Vert Phys Review Exam #3 - Chapter 26: Introduction to the...

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Chapter 26: Introduction to the Central Nervous System -The functional unit of the nervous system is the neuron, which transmits information in the form of nerve impulses down its axon and conveys that information to another nerve or muscle cell through synaptic contacts. 1. Bilateral Symmetry and the Great Leap Forward a. Animals acquired a longitudinal axis with the two ends of this axis being distinct i. Concentrate the sense organs in the front of the body so that the animal can have some knowledge of the environment directly ahead ii. The massing of sensory organs anteriorly requires that a large mass of neural tissue be situated anteriorly to receive the neurons from the sense organs iii. Encephalization: development of the brain 2. Basic Organization of the Vertebrate Nervous System a. Three major components: i. A sensory component that serves to inform the organisms about the conditions in the environment 1. Eyes and ears ii. An effector or motor component that sends or projects axons to the muscles of the body and thereby enables the organism to act upon its environment iii. A neuronal network interposed between the sensory nerves and motor nerves, that is best characterized as an integration system. b. the intermediate neurons are protects and are enclosed in the bony cranium and the vertebral column i. The enlarged cranial portion is called the brain and the narrower portion which runs down the hollow of vertebral column is the spinal cord ii. Make up the CNS iii. Composed almost entirely of intermediate neurons (several thousand to one motor neuron) and thus CNS integrates and processes sensory information and expresses the sum total of this integral activity in the form of appropriate motor activity. iv. Need plasticity: 1. Uses both motor and sensory systems 2. Peripheral nervous system consists of cranial and spinal nerves 3. Gross Topography of the Vertebrate Brain i. During the first month of human development the brain exhibits three distinct dilations or primary divisions 1. Forebrain (Prosenencephalon) 2. Midbrain (mesencephalon) 3. Hindbrain (rhomboencephalon)
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ii. by the fifth week of gestation, further development results in the appearance of five vesicles or divisions of the brain 1. Forebrain a. Endbrain (telencephalon), also called the cerebral hemispheres b. Between brain (diencephalons) characterized by the outgrowth of the optic vesicles or future eyes 2. Midbrain continues to develop and remains as one of the primary divisions 3. Hindbrain a. The more anterior or rostral portion becomes the future pons and cerebellum, which collectively comprise the metencephalon b. The more caudal portion is destined to become the medulla oblongata (mylencephalon) 4. Final Comments Concerning the Gross Topography of the Brain a. The endbrain can be further subdivided into three separate regions i. Olfactory bulb ii. Corpus Striatum: region of cell bodies and forms the bulk of the endbrain in submammalian animals iii. Cortex: layer of cells that covers the endbrain
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Vert Phys Review Exam #3 - Chapter 26: Introduction to the...

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