1. THE NERVOUS SYSTEM

2. General Structure of the Nervous System Neurons –React to changes in environment –Transmit nerve impulses –Dendrites –Axons –Nerve –Synapses –Neurotransmitters Neuroglia –Fill spaces, surround, support, and nourish neurons

3. Functions of the Nervous System Sensory Integrative Motor Sensory receptors  PNS  CNS  integration  decision  effectors  motor function

4. Divisions of the Nervous System

5. Neuron - Structure Cell body Neurofibrils Nissl bodies Dendrites Axon –Axonal hillock –Collateral branches –Synaptic knob Synaptic cleft

6. Myelinated vs. Unmyelinated Schwann cells form myelin sheath –Neurilemma –Nodes of Ranvier White matter Schwann cells do not form sheath Gray matter

7. Classification of Neurons

8. Neuroglia Schwann cells-form myelin sheath in PNS Astrocytes – blood-brain barrier Oligodendrocytes-forms myelin in the CNS Microglia –phagocytes Ependyma – regulate CSF

9. Neuron Growth and Repair Neurons can live and function for over 100 years. Mature neurons generally do not divide. Neurons develop from neural stem cells. Injury to the cell body usually kills the neuron – it cannot be replaced. The axon of a neuron may regenerate. Growth is extremely slow – 3-4 mm/day.

10. Nerve Impulse Transmission – Membrane Potential Cell membrane of a neuron is usually polarized – negative charge on the inside. (resting potential) Charge is maintained by open protein channels and Na+-K+ pumps.

11. Nerve Impulse Transmission – Nerve Impulse Formation A change in the environment opens gated ion channels. Na+ rushes into the cell if threshold potential is reached. (action potential) Voltage-gated K+ channels open to restore resting potential.

12. Nerve Impulse Transmission – Synaptic Transmission At the synaptic knob, voltage-gated Ca++ channels open  Ca++ enters cell. Ca++ causes release of neurotransmitters. Neurotransmitters diffuse across synaptic cleft to receptors on the next neuron’s dendrite or cell body.

13. Neurotransmitters NEURO- TRANSMITTER ACTIONSDISORDERS AND DRUGS ACETYLCHOLINESTIMULATES SKELETAL MUSCLE CONTRACTIONS ALZHEIMER DISEASE, NICOTINE NOREPINEPHRINESENSE OF FEELING GOOD, EXCITES OR INHIBITS ANS DEPRESSION, EPILEPSY, MANIA DOPAMINESAME AS NOREPINEPHRINEEPILEPSY, PARKINSON DISEASE, SCHIZOPHRENIA, NICOTINE, COCAINE SEROTONININHIBITORY, SLEEPINESSDEPRESSION, TRYPTOPHAN ENDORPHINSINHIBITORY, REDUCES PAIN

14. The Central Nervous System (CNS)

15. Meninges Between bone and CNS tissues Dura mater Arachnoid mater Subarachnoid space Pia mater

16. Spinal Cord Functions Center for spinal reflexes Conduit for nerve impulses to and from the brain

17. Spinal Cord Structure – Gross Anatomy From foramen magnum to intervertebral disk between L1 and L2 31 segments  spinal nerves Cervical enlargement Lumbar enlargement Cauda equina –Conus medullaris –Filium terminale

18. Spinal Cord Structure – Microscopic Cross-Section Anterior and posterior horns Gray commissure Central canal Funiculi Ascending and descending tracts

19. Spinal Reflexes Reflex arc –Sensory neuron  interneuron  motor neuron  effector Knee-jerk reflex Wthdrawal reflex

20. Brain Functions Contains nerve centers associated with sensory functions Sensations and perceptions Issues motor commands to skeletal muscle Memory and reasoning Coordinates muscular movements Regulates visceral activities Personality

21. Brain Development

22. Parts of the Brain Cerebrum Diencephalon Cerebellum Brain stem

23. Cerebrum - Structure Cerebral hemispheres Corpus callosum –Falx cerebri Convolutions (gyri) –Sulci –Fissures Lobes – frontal, parietal, temporal, occipital, insula

24. Cerebral Cortex

25. Cerebrum - Functions Interprets impulses from sense organs Initiates voluntary muscle movements Stores information as memory Retrieves information during reasoning Seat of intelligence and personality

26. Hemisphere Dominance

27. Basal Nuclei (Ganglia) Masses of gray matter deep within cerebral hemispheres Produce most of body’s dopamine Relay station for motor impulses

28. Ventricles

29. Cerebrospinal Fluid (CSF) Clear liquid with nutritive and protective functions –Helps maintain stable ion concentration –Pathway to the blood for waste –Absorbs forces to protect CNS –Forms from blood plasma at the choroid plexuses of the pia mater

30. Diencephalon Mostly gray matter Between cerebral hemispheres and above brain stem 7 components

31. Parts of the Diencephalon Thalamus – relay station for sensory impulses, awareness of pain, touch, and temperature Hypothalamus – regulates heart rate, arterial blood pressure, body temperature, water and electrolyte balance, control of hunger and body weight, control of stomach and intestines, control of pituitary gland hormone release, sleep and wakefulness

32. Parts of the Diencephalon continued… Optic chiasma – crossing over of optic nerves Infundibulum – attaches to pituitary Posterior pituitary gland Mammillary bodies Pineal gland

33. Limbic System Made of parts of the frontal and temporal lobes, hypothalamus, thalamus, and basal ganglia Controls emotional experience and expression Guides behavior to increase chances of survival during upsetting experiences

34. Midbrain –Reflex centers associated with eye and head movements Pons –Centers that regulate rate and depth of breathing Medulla oblongata –Transmits all ascending and descending impulses –Contains vital reflex centers: cardiac, vasomotor, respiratory –Contains centers for other reflexes: coughing, sneezing, swallowing, vomiting Brain Stem

35. Reticular Formation Complex network of nerve fibers associated with tiny islands of gray matter throughout the brain stem Wakefulness and sleep Coma

36. Cerebellum Inferior to occipital lobes, posterior to pons and medulla oblongata Coordinates skeletal muscle activity Maintains posture and equilibrium Cerebellar cortex Arbor vitae Cerebellar peduncles

37. Peripheral Nervous System (PNS)

38. Cranial Nerves 12 pair of nerves that arise from underside of brain All except 1 st pair originate from brain stem Pass through foramina of the skull

40. 31 pair that originate from the spinal cord and pass through the intervertebral foramina Provide communication between spinal cord and parts of the upper and lower limbs, neck, and trunk Roots Plexuses

41. Somatic and Special Senses Touch Pain Temperature Smell Taste Hearing Equilibrium Sight

43. Types of Receptors 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

44. Mechanoreceptors Touch and pressure sensors –Sensory nerve fibers –Meissner’s corpuscles –Pacinian corpuscles

45. Temperature sensors –Heat receptors – 25-45*C –Cold receptors – 10-20*C Thermoreceptors

46. Pain Pain receptors are free nerve endings found everywhere except the brain. Poorly understood how stimulation occurs. Most pain fibers terminate in the reticular formation. Referred pain Pain fibers adapt poorly.

47. Sense of Smell - Anatomy Nasal cavity Olfactory receptors Olfactory organs –Olfactory receptor cells –Cilia Olfactory bulbs

48. Physiology of Smell 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.

49. Sense of Taste - Anatomy Taste buds –Papillae –Taste pore Taste cells –Taste hairs

50. Physiology of Taste 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.

51. Taste Sensations Sweet Sour Salty Bitter Savoriness ? Alkaline? Metallic? Pain

53. Ear Structure Auricle (pinna) External auditory meatus (ear canal) Middle ear –Tympanic cavity –Eardrum (tympanic membrane) –Auditory ossicles (malleus, incus, stapes) –Eustachean tube (auditory tube)

54. Inner Ear Structure Labyrinths –Osseous labyrinth –Membranous labyrinth –Perilymph –Endolymph Semicircular canals Cochlea

55. Hearing Apparatus Organ of Corti –Hair cells –Tectorial membrane

56. Physiology of Hearing 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.

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

61. Orbital Eyelid – skin, muscle, conjunctiva Lacrimal gland Extrinsic muscles Accessory Structures of the Eye

62. Layers of the Eye Outer tunic (sclera) –Cornea Middle tunic –Lens –Iris –Pupil –Aqueous humor Inner tunic (retina)

63. Inner Anatomy of the Eye Fovea centralis Optic disk Vitreous humor Retina

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

66. Physiology of Sight Light waves enter the eye. The cornea and lens refract waves to focus an image on the retina. Light-sensitive pigments in rods and cones decompose and trigger a complex series of reactions that initiate nerve impulses. Impulses travel through optic nerves to the optic chiasma. Impulses enter the thalamus then travel optic radiations to the visual cortex.