Chapter 12 the nervous system
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Chapter 12 the nervous system

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Chapter 12 the nervous system Chapter 12 the nervous system Presentation Transcript

  • Chapter 12: a glance at the nervous system
    By Shawna Miller
  • Functions and organs
    The functions of the nervous system are to coordinate and control body functions.
    Receives sensory output
    Makes decisions
    Orders body responses
    The organs of the nervous system are:
    Brain
    Nerves
    Spinal cord
  • Nervous tissue
    Consists of two cell types
    Neurons- individual nerve cells
    Dendrite- branched projections, receive impulses
    Nerve cell body- contains nucleus/other organelles
    Axon-projection from the nerve cell body, conducts electrical impulses to destination
    The point which the axon of one neuron meets the dendrite of another neuron is called a synapse.
    The gap between two neurons is called a synaptic cleft.
    The electrical impulses need help from chemical messengers caller neurotransmitters.
    Different neuroglial cells are in nervous tissue
    Some produce myelin-a fatty substance which acts like insulation for axons
    They do not conduct electrical impulses
  • Central nervous system
    Receives impulses from all over the body.
    The system is made of grey and white matter.
    Grey matter is uncovered cell bodies and dendrites.
    White matter is myelinated nerve fibers.
    The myelin sheath makes the nervous tissue look white.
    Tracts are bundles of nerve fibers that connect parts of the CNS.
    Meninges are what the CNS is encased and protected by. There are three of these membranes.
  • The Brain
    One of the largest organs in the body.
    Center for thought, judgement, memory, and emotion.
    Four sections:
    Cerebrum- largest section in the upper part of the brain. It processes problem solving, language, thoughts, and memory. It has an outer layer called the cerebral cortex which is made up of folds of grey matter.
    Diencephalon- below the cerebrum contains the thalmus and hypothalmus
    Thalmus- center for relaying impulses for eyes, ears, and skin to the cerebrum. What our pain perception is controlled by.
    Hypothalmus- below thalmus, controls body temperature, sleep appetite, and emotions.
    Cerebellum- second largest section, beneath the posterior part of the cerebrum. Helps to maintain body movements and maintain balance.
    Brain stem : has three parts
    Mid brain- acts as pathway between brain and spinal cord
    Pons- connects the cerebellum to rest of brain
    Medulla oblongata- most inferior portion of the brain; it connects the brain to the spinal cord
    A vital are that controls respiration, heart rate, and blood pressure
    Site where nerve tracts cross
    The brain has four interconnected cavities called ventricles. There is one in each hemisphere of the brain
    They contain CSF(cerebral spinal fluid) that protects the brain from shock/sudden movement to brain and spinal cord
  • A view of the brain
  • Spinal cord
    The spinal cord’s function is to provide a pathway for impulses traveling to and from the brain
    A column of nervous tissue that goes from the medulla oblongata down to the second level of the lumbar vertebra in the vertebral column
    Goes down to the center of the spinal cord in the central canal
    Outer portion is myelinated white matter- can be either ascending tracts(carrying sensory info to the brain) or descending tracts( carrying motor commands from the brain to a peripheral nerve
  • meninges
    Three layers of connective tissue membranes that surround the brain and spinal cord
    External to internal:
    Dura mater(tough mother)- tough fibrous sac around the CNS
    Subdural space- actual space between the dura mater and arachnoid layers
    Arachnoid layer(spiderlike)- thin, delicate layer attached to the pia mater by weblike filaments
    Subarachnoid space- space between the arachnoid and pia mater layers. It contains cerebrospinal fluid which cushions the brain from the outside
    Pia mater(soft mother)- innermost membrane layer which is applied directly to the spinal cord and surface of the brain
  • Peripheral nervous system
    Includes 12 pairs of cranial nerves and 31 pairs of spinal nerves
    Where the nerve originates determines if it is cranial or spinal
    The point where either type is attached to the CNS is called the nerve root
    Afferent neurons(sensory neurons)- carry sensory info from a sensory receptor to the CNS
    Efferent neurons(motor neurons)- carry activity instructions from the CNS to muscles/glands out in the body
    Nerves of the peripheral nervous system are subdivided into two areas: the autonomic nervous system(ANS) and somatic nerves which each serve a different part of the body
    The nerve cell bodies of the neurons are grouped together in a knot-like mass, called a ganglion
  • Autonomic nervous system
    Involved with control of involuntary or unconscious bodily functions
    May increase or decrease activity of smooth muscles
    Is divided into two divisions
    Sympathetic branch- control the “fight or flight” reaction during stress or crisis. These nerves increase heart rate, dilate airways, increase blood pressure, inhibit digestion, and stimulate adrenaline production
    Parasympathetic- counterbalance for sympathetic, the “rest and digest” reaction. They lower heart rate, decrease blood pressure, and stimulate digestion
    Somatic nerves- serve the skin and skeletal muscles. Mainly involved with the conscious/voluntary activities of the body. Largest ones found in dermis of skin like touch, pressure and pain. Also carry motor commands to skeletal muscles
  • Common terms
    Cerebrospinal, meningitis, analgesia, aphasia, dysphasia, quadriplegia, neuropathy, encephalitis, electroencephalogram
  • Definitions
    Cerebrospinal- pertaining to the cerebrum and spine
    Meningitis- meninges inflammation
    Analgesia- absence of pain or sensation
    Aphasia- lack of speech
    Dysphagia- difficult speech
    Quadriplegia- paralysis of four
    Neuropathy- nerve disease
    Electroencephalogram(EEG)- record of brain’s activity
  • tests
    Brain scan-image of the brain taken after an injection of radioactive isotopes into the circulation
    Echoencephalography- record of the ultrasonic echoes of the brain
    Myelography- injection of radiopaque dye into the spinal cord
    Positron emission tomography- use of positive radionuclides to reconstruct brain sections
  • treatments
    Nerve block- injection of regional anesthetic to stop the passage of sensory/pain impulses along a nerve path
    Laminectomy- removal of a portion of a vertebra in order to relieve pressure on the spinal nerve
    Tractotomy- surgical interruption of a nerve tract in the spinal cord
  • Medications
    Analgesics- non narcotics to treat pain(aspirin, tylenol, aleve, ibuprofen)
    Anesthetics- drug that produces a loss of sensation or loss of consciousness( propofol, novocain, lidocaine, nembutal)
    Hypnotic- drug that promotes sleep(restoril, seconal, temazepam)
    Sedative- drug that has a relaxing or calming effect(amytal, butisol, amobarbital)