1. Sensory Reception
Chapter 31

2. Sensation and Perception
Sensation is conscious awareness of a stimulus
Perception is understanding what a sensation means

3. Types of Receptors Mechanoreceptors Thermoreceptors Pain receptors
Chemoreceptors
Osmoreceptors
Photoreceptors

4. Assessing a Stimulus Action potentials don’t vary in amplitude
Brain tells nature of stimulus by:
Particular pathway that carries the signal
Frequency of action potentials along an axon
Number of axons recruited

5. Recordings of Action Potentials

6. Sensory Adaptation
A decrease in response to a stimulus that is being maintained at constant strength

7. Somatic Sensations
Touch
Pressure
Temperature
Pain
Motion
Position

8. Somatosensory Cortex

9. Hearing Ear detects pressure waves
Amplitude of waves corresponds to perceived loudness
Frequency of waves (number per second) corresponds to perceived pitch

10. Anatomy of Human Ear stirrup anvil auditory nerve hammer
auditory canal
eardrum
cochlea

11. Sound Reception Sound waves make the eardrum vibrate
Vibrations are transmitted to the bones of the middle ear
The stirrup transmits force to the oval window of the fluid-filled cochlea

12. Sound Reception
Movement of oval window causes waves in the fluid inside cochlea ducts

13. Sound Reception Fluid movement is sensed by the organ of Corti
Hair cells are bent against overlying tectorial membrane and fire

14. Balance and Equilibrium
In humans, organs of equilibrium are located in the inner ear
Vestibular apparatus

15. Vision Sensitivity to light does not equal vision
Vision requires two components
Eyes
Capacity for image formation in the brain

16. Camera Eyes Characteristic of octopuses, squids, and all vertebrates
Eye is structured like a camera
Interior is dark chamber
Light enters through pupil
Lens focuses light on photoreceptors

17. Human Eye sclera retina choroid iris fovea optic lens disk pupil
cornea
part of
optic
nerve
aqueous
humor
ciliary muscle
vitreous body

18. Pattern of Stimulation

19. Visual Accommodation Adjustments of the lens
Ciliary muscle encircles lens, attaches to it
When this muscle relaxes, lens flattens, moves focal point farther back
When it contracts, lens bulges, moves focal point toward front of eye

20. The Photoreceptors Rods Cones Contain the pigment rhodopsin
Detect very dim light, changes in light intensity
Cones
Three kinds; detect red, blue, or green
Provide color sense and daytime vision

21. To the Visual Cortex (2)
Visual cortex

22. Taste A special sense Chemoreceptors Five primary sensations
Sweet, sour, salty, bitter, and umami

23. Smell A special sense Olfactory receptors
Receptor axons lead to olfactory lobe
olfactory
bulb
receptor
cell

24. Sensory Perception
Sensory Cortexes; visual, auditory, smell, taste, somatosensory. Register current incoming sensory signals.
Sensory Association Areas for each sense store sensory memory and automatically compare current with past to provide meaning.

25. Common Integrating Area (CIA)
Integrates messages from sensory cortexes and association areas to understand.
Also known as the gnostic area = knowing
CIA capacity is limited = what your looking at and/or listening to.

26. Memory
CIA must Recall memory from the sensory association areas. Facilitated pathways help.
The the CIA Remembers (puts the separate sensory messages back together)

27. Thought Process CIA is in command
Sensory Association Areas provide memory
Frontal Lobes provide temporary storage, i.e., train of thought
Limbic System provides emotional imput