6 Neuron and Its PartsNeuron: Individual nerve cell; 100 billion in brainDendrites: Receive messages from other neurons; have thousands of branchesSoma: Cell body; metabolic center of neuron; contains genetic materialAxon: Carries information away from the cell body; longest part of neuronAxon Terminals: Branches that link the dendrites and soma of other neuronsSynaptic Gap: Space between the end of the axon of one neuron and the dendrites of an adjacent neuron
8 The Nerve ImpulseResting Potential: Electrical charge of an inactive neuronThreshold: Trigger point for a neuron’s firingAction Potential: Nerve impulse
9 Resting PotentialResting Potential: Tiny charge between inside & outside of neuronCreated by electrically charged particles (ions)Some concentrated outside the cell (sodium and chloride ions)Some concentrated inside the cell (Potassium ions)How is the charge maintained?Sodium-potassium pumpSelectively permeable cell membrane
10 Action PotentialAction potential: Change in potential, primarily because of messages from other neuronsExcitatory messages: Cell loses the negative charge; DepolarizationInhibitory messages: Cell becomes more negatively charged; Hyperpolarization
15 NeurotransmittersNeurotransmitters: Chemicals that alter activity in neurons; brain chemicals. Messages from one neuron to another pass over the synapse, the microscopic gap between neuronsReceptor Site: Areas on the surface of neurons and other cells that are sensitive to neurotransmittersAntagonist: drug that decreases activity of a neurotrans-mitter
16 Some Neurotransmitters Acetylcholine: involved in learning, memory, and muscle contractions. Botulism toxin prevents release of acetylcholine, resulting in paralysisDopamine: involved in arousal, mood, and movement. In Parkinson’s, receptors in brain fail to react to dopamine, leading to tremors, rigidity and problems initiating movementSerotonin and Norepinephrine: involved in arousal and mood. Cocaine blocks re-uptake of both neurotransmitters, resulting in “high”GABA (gamma-aminobutyric acid): main inhibitory neurotrans-mitter; lowers arousal and anxietyEndorphins: lower pain perception. Morphine and heroin bind to endorphin receptors, increasing endorphin activity.
17 Nerves and Neurons Nerves: Large bundles of neurons Myelin: Fatty layer of tissue that coats axonsMultiple Sclerosis (MS) occurs when myelin layer is destroyed; numbness, weakness, and paralysis occur
18 Demonstration of the speed of a neural impulse. A Little ExerciseDemonstration of the speed of a neural impulse.
19 An Organizational Pause: Organization of the Nervous System
20 Major Sections of the Nervous System Central Nervous System (CNS): Brain and spinal cordPeripheral Nervous System: All parts of the nervous system outside of the brain and spinal cord- Autonomic System: Serves internal organs and glands; controls automatic functions such as heart rate and blood pressure- Somatic System: Links spinal cord with skeletal muscles and sense organs; controls voluntary behavior
26 Three Components of Emotion Physical component: state of physiological arousal triggered by autonomic nervous systemBehavioral component: outward expression of the emotion, including facial expression & behaviorCognitive component: appraisal of the situation to determine which emotion we are experiencing and why
31 Somatic Nervous System Motor Nervous System: transfers messages from CNS to control function of voluntary musclesSensory Nervous System: transfers messages from sensory organs to CNS; brings information from outside the body to the brain to be processed
32 Structures in Somatic System Sensory neuron: neuron that transmits information from sensory organ to CNSMotor neuron: neuron that transmits information from CNS to voluntary muscleConnector neuron: neuron in spinal cord connecting sensory and motor neurons to form reflex arc.Reflex: An innate, automatic motor response to a specific sensory stimulus
37 A Little ExerciseA demonstration of the somatosensory system, using toothpicks and little rulers.
38 Part 3 The Central Nervous System The Spinal CordThe Brain- The Central Core- The Limbic System- The Cerebral Cortex
39 The Spinal CordSpinal Nerves: 31 of them; carry sensory and motor messages to and from the spinal cordCranial Nerves: 12 pairs that leave the brain directly; also work to communicate messagesSpinal cord functions to connect peripheral nervous system to the brain
40 The Central Core (aka the “old brain”) Medulla: Connects brain with the spinal cord and controls vital life functions such as heart rate and breathingCerebellum: Regulates posture, muscle tone, muscular coordination, and procedural learningReticular formation: Associated with levels of arousal and consciousness, as well as some reflexes (breathing, coughing, sneezing, vomiting)Thalamus: serves as a relay station for incoming sensory InformationBasal ganglia: involved in physical movement
42 The Limbic SystemAt the top border (limbus in Latin) of the brain stem.Hypothalamus: controls pituitary gland (directing activity of endocrine system) and autonomic nervous system; involved in basic drives (eating, drinking, sex)Hippocampus: involved in formation of memoriesAmygdala: involved in regulating emotional experiences, particularly initial emotional responses
44 Neocortex Cerebral Cortex: Outer layer of the cerebrum Cerebrum: Two large hemispheres that cover upper part of the brainCorticalization: Increase in size and wrinkling of the cortexCerebral Hemispheres: Right and left halves of the cerebrumCorpus Callosum: Bundle of fibers connecting cerebral hemispheres
48 Left Brain/Right Brain About 95 percent of our left brain is used for languageLeft hemisphere better at math, judging time and rhythm, and coordinating order of complex movementsProcesses information sequentiallyRight hemisphere good at perceptual skills, and at expressing and detecting other’s emotionsProcesses information simultaneously
50 Lobes of the Neocortex Occipital Lobe: Back of brain; vision center Parietal Lobe: Just above occipital; bodily sensations such as touch, pain, and temperature (somatosensory area)Temporal Lobe: Each side of the brain; auditory and language centersFrontal Lobe: Movement, sense of smell, higher mental functions; contains motor cortex; controls motor movement