Biological Bases of the Self Nervous System PDF

Biological Bases of the Self Nervous System Systems, Structures, and Cells That Make Up Your Nervous System Copyright © 2011 Pearson Education, Inc. All rights reserved. Objectives: ⚫ To discuss the importance of the Central Nervous System (CNS) ⚫ To...

Biological Bases of the Self Nervous System Systems, Structures, and Cells That Make Up Your Nervous System Copyright © 2011 Pearson Education, Inc. All rights reserved. Objectives: ⚫ To discuss the importance of the Central Nervous System (CNS) ⚫ To differentiate CNS to Peripheral Nervous System (PNS) ⚫ To discuss the process transporting neurological messages (Synapse) Copyright © 2011 Pearson Education, Inc. All rights reserved.  General Layout of the Nervous System ⚫ Central Nervous System (CNS) ⚫ Brain (in the skull) ⚫ Spinal Cord (in the spine) ⚫ Peripheral Nervous System (PNS) ⚫ Located outside of the skull and spine ⚫ Serves to bring information into the CNS and carry signals out of the CNS Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.2 The major divisions of the nervous system. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Meninges, Ventricles, and Cerebrospinal Fluid (CSF) ⚫ CNS encased in bone and covered by three meninges ⚫ Dura mater – tough outer membrane ⚫ Arachnoid membrane – web-like ⚫ Pia mater – adheres to CNS surface ⚫ Cerebrospinal fluid (CSF) ⚫ Fluid serves as cushion Copyright © 2011 Pearson Education, Inc. All rights reserved.  Protecting the Brain ⚫ Chemical protection ⚫ The blood-brain barrier – tightly-packed cells of blood vessel walls prevent entry of many molecules ⚫ Physical protection ⚫ Skull ⚫ Meninges ⚫ Cerebrospinal fluid (CSF) Copyright © 2011 Pearson Education, Inc. All rights reserved.  General Layout of the Nervous System Continued ⚫ Peripheral Nervous System ⚫ Somatic Nervous System ▪ Afferent nerves (sensory) ▪ Efferent nerves (motor) ⚫ Autonomic Nervous System ▪ Sympathetic and parasympathetic nerves ▪ Both are efferent Copyright © 2011 Pearson Education, Inc. All rights reserved.  Autonomic Nervous System ⚫ All nerves are efferent ⚫ Sympathetic and parasympathetic nerves generally have opposite effects ⚫ Two-stage neural paths, neuron exiting the CNS synapses on a second-stage neuron before the target organ Copyright © 2011 Pearson Education, Inc. All rights reserved.  Autonomic Nervous System Continued ⚫ Sympathetic ⚫ Parasympathetic ⚫ Thoracic and lumbar ⚫ Cranial and sacral ⚫ “Fight or flight” ⚫ “Rest and restore” ⚫ Second stage neurons ⚫ Second stage are far from the target neurons are near the organ target organ Copyright © 2011 Pearson Education, Inc. All rights reserved.  Cells of the Nervous System: Anatomy of Neurons ⚫ Neurons ⚫ Specialized cells for the reception, conduction, and transmission of electrochemical signals ⚫ Many sizes and shapes Copyright © 2011 Pearson Education, Inc. All rights reserved.  Structure of the Neuron ⚫ There are about 100 billion neurons in the nervous system. Its outer surface is made up of a semipermeable membrane which allows small molecules without electrical charges to pass through it and stops those larger molecules and those with high electrical charge from passing through. ⚫ Parts of a neuron soma: the cell body of the ⚫ dendrites: branch-like neuron, responsible for structures that receive maintaining the life of the messages from other cell neurons axon: long, tube-like structure that carries the neural message to other FIGURE 3.8 A unipolar neuron, a bipolar neuron, a multipolar neuron, and an interneuron. Copyright © 2011 Pearson Education, Inc. All rights reserved. Myelin or Myelin sheath: - white fatty coating on axon; coats and insulates axon and makes messages flow down axon quicker and more efficiently -multiple sclerosis and other diseases are a result of break down of myelin sheath Average thickness in females is greater May indicate females process certain information better than males??? Myelin sheath gif  Generating the Message: Neural Impulse ⚫ First step in neural transmission: Within a neuron by electrical charge ⚫ Ions: positive or negative charged particles in the fluids that bathe the neuron inside and out. Ions generate an electrical charge which sends messages down the axon Action potential-name for the electrical charge generated by the ions which sends messages down the axon Resting potential: the state of the neuron when not firing a neural impulse  Communication Between Neurons LO 2.2 How Neurons Use Neurotransmitters to Communicate Second Step Sending messages between neurons is a chemical process ⚫Synapse-small gap or space between 2 neurons. Neurons never touch ⚫Because of the synaptic gap, the electrical impulse cannot cross the gap and a chemical process must take the message across the gap Neuron Communication t o C o m m u⚫ Synaptic vesicles: sack-like n i structures found at the c a terminal buttons which are at t e the end of the axon and they contain chemicals ⚫ neurotransmitter: chemical found in the synaptic vesicles which, when released, has an effect on the next cell  Neuron Communication ⚫The action potential causes the synaptic vesicles to release the neurotransmitters into the synapse ⚫ Receptors—sites on the ⚫ dendrites which receive the neurotransmitter. The neurotransmitter fits into the receptor sites like a key into a lock  Neuroanatomical Tracing Techniques ⚫ Anterograde (forward) ⚫ tracing to where axons project away from an area ⚫ Retrograde (backward) ⚫ tracing from where axons are projecting into an area Copyright © 2011 Pearson Education, Inc. All rights reserved. Figure 2.15 The Motor and Somatosensory Cortex FIGURE 3.15 Anatomical directions in a human. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Directions in the Vertebrate Nervous System Continued ⚫ Anatomical directions ignore the fact that humans walk upright. Therefore, top of the head is both “dorsal” (back) and “superior” (top) ⚫ Other directions: ⚫ Medial – toward the middle ⚫ Lateral – toward the side ⚫ Proximal – close ⚫ Distal – far Copyright © 2011 Pearson Education, Inc. All rights reserved.  Sections of the Brain ⚫ Horizontal – a slice parallel to the ground ⚫ Frontal (coronal) – slicing bread or salami ⚫ Sagittal – a midsagittal section separates the left and right halves Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.16 Horizontal, frontal (coronal), and sagittal planes in the human brain and a cross section of the human spinal cord. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Spinal Cord ⚫ Gray matter – inner component, primarily cell bodies ⚫ White matter – outer area, mainly myelinated axons ⚫ Dorsal – afferent, sensory ⚫ Ventral – efferent, motor Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.17 The dorsal and ventral FIGURE 3.18 A schematic cross roots of the spinal cord. section of the spinal cord. Copyright © 2011 Pearson Education, Inc. All rights reserved. END OF DISCUSSION Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.19 The early development of the mammalian brain illustrated in schematic horizontal sections. Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.20 The divisions of the adult human brain. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Major Structures of the Brain ⚫ Myelencephalon = medulla ⚫ Composed largely of tracts ⚫ Origin of the reticular formation ⚫ Metencephalon ⚫ Many tracts ⚫ Pons – ventral surface ⚫ Cerebellum – coordination Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.21 Structures of the human myelencephalon (medulla) and metencephalon. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Major Structures of the Brain Continued ⚫ Mesencephalon = midbrain ⚫ tectum has inferior and superior colliculi ⚫ tegmentum has periaqueductal gray, substantia nigra, and red nucleus ⚫ Diencephalon ⚫ thalamus ⚫ hypothalamus Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.22 The human mesencephalon (midbrain). Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.23 The human diencephalon. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Telencephalon – Cerebral Cortex ⚫ Convolutions serve to increase surface area ⚫ Longitudinal fissure – a groove that separates right and left hemispheres ⚫ Corpus callosum – largest hemisphere-connecting tract Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.25 The major fissures of FIGURE 3.26 The lobes of the the human cerebral cortex. cerebral hemishphere. Copyright © 2011 Pearson Education, Inc. All rights reserved.  Telencephalon – Subcortical Structures ⚫ Limbic system – regulation of motivated behaviors ⚫ Mammillary bodies, hippocampus, amygdala, fornix, cingulate, septum ⚫ Basal ganglia motor system ⚫ Amygdala, striatum (caudate nucleus + putamen), globus pallidus Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.28 The major structures of the limbic system: amygdala, hippocampus, cingulate cortex, fornix, septum, and mammillary body. Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.29 The basal ganglia: amygdala, striatum (caudate plus putamen) and globus pallidus. Copyright © 2011 Pearson Education, Inc. All rights reserved. FIGURE 3.30 Summary of major brain structures. Copyright © 2011 Pearson Education, Inc. All rights reserved.