1. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Introduction to Nerves and the Nervous System Chapter 19

2. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Role of the Nervous System Controlling the functions of the human body Analyzing incoming stimuli Integrating internal and external responses

3. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Make Up of the Nervous System Central Nervous System (CNS) –Composed of the brain and spinal cord Peripheral Nervous System (PNS) –Sensory receptors bring information into the CNS –Motor nerves carry information away from the CNS Autonomic Nervous System (ANS) –Uses components of the CNS and PNS to regulate automatic or unconscious responses to stimuli

4. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Function of the Cells that Make Up the Nervous System Allow movement Allow realization of various sensations Provide response to internal and external stimuli Stimulate learning, thinking, and emotions

5. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neuron

6. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Axons Afferent Fibers –Nerve axons that run from peripheral receptors into the CNS Efferent Fibers –Nerve axons that carry nerve impulses from the CNS to the periphery to stimulate muscles or glands

7. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Action Potential

8. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Electrolytes Involved in Nerve Cell Action Sodium Potassium Calcium

9. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Movement of Electrolytes with Action Rest/Repolarization –Membrane is impermeable to sodium –Permeable to potassium Action/Depolarization –Sodium goes into the cell –Potassium leaves the cell

10. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Formation of Myelin Sheath

11. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Nerve Synapse Presynaptic Nerve Synaptic Cleft Postsynaptic Effector Cell

12. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Question What nerve axons carry nerve impulses from the central nervous system to the peripheral nervous system? a. Somatic axons b. Efferent fibers c. Afferent fibers d. Sensory axons

13. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer b. Efferent fibers Rationale: Efferent fibers: Nerve axons that carry nerve impulses from the CNS to the periphery to stimulate muscles or glands

14. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurotransmitters Acetylcholine –Communicates between nerves and muscles Norepinephrine and Epinephrine –Catecholamines released by nerves in the sympathetic branch of the ANS Dopamine –Involved in the coordination of impulses and responses

15. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurotransmitters (cont.) Gamma-aminobutyric Acid (GABA) –Inhibits nerve activity and is important in preventing over-excitability or stimulation such as seizure activity Serotonin –Important in arousal and sleep and in preventing depression and promoting motivation

16. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Central Nervous System Made up of brain and spinal cord Structures are covered by meninges Blood brain barrier Blood supply to the brain

17. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Anatomy of the Brain

18. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Hindbrain Runs from the top of the spinal cord into the midbrain Most primitive part of the brain - contains the brainstem Controls basic vital functions: –Breathing –Blood pressure –Swallowing –RAS

19. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Midbrain Contains the thalamus, the hypothalamus, and the limbic system The thalamus sends direct information into the cerebrum to transfer sensations Hypothalamus acts as major sensor activity in the body –Temperature regulation –Water balance –Appetite –Endocrine function

20. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Limbic System Contain high levels of the neurotransmitters –Epinephrine –Norepinephrine –Serotonin Controls expression of emotions

21. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Forebrain Made up of two cerebral hemispheres joined together by the corpus callosum Receives and sends nerve impulses, coordinates speech and communication, and facilitates learning

22. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Spinal Cord Made up of 31 pairs of spinal nerves Each spinal nerve has two components or roots –Sensory fiber (dorsal root) Brings information into the CNS from the periphery –Motor fiber (ventral root) Causes movement or reaction

23. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Function of Central Nervous System Sensory Functions Motor Functions Intellectual and Emotional Functions

24. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Intellectual and Emotional Function Two hemispheres of the brain process information differently Right Side –Artistic Left Side –Analytical When learning takes place and actual change occurs in a neuron

25. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Intellectual and Emotional Function (cont.) Some degree of stress helps facilitate learning Increased stress inhibits learning The limbic system plays a role in learning Emotions associated with memory as well as the present have an impact on stimulus response. The placebo effect is a documented effect of the mind on drug therapy: If a person perceives that a drug will be effective, it is much more likely to actually be effective.

26. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Question What is a documented phenomenon of the mind affecting drug therapy? a. Action potential b. Placebo effect c. Expectation effect d. Learning

27. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer b. Placebo effect Rationale: The placebo effect is a documented effect of the mind on drug therapy: If a person perceives that a drug will be effective, it is much more likely to actually be effective.