1. Module 5
Sensation

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

3. 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

4. p95 EYE

5. 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?

6. 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

7. 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

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

9. p96 RETINA

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

11. p97 VISUAL SYSTEM

12. 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

13. 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

14. Visual Impairment and the Artificial Eye

15. 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

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

18. 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

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

20. 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

21. 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

22. p107 OLFACTORY BULB

23. 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

24. 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

25. Smell Memory

26. TOUCH
Touch
includes pressure, temperature, and pain

27. p108 SKIN

28. 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

29. 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

30. p112 BRAIN PAIN

31. 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

32. 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