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