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Neuroanatomy

Neuroanatomy. Parts of the neuron Membrane Soma or cell body Cytoplasm Nucleus Endoplasmic reticulum Ribosomes Mitochondria Golgi apparatus Intracellular organelles. Neuroanatomy. Parts of the neuron Soma or cell body Dendrites (afferent to soma) Spines (postsynaptic)

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Neuroanatomy

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  1. Neuroanatomy • Parts of the neuron • Membrane • Soma or cell body • Cytoplasm • Nucleus • Endoplasmic reticulum • Ribosomes • Mitochondria • Golgi apparatus • Intracellular organelles

  2. Neuroanatomy • Parts of the neuron • Soma or cell body • Dendrites (afferent to soma) • Spines (postsynaptic) • Axon (efferent to soma) • Axonal hillock • Terminal (presynaptic) • Synapse

  3. Neuronal Signaling • Types of neuronal potentials • Resting membrane potential • Graded potentials • depolarizing • hyperpolarizing • Action potentials

  4. Neuronal Signaling • Resting membrane potential • Voltage difference across neuronal membrane • Typically -70 mV inside relative to outside neuron

  5. Neuronal Signaling • Resting membrane potential • Voltage difference across neuronal membrane • Membrane is semipermeable • Ion channels • Pores in membrane formed by proteins that allow ions to pass • K+ • Na+ • Cl- • Passive (nongated) • Active (gated) Na+ / K+ ATPase pump • 3 Na+ out for every 2 K+ in

  6. Neuronal Signaling • Resting membrane potential • Voltage difference across neuronal membrane • Membrane is semipermeable • Ion channels • Concentration gradients • More Na+ outside • More K+ inside • Electrical gradients • Negative charge inside, positive outside • Electrochemical or ionic equilibrium • Nernst equation

  7. Neuronal Signaling • Electrical conduction • Passive conduction • Electrotonic or decremental • Active conduction • Action potentials • Synaptic potentials • Receptor potential

  8. Neuronal Signaling • Electrical conduction • Passive conduction • Volume conduction • Amplitude of original current (V) • Resistance (R) and capacitance of membrane • Conductivity of intra- and extracellular fluids • Ohm's law V = IR or I = V / R

  9. Neuronal Signaling • Electrical conduction • Passive conduction • Active conduction • Action potential • Threshold • Depolarization • Hyperpolarization

  10. Neuronal Signaling • Electrical conduction • Passive conduction • Active conduction • Action potential • Threshold • All-or-none

  11. Neuronal Signaling • Electrical conduction • Passive conduction • Active conduction • Action potential • Threshold • All-or-none • Hodgkin-Huxley cycle • Influx of Na+ followed by efflux of K+ • Absolute refractory period • Relative refractory period

  12. Neuronal Signaling • Electrical conduction • Passive conduction • Active conduction • Action potential • Threshold • All-or-none • Hodgkin-Huxley cycle • Propagation • Saltatory conduction • Myelin • Node of Ranvier

  13. Neuronal Signaling • Electrical conduction • Synaptic Transmission • Transmembrane proteins • Ion channels • Polypeptides • Amino acids • 3-D structure

  14. Neuronal Signaling • Electrical conduction • Synaptic Transmission • Transmembrane proteins • Ion channels • Nongated

  15. Neuronal Signaling • Electrical conduction • Synaptic Transmission • Transmembrane proteins • Ion channels • Nongated • Gated • Voltage-gated

  16. Neuronal Signaling • Electrical conduction • Synaptic Transmission • Transmembrane proteins • Ion channels • Nongated • Gated • Voltage-gated • Chemically-gated - Receptors * Directly coupled * Indirectly coupled: second messenger

  17. Neuronal Signaling • Electrical conduction • Synaptic transmission • Transmembrane proteins • Chemical • Ca++ influx (voltage gated) • Vesicles • Transmitter release • Synaptic cleft

  18. Neuronal Signaling • Electrical conduction • Synaptic transmission • Transmembrane proteins • Chemical • Electrical • Gap junctions • Bidirectional • Rectifying

  19. Neuronal Signaling • Electrical conduction • Resting membrane potential • Graded potentials • Excitatory postsynaptic potentials (EPSPs) • depolarization • Inhibitory postsynaptic potentials (IPSPs) • hyperpolarization • Action potentials • Synaptic transmission

  20. Neuronal Signaling • Electrical conduction • Resting membrane potential • Graded potentials • Action potentials • Synaptic transmission • Transmembrane proteins • Chemical • Electrical

  21. Neurotransmitters • Synthesized and stored within presynaptic terminal • Released by presynaptic neuron following action potential • Postsynaptic neuron has receptor • When applied to postsynaptic neuron has same effect

  22. Neurotransmitters • Synthesis • Soma (large molecule) • Fast transport of neurotransmitter • Terminal (small molecule) • Slow transport of enzymes • Neuron may produce more than one • Inactivated after release • Reuptake • Enzymatic breakdown • Diffusion • Agonist vs antagonist

  23. Classes of NeurotransmittersE = generally excitatory / I = generally inhibitory • Amino acids • glutamate (E) • aspartate (E) • glycine (I) • gama-amniobutyric acid (GABA) (I)

  24. Classes of NeurotransmittersE = generally excitatory / I = generally inhibitory • Biogenic amines • acetylcholine (E in CNS, I in PNS) • dopamine (I) • norepinephrine (E & I in CNS, SNS) • epinephrine (E) • serotonin (I)

  25. Classes of NeurotransmittersE = generally excitatory / I = generally inhibitory • Neuropeptides • Tachykinins • substance P (E) • Neurohyphophyseal hormones • Hypothalamic releasing hormones • Opiods • endorphins (E) • Other • Some may be conditional

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