1. THE NERVOUS SYSTEM

2. Divisions of the NS Central Nervous System (CNS) Peripheral Nervous System (PNS) Fig. 11.32

3. Sensory vs. Motor Nerves SENSORY nerves: –Body  CNS MOTOR nerves: –CNS  Body Fig. 10.2

4. 2 Different Types of Motor Nerves Somatic NS –consciously controlled effectors Autonomic NS –involuntary effectors

5. Cells of the Nervous System NEUROGLIAL CELLS NEURONS vs.

6. NEUROGLIAL CELLS Fill spaces Provide structure Produce myelin Phagocytize bacteria & cellular debris Outnumber neurons Can divide (mitosis)

7. Neuron Anatomy Overview Dendrites  Cell body  Axon  Synaptic knobs at axon terminals  Effector

8. Neuron Anatomy Schwann cells –type of neuroglial cell –myelin sheath Nodes of Ranvier Fig. 10.3

9. Classification of Neurons THE DIRECTION THEIR SHAPE Fig. 10.6

10. Sensory, Motor, and Interneurons (Direction) Sensory neurons –PNS  CNS Motor neurons –CNS  PNS Interneurons –in between sensory and motor neurons Fig. 10.7

11. Shapes of Neurons Fig. 10.6

12. Neuron vs. a “Nerve” Neuron = a cell Nerve = bundles of neuron axons, and neuroglial cells bound together –outside brain/spinal cord Fig. 11.24

13. Neuron Physiology Sending neuron impulses = action potential –change in electrical charge in cell membrane –depends on electrolytes potassium (K + ) and sodium (Na + )

14. First Things First: Creating a Resting Potential Protein pumps –open and close –let ions through Active pumps –against a gradient Passive pumps –with the gradient Fig. 10.13 Na+/K+ Pump

15. Resting Potential Fig. 10.14

16. Action Potential Fig. 10.15 Action Potential

17. A Nerve Impulse- a series of action potentials Fig. 10.16 Computer activity http://outreach.mcb.harvard.edu/animations/actionpotential.swf

18. Action Potential Fig. 10.18 Action Potential Zoomed Out

19. What happens when the nerve impulse reaches the end of the axon? axon terminals – next to another neuron (as shown) or a muscle or gland Gap called a synapse Synapse Fig. 10.11

20. The Synapse Neurotransmitters Synaptic cleft Receptors Send a message Fig. 10.12

21. Neurotransmitters

22. Classification of Neurotransmitters EXCITATORY = depolarize the next neuron It tells the next neuron/muscle/gland to GO INHIBITORY = hyperpolarize the next neuron –prevent the nerve impulse from continuing It tells the next neuron/muscle/gland to STOP

23. Acetylcholine (ACH) First neurotransmitter discovered (1921) Mostly excitatory Skeletal muscle neuromuscular junctions & synapses between the brain and spinal cord Message = –muscles contract or –continue sending impulses

24. Acetylcholine cont. Nicotine –Activates acetylcholine receptors –Releases dopamine (coming later…) Alzheimers –Memory loss, depression, disorientation, dementia, hallucinations,death –Deficient acetylcholine

25. Glutamate Generally excitatory –helps send messages in the brain Involved in learning and memory Alcohol inhibits glutamate receptor function Monosodium Glutamate (MSG) –food additive –stimulates glutamate receptors in the taste buds

26. Serotonin Found in the brain Primarily inhibitory Sleep, mood and temperature regulation Insomnia – deficient serotonin Antidepressants (Prozac, Zoloft, Paxil, etc) –“SSRI’s” or Selective Serotonin Reuptake Inhibitors –Serotonin accumulates in the synapse –feel more content LSD blocks serotonin MDMA releases excess serotonin

27. Dopamine AKA “the brain reward” Regulates emotions, moods and subconscious control of skeletal muscle Nicotine –excess dopamine release Cocaine –blocks reuptake (leaves more in the synapse) Methamphetamine –excess dopamine release

28. Dopamine - cont’d Dopamine also sends signals that help coordinate your skeletal muscle movements Parkinson’s Disease –deficient dopamine production –tremors

29. GABA Found in the brain Generally inhibitory Prevents the receptor nerve from being overstimulated When it accumulates it has a sedative effect Valium, Xanax and Ativan work by allowing GABA to accumulate Huntington’s Disease – deficient GABA

30. Norepinephrine Found in the brain Alertness, regulation of moods Ritalin & Adderall- increase level of norepi and dopamine Strattera- increase only norepi Clinical depression – low norepi

31. Endorphins Flood the synaptic cleft during pain or stress –Usually inhibit neurons from firing, causing an analgesic effect –At lower levels can excite the next neuron Reduces pain and makes one feel good “Opiates” (heroin, codeine, morphine, oxycodone, hydrocodone, etc) –bind to endorphin receptors and mimic endorphins

32. Anandamide Involved in working memory, regulation of feeding behavior, generation of motivation and pleasure Anandamide receptors are called cannabinoid receptors –A lot of cannabinoid receptors in the hippocampus (short term memory), cerebellum (coordination) and basal ganglia (unconcious muscle movement) of brain THC (found in marijuana) mimics anandamides and binds to cannabinoid receptors

33. Peripheral Nervous System 12 pairs cranial nerves 31 pairs spinal nerves

34. PNS Flow Chart Peripheral Nervous System Motor Sensory nerves Somatic Autonomic nerves nerves Sympathetic Parasympathetic nerves nerves

35. PNS cont. Motor nerves are divided into –Somatic n.s.- conscious activities –Autonomic n.s. – unconscious activities Autonomic n.s is divided into –sympathetic and –parasympathetic divisions.

36. PNS cont. SYMPATHETIC “fight or flight” responses speeds up heart rate, breathing and other functions vital to survival Digestion and other less essential functions will be slowed for awhile. PARASYMPATHETIC when the body is not mobilized and active in fight or flight. speeds up digestion and other essential functions When the body is in this mode, heart rate and breathing are calm.

37. The Central Nervous System The BrainThe Spinal Cord

38. Central Nervous System - Spinal Cord Figs11.5, 11.6, & 11.7

39. Reflexes Fig. 11.8

40. Central Nervous System: The Brain Cerebrum –Largest part –Sensory & motor functions –Higher mental functions (memory, reasoning, etc) Brainstem –Connects the cerebrum to the spinal cord Cerebellum –Coordinates voluntary muscle movements Diencephalon –Processes sensory info Fig. 11.15

41. The Cerebrum Divided into right and left cerebral hemispheres Covered by folds called convolutions/gyri and grooves called sulci (little groves) and fissures (big grooves) Connected by the corpus callosum It has a cortex: an outer covering about 2 mm thick Gray matter vs. white matter

42. The Cerebrum cont. The cerebral cortex is divided into LOBES which control various functions FPOT Fig. 11.16 & 11.17

43. The Cerebrum cont. FRONTAL LOBE – –“Primary Motor Area” controls voluntary muscles –“Broca’s Area” motor speech usually L hemisphere –Voluntary eye movement –Concentration, planning, problem solving, analysis

44. The Cerebrum cont. PARIETAL LOBE –Sensory info: touch, taste, pressure, pain interpretation of sensory info, “awareness” of body –“Wernicke’s Area” sensory speech, understanding written & spoken language usually L hemisphere

45. The Cerebrum cont. OCCIPITAL LOBE –visual senses –analyzing visual patterns, combining visual images with other info (i.e. recognizing a person) TEMPORAL LOBE –sensory smell and hearing –interpretation of sensory experiences (understanding speech, reading)

46. Cerebral Hemispheres Hemisphere = half of sphere (brain) The right side of the brain controls the left side of the body and vice versa Corpus callosum

47. The Cerebellum Integrates sensory info –Balance, coordination of skeletal muscle, posture

48. Brainstem Brainstem: Connects the cerebrum to the spinal cord –Midbrain: visual and auditory reflex center –Pons: transfer nerve impulses –Medulla Oblongata: Cardiac center- heart rate Vasomotor center- smooth muscle in blood vessels/blood pressure Respiratory center- breathing rate Coughing, sneezing, swallowing and vomiting reflexes Fig. 11.21

49. Diencephalon 1.Thalamus- - Receives all sensory impulses (except smell) and relays them to the appropriate region of the cerebral cortex 2. Hypothalamus – –Maintain homeostasis –Links the nervous system to the endocrine system 3. Pituitary & pineal glands Fig. 11.19

50. Diencephalon cont. The limbic system is a collection of structures involved in emotional behavior and your feelings –Includes the amygdala and hippocampus

51. MEMORY Primarily occurs in the cerebrum and the hippocampus (in the diencephalon) 3 main types of memory: 1.Sensory memory = lasts momentarily and involves input from senses 2.Short term memory = lasts from a few seconds or minutes to hours (varies)

52. Memory cont. 3. Long term memory = the neurons actually change shape (dendrites extend, more are made, etc) and connect with other neurons. Lasts days to years (varies).