Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slides 7.1 – 7.22 Seventh Edition Elaine N. Marieb Chapter 7 The Nervous System Lecture Slides in PowerPoint by Jerry L. Cook

Functions of the Nervous System Slide 7.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  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

Functions of the Nervous System Slide 7.1b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Motor output  A response to integrated stimuli  The response activates muscles or glands

Structural Classification of the Nervous System Slide 7.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Central nervous system (CNS)  Brain  Spinal cord  Peripheral nervous system (PNS)  Nerve outside the brain and spinal cord

Functional Classification of the Peripheral Nervous System Slide 7.3a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sensory (afferent) division  Nerve fibers that carry information to the central nervous system Figure 7.1

The Term central nervous system refers to the: A.Autonomic and peripheral nervous systems B.Brain, spinal cord, and peripheral nerves C.Brain and cranial nerves D.Spinal cord and spinal nerves E.Brain and spinal cord

Functional Classification of the Peripheral Nervous System Slide 7.3b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Motor (efferent) division  Nerve fibers that carry impulses away from the central nervous system Figure 7.1

Functional Classification of the Peripheral Nervous System Slide 7.3c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Motor (efferent) division  Two subdivisions  Somatic nervous system = voluntary  Autonomic nervous system = involuntary Figure 7.1

Organization of the Nervous System Slide 7.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.2

Nervous Tissue: Support Cells (Neuroglia) Slide 7.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Astrocytes  Abundant, star-shaped cells  Brace neurons  Form barrier between capillaries and neurons  Control the chemical environment of the brain Figure 7.3a

Nervous Tissue: Support Cells Slide 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Microglia  Spider-like phagocytes  Dispose of debris  Ependymal cells  Line cavities of the brain and spinal cord  Circulate cerebrospinal fluid Figure 7.3b, c

Nervous Tissue: Support Cells Slide 7.7a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Oligodendrocytes  Produce myelin sheath around nerve fibers in the central nervous system Figure 7.3d

Ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid are: A.Ependymal cells B.Schwann cells C.oligodendrocytes D.astrocytes E.microglia

Nervous Tissue: Support Cells Slide 7.7b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Satellite cells  Protect neuron cell bodies  Schwann cells  Form myelin sheath in the peripheral nervous system Figure 7.3e

Nervous Tissue: Neurons Slide 7.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Neurons = nerve cells  Cells specialized to transmit messages  Major regions of neurons  Cell body – nucleus and metabolic center of the cell  Processes – fibers that extend from the cell body

Neuron Anatomy Slide 7.9a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cell body  Nissl substance – specialized rough endoplasmic reticulum  Neurofibrils – intermediate cytoskeleton that maintains cell shape Figure 7.4a

Neuron Anatomy Slide 7.9b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cell body  Nucleus  Large nucleolus Figure 7.4a

Neuron Anatomy Slide 7.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Extensions outside the cell body  Dendrites – conduct impulses toward the cell body  Axons – conduct impulses away from the cell body Figure 7.4a

Axons and Nerve Impulses Slide 7.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  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 Slide 7.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Schwann cells – produce myelin sheaths in jelly-roll like fashion  Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5

The part of the cell (mostly cytoplasm) that is external to the myelin sheath: A.Nissl substance B.axolemma C.neurilemma D.White matter E.Gray matter

The part of the neuron that normally receives stimuli is called a(n): A.axon B.dendrite C.neurolemma D.Schwann cell E.satellite cell

Neuron Cell Body Location Slide 7.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Most are found in the central nervous system  Gray matter – cell bodies and unmylenated fibers  Nuclei – clusters of cell bodies within the white matter of the central nervous system  Ganglia – collections of cell bodies outside the central nervous system

Which of the following is NOT a structural feature of a neuron: A.Synaptic cleft B.Cell body C.dendrites D.axon E.Node of Ranvier

Collections of nerve cell bodies outside the central nervous system are called: A.nuclei B.nerves C.ganglia D.tracts E.neuroglia

Functional Classification of Neurons Slide 7.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  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

Functional Classification of Neurons Slide 7.14b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Interneurons (association neurons)  Found in neural pathways in the central nervous system  Connect sensory and motor neurons

Which of the following are touch receptors: A.Naked nerve endings B.Pacinian corpuscles C.Golgi tendon organs D.Meissner’s corpuscles E.Muscle spindles

A neuron whose primary function is connecting other neurons is called a(n): A.Efferent neuron B.Afferent neuron C.Association neuron D.Glial cell E.Satellite cell

Neuron Classification Slide 7.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.6

Structural Classification of Neurons Slide 7.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Multipolar neurons – many extensions from the cell body Figure 7.8a

Structural Classification of Neurons Slide 7.16b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Bipolar neurons – one axon and one dendrite Figure 7.8b

Structural Classification of Neurons Slide 7.16c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Unipolar neurons – have a short single process leaving the cell body Figure 7.8c

Bipolar neurons are commonly: A.Motor neurons B.Called neuroglia C.Found in ganglia D.Found in the eye E.Abundant in adults

Functional Properties of Neurons Slide 7.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Irritability – ability to respond to stimuli  Conductivity – ability to transmit an impulse  The plasma membrane at rest is polarized  Fewer positive ions are inside the cell than outside the cell

Starting a Nerve Impulse Slide 7.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Depolarization – a stimulus depolarizes the neuron’s membrane  A depolarized membrane allows sodium (Na + ) to flow inside the membrane  The exchange of ions initiates an action potential in the neuron Figure 7.9a–c

The Action Potential Slide 7.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  If the action potential (nerve impulse) starts, it is propagated over the entire axon  Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane  The sodium-potassium pump restores the original configuration  This action requires ATP

Nerve Impulse Propagation Slide 7.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The impulse continues to move toward the cell body  Impulses travel faster when fibers have a myelin sheath Figure 7.9c–e

Continuation of the Nerve Impulse between Neurons Slide 7.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Impulses are able to cross the synapse to another nerve  Neurotransmitter is released from a nerve’s axon terminal  The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter  An action potential is started in the dendrite

Saltatory Conduction: A.Occurs only if the myelin sheath is continuous B.Occurs only if nodes of Ranvier are lacking C.Occurs only in the absence of axon hillocks D.Is faster than conduction on an unmyelinated fiber E.Is slower than conduction on an unmyelinated fiber

How Neurons Communicate at Synapses Slide 7.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.10

The point at which an impulse from one nerve cell is communicated to another nerve cell is the: A.Cell body B.synapse C.receptor D.effector E.Collateral branch

The substance that is released at axonal endings to propagate a nervous impulse is called: A.An ion B.Nerve glue C.A neurotransmitter D.The sodium-potassium pump E.An action potential

Questions?