Sensation Chapter 4 Sensory System How it works

Sensation Chapter 4

Sensory System: How it works • It is through our sensory system-vision, hearing, taste, smell and touch-that we experience and interact with the environment.

Receptors • Sensory organs (eyes, ears, nose, tongue, and skin) contain receptors that allow us to process information received from our environment. See below for receptors and stimuli: Eye: Wavelengths of light Ear: Vibrations of air molecules Nose: Gaseous molecules in the air On the tongue: Chemicals in food In the Skin: Pressure, temperature

Absolute Thresholds • For a sensation to occur, a minimum amount of stimulation is necessary. Absolute Thresholds: the minimum stimuli that can be detected by our main sensory systems. Example: One drop of perfume diffused into an entire three bedroom apartment.

How we perceive • The brain interprets the neural impulses as particular sensations. Perception: The brain organizes the sensory information to make it meaningful. • Scientists are not sure how all of this takes place, however, they do know it is all constructed inside our brain.

Sensory Coding • Each sensory system in the body uses a complex form of sensory coding. • Sensory coding sends messages to the brain. Sensory coding assists the brain in understanding what it is we are experiencing.

Touch, Pressure, Temperature and Pain Somatic receptors: receptors in the skin that respond to stimuli such as touch, pressure, temperature and pain. • Somatic receptors are found all over the body, though their density varies. • The more the receptors, the greater the sensitivity to stimuli. • Tongue, lips, face and hands have a great number of receptors.

How does the pain leave the body? • Endorphins- The body produces endorphins that can help reduce or eliminate pain. • Endorphins bind to receptors in the brain, just as narcotic drugs do, to reduce or eliminate pain.

Gate Control Theory • This theory states that pain is a function of the balance between the information traveling into the spinal cord through large nerve fibers and information traveling into the spinal cord through small nerve fibers. • Signals can be blocked or not blocked within the neurons that can stop pain. If they are not locked out, This is the reason given for the success of acupuncture. The needles inserted in appropriate places in the body affect the functioning of our pain gates.