End Show Slide 1 of 38 Copyright Pearson Prentice Hall 35-2 The Nervous System

End Show 35-2 The Nervous System Slide 2 of 38 Copyright Pearson Prentice Hall 35-2 The Nervous System What are the functions of the nervous system?

End Show 35-2 The Nervous System Slide 3 of 38 Copyright Pearson Prentice Hall 35-2 The Nervous System The nervous system controls and coordinates functions throughout the body and responds to internal and external stimuli.

End Show 35-2 The Nervous System Slide 4 of 38 Copyright Pearson Prentice Hall Neurons The messages carried by the nervous system are electrical signals called impulses. The cells that transmit these impulses are called neurons.

End Show 35-2 The Nervous System Slide 5 of 38 Copyright Pearson Prentice Hall Neurons Neurons are classified according to the direction in which an impulse travels. Sensory neurons carry impulses from the sense organs to the spinal cord and brain. Motor neurons carry impulses from the brain and spinal cord to muscles and glands. Interneurons connect sensory and motor neurons and carry impulses between them.

End Show 35-2 The Nervous System Slide 6 of 38 Copyright Pearson Prentice Hall Neurons Structures of a Neuron Axon terminals Myelin sheath Cell body Nodes Axon Dendrites Nucleus

End Show 35-2 The Nervous System Slide 7 of 38 Copyright Pearson Prentice Hall Neurons The largest part of a typical neuron is the cell body. It contains the nucleus and much of the cytoplasm. Cell body

End Show 35-2 The Nervous System Slide 8 of 38 Copyright Pearson Prentice Hall Neurons Dendrites extend from the cell body and carry impulses from the environment toward the cell body. Dendrites

End Show 35-2 The Nervous System Slide 9 of 38 Copyright Pearson Prentice Hall Neurons The axon is the long fiber that carries impulses away from the cell body. Axon terminals Axon

End Show 35-2 The Nervous System Slide 10 of 38 Copyright Pearson Prentice Hall Neurons The axon ends in axon terminals. Axon terminals Axon

End Show 35-2 The Nervous System Slide 11 of 38 Copyright Pearson Prentice Hall Neurons The axon is sometimes surrounded by an insulating membrane called the myelin sheath. There are gaps in the myelin sheath, called nodes, where the membrane is exposed. Impulses jump from one node to the next. Myelin sheath Nodes

End Show 35-2 The Nervous System Slide 12 of 38 Copyright Pearson Prentice Hall The Nerve Impulse The Resting Neuron (aka Resting Potental) When resting, the outside of the neuron has a net positive charge. The inside of the neuron has a net negative charge. Also, the inside of the cell has more potassium (K + ) ions and few sodium (Na + ) ions. Because… The sodium-potassium pump in the nerve cell membrane pumps potassium (K + ) ions into the cell and (Na + ) ions out of the cell by active transport.

End Show 35-2 The Nervous System Slide 13 of 38 Copyright Pearson Prentice Hall The Nerve Impulse Sodium-Potassium Pump

End Show 35-2 The Nervous System Slide 14 of 38 Copyright Pearson Prentice Hall The Nerve Impulse How is a nerve impulse transmitted?

End Show 35-2 The Nervous System Slide 15 of 38 Copyright Pearson Prentice Hall The Nerve Impulse The Moving Impulse An impulse begins when a neuron is stimulated by another neuron or by the environment.

End Show 35-2 The Nervous System Slide 16 of 38 Copyright Pearson Prentice Hall The Nerve Impulse During activity, the resting stage is reversed and an impulse moves along the axon. This is called an action potential.

End Show 35-2 The Nervous System Slide 17 of 38 Copyright Pearson Prentice Hall The Nerve Impulse During an action potential, the potassium pumps open, allowing K + ions to flow out of the neuron.

End Show 35-2 The Nervous System Slide 18 of 38 Copyright Pearson Prentice Hall The Nerve Impulse The impulse continues to move along the axon untill it reaches the axon terminal.

End Show 35-2 The Nervous System Slide 19 of 38 Copyright Pearson Prentice Hall The Nerve Impulse Threshold A stimulus MUST be strong enough to cause a neuron to send an impulse. The minimum level of a stimulus is called the threshold.

End Show 35-2 The Nervous System Slide 20 of 38 Copyright Pearson Prentice Hall The Nerve Impulse Just Read (Do Not Write) A stimulus that is stronger than the threshold produces an impulse. A stimulus that is weaker than the threshold produces no impulse.

End Show 35-2 The Nervous System Slide 21 of 38 Copyright Pearson Prentice Hall The Synapse At the end of the neuron, the impulse reaches an axon terminal. Usually the neuron makes contact with another cell at this site. The neuron may pass the impulse along to the second cell. The spot where an impulse is transferred to another cell is called a synapse.

End Show 35-2 The Nervous System Slide 22 of 38 Copyright Pearson Prentice Hall The Synapse A Synapse

End Show 35-2 The Nervous System Slide 23 of 38 Copyright Pearson Prentice Hall The Synapse Neurotransmitters are chemicals used by a neuron to transmit an impulse across a synapse to another cell. Vesicle Neurotransmitter

End Show 35-2 The Nervous System Slide 24 of 38 Copyright Pearson Prentice Hall The Synapse Neurotransmitters attach to membrane receptors on the next cell. A new impulse begins on the next neuron cell. Receptor

End Show 35-2 The Nervous System Slide 25 of 38 Copyright Pearson Prentice Hall The Synapse Moments after binding to receptors, neurotransmitters are released from the cell surface. The neurotransmitters may then be broken down by enzymes, or taken up and recycled by the axon terminal.

End Show 35-2 The Nervous System Slide 26 of 38 Copyright Pearson Prentice Hall 35-3 Divisions of the Nervous System

End Show 35-2 The Nervous System Slide 27 of 38 Copyright Pearson Prentice Hall The Nervous System The human nervous system has two major divisions: central nervous system (CNS) peripheral nervous system (PNS)

End Show 35-2 The Nervous System Slide 28 of 38 Copyright Pearson Prentice Hall The Central Nervous System The CNS relays messages, processes information, and analyzes information. The CNS consists of the brain and the spinal cord. The brain and spinal cord are wrapped in three layers of connective tissue known as meninges.

End Show 35-2 The Nervous System Slide 29 of 38 Copyright Pearson Prentice Hall The Central Nervous System Between the meninges and the CNS tissue is a space filled with cerebrospinal fluid. Cerebrospinal fluid acts as a shock absorber that protects the central nervous system. Cerebrospinal fluid also permits exchange of nutrients and waste products between blood and nervous tissue.

End Show 35-2 The Nervous System Slide 30 of 38 Copyright Pearson Prentice Hall The Brain Parts of The Human Brain Thalamus Pineal gland Cerebellum Spinal cord Hypothalamus Pituitary gland Cerebrum Brain stem Pons Medulla oblongata

End Show 35-2 The Nervous System Slide 31 of 38 Copyright Pearson Prentice Hall The Brain The brain is the place to which impulses flow and from which impulses originate.

End Show 35-2 The Nervous System Slide 32 of 38 Copyright Pearson Prentice Hall The Brain The Cerebrum Is the largest region of the brain. It controls the voluntary (conscious) activities. Used for intelligence, learning, and judgment.

End Show 35-2 The Nervous System Slide 33 of 38 Copyright Pearson Prentice Hall The Brain A deep groove divides the cerebrum into hemispheres, which are connected by a band of tissue called the corpus callosum. Each hemisphere is divided into regions called lobes.

End Show 35-2 The Nervous System Slide 34 of 38 Copyright Pearson Prentice Hall The Brain Lobes of the Cerebrum

End Show 35-2 The Nervous System Slide 35 of 38 Copyright Pearson Prentice Hall The Brain Each half of the cerebrum deals with the opposite side of the body: The left half of the cerebrum controls the right side of the body. The right half of the cerebrum controls the left side of the body.

End Show 35-2 The Nervous System Slide 36 of 38 Copyright Pearson Prentice Hall The Brain The outer layer of the cerebrum is called the cerebral cortex and consists of gray matter. The inner layer of the cerebrum consists of white matter, which is made up of bundles of axons with myelin sheaths.

End Show 35-2 The Nervous System Slide 37 of 38 Copyright Pearson Prentice Hall The BrainCerebellum

End Show 35-2 The Nervous System Slide 38 of 38 Copyright Pearson Prentice Hall The Brain The Cerebellum Is second largest region of the brain. It coordinates and balances the actions of the muscles so that the body can move gracefully and efficiently.

End Show 35-2 The Nervous System Slide 39 of 38 Copyright Pearson Prentice Hall The BrainPons Medulla oblongata Brain stem

End Show 35-2 The Nervous System Slide 40 of 38 Copyright Pearson Prentice Hall The Brain The Brain Stem The brain stem connects the brain and spinal cord. It has two regions: the pons and the medulla oblongata. Each region regulates information flow between the brain and the rest of the body. Blood pressure, heart rate, breathing, and swallowing are controlled in the brain stem.

End Show 35-2 The Nervous System Slide 41 of 38 Copyright Pearson Prentice Hall The BrainThalamus Hypothalamus

End Show 35-2 The Nervous System Slide 42 of 38 Copyright Pearson Prentice Hall The Brain The Thalamus and Hypothalamus The thalamus receives messages from all sensory receptors throughout the body and relays the information to the proper region of the cerebrum for further processing.

End Show 35-2 The Nervous System Slide 43 of 38 Copyright Pearson Prentice Hall The Brain The hypothalamus controls recognition and analysis of hunger, thirst, fatigue, anger, and body temperature.

End Show 35-2 The Nervous System Slide 44 of 38 Copyright Pearson Prentice Hall The Spinal Cord The spinal cord links the brain and the rest of the body. Information, including some kinds of reflexes, are processed directly in the spinal cord. A reflex is a quick, automatic response to a stimulus.

End Show 35-2 The Nervous System Slide 45 of 38 Copyright Pearson Prentice Hall The Peripheral Nervous System The PHS is all of the nerves and associated cells that are not part of the brain and the spinal cord. The PHS includes cranial nerves, spinal nerves, and ganglia. Ganglia are collections of nerve cell bodies.

End Show 35-2 The Nervous System Slide 46 of 38 Copyright Pearson Prentice Hall The Peripheral Nervous System Two divisions of the peripheral nervous system. The sensory division transmits impulses from sense organs to the central nervous system. The motor division transmits impulses from the central nervous system to the muscles or glands. The motor division is divided into the somatic nervous system and the autonomic nervous system.

End Show 35-2 The Nervous System Slide 47 of 38 Copyright Pearson Prentice Hall The Peripheral Nervous System The Somatic Nervous System The SNS regulates conscious control activities such as the movement of skeletal muscles. Some somatic nerves are involved with reflexes.

End Show 35-2 The Nervous System Slide 48 of 38 Copyright Pearson Prentice Hall The Peripheral Nervous System A reflex arc includes a sensory receptor, sensory neuron, motor neuron, and effector that are involved in a quick response to a stimulus.

End Show 35-2 The Nervous System Slide 49 of 38 Copyright Pearson Prentice Hall The Peripheral Nervous System Reflex Arc Sensory receptors Effector (responding muscle) Interneuron Spinal cord Sensory neuron Motor neuron

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End Show - or - Continue to: Click to Launch: Slide 51 of 38 Copyright Pearson Prentice Hall 35-2

End Show Slide 52 of 38 Copyright Pearson Prentice Hall 35-2 Neurons that carry impulses from the brain and spinal cord to the muscles are a.interneurons. b.sensory neurons. c.resting neurons. d.motor neurons.

End Show Slide 53 of 38 Copyright Pearson Prentice Hall 35-2 The part of the neuron that carries impulses toward the cell body is the a.axon. b.myelin sheath. c.dendrite. d.nodes.

End Show Slide 54 of 38 Copyright Pearson Prentice Hall 35-2 The minimum level of a stimulus that is required to activate a neuron is called its a.action potential. b.resting potential. c.threshold. d.synapse.

End Show Slide 55 of 38 Copyright Pearson Prentice Hall 35-2 Chemicals that are used by a neuron to transmit impulses are called a.neurotransmitters. b.synapses. c.axons. d.inhibitors.

End Show Slide 56 of 38 Copyright Pearson Prentice Hall 35-2 An action potential begins when a.sodium ions flow into the neuron. b.potassium ions flow into the neuron. c.sodium and potassium ions flow into the neuron. d.sodium and potassium ions flow out of the neuron.