Ch 12 Flashcards
Nervous Tissue definition
tissue replaced for rapid transformation of signals from cell to cell.
Works along with the Endocrine System to coordinate homeostasis and body activites.
CNS
Brain and Spinal Cord
Autonomic Nervous System
sympathetic (fight or flight)
parasympathetic (rest and digest)
Astrocytes
located in CNS
provide Nutrional support and the proper chemical environment to Neurons
Oligodendrocytes
in CNS
produce myelin sheaths
Microglia
in CNS
mobile macrophages
Ependymal Cells
in CNS
line brain ventricles of the Brain
produce CSF
Schwann cells
in PNS
produce Myelin sheaths
Neurolemma
the outermost layer of cell, contains nucleus
Satellite cells
in PNS
nutritional support
Resting Membrane Potential
electrical potential across the axon membrane
outside is positive, inside is negative
extracellular area has more Sodium and Chloride ions
the intracellular area has more potassium ions, phosphate, and amino acids
RMP is approx. equal to -70
Voltage-Gated Channels
located in the axolemma
open and close in response to changes in voltage
ex: voltage-gated Na+ channels
voltage-gated K+ channels
Sodium/Potassium ATPase Pumps
located in axolemma
takes care of ion Na+ and K+ leakage across the axon membrane
Depolarization
voltage-gated Na+ channels open in response to a stimulus the membrane voltage becomes more positive and positive ions rush inside the membrane
depolarization originates at Axon Hillock
Repolarization
recovery of the RMP
Action Potential
Depolarization + Repolarization
electrical signal that is propagated down the axon
Threshold Stimulus
any electrical stimulus that is strong enough to initiate as action potential
Continuous Conduction
propagation of nerve impulse in a step by step depolarization and repolarization of adjacent areas of sarcolemma
All or none principle
initial stimulus must reach threshold before an action potential is generated. Initial electrical stimulus will quickly dissipate if the threshold stimulus is not achieved.
Saltatory Conduction
(sends signal over)
action potential is moved along the myelinated portion of axolemma, passing through the node until the impulse reaches synapse
associated with myelinated neurons