Sensation Taste, Smell and Touch

Objectives• Discuss the role of the kinesthetic and vestibular senses in

body position, balance, and equilibrium. • Discuss the role played by the skin in the sensation of touch,

including the types and distribution of sensory receptors in the skin.

• Explain how taste sensations are produced and identify the basic taste categories.

• Define pheromones, and discuss the research evidence supporting the notion that human pheromones exist.

• Describe the process of olfaction, including the transmission of olfactory information to the brain.

Sensation• The process of detecting a physical stimulus,

such as light, sound, heat, pressure, etc,…

Sensory Receoptors

• Cells that specialize in each individual sense and respond to a specific type of stimulus.

Transduction

• The process by which a form of physical energy is converted into a coded neural signal that can be processed by the nervous system.

Sensory Threshold

• Our abilities to detect energy from the outside world is not infinite

• The point at which a stimulus is strong enough to be detected.

Absolute Threshold

• The smallest possible strength of a stimulus that can be detected half the time.

Gustation• Taste is a chemical sense.

• The little bumps on our tongues are actually called papillae

• Inside some of these papillae are clumps of taste cells.

• These clumps of cells are actually the taste buds.

Taste• On average, adults have about 7,500 taste buds.

• These receptor cells are located in the tongue and in the mouth.

• When food dissolves on these receptors, TRANSDUCTION occurs

• Damaged taste receptor cells are replaced within a few days to 2 weeks

Taste• Substances dissolved by saliva

activating the taste buds

• (cheeks, roof of mouth, throat, tongue)

• Taste Sensations

–sweet

–sour

–salty

–bitter

Supertasters

• People with an abundance of taste receptors

• Approximately 25% of the population

Nontasters

• People with a minimum of taste receptors

• Taste with less intensity than the rest of the population

• Approximately 25% of the population

Other Senses: Smell

Module 9: Sensation

Other Senses:

Olfaction

• Olfactory cells in the upper nasal passages detect molecules in the air.

• Taste and smell interact to produce flavor.

Olfaction• Smell is a chemical

sense.• Olfactory

receptors/cells in the upper nasal passages detect molecules in the air.

• Taste and smell interact to produce flavor.

Olfactory Cells

• The chemical receptor cells for smell

• Located in the nasal passages

Smell

Smell

Smell

Do Pheromones Influence Human Behavior?

• Please read the article on page 100 in your textbook and record your answer. Remember to explain your reasoning.

Other Senses: Touch

Touch

• Touch receptors are on the skin

• Four basic skin senses are

–Pain, warmth, cold, and pressure

• All skin sensations are a combination of these four basic senses

Sensitivity to Pain

Most Sensitive

• Back of knees

• Neck region

• Bend of elbow

Least Sensitive

• Tip of the Nose

• Sole of foot

• Ball of thumb

• Pain messages travel on one set of nerve fibers containing pain gates.

• The gates are open when pain is felt.

• Other sensory messages go through another set of fibers.

• The non-pain fibers can close the pain gates to stop the sense of pain.

Gate-control Theory of Pain

• Pain is a product of both physiological and psychological factors.

• The gates are open when pain is felt.

The last sense….

Maybe…….

Kinesthetic Sense• The technical name for the sense of

location and position of body parts in relation to one another.

• One’s leg “falling asleep” is a disruption of the kinesthetic sense

Proprioceptors• Sensory receptors, located in the muscles

and joints, that provide information about body position and movement.

Vestibular Sense

• DEFINITION: The technical name given to the sense of balance or equilibrium.

Sources of Sensory Information

• Semicircular canals

• Vestibular sacs

How Does It Work?• Both structures are filled with fluid and are

lined with tiny hairlike receptors. These structures shift in response to motion or changes in gravity.

I Need Three Volunteers

• Who thinks they have a decent vestibular sense?

Three Volunteers Please…

Do That.

Let’s Review

• Name the senses

• How many do you have?

• Think again…

The Senses

1. Vision

2. Hearing

3. Tasting

4. Touching

5. Smelling

6. Kinesthetic

7. Vestibular

Reviewing Our Objectives

• Winner gets three

• The other person gets two

Reviewing Our Objectives• Turn to your

neighbor and describe all objectives.

• Use as many vocabulary terms as possible.

• Discuss the role of the kinesthetic and vestibular senses in body position and balance.

• Discuss the role played by the skin in the sensation of touch.

• Explain how taste sensations are produced and identify the basic taste categories.

• Define pheromones, and discuss the research evidence supporting their existence.

• Describe the process of olfaction, including the transmission of olfactory information to the brain.

The End