Nervous System Flashcards
Neurons
Specialized nervous tissue
Neuroglia
cells that support and protect the neurons
Dendrites
Cytoplasmic extensions that receive information and transmit it toward the cell body
Cell Body (stoma)
Contains the nucleus and controls the metabolic activity of the neuron
Axon
Long cellular process that transmits impulses, action potentials, away from the cell body
Axon Hillock
Between the cell body and axon, incoming signals are summed and can trigger an action potential down the axon
Synaptic Terminals
Axons termination in swelling
Synapse
Gap between the axon terminals of one cell and the dendrites of the next cell
Myelin
Prevents leakage of signal from the axons and allows for faster conduction of impluses
Nodes of Ranvier
Gaps between the segments of myelin, where action potential actually propagates
Saltatory Conduction
Hopping in the Nodes of Ranvier
Oligodendrocytes
Glial cells that produce myelin in the central nervous system (Schwann cells in the peripheral nervous system)
Neuron Polarization
At rest, there is an unequal distribution of ions between the inside and outside of the cell
Resting Potential
-70 mV, negative inside
How is the membrane potential maintained at rest?
Selective permeability of ions through the sodium/potassium pump
Threshold Potential
-55 mV
Three Action Potential Phases
Depolarization, Repolarization, Hypepolarization
Depolarization
35 mV
Hyperpolarization
-75 mV
Refractory Period
A period of time after the action potential in which new action potentials are very difficult to initiate
Faster Impulses
Greater myelination, greater diameter of the axon
White Matter
Faster transmission times due to heavy myelination transmits across larger distances
Grey Matter
Slower transmission times due to less myelination and is used for processing information
Presynaptic Neuron
Axon terminal of one neuron
Postsynaptic Neuron
Dendrites of the next neuron
Effector Cells
Neurons can communicate with these postsynaptic cells such as muscles or glands
Neurotransmitters
Chemical messengers in membrane-bound vesicles that can diffuse across the synapse and act on receptor proteins
Removal of Neurotransmitters
Uptake, Reused, Degraded, Diffuse
Afferent Neurons
Carry sensory information about the external or internal environment to the brain or spinal cord