PSYC2410 Chapter 3 - Unit 4 - Anatomy of the Nervous System PDF

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PSYC2410 Chapter 3 - Unit 4Anatomy of the Nervous System77-General Layout of the Nervous System Central nervous system (CNS): the portion of the nervous system within the skull and spine. Peripheral nervous system (PNS): The portion of the nervous system OUTSIDE the skull and spine (AKA finger). Som...

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PSYC2410 Chapter 3 - Unit 4

Anatomy of the Nervous System 77-100 General Layout of the Nervous System Central nervous system (CNS): the portion of the nervous system within the skull and spine. Peripheral nervous system (PNS): The portion of the nervous system OUTSIDE the skull and spine (AKA finger). Somatic nervous system (SNS): The part of the peripheral nervous system that interacts with the external environment. Afferent nerves: Nerves that carry sensory signals to the central nervous system (arrive/advance). Efferent nerves: Nerves that carry motor signals from the central nervous system to the skeletal muscles or internal organs. (exit) Autonomic nervous system (ANS): The part of the peripheral nervous system that participates in the regulation of the body’s internal environment. Sympathetic nerves: Those motor nerves of the autonomic nervous system that project from the CNS in the lumbar (small of the back) and thoracic (chest area) region areas of the spinal cord. Parasympathetic nerves: Those autonomic motor nerves that project from the brain to the sacral (lower back) region of the spinal cord. Three important principles… 1.) sympathetic nerves stimulate, organize, and mobilize energy resources in threatening situations, a. parasympathetic nerves act to conserve energy 2.) Each autonomic target organ receives opposing sympathetic and parasympathetic input, and its activity is thus controlled by relative levels of sympathetic and parasympathetic activity 3.) Sympathetic = psychological arousal, parasympathetic changes = psychological relaxation. a. Although these principles are generally correct, there are significant qualifications and exceptions to each of them Cranial nerves: The 12 pairs of nerves extending from the brain (e.g., optic nerves, olfactory nerves, and vagus nerves).

Meninges: The three protective membranes that cover the brain and spinal cord (singular meninx). a.) Dura mater: The tough outer meninx. b.) Arachnoid membrane: The meninx that is located between the dura mater and the pia mater and has the appearance of a gauzelike spiderweb.  Subarachnoid space: The space beneath the arachnoid membrane, which contains many large blood vessels and cerebrospinal fluid. c.) Pia mater: The delicate, innermost meninx. Cerebrospinal fluid (CSF): The fluid that fills the subarachnoid space, the central canal, and the cerebral ventricles. Central canal: The small CSF-filled channel that runs the length of the spinal cord. Cerebral ventricles: The four CSF-filled internal chambers of the brain: the two lateral ventricles, the third ventricle, and the fourth ventricle. Choroid plexuses: The networks of capillaries that protrude into the ventricles from the pia mater and produce cerebrospinal fluid. Blood-brain barrier: The mechanism that impedes the passage of toxic substances from the blood into the brain.  Vessels that are loosely packed so that most molecules pass. And some large molecules need to be transported. Cells of the Nervous system Neurons: Cells of the nervous system that are specialized for the reception, conduction, and transmission of electrochemical signals Multipolar neuron: A neuron with more than two processes extending from its cell body.  Most neurons are multipolar. Bipolar neuron: A neuron with two processes extending from its cell body. Interneurons: Neurons with short axons or no axons at all, whose function is to integrate neural activity within a single brain structure

Nuclei: The DNA-containing structures of cells; also, clusters of neuronal cell bodies in the central nervous system (singular nucleus). Ganglia: Clusters of neuronal cell bodies in the peripheral nervous system (singular ganglion). Tracts: Bundles of axons in the central nervous system Nerves: Bundles of axons in the peripheral nervous system. Glial cells: Several classes of nonneural cells of the nervous system.  Equal amount of glia and neurons in the brain. a.) Oligodendrocytes: Glial cells that myelinate axons of the central nervous system; also known as oligodendroglia. Myelin: A fatty insulating substance. Myelin sheaths: Coverings on the axons of some neurons that are rich in myelin and increase the speed and efficiency of axonal conduction. b.) Schwann cells: The glial cells that compose the myelin sheaths of PNS axons and promote the regeneration of PNS axons. c.) Microglia: Glial cells that respond to injury or disease by engulfing cellular debris and triggering inflammatory responses. o Supportive role, regulation of cell death, synapse formation, and synapse. d.) Astrocytes: Large, star-shaped glial cells that play multiple roles in the CNS. o Largest glia cells. o play a role in allowing the passage of some chemicals from the blood into CNS neurons, blocking other chemicals, they contract or relax blood vessels based on the blood flow demands, respond to injury, and control the blood-brain barrier. - Glia are a lot more varied – 9 types of astrocytes. Neuroanatomical Techniques and Directions Golgi stain: A neural stain that completely darkens a few of the neurons in each slice of tissue, thereby revealing their silhouettes.  Reveals a few neurons silhouette.  Potassium dichromate and sliver nitrate. Nissl stain: A neural stain that has an affinity for structures in neuron cell bodies.  Bind the best to neuron cell bodies stained with cresyl violet. Electron microscopy: A microscopy technique used to study the fine details of cellular structure.  Great detail  First coating thin slices of neural tissue with an electron-absorbing substance that is taken up by different parts of neurons to different degrees, then passing a beam of electrons through the tissue onto a photographic film  So detailed can’t identify general aspects of the structure. Anterograde tracing methods –wants to trace the paths of axons projecting away from cell bodies located in a particular area.

 Injected by chemicals and transported along axons and button terminals.  Then brain is removed to see. Retrograde tracing methods – (opposite) want to trace the paths of axons projecting into a particular area. Inserts in a particular area -

Directions described in relation to the spinal cord. Reason humans are a bit different is because we walk about straight on two legs. Anterior: Toward the nose end of a vertebrate. Posterior: Toward the tail end of a vertebrate or toward the back of the head. Dorsal: Toward the surface of the back of a vertebrate or toward the top of the head. Ventral: Toward the chest surface of a vertebrate or toward the bot- tom of the head. Medial: Toward the midline of the body. Lateral: Away from the midline of the body of a vertebrate, toward the body’s lateral surfaces. Superior: Toward the top of the primate head. Inferior: Toward the bottom of the primate head or brain. Proximal: Close to something. Distal: Far from something. Horizontal sections: Any slices of brain tissue cut in a plane that are parallel to the top of the brain. Frontal sections: Any slices of brain tissue cut in a plane that is parallel to the face; also termed coronal sections. Sagittal sections: Any slices of brain tissue cut in a plane that is parallel to the side of the brain. midsagittal section: A section cut down the center of the brain, between the two hemispheres Cross section: Section cut at a right angle to any long, narrow structure of the CNS. Anatomy of the Central Nervous System Gray matter: Portions of the nervous system that are gray because they are composed largely of cell bodies and unmyelinated interneurons. White matter: Portions of the nervous system that are white because they are composed largely of myelinated axons. Dorsal horns: The two dorsal arms of the spinal gray matter. Ventral horns: The two ventral arms of the spinal gray matter.

Spinal nerve on the left and right at 31 different levels (62). Divides as it nears the cord. Axons joined to the cord via one of the two roots -Dorsal root or ventral root Dorsal root ganglia: Structures just outside the spinal cord that are composed of the cell bodies of dorsal root axons. Five major divisions of the brain - Forebrain, midbrain, and hindbrain – these swollen areas eventually became 5. - Fore and hind swelled into 2 diff. areas. - Telencephalon, diencephalon, mesencephalon (midbrain), metencephalon, and myelencephalon. (t =top, then by alpha). Brain stem: The part of the brain on which the cerebral hemispheres rest; in general, it regulates reflex activities that are critical for survival (e.g., heart rate and respiration). Myelencephalon (medulla): The most posterior of the five major divisions of the brain; the medulla.  Composed largely of tracts carrying signals between the rest of the brain and the body  Reticular formation: A complex network of about 100 tiny nuclei that occupies the central core of the brain stem. o Sometimes called the reticular activating system b/c plays a role in arousal. Metencephalon: One of the five major divisions of the brain; it includes the pons and cerebellum.  Pons: The metencephalic structure that creates a bulge on the ventral surface of the brain stem.  Cerebellum: A metencephalic structure that is thought to participate in the storage of memories of learned sensorimotor skills. o It is an important sensorimotor structure; cerebellar damage eliminates the ability to precisely control one’s movements and to adapt them to changing conditions. Mesencephalon: One of the five major divisions of the brain; it is composed of the tectum and tegmentum. 1. Tectum: The “roof,” or dorsal surface, of the mesencephalon; it includes the superior and inferior colliculi. o Inferior colliculi: The structures of the tectum that receive auditory input from the superior olives. o Superior colliculi: Two of the four nuclei that compose the tectum; they receive major visual input. 2. Tegmentum: The ventral division of the mesencephalon; it includes part of the reticular formation, substantia nigra, and red nucleus. o Periaqueductal gray: The gray matter around the cerebral aqueduct, which contains opiate receptors and activates a descending analgesia circuit.

o Cerebral aqueduct: A narrow channel that connects the third and fourth ventricles. o Substantia nigra: The midbrain nucleus whose neurons project via the nigrostriatal pathway to the striatum of the basal ganglia; it is part of the mesotelencephalic dopamine system. o Red nucleus: A structure of the sensorimotor system that is located in the tegmentum of the mesencephalon. Diencephalon: One of the five major divisions of the brain; it is composed of the thalamus and hypothalamus. 1. Thalamus: The large two-lobed diencephalic structure that constitutes the anterior end of the brain stem; many of its nuclei are sensory relay nuclei that project to the cortex. o Massa intermedia: The neural structure located in the third ventricle that connects the two lobes of the thalamus. o Sensory relay nuclei: Those nuclei of the thalamus whose main function is to relay sensory signals to the appropriate areas of cortex. o Lateral geniculate nuclei: The six-layered thalamic structures that receive input from the retinas and transmit their output to the primary visual cortex. o Medial geniculate nuclei: The auditory thalamic nuclei that receive input from the inferior colliculi and project to primary auditory cortex. o Ventral posterior nuclei: A thalamic relay nucleus in both the somatosensory and gustatory systems. 2. Hypothalamus: The diencephalic structure that sits just below the anterior portion of the thalamus. o Pituitary gland: The gland that dangles from, and is controlled by, the hypothalamus. o Optic chiasm: The X-shaped structure on the inferior surface of the diencephalon; the point where the optic nerves decussate. o Decussate: To cross over to the other side of the brain. o Contralateral: Projecting from one side of the body to the other. o Ipsilateral: On the same side of the body. o Mammillary bodies: The pair of spherical nuclei that are located on the inferior surface of the hypothalamus. Telencephalon: The most superior of the brain’s five major divisions.  Initiates voluntary movement, interprets sensory input, and mediates complex cognitive processes (learning, speaking, and problem solving). Cerebral cortex: The layer of neural tissue covering the cerebral hemispheres of humans and other mammals.

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deeply convoluted (furrowed). The convolutions have the ef-fect of increasing the amount of cerebral cortex without in-creasing the overall volume of the brain. most mammals are lissencephalic (smooth-brained).

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Fissures: The large furrows in a convoluted cortex. Sulci: Small furrows in a convoluted cortex. Gyri: The cortical ridges that are located between fissures or sulci. Longitudinal fissure: The large fissure that separates the two cerebral hemispheres. Cerebral commissures: Tracts that connect the left and right cerebral hemispheres. Corpus callosum: The largest cerebral commissure. Central fissure: The large fissure that separates the frontal lobe from the parietal lobe. Lateral fissure: The large fissure that separates the temporal lobe from the frontal lobe. Frontal lobe: The most anterior of the four cerebral lobes. Parietal lobe: One of the four cerebral lobes; it is located just posterior to the central fissure. Temporal lobe: One of the four major cerebral lobes; it lies adjacent to the temples and contains the hippocampus and amygdala. Occipital lobe: The most posterior of the four cerebral lobes; its function is primarily visual. Precentral gyrus: The gyrus located just anterior to the central fissure; its function is primarily motor. Postcentral gyrus: The gyrus located just posterior to the central fissure; its function is primarily somatosensory. Superior temporal gyrus: The large gyrus of the temporal lobe adjacent to the lateral fissure; the location of auditory cortex. Neocortex: Six-layered cerebral cortex of relatively recent evolution; it constitutes 90 percent of human cerebral cortex. Pyramidal cells: Large multipolar cortical neurons with a pyramidshaped cell body, an apical dendrite, and a very long axon. Stellate cells: Small star-shaped cortical interneurons. Columnar organization: The functional organization of the neocortex in vertical columns; the cells in each column form a mini circuit that performs a single function. Hippocampus: A structure of the medial temporal lobes that plays role in various forms of memory.

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Limbic system: A collection of interconnected nuclei and tracts that ring the thalamus.  Amygdala: A structure in the anterior temporal lobe, just anterior to the hippocampus; plays a role in emotion.  Cingulate cortex: The cortex of the cingulate gyri, which are located on the medial surfaces of the frontal lobes.  Cingulate gyri: Large gyri located on the medial surfaces of the frontal lobes, just superior to the corpus callosum.  Fornix: The major tract of the limbic system; it connects the hippocampus with the septum and mammillary bodies.  Septum: A midline nucleus of the limbic system, located near the anterior tip of the cingulate cortex.  Basal ganglia: A collection of subcortical nuclei (e.g., striatum and globus pallidus).  Caudate: The tail-like structure that is part of the striatum.  Putamen: A structure that is joined to the caudate by a series of fiber bridges; together the putamen and caudate compose the striatum.  Striatum: A structure of the basal ganglia that is the terminal of the dopaminergic nigrostriatal pathway.  Globus pallidus: A structure of the basal ganglia that is located between the putamen and thalamus....