1. NERVOUS SYSTEM III
SENSES

2. INTRODUCTION
General Senses: are those with receptors widely distributed throughout the body
EX. Skin, various organs and joints
Special senses: more specialized receptors and arise from receptors located primarily in the head.
EX. Eyes and ears

3. Receptors, Sensation and perception
Chemoreceptors- respond to changes in concentration of chemicals
Olfactory (smell) receptors
Detect changes in cerebrospinal fluid pH
Pain receptors (nociceptors)- respond to tissue damage.

4. Receptors, Sensation and perception
Thermoreceptors- sense temperature change
Mechanoreceptors- respond to touch, pressure, vibration, and stretch
Photoreceptors- detect changes in light intensity, color, and movement

5. Receptors, Sensation and perception
The brain interprets input from sensory receptors as perception.
Sensation- Conscious awareness of incoming sensory information
Sensory adaptation- ability to ignore unimportant stimuli
EX. Not constantly noticing/sensing your socks around your ankles

6. General Senses
Touch is the only one of the five senses that is considered a general sense
Detected by mechanoreceptors and thermoreceptors and pain receptors

7. Special Senses Vision:
Eyeball has outer, middle, and inner tunic (layers)
The outermost tunic of the eyeball is the sclera
The transparent anterior portion of the sclera is the cornea
Choroid Coat- Middle tunic
Retina- the inner tunic of the eye 


8. Special Senses Vision: Detected by photoreceptors
The blink reflex is designed to. D. keep the eyes moist.
The contractile structure that surrounds the pupil is the iris.
Lacrimal glands: constantly produce a fluid called tears.


9. Special Senses Hearing:
inner ear-contains the sense organs for hearing and balance 

The external ear terminates at the tympanic membrane.
 

The auditory tube equalizes air pressure between the middle ear and outside air.
The malleus, incus, and stapes transmit vibrations from the eardrum to the oval window. 


10. Special Senses Hearing:
Order of structures in the ear that vibrate when a sound wave enters the ear.
Eardrum
Ossicles
Oval window
Perilymph
Endolymph
Inner ear bones from lateral to medial:
Malleus

Incus
Stapes


11. Special Senses Taste: The sense of taste is called gustation.
Primary taste sensations:
Sweet 

Salty
Sour

Bitter 

umami

12. Special Senses
Smell:
Smell is the special sense relayed directly to the cerebral cortex without going to the thalamus
Detected by chemoreceptors called olfactory receptors

13. Special Senses
Smell:
In order for a molecule to be detected by the olfactory neurons, it must be dissolved in fluid covering the olfactory epithelium.
Inhaling deeply and slowly through the nose help to identify an odor because more air containing the odor is brought into contact with the olfactory epithelium
A person's nose run when he cries because tears drain into the nasal cavity via the nasolacrimal duct.


14. Special Senses Equilibrium:
Static equilibrium- maintenance of balance when the head and body are not moving
Dynamic equilibrium- maintenance of balance when the head and body are suddenly moved or rotated

15. Special Senses Equilibrium: Maintained by inner ear structures
The position of the head with respect to gravity is determined by the movements of otoliths in response to gravity.