1 Hole’s Human Anatomy and Physiology Twelfth Edition Shier  Butler  Lewis Chapter 10 Nervous System I: Basic Structure and Function Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 10.1: Introduction Cell types in neural tissue: Neurons Neuroglial cells (also known as neuroglia, glia, and glial) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dendrites Cell body Axon Nuclei of neuroglia © Ed Reschke

3 Divisions of the Nervous System Central Nervous System (CNS) Brain Spinal cord Peripheral Nervous System (PNS) Cranial nerves Spinal nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Brain (a) Spinal cord Spinal nerves Cranial nerves

4 Divisions of Peripheral Nervous System Sensory Division Picks up sensory information and delivers it to the CNS Motor Division Carries information to muscles and glands Divisions of the Motor Division: Somatic – carries information to skeletal muscle Autonomic – carries information to smooth muscle, cardiac muscle, and glands

5 Divisions Nervous System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sensory divisionSensory receptors Motor division Skeletal muscle Brain (a)(b) Spinal cord Spinal nerves Cranial nerves Central Nervous System (brain and spinal cord) Peripheral Nervous System (cranial and spinal nerves) Smooth muscle Cardiac muscle Glands Autonomic Nervous System Somatic Nervous System

6 10.2: General Functions of the Nervous System The three general functions of the nervous system: Receiving stimuli = sensory function Deciding about stimuli = integrative function Reacting to stimuli = motor function

7 Functions of Nervous System Sensory Function Sensory receptors gather information Information is carried to the CNS Integrative Function Sensory information used to create: Sensations Memory Thoughts Decisions Motor Function Decisions are acted upon Impulses are carried to effectors

8 10.3: Description of Cells of the Nervous System Neurons vary in size and shape They may differ in length and size of their axons and dendrites Neurons share certain features: Dendrites A cell body An axon

9 Neuron Structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cell body Neurofibrils Nucleus Nucleolus Dendrites Impulse Nodes of Ranvier Myelin (cut) Axon Chromatophilic substance (Nissl bodies) Axonal hillock Portion of a collateral Schwann cell Nucleus of Schwann cell Synaptic knob of axon terminal

10 Myelination of Axons White Matter Contains myelinated axons Considered fiber tracts Gray Matter Contains unmyelinated structures Cell bodies, dendrites Dendrite Node of Ranvier Myelinated region of axon Axon (a) Unmyelinated region of axon Neuron cell body Neuron nucleus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (c) Enveloping Schwann cell Schwann cell nucleus Unmyelinated axon Longitudinal groove

: Classification of Neurons and Neuroglia Neurons vary in function They can be sensory, motor, or integrative neurons Neurons vary in size and shape, and in the number of axons and dendrites that they may have Due to structural differences, neurons can be classified into three (3) major groups: Bipolar neurons Unipolar neurons Multipolar neurons

12 Classification of Neurons: Functional Differences Sensory Neurons Afferent Carry impulse to CNS Most are unipolar Some are bipolar Interneurons Link neurons Aka association neurons or internuncial neurons Multipolar Located in CNS Motor Neurons Multipolar Carry impulses away from CNS Carry impulses to effectors Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Central nervous systemPeripheral nervous system Cell body Interneurons Dendrites Axon Sensory (afferent) neuron Motor (efferent) neuron Cell body Axon (central process) Axon (peripheral process) Sensory receptor Effector (muscle or gland) Axon terminal