Bio Study Guide Exam 4

Bio Study Guide Exam 4 - Exam4 T ypes of Neurons A )...

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Exam 4 18:00 Types of Neurons A ) Sensory Neurons (afferent neurons ): impulses from sensory receptors CNS (brain/spinal cord) B) Motor Neurons (efferent neurons): Impulses from CNS effectors (muscles/glands) C) Interneurons (association neurons ): Located in CNS of all vertebrae Provide complex reflexes/higher associative functions (i.e. learning/memory) Nervous Systems A) PNS: made up of sensory and motor neurons B) Somatic Nervous System: made up of motor neurons that stimulate skeletal muscle C) Autonomic Nervous System:
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Made up of motor neurons that stimulate smooth and cardiac muscle and glands Broken down into sympathetic and parasympathetic: counterbalance each other in regulation of organ systems. Neuron Structure A) Cell body: large area containing the nucleus surface integrates the information arriving at dendrites
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after integration, surface triggers impulses away from cell body using the axon B) Dendrites: 1 or more cytoplasmic extensions coming from cell body receive information Motor/Interneurons have highly branched in order to receive info from several sources Dendritic spines: extensions from dendrites that increase surface area C) Axon: Carrier for response impulses triggered by cell body Each cell body contains only one axon May branch to stimulate multiple other cells Neuroglia ( supporting cells) very small but very numerous Functions: o Supply the neurons with nutrients o Remove waste from neurons o Guide axon migration o Provide immune functions Schwann cells: o Produce myelin sheath in the PNS that surround axons of neurons o PNS: myelinated axons are bundled together to form nerves Oligodendrocytes: o Produce myelin sheath in the CNS that surround axons of neurons
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o CNS: myelnated axons form the white matter and unmyelinated dendrites and axons form the grey matter Nodes of Ranvier: o Small gaps that interrupt the myelin sheath The Plasma Membrane Negative: side exposed to the cytoplasm Positive: side exposed to the extracellular fluid Resting Potential: when a neuron is not being stimulated Membrane Potential: affected by 1. Sodium-Potassium Pump : brings 2 K+ ions into cell for every 3 Na+ pumped out. Helps maintain the concentration gradient of high K+ /low Na+ inside the cell and high Na+ /low K+ outside the cell 2. Ion Channels : more ion channels for K+ than for Na+ , therefore the membrane is more permeable for K+ (will diffuse out of the cell) Resting Potential: significant concentration gradients created by the sodium- potassium pump : the concentration of K+ is higher inside the cell which allows for diffusion through open K+ channels. Membrane is not permeable to negative ions
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Bio Study Guide Exam 4 - Exam4 T ypes of Neurons A )...

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