Chapter 12: Structure and Function of Neurons PDF

Chapter 12: Structure and Function of Neurons Organs of nervous system: Brain Spinal cord Cranial nerves Spinal nerves Sympathetic nervous systems (autonomic nervous system) Parasympathetic nervous systems (autonomic nervous system) Means of communications Sensory input Motor output Brief...

Chapter 12: Structure and Function of Neurons Organs of nervous system: Brain Spinal cord Cranial nerves Spinal nerves Sympathetic nervous systems (autonomic nervous system) Parasympathetic nervous systems (autonomic nervous system) Means of communications Sensory input Motor output Brief outlines only. For details, please refer to the Lecture Text on Top Hat Cell types in the nervous system Nervous tissue: highly cellular densely packed cells only 20% extracellular space neurons and supporting cells cells are of ectodermal origin except microglia Brief outlines only. For details, please refer to the Lecture Text on Top Hat Supporting cells in the CNS Astrocytes Microglial cells Ependymal cells Oligodendrocytes Brief outlines only. For details, please refer to the Lecture Text on Top Hat Supporting cells in PNS Satellite cells Schwann cells Brief outlines only. For details, please refer to the Lecture Text on Top Hat Brief outlines only. For details, please refer to the Lecture Text on Top Hat Neurons Extreme longevity High metabolic rate Cell body - receptive or input region Axon - conducting component Axonal endings - secretory or output region perikaryon or soma 5 to 140 mm all cell organelles except centrioles Nissl's bodies represent rough ER Brief outlines only. For details, please refer to the Lecture Text on Top Hat Brief outlines only. For details, please refer to the Lecture Text on Top Hat Nuclei or nuclear areas Ganglion Tracts Nerves Brief outlines only. For details, please refer to the Lecture Text on Top Hat Types of Neurons: Structurally Multipolar neurons Bipolar neurons Unipolar neurons: Embryologically, the unipolar neurons originate as bipolar cells Brief outlines only. For details, please refer to the Lecture Text on Top Hat Types of Neurons: Functionally Sensory or afferent Motor or efferent Association neurons or interneurons Brief outlines only. For details, please refer to the Lecture Text on Top Hat Brief outlines only. For details, please refer to the Lecture Text on Top Hat Neurophysiology Neurons highly irritable Action potential (AP) generated due to ionic currents Positive and negative charges across the plasma membranes Membrane channels allow ions to cross Ions diffuse down the electrochemical gradient passive channels active channels chemically-gated voltage-gated Brief outlines only. For details, please refer to the Lecture Text on Top Hat Resting Membrane Potential -40 to -90 mV in most neurons ECF: more Na+ ICF : more K+ negatively charged non-diffusible molecules Role of Na+-K+ pump Electrochemical Gradients Brief outlines only. For details, please refer to the Lecture Text on Top Hat Membrane Potentials Depolarization Hyperpolarization Graded potential Types of graded potentials: receptor potential postsynaptic potential Brief outlines only. For details, please refer to the Lecture Text on Top Hat Action Potential Generated by excitable membranes only Axons and muscle cells Brief reversal of polarity Generation of Action Potential movement of Na+ and K+ ions across the membrane changes in membrane potential opening and closing of different types of channels different phases of action potential duration of action potential Brief outlines only. For details, please refer to the Lecture Text on Top Hat Brief outlines only. For details, please refer to the Lecture Text on Top Hat Propagation of Action Potential Flow of electrical current along the axon Self-propagating current Saltatory propagation Strength is not decreased Threshold All-or-None phenomenon Coding for stimulus intensity Absolute refractory period Relative refractory period Brief outlines only. For details, please refer to the Lecture Text on Top Hat Brief outlines only. For details, please refer to the Lecture Text on Top Hat Synapse Several types Neurons have 1000-10,000 axonal terminals making synapse Neuromuscular junctions and neuro-glandular junctions Brief outlines only. For details, please refer to the Lecture Text on Top Hat Types of Synapse Electrical synapse Chemical synapse Synaptic Transmission role of Ca2+ ions release of neurotransmitter postsynaptic potential: EPSPs or IPSPs type of neurotransmitters and receptors neurotransmitter degradation synaptic delay Characteristics of EPSPs and IPSPs Brief outlines only. For details, please refer to the Lecture Text on Top Hat Brief outlines only. For details, please refer to the Lecture Text on Top Hat Modification of Synaptic Events EPSPs IPSPs Brief outlines only. For details, please refer to the Lecture Text on Top Hat Neurotransmitters More than 50 chemicals Acetylcholine Epinephrine Norepinephrine Dopamine Brief outlines only. For details, please refer to the Lecture Text on Top Hat