” = taste buds
• Tongue is covered in papillae projections,
covered in “taste buds” or gustatory cells:
– Organic Molecules dissolve in saliva
– Molecules bind to gustatory cells
– Impulse sent to brain
(4) Taste Regions on Tongue
• Sweet:
– Receptors bind with monosaccharides and amino acids
– Location: Front & Center of Tongue
• Sour:
– Receptors bind with hydrogen ions (acid)
– Location: Sides of Tongue
• Salty:
– Receptors bind with metal ions
– Location: Front & Sides of Tongue
• Bitter:
– Receptors bind with alkaloids (typically nitrogenous)
– Location: Very Back of Tongue
• You can taste without smell! (That’s not what I heard!!)
(5) Touch
• Touch = Pressure against skin
• Skin contains pressure + temperature receptors…
– Meissner’s = Super Sensitive
• Palms, Feet, Lips, Eyelids
• Minimal pressure needed
– Paccinian = Deep Receptors
• Pressure + Vibration
– Nociceptors = Sense Pain
• Most Abundant on body
– Thermoreceptors = Sense Temperature
• Individual neurons for hot and for cold
• Increase nerve impulses with changes in temperature