1. Sensory reception of the five senses
The Somatic Senses
Sensory reception of the five senses

2. Receptors Five types of receptors
Chemoreceptor – changes in chemical concentrations
Pain – tissue damage
Temperature (thermoreceptors)- changes in temp
Mechanoreceptors – changes in pressure and movement
Photoreceptors – changes in light energy

3. Sensation – what is it?
When you touch an objects actually, are they really hot or cold?
What is happening when you touch hot water or step outside when it is very “cold” out?

4. Sensation is.. The feeling when the brain interprets sensory impulses.
What you feel when you touch something “hot” or “cold” is the energy transfer into or out of your body.

5. Projection is …
When the cerebral cortex causes the feeling to seem to come from the stimulated receptors. This is at the same time the sensation forms.
Basically the brain projects the sensation back to its apparent source.
This allows to pinpoint the region of stimulation.
The eyes seem to see; the ears seem to hear.

6. Sensory adaptation… When sensory receptors are continuously stimulated
As receptors adapt, the impulses decrease, and continue to decrease, and the reception may even stop
Change in strength of the stimulus will trigger impulses again

7. Touch and Pressure - Mechanoreceptors:
Three kinds of receptors: sensory nerve fibers (free end), Meissener’s Corpuscles, Pacinian corpuscles
These receptors perceive sensations such as pressure, vibrations, and texture.

8. Touch and Pressure - Mechanoreceptors:
Those found in the very top layers of the dermis and epidermis and are generally found in non-hairy skin such as the palms, lips, tongue, soles of feet, fingertips, eyelids, and the face.
Those located deeper in the dermis and along joints, tendons, and muscles
feel sensations such as vibrations traveling down bones and tendons, rotational movement of limbs, and the stretching of skin. This greatly aids your ability to do physical activities such as walking and playing ball.

9. Temperature Senses Two types of free nerve endings: warm and cold
Warm Receptors
Most sensitive at temps above 77oF
Unresponsive at temps above 113oF
This will stimulate pain receptors, produces burning sensation
Cold receptors
Most sensitive between 50-68oF
Temps below 50oF stimulate pain receptors, produces freezing sensation

10. Temperature Senses
Cold receptors are found in greater density than heat receptors. The highest concentration of thermoreceptors can be found in the face and ears (hence why your nose and ears always get colder faster than the rest of your body on a chilly winter day).

11. Pain receptors Free nerve endings
Widely distributed throughout the body, except in the nervous tissue and brain
Adapt poorly, if at all
Once stimulated, may continue to send impulses to the CNS = persistent pain
Pain is poorly understood

12. Pain
Pain elicited during a muscle cramp stems from sustained contraction that squeezes capillaries and interrupts blood flow.
Deficiency in oxygen-rich blood may trigger pain sensations

13. Referred pain
Pain that is coming from some part of the body other than the part being stimulated
Pain from the heart may be felt from the left shoulder or upper left limb.
Generally comes from visceral pain = deep within the body/ visceral tissue

14. Special Senses = smell, taste, sight, hearing /equilibrium,
Organ
Smell
Olfactory organs
Taste
Taste buds
Hearing/ equilbrium
Ears
Sight
eyes

15. Smell Olfactory receptor cells = bipolar
Stimulated fibers synapse with neurons in olfactory bulb
Impulses from the olfactory bulb travel along olfactory tracts to the limbic system
Major interpretation sites are found in the temporal lobes and parts of the frontal lobe.

16. Olfactory Stimulation
Uncertain how this stimulation begins
Smells are interpreted as a code
For example, if there are 10 receptors, parsley may stimulate receptors 3, 4, & 8 and chocolate might stimulate 1,5, & 10
Olfactory organs are located high in the nasal cavity
May need to force air in during inhale to get a faint smell
Undergo sensory adaptation rapidly

17. Taste Each taste bud has a group of taste cells
Each bud has cells replaced every three days
Entire structure is within the taste pore
Tiny projections are called taste hairs

18. Taste
Salivary glands dissolve chemicals in order for the tongue to taste
4-7 taste sensations
Sweet
Sour
Salty
Bitter
Metallic
Alkaline
Umami – detects MSG

19. Taste
Each taste cell can detect two sensations, although one sensation may dominate over the other
Taste cells undergo sensory adaptation rapidly
Impulses move from taste cells through facial, glossopharyngeal and vagus nerves to medulla oblongata
They then move to the thalamus to the parietal lobe

20. Hearing The ear has an external, middle and inner part
External ear has two parts – auricle and the external auditory meatus
Both direct sound waves toward the middle ear
Middle ear – includes tympanic cavity, eardrum, and auditory ossicles (three small bones)
Eardrum moves back and forth in response to vibrations of the sound wave
These vibrations are transferred to the auditory ossicles, which then stimulate the hearing receptors

21. Hearing The ear has an external, middle and inner part
Inner Ear – comprised of two labyrinths which include semicircular canals and the cochlea
Sound waves move through this area exciting hair cells (nerve cells)
Sound frequency stimulates only certain cells
Cells do not have dendrites or axons, but act very much like a neuron
Impulses are interpreted in the temporal lobe of the brain

22. Sight