7.1 Overview of the nervous systemCNS- brain and spinal cord, receives and processes info from sensory organs and the viscera to determine the state of external environment(sensory) and internal environment(vesciera).oDecides on appropriate action and sends instruction to organs.PNS- neurons that provide communication between the CNS and organs.oSeparated into afferent and efferent.oAfferent- transmit sensory and visceral info from organs to CNS such as somatic (skin muscles joints) special(vision, hearing, smell, taste) and visceral(fullness of stomach, bp, bl ph.) senses.oEfferent- transmit info from CNS to organs(effector organs- muscles and glands)Somatic-motor neurons that regulate skeletal contractions.Autonomic- neurons that regulate internal organs and involuntary things. Autonomic is divided into parasympathetic and sympathetic. oEnteric nervous system- network of neurons in gastrointestinal tract independent of the nervous system but communicates with autonomic system.7.2 Cells of the nervous systemNeurons- functional unit that carries out the function of a tissue. It is and excitable cell that transmit action potentials to communicate.Glial cells- 90% of nervous system, provides structure and metabolic support.NeuronsSoma- nucleus, er, golgi, free ribosomes, mitochondria but also mitochondria are throughout thecell.oCell body does protein synthesis and cellular metabolism and most functions. Neurons-retain nuclei but cannot undergo cell division so adults have most neurons they will ever have. New neurons can come from stem cells in SOME parts of the brain.Dendrites- branch from cell body and receive input at their synapse.oDifferent neurons, different branching pattern. Branching indicates # of synapses.Axon- (nerve fiber) that extends from cell body. Send Information. oBranches of axon are called collaterals, indicates capacity of communication with other cells.oAction Potential- change in membrane potential when cell is positive inside and outside is negative.oAxon hillock- where the axon comes from the body, initiation of action potential.oAxon terminal- where neurotransmitter is released b/e of action potential.Post synaptic cell- receives neurotransmitterwhich is a dendrite, cell body or efferent organ.Pre synaptic cell- axon terminal that releases neurotransmitter.For axons to function is have to have enzymes that synthesize neurotransmitters, transporter molecules to move neurotransmitters or their substrates across membrane, and vesicles to hold neurotransmittersAxonal Transport- special transport mechanism oAnterograde transport-from cell body to axon terminal oRetrograde transport- axon terminal to cell body.
oSlow axonal transport- movement of small molecules in the cytosoloFast axonal transport- movement of vesicles. Microtubules extend the length of the axonand serve as a track for transport molecules. Kinesins(protein) walk down the track
You've reached the end of your free preview.
Want to read all 7 pages?
- Fall '08