Special SensesSmell

Testing sensory adaptation- smell

1. As we pass each container down the row, identify the odor by writing the name on your note page. (Please don’t share your thoughts.)

2. All of the odors are safe. None will trigger a pain receptor!!!!!

Things to think about:3. Can you continue to smell after inhaling an odor again

and again?4. When you try to smell the next odor, do you still smell

the previous odor?

During the activity you experienced sensory adaptation.

What is sensory adaptation?

The ability of the sensory system to filter out old information and ignore it in an attempt to be prepared for new incoming sensory stimuli.

Why is sensory adaptation important?

Muscle stretch receptors and position receptors

PhotoreceptorsMechanoreceptorsChemoreceptors Pain receptors

The sense of smell

Organ of smell

Nose

Receptor and how it functions

Chemoreceptor• Odorants dissolve in mucus found in

the nasal cavity

•  Cilia on olfactory cells found in the nasal cavity detect odorant molecules

•  a nerve impulse is sent through olfactory cells into the olfactory nerve fiber

Olfactory neurons are the only neurons exposed to the external environment.

The cilia on these neurons are immovable

Nerve that leads to the brain

Olfactory bulbsTo Olfactory tracts

Part of the brain that interprets smell

Primary destination:Temporal LobePrimary olfactory cortexHippocampus (memory)

Secondary destinations:Frontal lobeOrbitofrontal cortex(integrates smell and taste)

Fun Facts

Most humans can detect A. 100 different odorsB. 500 different odorsC. 1000 different odorsD. 2,000 to 4,000 different odors

Some people can detect up to 10,000 different odors.

True or False? Women are more sensitive to odor than men.True, and women are more sensitive during ovulation

True or False? We can detect odor concentrations as low as a few parts per trillion.True

True or False: Dogs can not smell the difference between identical twins?True

Taste

Why do we like the taste of sweets?Our body needs carbohydrates for energy production.

Why do we crave salt?Ions- Na and Cl Nerve Impulses

Why do we avoid sour and bitter?Sour = RancidBitter = Poison

Why do we love bacon? (umami)Our body needs protein (muscle, enzymes, antibodies)

Sense Organ

Taste Bud

ChemoreceptorsMechanoreceptorsThermoreceptorsPain Receptors

• Chemical dissolves in saliva• Taste hairs of taste cells

receive stimulus

Taste buds are found on your tongue, sides and roof of mouth and pharynx.

Types of Receptors

Taste bud fun facts

• Children have about 10,000 taste buds whereas adults have about 5,000.

• Each taste bud has 50-150 receptor cells that live for 1-2 weeks.

• They are replaced daily by stem cells.

Nerve Pathway

Brain Interpretation

Thalamus- relays message to parietal lobe of brain where we become conscious of taste

Hypothalamus- trigger autonomic nervous system (salivating, gagging, vomitting)

How are taste and smell related?

Jelly Bean Challenge1. The subject closes their eyes, plugs their nose, and

holds out their hand.2. The partner places a jelly bean into the open hand

and notes the color.3. The subject tries to determine the flavor of the

jelly bean with a plugged nose.4. While chewing, the nose is unplugged and the

person has another opportunity to determine the flavor of the jelly bean.

Describe what happens and why. What happens to our ability to taste when we have a cold?Why? From a safety standpoint, why is the nose located over the mouth?