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LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 49 Nervous Systems Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Overview: Command and Control Center • “Brainbow” - method for expressing combinations of colored proteins in brain cells • may allow researchers to develop detailed maps of information transfer between regions of the brain © 2011 Pearson Education, Inc. Concept 49.1: Nervous systems consist of circuits of neurons and supporting cells Nerve net a series of interconnected nerve cells • Nerves are bundles that consist of the axons of multiple nerve cells • Sea stars have a nerve net in each arm connected by radial nerves to a central nerve ring © 2011 Pearson Education, Inc. Figure 49.2a Radial nerve Nerve net (a) Hydra (cnidarian) Nerve ring (b) Sea star (echinoderm) • Cephalization - clustering of sensory organs at the front end of the body • Bilaterally symmetrical animals • Relatively simple cephalized animals, such as flatworms, have a central nervous system (CNS) • The CNS consists of a brain and longitudinal nerve cords © 2011 Pearson Education, Inc. • Annelids and arthropods have segmentally arranged clusters of neurons called ganglia Brain Brain Ventral nerve cord Segmental ganglia (d) Leech (annelid) © 2011 Pearson Education, Inc. Ventral nerve cord Segmental ganglia (e) Insect (arthropod) Figure 49.2c Ganglia Brain Ventral nerve cord Segmental ganglia (e) Insect (arthropod) Anterior nerve ring Longitudinal nerve cords (f) Chiton (mollusc) Figure 49.2d Brain Brain Ganglia (g) Squid (mollusc) Spinal cord (dorsal nerve cord) Sensory ganglia (h) Salamander (vertebrate) • In vertebrates – The CNS: composed of brain and spinal cord – The peripheral nervous system (PNS): composed of nerves and ganglia © 2011 Pearson Education, Inc. Organization of the Vertebrate Nervous System • The spinal cord also produces reflexes independently of the brain • A reflex is the body’s automatic response to a stimulus – For example, a doctor uses a mallet to trigger a knee-jerk reflex © 2011 Pearson Education, Inc. Figure 49.3 Quadriceps muscle Cell body of sensory neuron in dorsal root ganglion Gray matter White matter Hamstring muscle Spinal cord (cross section) Sensory neuron Motor neuron Interneuron Figure 49.4 Central nervous system (CNS) Brain Peripheral nervous system (PNS) Cranial nerves Spinal cord Ganglia outside CNS Spinal nerves • The spinal cord and brain develop from the embryonic nerve cord • The nerve cord gives rise to the central canal and ventricles of the brain © 2011 Pearson Education, Inc. • Ventricles of the brain are hollow, filled with cerebrospinal fluid • The cerebrospinal fluid is filtered from blood and functions to cushion the brain and spinal cord as well as to provide nutrients and remove wastes • The brain and spinal cord contain – Gray matter, which consists of neuron cell bodies, dendrites, and unmyelinated axons – White matter, which consists of bundles of myelinated axons © 2011 Pearson Education, Inc. Glia • have numerous functions to nourish, support, and regulate neurons – Embryonic radial glia form tracks along which newly formed neurons migrate – Astrocytes induce cells lining capillaries in the CNS to form tight junctions, resulting in a blood-brain barrier and restricting the entry of most substances into the brain © 2011 Pearson Education, Inc. Figure 49.6a CNS PNS Neuron VENTRICLE Cilia Astrocyte Oligodendrocyte Schwann cell Microglial cell Capillary Ependymal cell The Peripheral Nervous System • The PNS transmits information to and from the CNS and regulates movement and the internal environment • In the PNS, afferent neurons transmit information to the CNS and efferent neurons transmit information away from the CNS © 2011 Pearson Education, Inc. • The PNS has two efferent components: the motor system and the autonomic nervous system • The motor system carries signals to skeletal muscles and is voluntary • The autonomic nervous system regulates smooth and cardiac muscles and is generally involuntary © 2011 Pearson Education, Inc. Figure 49.7 Central Nervous System (information processing) Peripheral Nervous System Efferent neurons Afferent neurons Sensory receptors Autonomic nervous system Motor system Control of skeletal muscle Internal and external stimuli Sympathetic Parasympathetic Enteric division division division Control of smooth muscles, cardiac muscles, glands • The autonomic nervous system has sympathetic, parasympathetic, and enteric divisions • The sympathetic division regulates arousal and energy generation (“fight-or-flight” response) • The parasympathetic division has antagonistic effects on target organs and promotes calming and a return to “rest and digest” functions © 2011 Pearson Education, Inc. • The enteric division controls activity of the digestive tract, pancreas, and gallbladder © 2011 Pearson Education, Inc. Figure 49.8 Sympathetic division Parasympathetic division Action on target organs: Action on target organs: Constricts pupil of eye Dilates pupil of eye Stimulates salivary gland secretion Inhibits salivary gland secretion Constricts bronchi in lungs Cervical Sympathetic ganglia Relaxes bronchi in lungs Slows heart Accelerates heart Stimulates activity of stomach and intestines Inhibits activity of stomach and intestines Thoracic Stimulates activity of pancreas Inhibits activity of pancreas Stimulates gallbladder Stimulates glucose release from liver; inhibits gallbladder Lumbar Stimulates adrenal medulla Promotes emptying of bladder Promotes erection of genitalia Inhibits emptying of bladder Sacral Synapse Promotes ejaculation and vaginal contractions Figure 49.8a Parasympathetic division Sympathetic division Action on target organs: Action on target organs: Constricts pupil of eye Dilates pupil of eye Stimulates salivary gland secretion Inhibits salivary gland secretion Constricts bronchi in lungs Slows heart Stimulates activity of stomach and intestines Stimulates activity of pancreas Stimulates gallbladder Cervical Sympathetic ganglia Figure 49.8b Parasympathetic division Sympathetic division Relaxes bronchi in lungs Accelerates heart Inhibits activity of stomach and intestines Thoracic Inhibits activity of pancreas Stimulates glucose release from liver; inhibits gallbladder Lumbar Stimulates adrenal medulla Promotes emptying of bladder Promotes erection of genitalia Inhibits emptying of bladder Sacral Synapse Promotes ejaculation and vaginal contractions Concept 49.2: The vertebrate brain is regionally specialized • Specific brain structures are particularly specialized for diverse functions • These structures arise during embryonic development © 2011 Pearson Education, Inc. Figure 49.9b Brain structures in child and adult Embryonic brain regions Telencephalon Cerebrum (includes cerebral cortex, white matter, basal nuclei) Diencephalon Diencephalon (thalamus, hypothalamus, epithalamus) Forebrain Midbrain Mesencephalon Midbrain (part of brainstem) Metencephalon Pons (part of brainstem), cerebellum Myelencephalon Medulla oblongata (part of brainstem) Hindbrain Cerebrum Mesencephalon Midbrain Hindbrain Metencephalon Diencephalon Diencephalon Midbrain Myelencephalon Forebrain Telencephalon Embryo at 1 month Embryo at 5 weeks Pons Medulla oblongata Spinal cord Cerebellum Spinal cord Child Figure 49.9c Left cerebral hemisphere Right cerebral hemisphere Cerebral cortex Corpus callosum Cerebrum Basal nuclei Cerebellum Adult brain viewed from the rear Figure 49.9d Diencephalon Thalamus Pineal gland Hypothalamus Brainstem Midbrain Pituitary gland Pons Medulla oblongata Spinal cord Arousal and Sleep • The brainstem and cerebrum control arousal and sleep • The core of the brainstem has a diffuse network of neurons called the reticular formation • regulates the amount and type of information that reaches the cerebral cortex and affects alertness • The hormone melatonin is released by the pineal gland and plays a role in bird and mammal sleep cycles © 2011 Pearson Education, Inc. Figure 49.10 Eye Reticular formation Input from touch, pain, and temperature receptors Input from nerves of ears Key • Sleep is essential and may play a role in the consolidation of learning and memory • Dolphins sleep with one brain hemisphere at a time and are therefore able to swim while “asleep” Low-frequency waves characteristic of sleep High-frequency waves characteristic of wakefulness Location Left hemisphere Right hemisphere Time: 0 hours Time: 1 hour Biological Clock Regulation • Cycles of sleep and wakefulness are examples of circadian rhythms, daily cycles of biological activity • Mammalian circadian rhythms rely on a biological clock, molecular mechanism that directs periodic gene expression • Biological clocks are typically synchronized to light and dark cycles © 2011 Pearson Education, Inc. • In mammals, circadian rhythms are coordinated by a group of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN) • The SCN acts as a pacemaker, synchronizing the biological clock © 2011 Pearson Education, Inc. Emotions • Limbic System • Generation and experience of emotions involve many brain structures including the amygdala, hippocampus, and parts of the thalamus • The limbic system also functions in motivation, olfaction, behavior, and memory Thalamus Hypothalamus Olfactory bulb Amygdala © 2011 Pearson Education, Inc. Hippocampus • Generation and experience of emotion also require interaction between the limbic system and sensory areas of the cerebrum • The structure most important to the storage of emotion in the memory is the amygdala, a mass of nuclei near the base of the cerebrum Nucleus accumbens Happy music © 2011 Pearson Education, Inc. Amygdala Sad music