NeurophysiologyI. BackgroundA. Cell Types1. Neurons2. GliaB. Subtypes1. Differ based on their structure, chemistry and functionC. Relative distribution1. 100 billion neurons (give or take 100 million)2. 10 times as many glia as neuronsD. Functional significance1. Neurons confer the unique functions of the nervous systemII. Cellular Structure of NeuronsA. Neurons contain the same basic structures as most other cellsB. Structure of animal cells
1. Cell body (soma)a. 20 um in diameterb. Surrounded by a membrane that separates the inside of the cell from theoutsidei. 5 nm thick2. Cellular contentsa. Everything within the cell membrane other than the nucleus is theconsidered cytoplasm3. Nucleusa. Contain the chromosomes that confer the heritable material—DNAb. Gene expressioni. DNA to Protein
ii. DNA (transcription) mRNA (translation) Protein3. Ribosomesa. Site where protein is made4. Endoplasmic reticuluma. Roughi. Have ribosomesb. Smoothi. Transport completed protein to other cellular sites5. Mitochondriaa. Site where metabolic functions are performed6. Golgi apparatusa. Post-translational modification of proteins7. Neuronal membranea. Cannot understand the function of the brain without understanding thestructure and function of the membrane and its associated proteinsC. Unique features of neurons1. Morphological regionsa. Cell body (soma or perikaryon)b. Neurites2. Types of neuritesa. Axonsb. Dendrites3. Axonsa. Cell body usually gives rise to a single axoni. Conducts nerve impulse from one neuron to the next
ii. Up to 1 meter in lengthiii. Speed of the nerve impulse is a function of the diameter of the axon4. Dendritesa. Smalli. Rarely more than 2mmb. Organized symmetricallyi. Antennaec. Dendritic treei. Collective term for all neurites of a given neuronD. Neural signals1. Efferenta. Away from the cell body2. Afferentb. Towards the cell bodyE. Synapse
1. Site of neurotransductiona. Electrical to chemical signal2. Structural elementsa. Axon terminali. Site where axon comes in contact with another neuronb. Presynaptic terminalc. Postsynaptic terminali. Usually found on dendrited. Clefti. Space between the two sides of a synapse3. Synaptic transmissiona. Process by which information is transferred from one side of the synapse tothe otherb. Most adult vertebrate synapses are electrical
c. Electrical impulse that travels down the axon is converted to a chemicalmessage4. Neurotransmittera. Chemical signalb. Different neurons use different types of neurotransmitters5. Receptora. Specialized proteins responsible for detecting neurotransmittersb. Involved in transduction of signalIII. Non-Neuronal CellsA. Glia1. Support neuronal function2. Typesa. Astrocytesi. Regulate extracellular spaceii. Remove neurotransmitters, restrict movement of neurotransmitterfrom synapse, etc.