The master communication center of the body. The Nervous System The master communication center of the body. 1

The Nervous System 3 Main Functions: Monitor all information about changes occurring both inside and outside the body. Process and interprets the information received and integrates it in order to make decisions. Command responses by activating muscles, glands, and other parts of the nervous system. Our nervous system allows us to feel pain. 2

12 pairs of cranial nerves Structural Classification CNS Brain & Spinal Cord PNS Cranial Nerves & Spinal Nerves 12 pairs of cranial nerves 32 pairs of spinal nerves CLICK HYPER LINK ON PICTURE FIRST The parts of the nervous system can be classified based on structure or function The structural classification is the Central nervous system the brain and spinal cord and the peripheral nervous system which include 12 pairs of cranial nerves and 32 pairs of spinal nerves 3

Functional Organization Figure 7.2

Functional Classification Autonomic motor Autonomic sensory The central nervous system talks only to the peripheral nervous system The peripheral nervous system has to deal with both motor and sensory systems and as far as function goes there are two main divisions of the nervous system - Somatic and Autonomic Someone tell me what the Autonomic nervous systems deal with? – controls the nerve impulses that deal with involuntary movement Give me some examples – digestion the food we had for lunch, heart beating What do the somatic nervous systems deal with? – controls the flow of nerve impulses necessary for voluntary movements. Give me some examples of voluntary movements – walking, lifting, reaching, tilting your head 5

Neurons Nerve Cells http://www.morphonix.com

Neuron Anatomy Extensions outside the cell body Dendrites – conduct impulses toward the cell body Axons – conduct impulses away from the cell body Figure 7.4a

Mad, Mad, Mad scientist The Neuron Cell body Nucleus Axon Draw a neuron and label the dendrites, the axon terminals, the axon, the nucleus, cell body and myelin sheath. Then draw arrows to show the direction the impulse goes. A nerve is an organ containing a bundle of neurons Axon terminals Cell body Dendrites Nucleus Myelin sheath Axon 8

Physiology of Neurons 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

Neuron Classification Figure 7.6

(Afferent)carry impulses from receptors to CNS Neurons Sensory neuron (Afferent)carry impulses from receptors to CNS relay neuron impulses from sensory to motor nerves Motor neuron (Efferent) carry impulses from CNS to effector (muscle or gland) There are three kinds of neurons. Each is designed to carry out its job. Sensory Neurons Carry impulses from receptors e.g pain receptors in skin to the Central Nervous Syystem ( brain or spinal cord) Relay neurons relay impulses from sensory nerves to motor nerves. Motor neurons carry impulses from central nervous syste, to effector e.g. muscle to bring about movement or gland to bring about secretion of hormone e.g ADH 11

Axons and Nerve Impulses 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

Nerve Fiber Coverings Schwann cells – produce myelin sheaths Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5

Structural Classification of Neurons Multipolar neurons – many extensions from the cell body Since all motor and association neurons are multipolar, this is the most common structural type. Figure 7.8a

Structural Classification of Neurons Bipolar neurons – one axon and one dendrite Bipolar neurons are rare in adults, found only in some special sense organs (eye, ear) where they act as sensory receptor cells. Figure 7.8b

Structural Classification of Neurons Unipolar neurons – have a short single process leaving the cell body Sensory neurons found in the PNS ganglia (a mass of nerve cell bodies) are unipolar. Figure 7.8c

Crossing the Synapses The neurons are not touching each other, there is a space called a synapse that the signal has to cross it does with the use chemical and receptors. 17

Find information regarding different types of “supporting” neurons. Neuroglia: The Supporting Neurons Find information regarding different types of “supporting” neurons. Use your book to fill in the information about the various Glial cells: Astrocyte, Microglia, Ependymal, Oligodendrocyte, and Schwann cells. 19

Types of Neuroglial Cells