The Nervous SystemNervous system- the body’s electrochemical communication circuitryCharacteristics of the Nervous System• Complexity- enormously complex• Integration- efficient at pulling information together• Adaptability-the brain and nervous system serve as our agent in adapting to the world. They have a biological function but are constantly adapting to changesin the body and the environment• Plasticity- the brain’s special capacity for change• By changing the way you think you can literally change the brain’s processes, wiring and rewiring, and even shape• Electrochemical Transmission- the brain and nervous system function as an information-processing system that is powered by electrical impulses andchemical messengersPathways in the Nervous SystemThe nervous system possesses specialized pathways that are adapted for different functions. They are made up of afferent nerves, efferent nerves, and neuralnetworks. • Afferent nerves- sensory nerves, carry information to the brain and spinal cord. Communicate information about the external environment and internal bodyprocesses• Efferent nerves- carry information out of the brain and spinal cord (the nervous system’s output). • Neural networks-networks of nerve cells that integrate sensory input and motor output, where most information processing occurs. They make up most of thebrainDivisions of the Nervous SystemTwo Primary divisions: central nervous system and the peripheral nervous system• CNS- made up of the brain and spinal cord• Contains over 99% of all nerve cells• PNS- network of nerves that connect the brain and the spinal cord• functions: bring information to and from the brain and spinal cord and to carry out the commands of the CNS to execute various muscular and glandularactivities• 2 major divisions• Somatic nervous system• Sensory nerves- convey information from the skin and muscles to the CNS about conditions such as pain and temperature• Motor nerves- tell muscles what to do• Autonomic nervous system- take messages to and from the body’s internal organs, monitoring processes like breathing, heart rate, and digestion• Sympathetic nervous system- arouses the body to mobile it for action (involved in experience of stress)• Para-sympathetic nervous system- calms the bodyStress As It Relates To The Nervous SystemStress- the body’s response to stressors(circumstances and events that threaten individuals and tax their coping abilities Stress Response• Begins with the ‘flight or flight’ reaction, one of the functions of the sympathetic nervous system• mobilizes the body’s physiological resources to prepare the organism to deal with threats to survival• Noticeable in the feeling of your heart pounding and hands sweating• Release of corticosteroids( powerful stress hormones)• allow us to focus our attention on what needs to be done now• Acute stress- momentary stress that occurs in response to life experiences• Chronic stress- stress that goes on continuously, can lead to permanent autonomic nervous system arousal• over time, it can break down the nervous systemNeuronsTwo types of cells in the nervous system: neurons and glial cells• Neurons- nerve cells that handle the information-processing function• mirror neurons are activated when we preform an action but also when we watch someone else preform the same task. May play a role in empathy andunderstanding of others• Glial cells- provide support, nutritional benefice, and other functions in the nervous system. Keep neurons running smoothly and outnumber them about 10:1Specialized cell structureNeurons are developed early in life, but their shape, size and connections can change throughout their life span. aka PlasticityEvery neuron has 3 parts:• Cell body- contains the nucleus, directs the manufacture of substances that the neuron needs for growth and maintenance• Dendrites- treelike fibers projecting from the neuron, receive information and orient it toward the neuron’s cell body• Axon- par of the neuron that carries information aaa from the cell body towards the other cells• most are encased by a myelin sheath, which consists of a layer of cells containing fat. They insulate axons and speed up transition of nerve impulses• A disorder associated with the myelin sheath is Multiple Sclerosis (MS), which causes hardening of the myelin sheath, disruption the flow of informationthrough neurons. • The development of the myelin sheath can be likened to the evolution of interstate highways as cities grew. As the brain got larger, it becamenecessary for information to travel over longer distances, thus the myelin sheath came about.Semipermeable membranes cover the surface of neurons.The Neural
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