Chapter 10 Nervous System I Cell Types of Neural Tissue neurons neuroglial cells 10-2

Divisions of the Nervous System Central Nervous System Peripheral Nervous System 10-1

Divisions of Peripheral Nervous System Sensory Division Motor Division Divisions of the Motor Division Somatic – Autonomic – 10-4

Divisions Nervous System 10-5

Functions of Nervous System Sensory Function Integrative Function sensory information used to create sensations memory thoughts decisions Motor Function decisions are acted upon impulses are carried to effectors 10-6

Neuron Structure 10-7

Myelination of Axons White Matter Gray Matter cell bodies, dendrites 10-8

Classification of Neurons Bipolar two processes eyes, ears, nose Unipolar one process ganglia Multipolar many processes most neurons of CNS 10-9

Classification of Neurons Sensory Neurons most are unipolar some are bipolar Interneurons link neurons multipolar Motor Neurons multipolar 10-10

Types of Neuroglial Cells Schwann Cells peripheral nervous system myelinating cell Oligodendrocytes CNS myelinating cell Astrocytes CNS scar tissue mop up excess ions, etc induce synapse formation connect neurons to blood vessels Microglia CNS phagocytic cell Ependyma CNS ciliated line central canal of spinal cord line ventricles of brain 10-11

Resting Membrane Potential polarized membrane due to distribution of ions Na + /K + pump exe

Potential Changes sodium channels open and membrane depolarizes potassium leaves cytoplasm and membrane repolarizes 10-15

Local Potential Changes occur on membranes of dendrites and cell bodies caused by various stimuli if membrane potential becomes more negative, it has hyperpolarized if membrane potential becomes more positive, it has depolarized summation can lead to threshold stimulus that starts an action potential exe

Action Potentials nerve impulse occur on axons refractory period absolute - time when threshold stimulus does not start another action potential relative – time when stronger threshold stimulus can start another action potential 10-17

Action Potentials 10-18

The Synapse Nerve impulses pass from neuron to neuron at synapses 10-21

Synaptic Transmission exe

Neurotransmitters 10-25

Impulse Processing Neuronal Pools groups of interneurons that make synaptic connections with each other interneurons work together to perform a common function each pool receives input from other neurons each pool generates output to other neurons 10-26

Convergence neuron receives input from several neurons incoming impulses represent information from different types of sensory receptors allows nervous system to collect, process, and respond to information makes it possible for a neuron to sum impulses from different sources 10-27

Divergence one neuron sends impulses to several neurons can amplify an impulse impulse from a single neuron in CNS may be amplified to activate enough motor units needed for muscle contraction 10-28

Clinical Application Multiple Sclerosis Symptoms blurred vision numb legs or arms can lead to paralysis Causes myelin destroyed in various parts of CNS hard scars (scleroses) form nerve impulses blocked muscles do not receive innervation may be related to a virus Treatments no cure bone marrow transplant interferon (anti-viral drug) hormones 10-29