1. The PNS and Special Senses

2. Nerves and ganglia outside the central nervous system Nerve = bundle of neuron fibers Neuron fibers are bundled by connective tissue

3. Endoneurium surrounds each fiber Groups of fibers are bound into fascicles by perineurium Fascicles are bound together by epineurium

4. Mixed nerves Both sensory and motor fibers Sensory (afferent) nerves Carry impulses toward the CNS Motor (efferent) nerves Carry impulses away from the CNS

5. 12 pairs of nerves that mostly serve the head and neck Only the pair of vagus nerves extend to thoracic and abdominal cavities Most are mixed nerves, but three are sensory only

6. I Olfactory nerve — sensory for smell II Optic nerve — sensory for vision III Oculomotor nerve — motor fibers to eye muscles IV Trochlear — motor fiber to eye muscles

7. V Trigeminal nerve — sensory for the face; motor fibers to chewing muscles VI Abducens nerve — motor fibers to eye muscles VII Facial nerve — sensory for taste; motor fibers to the face VIII Vestibulocochlear nerve — sensory for balance and hearing

8. IX Glossopharyngeal nerve — sensory for taste; motor fibers to the pharynx X Vagus nerves — sensory and motor fibers for pharynx, larynx, and viscera XI Accessory nerve — motor fibers to neck and upper back XII Hypoglossal nerve — motor fibers to tongue

9. There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Formed by the combination of the ventral and dorsal roots of the spinal cord Named for the region from which they arise

10. Motor subdivision of the PNS Consists only of motor nerves Also known as the involuntary nervous system Regulates activities of cardiac and smooth muscles and glands Two subdivisions Sympathetic division Parasympathetic division

11. Figure 7.27

12. Sympathetic—“fight or flight” Response to unusual stimulus Takes over to increase activities Remember as the “E” division Exercise, excitement, emergency, and embarrassment

13. Parasympathetic— “housekeeping” activities Conserves energy Maintains daily necessary body functions Remember as the “D” division digestion, defecation, and diuresis

15. General senses of touch Temperature Pressure Pain Special senses Smell Taste Sight Hearing Equilibrium

17. RECEPTOR TYPESTIMULATED BYEXAMPLES CHEMORECEPTORSCHANGE IN CHEMICAL CONCENTRATION OF A SUBSTANCE TASTE SMELL PAIN RECEPTORSTISSUE DAMAGEFREE NERVE ENDINGS IN SKIN THERMORECEPTORSCHANGE IN TEMPERATURE FREE NERVE ENDINGS IN SKIN MECHANORECEPTORSCHANGE IN PRESSURE OR MOVEMENT MEISSNER’S CORPUSCLE PACINIAN CORPUSCLE HEARING EQUILIBRIUM PHOTORECEPTORSLIGHT ENERGYSIGHT

18. Touch and pressure sensors Sensory nerve fibers Meissner’s corpuscles Pacinian corpuscles Temperature sensors Heat receptors – 25- 45*C Cold receptors – 10- 20*C

19. Houses two senses Hearing Equilibrium (balance) Receptors are mechanoreceptors Different organs house receptors for each sense

20. The ear is divided into three areas External (outer) ear Middle ear (tympanic cavity) Inner ear (bony labyrinth)

21. Involved in hearing only Structures of the external ear Auricle (pinna) External acoustic meatus (EAS) (auditory canal) Narrow chamber in the temporal bone Lined with skin and ceruminous (wax) glands Ends at the tympanic membrane

22. Air-filled cavity within the temporal bone Only involved in the sense of hearing Two tubes are associated with the inner ear The opening from the auditory canal is covered by the tympanic membrane The auditory tube connecting the middle ear with the throat Allows for equalizing pressure during yawning or swallowing This tube is otherwise collapsed

23. Three bones (ossicles) span the cavity Malleus (hammer) Incus (anvil) Stapes (stirrip) Function Vibrations from eardrum move the malleus  anvil  stirrup  inner ear

24. Includes sense organs for hearing and balance Filled with perilymph A maze of bony chambers within the temporal bone Cochlea Vestibule Semicircular canals

25. Static equilibrium Maintains stability and posture when the head and body are still Vestibule of semicircular canals and cochlea Dynamic equilibrium Detects motion and maintains balance Semicircular canals lie in right angles to each other Cerebellum interprets impulses

26. Maculae — receptors in the vestibule Report on the position of the head Send information via the vestibular nerve Anatomy of the maculae Hair cells are embedded in the otolithic membrane Otoliths (tiny stones) float in a gel around the hair cells Movements cause otoliths to bend the hair cells

27. Organ of Corti Located within the cochlea Receptors = hair cells on the basilar membrane Gel-like tectorial membrane is capable of bending hair cells Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe

28. Auricle collects sound waves and directs them into external auditory meatus. Sound waves change pressure on the eardrum, causing vibrations. Auditory Ossicles transmit vibrations to inner ear. Vibrations move fluid within inner ear and travel through cochlea to the organ of Corti. Hair of the organ of Corti vibrate against the tectorial membrane and stimulate receptor cells. Receptor cells release neurotransmitters that stimulate sensory nerve fibers. Impulses are transmitted to the auditory cortex.

30. Orbital Eyelid – skin, muscle, conjunctiva Lacrimal gland Extrinsic muscles

31. Outer tunic Sclera white of the eye Cornea Transparent, central anterior portion Middle tunic Lens Iris Pupil Aqueous humor Inner tunic (retina)

32. Optic disk (blind spot) is where the optic nerve leaves the eyeball Vitreous humor Gel-like substance posterior to the lens Prevents the eye from collapsing Retina Contains pigments, rods, and cones Fovea centralis only has cones Aqueous Humor located between cornea and lens (Add this to your notes)

33. Rods Vision in dim light Colorless vision General outlines of objects Cones Sharp images Color vision – red, green, blue Dense in fovea centralis

35. Light must be focused to a point on the retina for optimal vision The eye is set for distance vision (over 20 feet away) Accommodation—the lens must change shape to focus on closer objects (less than 20 feet away)

36. Image formed on the retina is a real image Real images are Reversed from left to right Upside down Smaller than the object

37. Optic chiasma Location where the optic nerves cross Fibers from the medial side of each eye cross over to the opposite side of the brain Optic tracts Contain fibers from the lateral side of the eye on the same side and the medial side of the opposite eye

38. nearsighted farsighted

39. Nasal cavity Olfactory receptors Olfactory organs Olfactory receptor cells Cilia Olfactory bulbs

40. Chemicals enter nasal cavity as gases and dissolve in fluids that surround cilia. Receptors detect chemicals and send impulses to olfactory bulbs. Olfactory bulbs analyze impulses and transmit info along olfactory tracts to the limbic system. Interpretation occurs within olfactory cortexes. Receptors adapt quickly.

41. Taste buds Papillae Taste pore Taste cells Taste hairs

42. Chemical stimulus dissolves in saliva. Receptor cells are stimulated and send impulses along facial, glossopharyngeal, and vagus nerves to the medulla oblongata. Impulses are sent to the thalamus and then to the gustatory complex.

43. Sweet receptors(sugars) Saccharine Some amino acids Sour receptors Acids Bitter receptors Alkaloids Salty receptors Metal ions Draw this picture in your notes. You need it for your lab.