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PHA 618 LAB NERVOUS SYTEMNERVOUS SYSTEMMajorcontrolling,regulatory,andcommunicating system inside the bodyANATOMICAL DIVISIONS• Central nervous system (CNS)-Brain and spinal cord-Serve as central processing center-Body’s neuralcontrol center• Peripheral nervous system (PNS)-Network of all the nerves in the body that sendsmessages to and from the central processing center-Located outside the nervous system-Consists of nerves and sensory receptors-Receptors-EffectorsFUNCTIONAL DIVISIONSSensory division (afferent)-sensory neurons carry afferent or incomingmessages to the brain or spinal cord-Carries impulses from sensory receptors to theCNSMotor division (efferent)-motor neurons carry efferent or outgoingmessages away from the brain or spinal cord-Carries impulses from CNS to effectors-Motor division has two divisions:Somatic nervous systemVoluntary control of skeletalmusclesome of the efferent messagestravel on motor neurons tostimulate the skeletal muscles tomove the body (somato motordivisionwherethesomaticnervous system)Autonomic nervous systemInvoluntary control of cardiacmuscle, smooth muscle, andglandsOther efferent messages go toglands, a cardiac muscle wherethe smooth muscle of holloworgans and blood vessels. Thesemessages make up the motorneuron of autonomic nervoussystemORGANIZATION OF THE NERVOUS SYSTEMUnderautonomicdivisionthere’sparasympathetic and sympatheticParasympathetic:sends electrical messages tocarry out functions for vegetative activities suchas digestion, defecation, and urination. For restand digestion function.-increase digestion and salivation; decreaseheart rate (calm)-rest and digest-conserves energySympathetic:sendselectricalmessagestoprepare the body for physical activity.For fight-and-flight reaction-increases energy, heart rate, blood pressure,sweat glandsANATOMY OF THE NERVOUS SYSTEMAnatomy of aNeuron or Nerve CellNeurons cannot function alone for every 1 neuronthere are approximately 50 support cells which are calledneuroglia• Neurons havebasically three parts:
-dendrites (one or more)that receive information orsignals-cell bodiesthat are involved in protein synthesis; a bodycontaining the nucleus and organelles for photosynthesis-axonsthat transmit electrical impulses; carry nerveimpulse along its length• Axons may or may not haveor intermittently coveredwith a myelin sheath.Myelin is lipid rich and insulates the axons much likethe wire coating insulates the wires of electricalappliances in the householdTYPES OF NEURONSTo differentiate the types of neurons, you needto locate the neuron’s cell body and observe theprocesses or projections that are attached to itMultipolar-has several dendrites and one axon coming offof its cell body-most common type of neuron in the brain andspinal cord-motor neurons are multipolar, they carryelectrical messages away from the brain andspinal cordBipolar-one dendrite and one axon coming off its cellbody

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