Ch-4. 11 Nervous Overview2.doc

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University of British Columbia
KIN 190
Blythe Nielson

NOTE – The quiz will have question ONLY from the material we get through on Tuesday. The first midterm will cover all material from day one until the lecture before the second midterm. Learning expectations for BIOL 131. Chapters 11, Nervous System Overview Read Chapter 11. You should be able to: • Describe the overall structure and organization of the nervous system. - Overall nervous system: CNS/PNS - PNS consists of sensory (afferent)/motor (efferent) - Motor: somatic/autonomic nervous system - Autonomic: sympathetic/parasympathetic/ (enteric) • List the divisions and subdivision of the nervous system describing the basic roles of each division. - CNS: spinal cord/brain (processes info, initiates responses, integrates mental processes) - PNS: neurons, ganglia, sensory receptors, plexuses, all nervous tissue outside of CNS - Afferent (sensory): transmits action potentials from sensory receptors to CNS - Efferent (motor): transmits action potentials from CNS to effector organs (muscles/glands) - Motor: Somatic: action potential to CNS (neuromuscular junctions: synapse between neuron from CNS and skeletal muscle cell). - Motor: Autonomic: To smooth muscles (neuron from CNS synapses with second neuron in ganglion, second neuron then synapses with effector) - ANS: Sympathetic: prepares body for exercise - ANS: Parasympathetic: prepares body for relaxation (emptying urine, digesting food) - ANS: Enteric: Plexuses within walls of digestive tract, enteric neurons monitor/control digestive tract independently of CNS through local reflexes. • Differentiate between the terms efferent and afferent, sensory and motor. - Efferent (motor): transmits action potentials from CNS to effector (muscle, gland) - Afferent (sensory): transmits action potentials from sensory receptors to CNS (cell bodies of sensory neurons in dorsal root ganglia near spinal cord/ganglia near origin of certain cranial nerves) • Define “neuromuscular junction”, “synapse”, “ganglion” and “fiber”. - Neuromuscular junction: Synapse between neuron from CNS and skeletal muscle cell - Synapse: functional membrane to membrane contact of nerve cell with another nerve cell, muscle gland, sensory receptor (transmits action potential from one cell to another). - Ganglion: Group of nerve cell bodies in PNS - Fiber: Makes up muscles • List the cells of the nervous system and describe their functions. - Neuroglia: support, protect, influence neurons - Neurons: receive stimuli and transmit action potentials (nerve cells) o Sensory (afferent): AP towards CNS o Motor (efferent): AP away from CNS o Interneurons: within CNS from one neuron to another • Label or list the parts of a neuron and state the function of each. - Cell body: contains nucleus (source of info/protein synthesis), little nucleolus in nucleus, rough ER (endoplasmic reticulum) and Golgi apparatus surround nucleus (other organelles/mitochondria present), Nissl bodies primary site of protein synthesis in neurons. - Dendrites: short, highly branched cytoplasmic extensions tapered from base of neuron cell body to the tips. Dendritic spines (small extensions axons of other neurons form synapses with other dendrites) - Axons: branch to form collaterals, trigger zone ( site where action potentials are generated), presynaptic terminals (extensions w/ long ends). • Describe neuronal transport. - Axoplasm moves from cell body towards terminals - Recycled plasma membrane and substances taken in by endocytosis transported up axon to cell body to be reused/get rid of (retrograde) - ** Rabies/herpes enter axons in damaged skin/transported to CNS. • Describe the different types of neuroglia – describe their roles and where they are found. - CNS NEUROGLIA - Astrocytes: Cover surface of neurons/bvs, form blood brain barrier (bbb) regulates which substances reach CNS (drugs/alcohol difficult to penetrate), CNS version of cells that wrap around other cells. - Ependymal cells: Lines hollow parts of CNS – form choroid plexuses (secretes cerebrospinal fluid into ventricles of brain), free surface contains cilia to move fluid throughout brain cavities. - Microglia: in CNS become mobile and phagocytic in response to inflammation. Phagocytize necrotic tissue, microorganisms, other foreign substances in CNS. Migrate to area of infection. - Oligodendrocytes: cytoplasmic extensions surrounding axons (wrapped several times = myelin sheaths). Forms myelin sheaths around portions of several axons ** - PNS NEUROGLIA - Schwann cells: wrap several times around axons to form myelin sheaths around only ONE axon. - Satellite cells: surround neuron cell bodies in sensory ganglia. Provide support/nutrition to neurons, protect from heavy metal poisons (absorb them/reduce access to neuron cells) • Differentiate between grey matter and white matter. - White matter: bundles of parallel axons w myelin sheaths, forms conduction pathways propogating AP’s from one area of CNS to another. - Nodes of Ranvier (gaps between one myelinating cell and the next) - 1 yr old, axons aren’t myelinated yet, don’t have as much control over actions - Grey matter: groups of neuron cell bodies/dendrites, very little myelin. Gray matter on surface of brain (cortex), clusters deeper in brain (nuclei). PNS = ganglion • Describe in detail how resting membrane potentials are produced and maintained. - Potential difference = unequal distribution of charge btw inside/outside of plasma (-70 to -90mV) - Inside negative of outside - Potential difference maintained by sodium/potassium pump. Each ATP, 3 sodium move out, 2 potassium move in - Outside plasma membrane is therefore slightly positive (polarized membrane because 2 sides are different) • Differentiate between depolarization and hyperpolarization – when they occur and how they may or may not contribute to graded, summated or action potentials. - Depolarization: potential difference becomes smaller (less polar) - Hyperpolarization: potential difference becomes greater (more polar) • Describe in detail how action potentials are produced and how they are propagated in myelinated and unmyelinated axons. Make sure to include the ions involved. - When graded potentials cause depolarization of plasma membrane to threshold (series of permeability changes) results in action potential. - Depolarization (membrane potential moves away from resting state, becoming more positive), Repolarization (membrane potential returns towards resting state becoming more negative), Afterpotential (plasma membrane is slightly hyperpolarized for short period of time). - Propogate (AP at one location stimulates production of new AP at adjacent location, stimulates another, etc. > domino effect) - unmyelinated axons (continuous conduction) – next AP generated directly adjacent to first AP, inside of membrane more positive than outside, on outside positive ions from adjacent area attach to negative charges of AP site. On inside, positive charged ions on AP sit
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