1. Functions of the Nervous System Functions of the Nervous System  Sensory input – gathering information  To monitor changes occurring inside and outside the body  Changes = stimuli  Integration  To process and interpret sensory input and decide if action is needed  Motor output  A response to integrated stimuli  The response activates muscles or glands

3. Organization of the Nervous System 2 big initial divisions: 1.Central Nervous System CNS The brain + the spinal cord – The center of integration and control 2.Peripheral Nervous System PNS The nervous system outside of the brain and spinal cord Consists of: – 31 Spinal nerves » Carry info to and from the spinal cord – 12 Cranial nerves » Carry info to and from the brain

4. Peripheral Nervous System Responsible for communication between the CNS and the rest of the body. Can be divided into: – Sensory Division Afferent division – Conducts impulses from receptors to the CNS – Informs the CNS of the state of the body interior and exterior – Sensory nerve fibers can be somatic (from skin, skeletal muscles or joints) or visceral (from organs w/i the ventral body cavity) – Motor Division Efferent division – Conducts impulses from CNS to effectors (muscles/glands) – Motor nerve fibers

6. Motor Efferent Division Can be divided further: – Somatic nervous system VOLUNTARY (generally) Somatic nerve fibers that conduct impulses from the CNS to skeletal muscles – Autonomic nervous system INVOLUNTARY (generally) Conducts impulses from the CNS to smooth muscle, cardiac muscle, and glands.

7. Autonomic Nervous System Can be divided into: – Sympathetic Nervous System “Fight or Flight” – Parasympathetic Nervous System “Rest and Digest” These 2 systems are antagonistic. Typically, we balance these 2 to keep ourselves in a state of dynamic balance.

8. Nervous Tissue 2 cell types 1.Neurons Functional, signal conducting cells 2.Neuroglia Supporting cells 1. 2.

9. Neuroglia Outnumber neurons by about 10 to 1 (the guy on the right had an inordinate amount of them). 6 types of supporting cells – 4 are found in the CNS: 1.Astrocytes Star-shaped, abundant, and versatile Controls the chemical environment of the brain Involved in the formation of the blood brain barrier Function in nutrient transfer

10. Neuroglia 2.Microglia Specialized immune cells that act as the macrophages of the CNS Spider-like phagocytes dispose of debris 3.Ependymal Cells Line cavities of the brain and spinal cord Some are ciliated which facilitates the circulation of cerebrospinal fluid

11. Neuroglia 4. Oligodendrocytes Produce the myelin sheath which provides the electrical insulation for certain neurons in the CNS

12. 2 types of glia in the PNS 1.Satellite cells Surround clusters of neuronal cell bodies in the PNS Unknown function 2.Schwann cells Form myelin sheaths around the larger nerve fibers in the PNS. Vital to neuronal regeneration Neuroglia

13. Neurons The functional and structural unit of the nervous system Specialized to conduct information from one part of the body to another There are many, many different types of neurons but most have certain structural and functional characteristics in common: -Cell body (soma) -One or more specialized, slender processes (axons/dendrites) -An input region (dendrites/soma) -A conducting component (axon) -A secretory (output) region (axon terminal)

14. Neuron Anatomy Slide 7.10  Extensions outside the cell body  Dendrites – conduct impulses toward the cell body  Axons – conduct impulses away from the cell body Figure 7.4a

15. Axons and Nerve Impulses Slide 7.11  Axons end in axonal terminals  Axonal terminals contain vesicles with neurotransmitters  Axonal terminals are separated from the next neuron by a gap  Synaptic cleft – gap between adjacent neurons  Synapse – junction between nerves

16. Functional Classification of Neurons Slide 7.14a  Sensory (afferent) neurons  Carry impulses from the sensory receptors  Cutaneous sense organs  Proprioceptors – detect stretch or tension  Motor (efferent) neurons  Carry impulses from the central nervous system  Interneurons (association neurons)  Found in neural pathways in the central nervous system  Connect sensory and motor neurons