Chapter 2 Study Guide Nervous system body s electrochemical communication circuitry Number of nerve cells in a cubic centimeter of the brain over 50 million Transmission Complexity Adaptability Integration Electrochemical o Complexity extensive assemblies of nerve cells participate o Adaptability The brain has a special capacity for change in every activity we do referred to as plasticity o Integration the brain does an adept job at pulling information together as we function in the world o Electrochemical transmission the brain and the nervous system function as an information processing system that is powered by electrical impulses and chemical messengers Afferent neurons sensory nerves carry information about the external environment to the brain and spinal cord via sensory receptors Efferent nerves motor nerves carry information out of the brain and spinal cord to other areas of the body o Think afferent arrives at the CNS and efferent exits the CNS Neural networks networks of nerve cells that integrate sensory input and motor output Responsible for translating the input your eyes receive to neural cods for letters words associations and meanings Nervous system o Central made up of the brain and spinal cord Contains more than 99 of all our nerve cells o Peripheral network of nerves that connects the brain and spinal cord to other parts of the body Carries information to and from the brain and spinal cord to carry out the commands of the CNS to execute various muscular and glandular activities Somatic Nervous System consists of the sensory nerves whose function is to convey information from the skin and muscles to the CNS about conditions such as pain and temperature and the motor nerves whose function is to tell the muscles what to do Autonomic Nervous System takes messages to and from the body s internal organs monitoring such processes as breathing heart rate and digestion Sympathetic arouses the body to mobilize it for action and thus is involved in the experience of stress Parasympathetic calms the body Fight or flight first part of the stress response that mobilizes the body s physiological resources to prepare the organism to deal with threats to survival Acute vs Chronic Stress o Acute momentary stress that occurs in response to life experiences Ends when stressful situation ends o Chronic stress that goes on continuously that may lead to persistent autonomic nervous system arousal Synapses tiny spaces between neurons the gaps between neurons are referred to as synaptic gaps Lie between the axon of one neuron and the dendrites or cell body of another neuron Glial cells second of two types of cells in the nervous system first being neurons They provide support nutritional benefits and other functions and keep neurons running smoothly Out number neurons about 10 1 Resting and action potentials o Resting the stable negative charge of an inactive neuron o Action the brief wave of positive electrical charge that sweeps down the axon All or nothing principle the principle that once the electrical impulse reaches a certain level of intensity its threshold it fires and moves all the way down the axon without losing any intensity Types of neurotransmitters chemical substances that are stored in very tiny sacs within the terminal buttons and involved in transmitting information across a synaptic gap to the next neuron o Acetycholine stimulates the firing of neurons and is involved in the action of muscles learning and memory Alzheimer s is a lack of Acetycholine and a black widow s venom causes an outburst of it causing violent spasms o GABA found in the CNS present in as many as 1 3 of the brain s synapses Keeps many neurons from firing helps to control precision of the signal being carried from one neuron to the next o Norepinephrine inhibits the firing of neurons in the CNS Excites the heart muscles intestines and urogenital tract o Dopamine helps to control voluntary movement and effects sleep mood attention learning and the ability to recognize rewards in the environment Low levels are associated with Parkinson s disease o Serotonin involved in the regulation of sleep mood attention and learning o Endorphins natural opiates that mainly stimulate the firing of neurons Shield the body from pain and elevate feelings of pleasure o Oxytocin a hormone and neurotransmitter that plays an important role in the experience of love and social bonding Antagonist vs agonist o Antagonist a drug that blocks a neurotransmitter s effects Ex Schizophrenia medicine is used to block dopamine o Agonist a drug that mimics or increases a neurotransmitter s effects Ex morphine to stimulate endorphins Lesioning abnormal disruption in the tissue of the brain resulting from injury or disease EEGs PET scans CAT scans MRIs and fMRIs o EEG records the brain s electrical activity Can access brain damage epilepsy o PET Scan measures the amount of glucose in various areas of the brain and then sends this information to a computer for analysis o CAT or Ct scan produces a 3 D image obtained from x rays of the head that are assembled into a composite image by a computer Think Derek Sheppard a neurosurgeon trying to locate tumors in a patient s brain o MRI involves creating a magnetic field around a person s body and using radio waves to construct images of the person s tissues and biochemical activities o fMRIs allows scientists to see what is happening in the brain while it is working Hindbrain Midbrain and forebrain o Hindbrain located at the rear of the skull lowest portion of the brain consists of the medulla cerebellum and pons Medulla where spinal cord enters skull controls functions such as breathing and heart rate Also regulates reflexes Cerebellum just above medulla two rounded structures that play a role in motor coordination Pons connects the cerebellum and the brain stem Involved in sleep and arousal o Midbrain located between hindbrain and forebrain an area in which many nerve fiber systems ascend and descend to connect the higher and lower portions of the brain in particular the midbrain relays information between the brain and the eyes and ears Reticular formation a system in the midbrain comprising a diffuse collection of neurons involved in stereotypical patterns of behavior such as walking sleeping and turning to attend a certain noise Small groups of neurons that use the neurotransmitters serotonin dopamine and norepinephrine o Forebrain brain s largest division and most forward part
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