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Human Physiology 2A: Neurophysiology Supplemental Instruction Iowa State University Leader: Course: Instructor: Date: Paige Stieneke BIOL 256 Dr. Karri Haen February 10, 2013 Basic Types of Cell Signaling Matching. Select the best option for the following statements: 1. 2. 3. 4. 5. ___ Diffuses to nearby target cell (neighbors) ___ Secretion of hormone into the blood, goes into circulatory system ___ Via cytoplasm via gap junctions ___ Signal substance affects secretory cell (itself) ___ Neuron’s axon terminal secretes neurotransmitter Neurophysiology Nodes of Ranvier Nucleus Oligodendrocytes Axon Myelin Sheath a. b. c. d. e. Cell-to-cell Paracrine Autocrine Synaptic Endocrine Neurons Neurons transmit nerve impulses as ____________________ (two words) Information always travels from (dendrite, axon) to (dendrite, axon) Glial Cells: support neurons a. _________________ are cells that produce the myelin sheath of the (CNS, PNS) and is known as “white matter” b. _________________ produce the myelin sheath of the (CNS, PNS) c. _________________ = insulation to conduct action potentials! Cell Membrane Potentials Voltage across a membrane due to differential concentration and charges of ions inside/outside the cell Two types of signals: a. ___________________: Small changes in membrane potential, leads to action potential b. ___________________: Neuron sends an impulse, an all-or-none response Graded Potential Magnitude varies directly with the strength of the stimulus a. ____________ Summation: Summed up over time b. ____________ Summation: Summed over multiple inputs Resting Membrane Potential What is the charge of a neuron at rest? (always the charge INSIDE the cell!) AT REST: There is more K+ (inside, outside) the cell, and Na+ (inside, outside) the cell Supplemental Instruction 1060 Hixson-Lied Student Success Center 294-6624 www.si.iastate.edu Action Potential Stage Charge (mV) Function Resting Depolarization Repolarization Hyperpolarization Steps of the Action Potential 1. _________________ (ligand) binds to ligand-gated channel 2. Binding of the ligand causes a _____________________ 3. If graded potential strong enough, then the ___________________ is initiated at the axon hillock! It will start to occur when the threshold inside of the cell is -55 mV (a charge in mV) 4. : Voltage-gated Na+ channels open, and Na+ rushes (into, outside) the cell. In other words, the cell becomes more (positive, negative) and the charge goes from ________ to _________. Voltage-gated K+ channels (open, close) allowing K+ to flow (into, outside) the cell Voltage-gated Na+ channels (open, close) at the peak of the action potential (+30 mV) 5. : Starts due to halted influx of Na+. Voltage-gated K+ channels also start to (open, close). In other words, the charge changes from +30 mV back to -70 mV. However, the resting potential is overshot to _______. 6. : The resting potential is overshot to ________. So how does the cell return to its resting potential? ______________ pumps _________ out for every ________ in to return to the resting potential Refractory Period How does the cell maintain the all-or-none response of an action potential? ______________________________: Enforces one-way of a nerve transmission to prevent a 2nd action potential from occurring too soon ______________________________: Follows the absolute refractory period, occurs during repolarization and will allow a new action potential to occur when the threshold level is reached (approx. -70 mV) Supplemental Instruction 1060 Hixson-Lied Student Success Center 294-6624 www.si.iastate.edu