1. 1 Nervous System Cell Types of Neural Tissue neurons neuroglial cells

2. 2 Neuron Structure

3. 3 Myelination of Axons White Matter contains myelinated axons Gray Matter contains unmyelinated structures cell bodies, dendrites

4. 4 Classification of Neurons – Structural Differences Bipolar two processes eyes, ears, nose Unipolar one process ganglia Multipolar many processes most neurons of CNS

5. 5 Classification of Neurons – Functional Differences Sensory Neurons afferent carry impulse to CNS most are unipolar some are bipolar Interneurons link neurons multipolar in CNS Motor Neurons multipolar carry impulses away from CNS carry impulses to effectors

6. 6 The Synapse Nerve impulses pass from neuron to neuron at synapses

7. 7 Synaptic Transmission Neurotransmitter s are released when impulse reaches synaptic knob

8. 8 Functions of Nervous System Sensory Function sensory receptors gather information information is carried to the CNS Integrative Function sensory information used to create sensations memory thoughts decisions Motor Function decisions are acted upon impulses are carried to effectors

9. 9 Divisions of the Nervous System Central Nervous System brain spinal cord Peripheral Nervous System nerves cranial nerves spinal nerves

10. 10 Divisions Nervous System

11. 11 Types of Neuroglial Cells in the PNS Schwann Cells produce myelin found on peripheral myelinated neurons speed neurotransmission Satellite Cells support clusters of neuron cell bodies (ganglia)

12. 12 Types of Neuroglial Cells in the CNS Astrocytes scar tissue mop up excess ions, etc induce synapse formation connect neurons to blood vessels Oligodendrocytes myelinating cell Ependyma ciliated line central canal of spinal cord line ventricles of brain Microglia phagocytic cell

13. 13 Types of Neuroglial Cells

14. 14 Meninges membranes surrounding CNS protect CNS three layers dura mater – outer, tough arachnoid mater – thin, weblike pia mater – inner, very thin Central Nervous System(CNS)

15. 15 Meninges of the Spinal Cord

16. 16 Ventricles interconnected cavities within cerebral hemispheres and brain stem continuous with central canal of spinal cord filled with cerebrospinal fluid (CSF) lateral ventricles third ventricle fourth ventricle cerebral aqueduct

17. 17 Spinal Cord slender column of nervous tissue continuous with brain extends downward through vertebral canal begins at level of foramen magnum and terminates near first and second lumbar

18. 18 Cerebrospinal Fluid secreted by choroid plexus circulates in ventricles, central canal of spinal cord, and subarachnoid space completely surrounds brain and spinal cord clear liquid nutritive and protective helps maintain stable ion concentrations in CNS

19. 19 Cross Section of Spinal Cord

20. 20 Reflex Arcs Reflexes – automatic, subconscious responses to stimuli within or outside the body

21. 21 Functions of Spinal Cord center for spinal reflexes conduit for nerve impulses to and from the brain

22. 22 General Components of a Spinal Reflex

23. 23 Reflex Behavior example is the knee-jerk reflex simple monosynaptic reflex helps maintain an upright posture

24. 24 Reflex Behavior example is a withdrawal reflex prevents or limits tissue damage

25. 25 Brain Functions interprets sensations determines perception stores memory reasoning makes decisions coordinates muscular movements regulates visceral activities determines personality Major Parts cerebrum two hemispheres basal nuclei diencephalon brainstem cerebellum

26. 26 Brain

27. 27 Structure of Cerebrum corpus callosum connects cerebral hemispheres convolutions bumps or gyri sulci grooves longitudinal fissure separates hemispheres transverse fissure separates cerebrum from cerebellum

28. 28 Lobes of Cerebral Hemispheres Frontal Parietal Temporal Occipital Insula

29. 29 Functions of the Cerebrum interpreting impulses initiating voluntary movements storing information as memory retrieving stored information reasoning seat of intelligence and personality

30. 30 Functional Regions of Cerebral Cortex Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; contains 75% of all neurons in nervous system

31. 31 Sensory Areas Cutaneous Sensory Area parietal lobe interprets sensations on skin Visual Area occipital lobe interprets vision Auditory Area temporal lobe interprets hearing Sensory Area for Taste near bases of the central sulci Sensory Area for Smell arise from centers deep within the cerebrum

32. 32 Association Areas regions that are not primary motor or primary sensory areas widespread throughout the cerebral cortex analyze and interpret sensory experiences provide memory, reasoning, verbalization, judgment, emotions

33. 33 Association Areas Frontal Lobe Association Areas concentrating planning complex problem solving Parietal Lobe Association Areas understanding speech choosing words to express thought Temporal Lobe Association Areas interpret complex sensory experiences store memories of visual scenes, music, and complex patterns Occipital Lobe Association Areas analyze and combine visual images with other sensory experiences

34. 34 Hemisphere Dominance The left hemisphere is dominant is most individuals Dominant hemisphere controls speech writing reading verbal skills analytical skills computational skills Nondominant hemisphere controls nonverbal tasks motor tasks understanding and interpreting musical and visual patterns provides emotional and intuitive thought processes

35. 35 Memory Short Term working memory closed neuronal circuit circuit is stimulated over and over when impulse flow ceases, memory does also unless it enters long- term memory via memory consolidation Long Term changes structure or function of neurons enhances synaptic transmission

36. 36 Motor Areas Primary Motor Areas frontal lobes control voluntary muscles Broca’s Area anterior to primary motor cortex usually in left hemisphere controls muscles needed for speech Frontal Eye Field above Broca’s area controls voluntary movements of eyes and eyelids

37. 37 Basal Nuclei masses of gray matter deep within cerebral hemispheres caudate nucleus, putamen, globus pallidus produce dopamine control certain muscular activities primarily by inhibiting motor functions

38. 38 Diencephalon between cerebral hemispheres and above the brainstem surrounds third ventricle thalamus hypothalamus optic tracts optic chiasma infundibulum posterior pituitary mammillary bodies pineal gland

39. 39 Diencephalon Thalamus gateway for sensory impulses heading to cerebral cortex receives all sensory impulses (except smell) channels impulses to appropriate part of cerebral cortex for interpretation Hypothalamus maintains homeostasis by regulating visceral activities links nervous and endocrine systems

40. 40 Functions controls emotions produces feelings interprets sensory impulses Diencephalon Consists of portions of frontal lobe portions of temporal lobe hypothalamus thalamus basal nuclei other deep nuclei Limbic System

41. 41 Brain Stem Three Parts 1.Midbrain 2.Pons 3.Medulla Oblongata

42. 42 Midbrain between diencephalon and pons contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain cerebral aqueduct cerebral peduncles – bundles of nerve fibers corpora quadrigemina – centers for visual and auditory reflexes

43. 43 Pons rounded bulge on underside of brainstem between medulla oblongata and midbrain helps regulate rate and depth of breathing relays nerve impulses to and from medulla oblongata and cerebellum

44. 44 Medulla Oblongata enlarged continuation of spinal cord conducts ascending and descending impulses between brain and spinal cord contains cardiac, vasomotor, and respiratory control centers contains various nonvital reflex control centers (coughing, sneezing, swallowing, vomiting)

45. 45 Reticular Formation complex network of nerve fibers scattered throughout the brain stem extends into the diencephalon connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum filters incoming sensory information arouses cerebral cortex into state of wakefulness

46. 46 Cerebellum inferior to occipital lobes posterior to pons and medulla oblongata two hemispheres vermis connects hemispheres cerebellar cortex – gray matter arbor vitae – white matter cerebellar peduncles – nerve fiber tracts dentate nucleus – largest nucleus in cerebellum integrates sensory information concerning position of body parts coordinates skeletal muscle activity maintains posture

47. 47 Divisions of Peripheral Nervous System Sensory Division picks up sensory information and delivers it to the CNS Motor Division carries information to muscles and glands Divisions of the Motor Division Somatic – carries information to skeletal muscle Autonomic – carries information to smooth muscle, cardiac muscle, and glands

48. 48 Cranial Nerves arising form the brain Spinal nerves arising from the spinal cord –Somatic fibers connecting to the skin and skeletal muscles –Autonomic fibers connecting to the viscera Peripheral Nervous System

49. 49 Autonomic Nervous System functions without conscious effort controls visceral activities regulates smooth muscle, cardiac muscle, and glands efferent fibers typically lead to ganglia outside CNS Two Divisions sympathetic – prepares body for fight or flight situations parasympathetic – prepares body for resting and digesting activities

50. 50 Control of Autonomic Activity Controlled largely by CNS Medulla oblongata regulates cardiac, vasomotor and respiratory activities Hypothalamus regulates visceral functions, such as body temperature, hunger, thirst, and water and electrolyte balance Limbic system and cerebral cortex control emotional responses

51. 51 Life-Span Changes Brain cells begin to die before birth Over average lifetime, brain shrinks 10% Most cell death occurs in temporal lobes By age 90, frontal cortex has lost half its neurons Number of dendritic branches decreases Decreased levels of neurotransmitters Fading memory Slowed responses and reflexes Increased risk of falling Changes in sleep patterns that result in fewer sleeping hours

52. 52 Clinical Application Drug Addiction occurs because of the complex interaction of neurons, drugs, and individual behaviors understanding how neurotransmitters fit receptors can help explain the actions of certain drugs drugs have different mechanisms of action several questions remain about the biological effects of addiction, such as why some individuals become addicted and others do not

53. 53 Clinical Application Cerebral Injuries and Abnormalities Concussion brain jarred against cranium loss of consciousness temporary loss of memory mental cloudiness headache recovery usually complete Cerebral Palsy motor impairment at birth caused by blocked cerebral blood vessels during development seizures learning disabilities Cerebrovascular Accident stroke sudden interruption in blood flow brain tissues die