1. Our Five Senses Systems
Vision
Hearing
Taste
Smell
Touch

2. Properties of Sensory Systems
Stimulus
Internal
External
Receptors
Sense organs - structures
specialized to respond to stimuli
Conduction
Afferent pathway
Nerve impulses to the CNS
Translation
CNS integration and information processing
Sensation and perception – your reality

3. Different Types of Receptors
Mechanoreceptors – respond to touch, pressure, vibration, stretch, and itch
Thermoreceptors – sensitive to changes in temperature
Photoreceptors – respond to light energy (e.g., retina)
Chemoreceptors – respond to chemicals (e.g., smell, taste, changes in blood chemistry)
Pain Receptors – sensitive to pain-causing stimuli

4. Anatomy of the Eyeball Function of the eyeball
Protect and support the photoreceptors
Gather, focus, and process light into precise images

5. The Inner Layer (Retina)
Retina is the innermost layer of the eye lining the posterior cavity
It contains the photoreceptors – cones and rods

6. Photoreceptors Two main types Rod cells More sensitive to light
Allow vision in dim light
In periphery
Cone cells
Operate best in bright light
High-acuity
Color vision – blue, green, red cones
Concentrated in fovea

7. The Ear: Hearing and Equilibrium
The ear – receptor organ for hearing and equilibrium
Composed of three main regions
Outer ear – functions in hearing
Middle ear – functions in hearing
Inner ear – functions in both hearing and equilibrium

8. The Outer (External) Ear
The air inside your ear canal vibrates which causes the ear drum to also vibrate
The ear drum forms the boundary between the external and middle ear

9. The Middle Ear Contain the ear ossicles – smallest bones in the body
Malleus
Incus
Stapes
Attach to the eardrum which vibrates as soundwaves come through the ear
Figure 16.17

11. The Inner (Internal) Ear
Inner ear – a cavity consisting of three parts
Semicircular canals
Vestibule
Cochlea
The inner ear cavity is filled with fluid – vibrations produce pressure waves in this fluid
The sound receptors (mechanoreceptors) are minute hair cells located inside the cochlea

13. The Chemical Senses: Taste and Smell
Taste – gustation
Smell – olfaction
Receptors – classified as chemoreceptors
Respond to chemicals

14. Taste – Gustation Taste receptors Occur in taste buds
Most are found on the surface of the tongue
Located within tongue papillae

15. Taste Buds Collection of 50 –100 epithelial cells
Contain long microvilli – extend through a taste pore
Four basic qualities of taste
Sweet, sour, salty, and bitter
A fifth taste – umami, “deliciousness”
No structural difference among taste buds

16. Smell (Olfaction)
The lining of the nose has olfactory receptors, (chemoreceptors)
Nasal surfaces are coated with secretions from olfactory glands
Olfactory reception involves detecting dissolved chemicals as they interact with odorant-binding proteins

18. Touch The skin contains many different types of receptors
Pain receptors detect whether objects are sharp or dangerous
There are hot and cold thermoreceptors
There are also mechanoreceptors that detect pressure and movement on your skin