 If you had to live without one of your five senses, which one would you choose to lose and why?

An Introduction

 Sensation  The stimulation of sensory receptors and transmission of information to the central nervous system.  Perception  Psychological process through which we interpret sensory stimulation

 Absolute Threshold  The weakest amount of stimulus that can be sensed.  Difference Threshold  The minimum amount of difference that can be detected between two stimuli.

SenseStimulusReceptorsThreshold VisionElectromagnt ic Energy Rods and cones in the retina A candle flame viewed from a distance of about 30 miles on a dark night. HearingSound WavesHair cells of the inner ear The ticking of a watch from about 20 feet away in a quiet room. SmellChemical substances in the air Receptor cells in the nose About one drop of perfume diffused throughout a small house. TasteChemical substances in saliva Taste buds on the tongue About 1 teaspoon of sugar dissolved in 2 gallons of water. TouchPressure on the skin Nerve endings in the skin The wing of a fly falling on a check from a distance of about.4 inch.

 Signal-Detection Theory  Your environment, physical state, mood, and your attitude can affect sensitivity to stimuli.  Sensory Adaptation  Process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli.

 Light is electromagnetic energy.  We only see ROYGBIV, this is only a fraction of all the possible colors in the electromagnetic spectrum. (infrared and ultraviolet light)

 The Pupil  Lets in light. (think of a camera lens)  Pupil size is sensitive to light and emotions.  Allows dark and light adaptation for up to 45 minutes.

 Lens  Adjusts to the distance of objects by changing its thickness.  When people squint, they are adjusting the thickness of the lenses in their eyes.

 Retina  Sensitive surface – acts like the film of a camera.  Photoreceptors make it possible for the optic nerve to carry the message to the brain.

 Cornea  Protects the eye from germs, dust, etc.  Contributes most of the eyes focusing power.

 Iris  Colored portion of the eye.

 Optic Nerve  Transmits visual information to the occipital lobe of the brain.

 Blind Spot  Spot where optic nerve leaves the eye  Rods and Cones  Located in the Retina  Rods are sensitive only to light, black and white.  Cones provide color vision.  Visual Acuity  The sharpness of vision

 Afterimages  The color’s complementary color.

 Colorblindness  People who do not have normal color vision. They are partially or totally unable to distinguish color due to an absence of, or malfunction in, the cones.  Total color blindness is rare.  Partial color blindness is fairly common.  Red-Green color blindness is the most common.  Far more common among men because the deficiency is carried in the X chromosome.

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 Colorblindness occurs in ______________ more often than in ______________.  What is the function of the Rods and Cones in the eye?  What happens if there is a problem with the Cones?  What are afterimages?  What is the spot called where the optical nerve leaves the eye?

 Sound travels through the air in waves.  Changes in air pressure that result from vibration causes sound waves.  Anything that makes a sound causes a vibration. 

 Pitch  How high or low a sound is.  The Human ear can hear sound waves from 20 to 20,000 cycles per second.  Loudness  Is determined by amplitude – Sound Waves.  Loudness is measured by decibels (dB)  0 dB is the lowest we can hear.

 The shape of the ear is specifically made to capture sound.  3 sections of the ear  Outer (what we typically think of as the ear)  Middle (stretches from the eardrum through 3 small bones)  Inner (consists of the cochlea and attaches to the auditory nerve)

 Eardrum is the gateway for outer to middle ear.  As it vibrates it sends the vibration to 3 small bones in the middle ear.  Hammer  Anvil  Stirrup

 Those bones then send the vibration to the inner ear.  It reaches the cochlea, which looks like a snail, but is a bony fluid filled tube that contains neurons and then connects to the auditory nerve.

 About 2 million Americans are deaf.  Deafness may be inherited, caused by disease, injury or old age.  Conducive deafness is caused by damage to the middle ear.  Usually in older people (can be helped with hearing aids.  Sensorineural deafness is caused by damage to the inner ear.  Usually caused by damage to the auditory nerve through disease or prolonged exposure to very loud noises.

Smell, Taste, and Touch

 The receptor for the sensation of smell is the nose.  The olfactory nerve is the connection to the brain from the nose.  Taste and Smell are closely related.

 There are four basic taste qualities.  Sweet  Sour  Salt  Bitter  Taste is sensed through receptors on the tongue called taste buds.  Scraping or burning your tongue kills taste buds, they renew in about a weeks time.

 The are three ways we understand touch.  Pressure  Temperature  Pain  Pressure is received by receptors around hair roots.  Different parts of the body are more sensitive than others.  Temperature is sensors that help you adapt to temperature changes. These are neurons just below the skin.

 Pain is adaptive because it motivates us to do something to make it stop.  Pain goes from its point of contact – the spinal cord – to the thalamus – to the cerebral cortex, where prostaglandins, or chemicals that tell the brain of the pain, are released.  The Gate Theory suggests that only a certain amount of information can be processed so if you rub or scratch the area it helps pain go away. By doing so you flood the neurons.

 Vestibular Sense tells you whether you are physically upright or upside down.  Sensory organs located in the ear monitor the body’s motion, balance, and tells you whether you are upside down or falling.  Kinesthesis is “to move” and “perception. It is when information is fed to the brain from sensory organs in the joints, tendons, and muscles.