© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 28 Nervous Systems

Introduction  Spinal cord injuries disrupt communication between –the central nervous system (brain and spinal cord) and –the rest of the body. © 2012 Pearson Education, Inc.

 Over 250,000 Americans are living with spinal cord injuries.  Spinal cord injuries –happen more often to men, –happen mostly to people in their teens and 20s, –are caused by vehicle accidents, gunshots, and falls, and –are usually permanent because the spinal cord cannot be repaired. Introduction © 2012 Pearson Education, Inc.

Figure 28.0_1 Chapter 28: Big Ideas Nervous System Structure and Function The Human BrainAn Overview of Animal Nervous Systems Nerve Signals and Their Transmission

Figure 28.0_2

NERVOUS SYSTEM STRUCTURE AND FUNCTION © 2012 Pearson Education, Inc.

28.1 Nervous systems receive sensory input, interpret it, and send out appropriate commands  The nervous system –obtains sensory information, sensory input, –processes sensory information, integration, and –sends commands to effector cells (muscles) that carry out appropriate responses, motor output. © 2012 Pearson Education, Inc.

Figure 28.1A Sensory receptor Effector cells Sensory input Motor output Integration Brain and spinal cord Central nervous system (CNS) Peripheral nervous system (PNS)

 The central nervous system (CNS) consists of the –brain and –spinal cord (vertebrates).  The peripheral nervous system (PNS) –is located outside the CNS and –consists of –nerves (bundles of neurons wrapped in connective tissue) and –ganglia (clusters of neuron cell bodies) Nervous systems receive sensory input, interpret it, and send out appropriate commands © 2012 Pearson Education, Inc.

 Sensory neurons –convey signals from sensory receptors –to the CNS.  Interneurons –are located entirely in the CNS, –integrate information, and –send it to motor neurons.  Motor neurons convey signals to effector cells Nervous systems receive sensory input, interpret it, and send out appropriate commands © 2012 Pearson Education, Inc.

Figure 28.1B Sensory receptor Sensory neuron Brain Spinal cord Interneuron CNS PNS Nerve Flexor muscles Quadriceps muscles Ganglion Motor neuron

28.2 Neurons are the functional units of nervous systems  Neurons are –cells specialized for carrying signals and –the functional units of the nervous system.  A neuron consists of –a cell body and –two types of extensions (fibers) that conduct signals, –dendrites and –axons. © 2012 Pearson Education, Inc.

 Myelin sheaths –enclose axons, –form a cellular insulation, and –speed up signal transmission Neurons are the functional units of nervous systems © 2012 Pearson Education, Inc.

Figure 28.2 Signal direction Nucleus Myelin sheath Schwann cell Dendrites Cell body Axon Nodes of Ranvier Signal pathway Node of Ranvier Synaptic terminals Nucleus Schwann cell Cell body Layers of myelin

Figure 28.2_1 Signal direction Nucleus Myelin sheath Schwann cell Dendrites Cell body Axon Nodes of Ranvier Signal pathway Synaptic terminals

Figure 28.2_2 Node of Ranvier Layers of myelin Nucleus Schwann cell

Figure 28.2_3 Cell body

NERVE SIGNALS AND THEIR TRANSMISSION © 2012 Pearson Education, Inc.

28.3 Nerve function depends on charge differences across neuron membranes  At rest, a neuron’s plasma membrane has potential energy—the membrane potential, in which –just inside the cell is slightly negative and –just outside the cell is slightly positive.  The resting potential is the voltage across the plasma membrane of a resting neuron. © 2012 Pearson Education, Inc.

 The resting potential exists because of differences in ion concentration of the fluids inside and outside the neuron. –Inside the neuron –K + is high and –Na + is low. –Outside the neuron –K + is low and –Na + is high Nerve function depends on charge differences across neuron membranes © 2012 Pearson Education, Inc.

Animation: Resting Potential Right click on animation / Click play

Figure 28.3 Neuron Axon Plasma membrane Na  channel Outside of neuron K  channel Inside of neuron Na  KK KK KK KK KK KK KK KK KK KK KK KK KK KK KK KK Na  -K  pump ATP KK

Figure 28.3_1 Neuron Axon Plasma membrane

Figure 28.3_2 Plasma membrane Na  channel Outside of neuron K  channel Inside of neuron Na  KK KK KK KK KK KK KK KK KK KK KK KK KK Na  -K  pump ATP KK KK KK Na  KK

28.4 A nerve signal begins as a change in the membrane potential  A stimulus is any factor that causes a nerve signal to be generated. A stimulus –alters the permeability of a portion of the membrane, –allows ions to pass through, and –changes the membrane’s voltage. © 2012 Pearson Education, Inc.

 A nerve signal, called an action potential, is –a change in the membrane voltage, –from the resting potential, –to a maximum level, and –back to the resting potential A nerve signal begins as a change in the membrane potential © 2012 Pearson Education, Inc.

Animation: Action Potential Right click on animation / Click play

Figure 28.4 Na  KK Additional Na  channels open, K  channels are closed; interior of cell becomes more positive. Na  2 KK A stimulus opens some Na  channels; if threshold is reached, an action potential is triggered. Na  KK 1 Resting state: Voltage-gated Na  and K  channels are closed; resting potential is maintained by ungated channels (not shown). Sodium channel Potassium channel Outside of neuron Plasma membrane Inside of neuron Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50  Na  KK 4 Na  channels close and inactivate; K  channels open, and K  rushes out; interior of cell is more negative than outside. Na  KK The K  channels close relatively slowly, causing a brief undershoot. 5 1 Return to resting state.

Figure 28.4_s1 Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50  Resting state: Voltage- gated Na  and K  channels are closed; resting potential is maintained by ungated channels (not shown). 1 Na  KK Sodium channel Outside of neuron Plasma membrane Inside of neuron Potassium channel

Figure 28.4_s2 Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50  Na  A stimulus opens some Na  channels; if threshold is reached, an action potential is triggered. Na  KK 2

Figure 28.4_s3 Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50  Na  KK Additional Na  channels open, K  channels are closed; interior of cell becomes more positive.

Figure 28.4_s4 Na  KK Na  channels close and inactivate; K  channels open, and K  rushes out; interior of cell is more negative than outside. Na  Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50 

Figure 28.4_s5 Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50  The K  channels close relatively slowly, causing a brief undershoot.

Figure 28.4_s6 Action potential Threshold Resting potential Time (msec) Membrane potential (mV)  50 0  50  Na  KK Return to resting state.

28.5 The action potential propagates itself along the axon  Action potentials are –self-propagated in a one-way chain reaction along a neuron and –all-or-none events. © 2012 Pearson Education, Inc.

Figure 28.5_s1 Plasma membrane Axon segment Action potential Na  1

Figure 28.5_s2 Na  1 KK KK Action potential 2 Plasma membrane Axon segment Action potential

Figure 28.5_s3 Na  1 KK KK Action potential 2 Plasma membrane Axon segment Action potential Na  KK KK 3

Figure 28.5 Axon Plasma membrane Axon segment Action potential Na  Action potential Na  Action potential KK KK KK KK Na  1 2 3

 The frequency of action potentials (but not their strength) changes with the strength of the stimulus The action potential propagates itself along the axon © 2012 Pearson Education, Inc.

28.6 Neurons communicate at synapses  Synapses are junctions where signals are transmitted between –two neurons or –between neurons and effector cells. © 2012 Pearson Education, Inc.

 Electrical signals pass between cells at electrical synapses.  At chemical synapses –the ending (presynaptic) cell secretes a chemical signal, a neurotransmitter, –the neurotransmitter crosses the synaptic cleft, and –the neurotransmitter binds to a specific receptor on the surface of the receiving (postsynaptic) cell Neurons communicate at synapses © 2012 Pearson Education, Inc.

Animation: Synapse Right click on animation / Click play

Figure 28.6 Axon of sending cell Synaptic terminal of sending cell Dendrite of receiving cell Sending cell Synaptic vesicles Synaptic terminal Synaptic cleft Vesicle fuses with plasma membrane Action potential arrives Neurotransmitter is released into synaptic cleft Neurotransmitter binds to receptor Neurotransmitter molecules Neurotransmitter broken down and released Ion channel closes Ions Receptor Receiving cell Neurotransmitter Ion channels Ion channel opens

Figure 28.6_1 Axon of sending cell Synaptic terminal of sending cell Dendrite of receiving cell Sending cell Synaptic vesicles Synaptic terminal Synaptic cleft Vesicle fuses with plasma membrane Action potential arrives Neurotransmitter is released into synaptic cleft Neurotransmitter molecules Receiving cell Ion channels Neurotransmitter binds to receptor

Figure 28.6_2 Neurotransmitter broken down and released Ion channel closes Neurotransmitter Ion channel opens Ions Receptor 6 5

28.7 Chemical synapses enable complex information to be processed  Some neurotransmitters –excite a receiving cell, and –others inhibit a receiving cell’s activity by decreasing its ability to develop action potentials. © 2012 Pearson Education, Inc.

 A receiving neuron’s membrane may receive signals –that are both excitatory and inhibitory and –from many different sending neurons.  The summation of excitation and inhibition determines if a neuron will transmit a nerve signal Chemical synapses enable complex information to be processed © 2012 Pearson Education, Inc.

Figure 28.7 Dendrites Myelin sheath Axon Synaptic terminals Inhibitory Excitatory Receiving cell body Synaptic terminals

Figure 28.7_1 Synaptic terminals

28.8 A variety of small molecules function as neurotransmitters  Many small, nitrogen-containing molecules are neurotransmitters. –Acetylcholine is a neurotransmitter –in the brain and –at synapses between motor neurons and muscle cells. –Biogenic amines –are important neurotransmitters in the CNS and –include serotonin and dopamine, which affect sleep, mood, and attention. © 2012 Pearson Education, Inc.

–Many neuropeptides –consist of relatively short chains of amino acids important in the CNS and –include endorphins, decreasing our perception of pain. –Nitric oxide –is a dissolved gas and –triggers erections during sexual arousal in men A variety of small molecules function as neurotransmitters © 2012 Pearson Education, Inc.

28.9 CONNECTION: Many drugs act at chemical synapses  Many psychoactive drugs –act at synapses and –affect neurotransmitter action.  Caffeine counters the effect of inhibitory neurotransmitters.  Nicotine acts as a stimulant by binding to acetylcholine receptors.  Alcohol is a depressant. © 2012 Pearson Education, Inc.

Figure 28.9

AN OVERVIEW OF ANIMAL NERVOUS SYSTEMS © 2012 Pearson Education, Inc.

28.10 EVOLUTION CONNECTION: The evolution of animal nervous systems reflects changes in body symmetry  Radially symmetrical animals have a nervous system arranged in a weblike system of neurons called a nerve net. © 2012 Pearson Education, Inc.

Figure 28.10A Nerve net Neuron Hydra (cnidarian)

 Most bilaterally symmetrical animals evolved –cephalization, the concentration of the nervous system at the head end, and –centralization, the presence of a central nervous system distinct from a peripheral nervous system EVOLUTION CONNECTION: The evolution of animal nervous systems reflects changes in body symmetry © 2012 Pearson Education, Inc.

Figure 28.10B Eyespot Brain Nerve cord Transverse nerve Flatworm (planarian)

Figure 28.10C Brain Ventral nerve cord Segmental ganglion Leech (annelid)

Figure 28.10D Brain Ventral nerve cord Ganglia Insect (arthropod)

Figure 28.10E Brain Giant axon Squid (mollusc)

 In the vertebrates, the central nervous system (CNS) –consists of the brain and spinal cord and –includes spaces filled with cerebrospinal fluid –forming ventricles of the brain, –forming the central canal of the spinal cord, and –surrounding the brain.  The vertebrate peripheral nervous system (PNS) consists of –cranial nerves, –spinal nerves, and –ganglia Vertebrate nervous systems are highly centralized © 2012 Pearson Education, Inc.

Figure 28.11A Central nervous system (CNS) Peripheral nervous system (PNS) Spinal cord Cranial nerves Ganglia outside CNS Spinal nerves Brain

Figure 28.11B Brain Cerebrospinal fluid Meninges Gray matter White matter Dorsal root ganglion (part of PNS) Spinal nerve (part of PNS) Central canal Spinal cord (cross section) Ventricles Central canal of spinal cord Spinal cord

28.12 The peripheral nervous system of vertebrates is a functional hierarchy  The PNS can be divided into two functional components: 1.the motor system, mostly voluntary, and 2.the autonomic nervous system, mostly involuntary. © 2012 Pearson Education, Inc.

 The motor nervous system –carries signals to and from skeletal muscles and –mainly responds to external stimuli.  The autonomic nervous system –regulates the internal environment and –controls smooth and cardiac muscle and organs and glands of the digestive, cardiovascular, excretory, and endocrine systems The peripheral nervous system of vertebrates is a functional hierarchy © 2012 Pearson Education, Inc.

Figure 28.12A Peripheral nervous system (to and from the central nervous system) Motor system (voluntary and involuntary; to and from skeletal muscles) Autonomic nervous system (involuntary; smooth and cardiac muscles, various glands) Parasympathetic division (“Rest and digest”) Sympathetic division ( “ Flight and fight ” ) Enteric division (muscles and glands of the digestive system)

28.12 The peripheral nervous system of vertebrates is a functional hierarchy  The autonomic nervous system is composed of three divisions. 1.The parasympathetic division primes the body for activities that gain and conserve energy for the body. 2.The sympathetic division prepares the body for intense, energy-consuming activities. 3.The enteric division consists of networks of neurons in the digestive tract, pancreas, and gallbladder that control secretion and peristalsis. © 2012 Pearson Education, Inc.

Figure 28.12B Brain Parasympathetic division Eye Constricts pupil Lung Constricts bronchi Stimulates saliva secretion Stimulates stomach, pancreas, and intestines Salivary glands Sympathetic division Dilates pupil Inhibits saliva secretion Relaxes bronchi Accelerates heart Heart Liver Stomach Adrenal gland Stimulates epinephrine and norepi- nephrine release Pancreas Intestines Bladder Stimulates glucose release Inhibits stomach, pancreas, and intestines Inhibits urination Slows heart Stimulates urination Spinal cord Genitalia Promotes erection of genitalia Promotes ejacu- lation and vaginal contractions

Figure 28.12B_1 Parasympathetic division Eye Constricts pupil Lung Constricts bronchi Stimulates saliva secretion Salivary glands Dilates pupil Inhibits saliva secretion Relaxes bronchi Accelerates heart Heart Slows heart Sympathetic division

Figure 28.12B_2 Parasympathetic division Sympathetic division Stimulates stomach, pancreas, and intestines Liver Stomach Adrenal gland Stimulates epinephrine and norepi- nephrine release Pancreas Intestines Bladder Stimulates glucose release Inhibits stomach, pancreas, and intestines Inhibits urination Stimulates urination Genitalia Promotes erection of genitalia Promotes ejacu- lation and vaginal contractions

28.13 The vertebrate brain develops from three anterior bulges of the neural tube  The vertebrate brain evolved by the enlargement and subdivision of the –forebrain, –midbrain, and –hindbrain.  In the course of vertebrate evolution, the forebrain and hindbrain gradually became subdivided –structurally and –functionally. © 2012 Pearson Education, Inc.

Figure Embryonic Brain Regions Brain Structures Present in Adult Forebrain Midbrain Hindbrain Midbrain Forebrain Embryo (1 month old) Fetus (3 months old) Cerebrum (cerebral hemispheres; includes cerebral cortex, white matter, basal ganglia) Diencephalon (thalamus, hypothalamus, posterior pituitary, pineal gland) Pons (part of brainstem), cerebellum Medulla oblongata (part of brainstem) Cerebrum Diencephalon Midbrain Pons Cerebellum Medulla oblongata Spinal cord Midbrain (part of brainstem)

Figure 28.13_1 Embryonic Brain Regions Brain Structures Present in Adult Forebrain Midbrain Hindbrain Cerebrum (cerebral hemispheres; includes cerebral cortex, white matter, basal ganglia) Diencephalon (thalamus, hypothalamus, posterior pituitary, pineal gland) Pons (part of brainstem), cerebellum Medulla oblongata (part of brainstem) Midbrain (part of brainstem)

Figure 28.13_2 Hindbrain Midbrain Forebrain Embryo (1 month old) Fetus (3 months old) Cerebrum Diencephalon Midbrain Pons Cerebellum Medulla oblongata Spinal cord

 In birds and mammals the cerebrum –is much larger and –correlates with their sophisticated behavior The vertebrate brain develops from three anterior bulges of the neural tube © 2012 Pearson Education, Inc.

THE HUMAN BRAIN © 2012 Pearson Education, Inc.

28.14 The structure of a living supercomputer: The human brain  The human brain is –more powerful than the most sophisticated computer and –composed of three main parts: 1.forebrain, 2.midbrain, and 3.hindbrain. © 2012 Pearson Education, Inc.

Figure 28.14A Cerebral cortex (outer region of cerebrum) Cerebrum Thalamus Hypothalamus Pituitary gland Midbrain Forebrain Hindbrain Pons Medulla oblongata Cerebellum Spinal cord

 The midbrain, subdivisions of the hindbrain, the thalamus, and the hypothalamus –conduct information to and from higher brain centers, –regulate homeostatic functions, –keep track of body position, and –sort sensory information The structure of a living supercomputer: The human brain © 2012 Pearson Education, Inc.

Figure 28.14B Left cerebral hemisphere Right cerebral hemisphere Thalamus Basal nuclei Medulla oblongata Corpus callosum Cerebrum Cerebellum

Table 28.14

Table 28.14_1

Table 28.14_2

 The cerebrum is –part of the forebrain and –the largest and most complex part of the brain. –Most of the cerebrum’s integrative power resides in the cerebral cortex of the two cerebral hemispheres The structure of a living supercomputer: The human brain © 2012 Pearson Education, Inc.

28.15 The cerebral cortex is a mosaic of specialized, interactive regions  The cerebral cortex –is less than 5 mm thick and –accounts for 80% of the total human brain mass.  Specialized integrative regions of the cerebral cortex include –the somatosensory cortex and –centers for vision, hearing, taste, and smell. © 2012 Pearson Education, Inc.

 The motor cortex directs responses.  Association areas –make up most of the cerebrum and –are concerned with higher mental activities such as reasoning and language.  In a phenomenon known as lateralization, right and left cerebral hemispheres tend to specialize in different mental tasks The cerebral cortex is a mosaic of specialized, interactive regions © 2012 Pearson Education, Inc.

Figure Frontal lobeParietal lobe Occipital lobeTemporal lobe Frontal association area Speech Smell Speech Motor cortex Hearing Reading Vision Visual association area Somatosensory association area Auditory association area Somatosensory cortex

28.16 CONNECTION: Injuries and brain operations provide insight into brain function  Brain injuries and surgeries reveal brain functions. –After a 13-pound steel rod pierced his skull, Phineas Gage appeared to have an intact intellect but his associates noted negative changes to his personality. –Stimulation of the cerebral cortex during surgeries caused patients to recall sensations and memories. –Cutting the corpus callosum revealed information about brain lateralization. © 2012 Pearson Education, Inc.

Figure 28.16A

Figure 28.16B

28.17 CONNECTION: fMRI scans provide insight into brain structure and function  Functional magnetic resonance imaging (fMRI) is –a scanning and imaging technology used to study brain functions, –used on conscious patients, –monitors changes in blood oxygen usage in the brain, and –correlates to regions of intense brain function. © 2012 Pearson Education, Inc.

Figure 28.17

28.18 Several parts of the brain regulate sleep and arousal  Sleep and arousal involve activity by the –hypothalamus, –medulla oblongata, –pons, and –neurons of the reticular formation. © 2012 Pearson Education, Inc.

 Sleep –is essential for survival, –is an active state, and –may be involved in consolidating learning and memory Several parts of the brain regulate sleep and arousal © 2012 Pearson Education, Inc.

28.19 The limbic system is involved in emotions, memory, and learning  The limbic system is –a functional group of integrating centers in the –cerebral cortex, –thalamus, –hypothalamus, and –involved in –emotions, such as nurturing infants and bonding emotionally to other people, –memory, and –learning. © 2012 Pearson Education, Inc.

Figure Cerebrum Hippocampus Amygdala Olfactory bulb Thalamus Hypothalamus Prefrontal cortex Smell

28.20 CONNECTION: Changes in brain physiology can produce neurological disorders  Many neurological disorders can be linked to changes in brain physiology, including –schizophrenia, –major depression, –Alzheimer’s disease, and –Parkinson’s disease. © 2012 Pearson Education, Inc.

28.20 CONNECTION: Changes in brain physiology can produce neurological disorders  Schizophrenia is –a severe mental disturbance and –characterized by psychotic episodes in which patients lose the ability to distinguish reality. © 2012 Pearson Education, Inc.

28.20 CONNECTION: Changes in brain physiology can produce neurological disorders  Depression –Two broad forms of depressive illness have been identified: 1.major depression and 2.bipolar disorder, manic-depressive disorder. –Treatments may include selective serotonin reuptake inhibitors (SSRIs), which increase the amount of time serotonin is available to stimulate certain neurons in the brain. © 2012 Pearson Education, Inc.

Figure 28.20A

Figure 28.20B Year Prescriptions (millions)

 Alzheimer’s disease is –characterized by confusion, memory loss, and personality changes and –difficult to diagnose CONNECTION: Changes in brain physiology can produce neurological disorders © 2012 Pearson Education, Inc.

 Parkinson’s disease is –a motor disorder and –characterized by –difficulty in initiating movements, –slowness of movement, and –rigidity CONNECTION: Changes in brain physiology can produce neurological disorders © 2012 Pearson Education, Inc.

Figure 28.20C

1.Describe the structural and functional subdivisions of the nervous system. 2.Describe the three parts of a reflex, distinguishing the three types of neurons that may be involved in the reaction. 3.Describe the structures and functions of neurons and myelin sheaths. 4.Define a resting potential and explain how it is created. You should now be able to © 2012 Pearson Education, Inc.

5.Explain how an action potential is produced and the resting membrane potential restored. 6.Explain how an action potential propagates itself along a neuron. 7.Compare the structures, functions, and locations of electrical and chemical synapses. 8.Compare excitatory and inhibitory neurotransmitters. 9.Describe the types and functions of neurotransmitters known in humans. You should now be able to © 2012 Pearson Education, Inc.

10.Explain how drugs can alter chemical synapses. 11.Describe the diversity of animal nervous systems and provide examples. 12.Describe the general structure of the brain, spinal cord, and associated nerves of vertebrates. 13.Compare the functions of the motor nervous system and autonomic nervous system. You should now be able to © 2012 Pearson Education, Inc.

14.Compare the structures, functions, and interrelationships of the parasympathetic, sympathetic, and enteric divisions of the peripheral nervous system. 15.Explain how the vertebrate brain develops from an embryonic tube. 16.Describe the main parts and functions of the human brain. 17.Explain how injuries, illness, and surgery provide insight into the functions of the brain. You should now be able to © 2012 Pearson Education, Inc.

18.Explain how fMRI scans help us understand brain functions. 19.Explain how the brain regulates sleep and arousal. 20.Describe the structure and functions of the limbic system. 21.Describe the causes, symptoms, and treatments of schizophrenia, depression, Alzheimer’s disease, and Parkinson’s disease. You should now be able to © 2012 Pearson Education, Inc.

Figure 28.UN01 Sensory receptor Effector cells Sensory input Motor output Integration Peripheral nervous system Central nervous system

Figure 28.UN02 Dendrites Cell body Axon Myelin sheath (speeds signal transmission) Synaptic terminals signal Action po te nti al

Figure 28.UN03 Central Nervous System (CNS) Spinal cord: nerve bundle that communicates with body Peripheral Nervous System (PNS) Motor system: voluntary control over muscles Autonomic nervous system: involuntary control over organs Parasympathetic division: rest and digest Sympathetic division: fight or flight Brain

Figure 28.UN04 (e) (d) (b) (a) (f) (g) (i) (h)  brain (c)

Figure 28.UN05