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
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
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
Figure 49.2a Radial nerve Nerve net Nerve ring (a) Hydra (cnidarian) (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
Annelids and arthropods have segmentally arranged clusters of neurons called ganglia Brain Brain Ventral nerve cord Ventral nerve cord Segmental ganglia Segmental ganglia (d) Leech (annelid) (e) Insect (arthropod)
Figure 49.2c Ganglia Brain Ventral nerve cord Segmental ganglia Anterior nerve ring Longitudinal nerve cords (e) Insect (arthropod) (f) Chiton (mollusc)
Figure 49.2d Brain Brain Ganglia Spinal cord (dorsal nerve cord) Sensory ganglia (g) Squid (mollusc) (h) Salamander (vertebrate)
In vertebrates The CNS: composed of brain and spinal cord The peripheral nervous system (PNS): composed of nerves and ganglia
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
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 Spinal cord Peripheral nervous system (PNS) Cranial nerves 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
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
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
Figure 49.6a VENTRICLE Cilia CNS Neuron Astrocyte PNS 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
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
Figure 49.7 Central Nervous System (information processing) Peripheral Nervous System Afferent neurons Efferent neurons Sensory receptors Autonomic nervous system Motor system Control of skeletal muscle Internal and external stimuli Sympathetic division Parasympathetic division Control of smooth muscles, cardiac muscles, glands Enteric division
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
The enteric division controls activity of the digestive tract, pancreas, and gallbladder
Figure 49.8 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 Cervical Sympathetic ganglia Relaxes bronchi in lungs Slows heart Accelerates heart Stimulates activity of stomach and intestines Stimulates activity of pancreas Thoracic Inhibits activity of stomach and intestines Inhibits activity of pancreas Stimulates gallbladder Lumbar Stimulates glucose release from liver; inhibits gallbladder Stimulates adrenal medulla Promotes emptying of bladder Inhibits emptying of bladder Promotes erection of genitalia Synapse Sacral Promotes ejaculation and vaginal contractions
Figure 49.8a Parasympathetic division Action on target organs: Constricts pupil of eye Stimulates salivary gland secretion Constricts bronchi in lungs Slows heart Stimulates activity of stomach and intestines Stimulates activity of pancreas Cervical Sympathetic ganglia Sympathetic division Action on target organs: Dilates pupil of eye Inhibits salivary gland secretion Stimulates gallbladder
Figure 49.8b Parasympathetic division Sympathetic division Relaxes bronchi in lungs Accelerates heart Thoracic Lumbar Inhibits activity of stomach and intestines Inhibits activity of pancreas Stimulates glucose release from liver; inhibits gallbladder Stimulates adrenal medulla Promotes emptying of bladder Inhibits emptying of bladder Promotes erection of genitalia Synapse Sacral 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
Figure 49.9b Embryonic brain regions Brain structures in child and adult Forebrain Midbrain Telencephalon Diencephalon Mesencephalon Cerebrum (includes cerebral cortex, white matter, basal nuclei) Diencephalon (thalamus, hypothalamus, epithalamus) Midbrain (part of brainstem) Hindbrain Metencephalon Myelencephalon Pons (part of brainstem), cerebellum Medulla oblongata (part of brainstem) Midbrain Hindbrain Mesencephalon Cerebrum Metencephalon Diencephalon Myelencephalon Diencephalon Midbrain Pons Forebrain Telencephalon Spinal cord Medulla oblongata Cerebellum Spinal cord Embryo at 1 month Embryo at 5 weeks 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 Pituitary gland Brainstem Midbrain 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
Figure 49.10 Eye Reticular formation Input from nerves of ears Input from touch, pain, and temperature receptors
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 Time: 0 hours Time: 1 hour Left hemisphere Right hemisphere
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
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
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 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 Amygdala Happy music Sad music