The document provides an overview of the nervous system, including its main functions and classifications. It describes the central nervous system (brain and spinal cord) and peripheral nervous system. It also discusses the structure and function of neurons, how impulses are transmitted, and the main regions and components of the brain and spinal cord.

1. The Nervous System Anatomy & Physiology Essentials of Human Anatomy & Physiology

2. Functions of the Nervous System Sensory input – gathering information To monitor changes occurring inside and outside the body Integration - To process and interpret sensory input and decide if action is needed Motor output A response to stimuli Activates muscles or glands

3. Classification of the Nervous System Central nervous system (CNS): Brain Spinal cord Peripheral nervous system (PNS): Nerves outside the brain and spinal cord

4. The Peripheral Nervous System Sensory (afferent) division - Nerve fibers that carry information to the central nervous system Motor (efferent) division - Nerve fibers that carry impulses away from the central nervous system. Somatic system : voluntary Autonomic system : involuntary

5. Autonomic Nervous System The involuntary branch of the nervous system Consists of only motor nerves Divided into two divisions Sympathetic division – “fight or flight” response Parasympathetic division – “housekeeping”

6. Nervous System Histology Neurons = nerve cells Cells specialized to transmit electrochemical messages Major regions of neurons Cell body – nucleus and metabolic center of the cell Processes – fibers that extend from the cell body

7. Neuron Anatomy Dendrites – conduct impulses toward the cell body Cell body (soma): contains organelles & Nissl substance (specialized rough ER) Axons – conduct impulses away from the cell body Schwann cells – produce myelin sheaths in jelly-roll like fashion Nodes of Ranvier – gaps in myelin sheath along the axon

8. Classification of Neurons Sensory (afferent) neurons Carry impulses from the sensory receptors Cutaneous sense organs Receptors – detect stretch or tension Interneurons (association): “connector” Motor (efferent) neurons Carry impulses from the central nervous system

9. Neuron Classification Figure 7.6

10. Electrochemical Nerve Impulses Dendrite depolarization – a stimulus depolarizes the dendrite’s membrane Sodium (Na + ) flows inside the membrane with the help of Na+ pumps This exchange of ions initiates an (+) action potential in the neuron

11. The Action Potential If the action potential (nerve impulse) starts, it is propagated to the end of the axon Potassium (K+) ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane The sodium-potassium pump restores the original configuration - which is resting potential (-) *** This action requires ATP ***

12. Continuation of the Nerve Impulse between Neurons Impulses are able to cross the synapse to another neuron Neurotransmitter is released from a neuron’s axon terminal The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter An action potential is started in the dendrite

13. How Neurons Communicate at Synapses Figure 7.10

14. The Reflex Arc Reflex – rapid, predictable, and involuntary responses to stimuli Reflex arc – direct route from a sensory neuron, to an interneuron, to an effector

15. Regions of the Brain Cerebral hemispheres Diencephalon Brain stem Cerebellum

16. Cerebral Hemispheres (Cerebrum) Paired (left and right) superior parts of the brain Include more than half of the brain mass The surface is made of ridges (gyri) and grooves (sulci)

17. Specialized Area of the Cerebrum Figure 7.13c

18. Specialized Areas of the Cerebrum Figure 7.13c

19. Diencephalon Sits on top of the brain stem Enclosed by the cerebral hemispheres Three parts: Thalamus Hypothalamus Epithalamus

20. Brain Stem Attaches to the spinal cord Parts of the brain stem: Midbrain Pons Medulla oblongata

21. Cerebellum Two hemispheres with convoluted surfaces Provides involuntary coordination of body movements “ Arbor vitae” design of white & grey matter

22. Spinal Cord Anatomy Extends from the medulla oblongata to the region of T12 Below T12 is the cauda equina (a collection of spinal nerves) Carries sensory and motor information Figure 7.18

23. Cranial Nerves 12 pairs of nerves that mostly serve the head and neck Numbered in order, front to back Most are mixed nerves, but three are sensory only

24. Cranial Nerves 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 V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles VI Abducens nerve – motor fibers to eye muscles

25. Cranial Nerves VII Facial nerve – sensory for taste; motor fibers to the face VIII Vestibulocochlear nerve – sensory for balance and hearing 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

26. Use a Mnemonic Device! “ On Old Olympus’ Towering Top A Fierce Viking Grew Vines and Hops”

27. Use a Mnemonic Device! “ Some say money matters but my brother says big brains matter more.”

28. The Brachial Plexus (Arm) Spinal Nerves to know: Ulnar Nerve – Motor & Sensory, “the funny bone” Radial Nerve – Motor & Sensory Median Nerve – Motor & Sensory

29. The Lumbrosacral Plexus (Leg) Spinal Nerves : Sciatic – M,S Femoral – M,S Obturator – M,S Tibial – M,S Common Fibular – M,S

30. “ You just nailed me in the head!” - Travis Bogumill (21) Eau Claire, WI 1998