Module 5 Sensation

Sensations Sensation is direct input from sense organs Vision Hearing Vestibular system Taste Olfaction Touch

sent to brain for processing EYE: VISION Structure and function 1. Gather and focus light Absorb and transform light waves into electrical impulses process called transduction physical energy electrical signals neural impulses sent to brain for processing

p95 EYE

EYE: VISION Structure and function Vision: 7 steps Image reversed/Light waves Cornea Pupil Iris Lens Retina Which 2 areas bend and focus light into narrower beams?

EYE: VISION Structure and function Cornea bends and focuses light waves into a narrower beam of light Pupil allows light waves to pass into the eye’s interior

EYE: VISION Structure and function Iris controls the amount of light entering the eye Lens bends and focuses light waves into an even narrower beam

EYE: VISION Structure and function Retina extremely sensitive to light begins the process of transduction by absorbing light waves

p96 RETINA

EYE: VISION Visual pathways: Eye to brain Optic nerve Primary visual cortex Visual association areas

p97 VISUAL SYSTEM

EYE: VISION Visual pathways: eye to brain Optic nerve nerve impulses flow through the optic nerve as it exits from the back of the eye to the brain the exit point is the “blind spot” (Why don’t you notice the blind spot?) the optic nerves partially cross and pass through the thalamus the thalamus relays impulses to the back of the occipital lobe in the right and left hemisphere

Leading a person who is blind Offer your assistance Keep the person on the leader’s left Allow the person to take your arm Give clear/brief/accurate information People who are blind respond well to intelligence Demonstrate veering

Visual Impairment and the Artificial Eye

Baby crying Rock concert EAR: AUDITION Measuring sound waves decibel: unit to measure loudness threshold for hearing: 0 decibels (no sound) 140 decibels (pain and permanent hearing loss) Baby crying Rock concert

EAR: AUDITION Outer ear function pick up sound waves and then send them down the auditory canal

EAR: AUDITION Outer, middle, and inner ear Inner ear contains two structures sealed by bone cochlea: involved in hearing vestibular system: involved in sensing the position of the head, keeping the head upright, and maintaining balance

CHEMICAL SENSES (CONT.) Tongue Five basic tastes sweet salty sour bitter umami: meaty-cheesy taste

CHEMICAL SENSES (CONT.) Taste buds shaped like miniature onions receptors for taste chemicals dissolved in saliva activate taste buds produce nerve impulses that reach areas of the brain’s parietal lobe brain transforms impulses into sensations of taste

CHEMICAL SENSES (CONT.) Smell, or olfaction Olfaction called a chemical sense because its stimuli are various chemicals that are carried by the air Function of olfaction receptors, through transduction, transform chemical reactions into nerve impulses

p107 OLFACTORY BULB

CHEMICAL SENSES (CONT.) Smell, or olfaction Sensations and memories nerve impulses travel to the olfactory bulb impulses are relayed to the primary olfactory cortex cortex transforms nerve impulses into olfactory sensations Can identify as many as 10,000 different odors we stop smelling our deodorants or perfumes because of decreased responding called adaptation

CHEMICAL SENSES (CONT.) Smell, or olfaction Functions of olfaction one function: to intensify the taste of food second function: to warn of potentially dangerous foods third function: elicit strong memories; emotional feelings

Smell Memory

TOUCH Touch includes pressure, temperature, and pain

p108 SKIN

TOUCH (CONT.) Receptors in the skin skin hair receptors - when first bent (after being bent=sensory adaptation) free nerve endings – temperature and pain Pacinian corpuscle – vibrations Somatosensory cortex (parietal lobe) transforms nerve impulses into sensations of touch temperature, and pain

PAIN What causes pain? pain: unpleasant sensory and emotional experience that may result from tissue damage, one’s thoughts or beliefs, or environmental stressors pain results from many different stimuli

p112 BRAIN PAIN

PAIN (CONT.) How does the mind stop pain? gate control theory of pain nonpainful nerve impulses compete with pain impulses in trying to reach the brain creates a bottleneck or neutral gate shifting attention or rubbing an injured area decreases the passage of painful impulses result: pain is dulled

PAIN (CONT.) Endorphins chemicals produced by the brain and secreted in response to injury or severe physical or psychological stress pain reducing properties of endorphins are similar to those of morphine brain produces endorphins in situations that evoke great fear, anxiety, stress or bodily injury as well as intense aerobic activity