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Transcript
Chapter 12 Nervous Tissue Functional composition of the PNS. Fig. 48.17 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings A closer look at the (often antagonistic) divisions of the autonomic nervous system (ANS). Fig. 48.18 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Nervous System Sensory Motor Integrative / association Neuroglia Astrocytes Microglia Ependymal Cells Oligodendrocytes Schwann Cells Satellite cells Found in the CNS only Schwann cells are found within the PNS. Form a myelin sheath by insulating axons. Fig. 48.5 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Measuring Membrane Potentials. An unstimulated cell usually have a resting potential of -70mV. Fig. 48.6a Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings The Action Potential: All or Nothing Depolarization. If graded potentials sum to -55mV a threshold potential is achieved. This triggers an action potential. Axons only. Fig. 48.8c Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Saltatory conduction. In myelinated neurons only unmyelinated regions of the axon depolarize. Thus, the impulse moves faster than in unmyelinated neurons. Fig. 48.11 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Words to Know Wallerian degeneration Multiple sclerosis Epilepsy Neuropathy Guillain-Barre Syndrome Rabies Summation: graded potentials (EPSPs and IPSPs) are summed to either depolarize or hyperpolarize a postsynaptic neuron. Fig. 48.14 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings produce different effects on different types of cells Acetylcholine. Excitatory to skeletal muscle. Inhibitory to cardiac muscle. Secreted by the CNS, PNS, and at vertebrate neuromuscular junctions. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Some trivia Myelinated neurons travel at 268 miles/hr. Unmyelinates at 1 mph 100,000 miles of myelinated neurons in the brain 100 Trillion neural connections in the brain Biogenic Amines. Epinephrine and norepinephrine. Can have excitatory or inhibitory effects. Secreted by the CNS and PNS. Secreted by the adrenal glands. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Dopamine Generally excitatory; may be inhibitory at some sites. Widespread in the brain. Affects sleep, mood, attention, and learning. Secreted by the CNS and PNS. A lack of dopamine in the brain is associated with Parkinson’s disease. Excessive dopamine is linked to schizophrenia. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Serotonin. Generally inhibitory. Widespread in the brain. Affects sleep, mood, attention, and learning Secreted by the CNS. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings