Bio100Ch45Notes

Bio100Ch45Notes - 1. Principles of Electrical Signaling 1....

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1. Principles of Electrical Signaling 1. Nerve cells or neurons transmit information 2. Sensory Neuron – a nerve cell is a sensory receptor cell transmits the information it receives 3. Nerves – long, tough strands of nervous tissue. 4. Central nervous system (CNS) – brain and the spinal cord 1. It’s function is to integrate information from many sensory neurons 5. Interneurons – cells in the CNS 6. Motor neurons – nerve cells that send signals to effector cells in glands or muscles 7. Peripheral nervous system (PNS) – all neurons and other components of the nervous system that are outside the CNS 8. Information goes from the PNS CNS and the brain directs appropriate response 9. Some information never reaches the brain 10. Reflex – direct response to a signal without the integration by the brain 1. When pain receptors are stimulated, sensory neurons activate interneurons in the spinal cord that directly activate motor neurons serving muscles. 2. Anatomy of a Neuron 1. Dentrite – short projections that receives an electrical signal from the axons from adjacent cells 2. Axon – long projections that sends the signal to the dendrites and cell bodies of other neurons
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3. Cell body / Soma – also receives signals from axons. Also where incoming signals are integrated and an outgoing signal is sent to the axon 3. An Introduction to Membrane Potentials 1. Electrical potential/voltage - difference of electrical charge between any two points creates a difference in voltage 2. Membrane potential – separation of charges, electrical potential exists on either side of a plasma membrane 1. Membrane potential are measured in units called millivolts(mV) 2. Volt – standard unit of electrical potential 3. In neurons, membrane potentials are typically about 70-80mV 3. Electrical current – flow of charge 4. How is the Resting Potential Maintained? 1. Resting potential – neuron is not transmitting an electrical signal but is merely sitting in extracellular fluid at rest 2. According to the concentration gradient, organic anions and K + would leave the cell while Na + and Cl - would enter but ions cannot cross the membrane so easily 3. Ions cross the plasma membrane by 1. Flowing along their electrochemical gradient through an ion channel 2. Carried, via a membrane cotransporter, with an ion that experiences a strong electrochemical gradient 3. Pumped against an electrochemical gradient by a membrane protein that hydrolyses ATP 4. Ion channels – pores in the membrane that allows only specific ions to pass through 5. Resting neurons are most permeable to K + ions, which cross the membrane easily along their concentration gradient 1. Potassium channels are sometimes called leak channels because they allow K + to leak out of the cell 6. Equilibrium potential – no net movement of ions 7. Na + / K + -ATPase actively pumps Na + out of the cell and K + into the cell
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5. What is an Action Potential? 1.
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This note was uploaded on 04/12/2010 for the course BIOLOGY 3363 taught by Professor Sokolove during the Fall '09 term at UMBC.

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Bio100Ch45Notes - 1. Principles of Electrical Signaling 1....

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