Ch 48 %28doc%290 - Chapter 48 Slide: 1 Nervous systems...

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Chapter 48 Slide: 1 Nervous systems Chapter 48 (and a bit of 49) Slide: 2 What is a Nervous system? The collection of organs, tissues and cells that coordinates, records and distributes information by electrical and chemical signals between the brain and other parts of the body allowing response to external stimuli and control of other organ systems. Slide: 3 Animal Nervous systems Most animals have a nervous system (except sponges). Many are cephalized with neurons clustered on one end into a brain Figure 49.2 (Campbell 8th ed) Slide: 4 Nervous system comprised of 2 general cell types Neurons - Transfer information via electrochemical energy Glial Cells - Support cells for neurons Slide: 5 Neuron Structure Most neurons have three main parts: 1. Dendrites - bring electrical stimuli from other neurons or sensory epithelial cells to the cell body. - several to many per neuron 2. Cell body - receives stimuli from dendrites or other neurons and propagates to axon - synthesizes some neurotransmitters (or neurohormones) - contains nucleus and other cell organelles 3. Axon - receives stimulus from cell body of neuron and propagates signal to synapse - only 1/ cell but distal end has several to many branches (thus each neuron can contact many other neurons) - synthesizes some neurotransmitters in synaptic terminals Slide: 6 Neuron Structure Most neurons join via a synapse to: other neurons muscle cells glands Synapse = narrow space between 2 cells Neurotransmitters pass info across synapse from pre- to postsynaptic cell (i.e. are a paracrine signal) Some neurons (neurosecretory cells) transmit chemicals (neurohormones) directly into the blood stream (e.g. hypothalamus neurosecretory cells produce neurohomones that act on the anterior pituitary). Neurotransmitters vs neurohormones Neurohormones enter blood vs. neurotransmitters are paracrine regulators Neurotransmitters act on specific cells to which they have a synaptic connection vs. neurohormones act on many cells via circulatory system. Figure 48.4 (Campbell 8th ed)
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Slide: 7 4 Functional Types of Neurons Sensory (afferent) – transmit info from external or internal sensors to the brain (or ganglia) - e.g. light, odor, taste, temperature, pressure, pain, position, etc… Interneurons – Analyze and interpret sensory input - Found exclusively within the spinal cord and brain - Stimulated by sensory neurons, other interneurons or both - Hundreds or more types of interneurons - Have many more dendrites than other neuron types (~100k) Motor (efferent) – transmit signals to muscle and gland cells from the brain (or ganglia) - primarily stimulated by interneurons Neurosecretory – transmit chemicals into blood which act on distant targets
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This note was uploaded on 11/08/2011 for the course BSC 2011C taught by Professor Klowden/crampton during the Fall '11 term at University of Central Florida.

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Ch 48 %28doc%290 - Chapter 48 Slide: 1 Nervous systems...

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