2. 3 Functions of the Nervous System (SIM) 1. Sensory input—gathering information – monitor changes inside and outside the body – changes = stimuli – sensory receptors responsible for input 2. Integration – decide if and what action is needed 3. Motor Output – a response – activates muscles or glands (effectors)

3. Functions of the Nervous System Figure 7.1

4. Organization of the Nervous System

5. Structural Classification of the Nervous System 2 Main Divisions 1.Central nervous system (CNS) – Brain – Spinal cord 2. Peripheral nervous system (PNS) Spinal nerves (to and from spinal cord) Cranial nerves (to and from brain)

6. Functional Classification of the Peripheral Nervous System Sensory (afferent) division – carry information to the central nervous system – Keep the body informed of internal and external environment Motor (efferent) division – carry impulses away from the central nervous system – Cause some sort of effect

7. Functional Classification of the Peripheral Nervous System – Two subdivisions of the Motor (efferent) division 1.Somatic nervous system = voluntary Skeletal muscles (except reflexes) 2.Autonomic nervous system = involuntary smooth muscle, cardiac muscle, glands

8. Functional Classification of the Peripheral Nervous System Two subdivisions of the Autonomic nervous system 1. Sympathetic  Concerned with processes involving expending energy.  Active during times of extreme stress, emotion, and exercise. 2.Parasympathetic  Concerned with conservation of energy  Can dominate sympathetic system. Books says antagonistic, but they are more complimentary

10. Nervous Tissue: 2 Main Types of Cells 1. Neurons carry messages (impulses) 2. Supporting cells or neuroglia

11. Nervous Tissue: Neurons specialized to transmit messages – structures may differ, but all neurons have: PARTS: 1. Cell body – contains transparent nucleus – large conspicuous nucleolus – metabolic center of the cell

12. Nervous Tissue: Neurons 2 Types of Processes fibers that extend from the cell body – Dendrites—conduct impulses toward the cell body – Axons—conduct impulses away from the cell body

13. Nervous Tissue: Neurons Figure 7.4

14. Axon Terminals- axon ends contain vesicles with neurotransmitters do not touch dendrite of next neuron OR muscle – Synaptic cleft—gap between adjacent neurons – Synapse—junction between nerves

15. Nervous Tissue: Neurons Myelin sheath—whitish, fatty material covering axons Schwann cells—produce myelin sheaths in jelly roll–like fashion Nodes of Ranvier—gaps in myelin sheath along the axon

16. Neurons Figure 7.4

17. Functional Classification of Neurons Sensory (afferent) neurons – Carry impulses from the sensory receptors to the CNS Cutaneous sense organs – Heat, cold, pressure, pain Proprioceptors—detect stretch or tension (found in muscles, tendons and joints) Motor (efferent) neurons – Carry impulses from the central nervous system to viscera, muscles, or glands

18. Functional Classification of Neurons Interneurons (association neurons) – Found in neural pathways in the central nervous system – Connect sensory and motor neurons Receptors – Specialized dendritic endings Simple: cutaneous receptors (pain, touch) Complex: special sense organs (eye, nose)

19. Figure 7.6

20. 6 Types of Support Cells 1. Astrocytes (CNS) – star-shaped cells – Most abundant of the glial cells Mainly function between neurons and capillaries Bridging the two Communication between the two Barrier between the two – Control the chemical environment of the brain (taking in extra K+ or neurotransmitters)

21. Nervous Tissue: Support Cells 2. Microglia (CNS) – Spiderlike phagocytes (phago- eat) – Dispose of debris (dead brain cells and bacteria)

22. Nervous Tissue: Support Cells 3. Ependymal cells (CNS) – Line cavities of the brain and spinal cord – Ciliated cuboidal epithelial cells – Circulate cerebrospinal fluid – Help in production of cerebrospinal fluid

23. Nervous Tissue: Support Cells 4. Oligodendrocytes (CNS) – Wrap around nerve fibers in the central nervous system – Produce myelin sheaths in CNS 5. Schwann cells (PNS) – Form myelin sheath in the PNS

24. Nervous Tissue: Support Cells 6. Satellite cells (PNS) – Protect neuron cell bodies by providing cushion

25. Regions of a Typical Neuron

26. Vocabulary Tract- bundles of nerve fibers running through the CNS. Nerves-bundles of nerve fibers running through the PNS White matter- Consists of dense collections of myelinated fibers Gray matter- Consists of mostly unmyelinated fibers and cell bodies