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The Nervous System Eric Mennen. Introduction The nervous system is the master controlling and communication system of the body  Communicates through.

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Presentation on theme: "The Nervous System Eric Mennen. Introduction The nervous system is the master controlling and communication system of the body  Communicates through."— Presentation transcript:

1 The Nervous System Eric Mennen

2 Introduction The nervous system is the master controlling and communication system of the body  Communicates through electrical impulses  Every thought, action, and emotion reflects its activity Functions 1. Monitor changes (sensory input) 2. Process and interpret sensory input (integration) 3. Effects a response (motor output)

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4 Structural Classification Central Nervous System (CNS) – brain and spinal cord  Occupies the dorsal body cavity  Acts as the command center of the nervous system Peripheral Nervous System (PNS) – nerves that extend from brain and spinal cord  Consists mainly of the nerves that extend from the brain and spinal cord  Spinal Nerves – carry impulses to and from the spinal cord  Cranial Nerves – carry impulses to and from the brain

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6 Functional Classification Afferent (sensory) Division - nerve fibers that carry impulses to the CNS  Keeps the CNS constantly informed on events inside and outside the body Efferent (motor) Division - nerve fibers that carry impulses from the CNS to the effector organs  These impulses activate or bring about a motor response

7 Functional Classification cont.. Two Motor Subdivisions  Somatic Nervous System - allows us to consciously or voluntarily control our muscles  Autonomic Nervous System – regulates events that are automatic or involuntary Sympathetic- mobilizes the body during extreme situations Parasympathetic- allows us to unwind and conserve energy

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9 Nervous Tissue Supporting Cells (neuroglia) - cells that support, insulate, and protect delicate neurons 4 types Astrocytes - (star shaped) protect neurons from harmful substances in the blood Microglia - dispose of debris and foreign substances (ex. Dead brain cells) Ependymal cells - helps circulate cerebrospinal fluid and create a cushion  Line cavities of the brain and spinal cord Oligodendrocytes - insulated covering of nerve cells called myelin sheaths

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11 Nervous Tissue Neurons (nerve cells) - transmit messages called a nerve impulse from one part of the body to another  Neurons differ structurally but have many common features (Ex. They all possess a cell body and one or more processes extending from the cell body)  Neurons communicate with each other through tiny gaps called synaptic clefts (Synapses).

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13 Neurons Anatomy Cell Body (perikaryon) - the metabolic center of the neuron Contains the usual organelles Contains neuroplasm which is the cytoplasm of the neuron Nissl Substance (rough ER) – produce proteins Neurofibrils – intermediate filaments that are important in maintaining cell shape  abundant in the cell body

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15 Neurons Anatomy cont. Processes – arm like extension of the cell body that sends and receive electrical signals  Can be 3 to 4 feet (Ex. Lumbar – Big toe) Two Types:  Dendrites – convey incoming messages (electrical signals) – afferent process  Axons – generate nerve impulses and send them away from the cell body - efferent process Each neuron can have hundreds of dendrites but only 1 axon

16 Neurons Anatomy Cont. Axon hillock – conelike region where axon meets cell body Axon terminals – branches at the end of the axon  Contain neurotransmitters  Each axon terminal is separated from the next neuron by a tiny gap called the synaptic cleft (synapse)  Schwann cells are supporting cells that wrap themselves around the axon and form the myelin sheath encloses the axon

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18 The Central Nervous System Consists of the Brain and Spinal Cord  They act as a control center for all activities The Brain is divided into four major regions 1. Cerebral hemispheres 2. Diencephalon 3. Brain stem 4. Cerebellum

19 The Central Nervous System Fun Facts!  The brain weighs roughly 3 lbs and is about the size of your two fist put together  The brain gives us consciousness, memory, perception, and the ability to evaluate situations and feel emotions

20 Cerebral Hemispheres Together called the cerebrum, the most superior part of the brain Frontal lobe: Conscience choice, motor movements, speech, language comprehension. Temporal lobe: auditory, olfactory, long term memory. Parietal lobe: somatic sensory (pain, temp., touch), gustatory, Occipital lobe: vision, spatial interpretation

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22 Diencephalon (Interbrain) Thalamus: recognizes pleasant and unpleasant senses, sleep, alertness Hypothalamus: regulation of temperature, water balance,metabolism, moods,regulates sex drive and emotional memory (Limbic system) Pituitary gland: important in hormone production “Master Hormone Gland”

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24 Brain Stem Midbrain: vision and hearing reflexes Pons: breathing Medulla Oblongata: regulates heart rate, blood pressure, breathing, swallowing, and vomiting Reticular Formation: motor control of the visceral organs (abdomen)  Damage to this area can result in permanent unconsciousness (coma)

25 Cerebellum Large cauliflower projection under the occipital lobe Functions: 1. Skeletal muscle activity 2. Balance and equilibrium (Coordination) 3. Regulates body position and tension of body parts

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28 The Spinal Cord A continuation of the brain stem Extends from brain to just below ribs (L 1 ) Enclosed in vertebral column Creates a two way pathway to and from the brain

29 Gray Matter Butterfly in shape Surrounds central the central canal of the spinal cord Damage can cause loss of sensation from body area Contains motor neurons of the somatic (voluntary) nervous system

30 White Matter Surrounds the gray matter Conducts impulses to the brain for sensory (afferent) and motor (efferent)

31 Peripheral Nervous System Consists of nerves and scattered neuronal cell bodies found outside of the Central Nervous System Cranial nerves- 12 pairs of nerves that extend from the brain Spinal nerves- 31 pairs of nerves that extend from the spinal cord

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33 Cranial Nerves Olfactory nerve - carries impulse for sense of smell Optic nerve - carries impulse for vision Oculomotor nerve - supplies motor fibers for eye muscles Facial nerve - activates muscle for facial expression and impulse for taste Vagus nerve - sensory and motor impulses for respiratory, cardiac and digestive activity

34 Cranial Nerves Cont’d Trochlear – supplies motor fibers for one external eye muscle Trigeminal – conducts sensory impulses from the skin of the face and mucosa of the nose and mouth: activates chewing muscles Abducens – supplies motor fibers to the lateral rectus muscle – rolls the eye laterally Vestibulocochlear – sensory; transmits impulses for the sense of balance and hearing

35 Cranial Nerves Cont’d Glossopharyngeal – supplies motor fibers to the pharnyx to promote swallowing and saliva production Accessory – motor fibers that activate sternocleidomastoid and trapezius muscle Hypoglossal – motor fibers control tongue movements

36 Spinal Nerves Named from vertebrae from which the extend C 1 -C 5 (Cervical)- serves muscles of shoulder and neck C 5 -C 8, T 1 (Brachial)- serves shoulder and arm muscles T 2 -T 12 (Thoracic)- serves muscles between ribs and mid trunk L 1 -L 4 (Lumbar)- serves muscles of abdomen, hips and upper leg

37 Spinal Nerves Cont. S 1 -S 4 - (Sacral)- serves muscles of lower leg and feet Sciatic Nerve - largest nerve in the body, serves muscles of the legs


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