2 - Cells of Nervous System Flashcards
Action potential moves along the __ because __ __ spread passively to nearby regions, which changes the membrane potential to threshold, opening more __ __
Axon | Na+ ions | Na+ Channels
When hyperpolarizations and depolarizations occur at the same time, they __
Cancel each other out
K+ moves into the cell because it is attracted to the __ __ (negatively charged particles)
Electrostatic Pressure
Other proteins associated with the membrane are __ that __ biochemical reactions
Enzymes | Catalyze
When the two forces are balanced. The membrane potential is still more negative inside (–70 mV).
Equilibrium Potential for Potassium
Transmission: effect on receiving cells may be __ or _
Excitatory | Inhibitory
If Cl– channels are stimulated to open, Cl– enters cell and results in __, which is inhibitory
If gated K+ channels open, K+ leaves the cell, which also results in __
Hyperpolarization
Local potentials are graded. The larger the stimulus, the greater the magnitude of __ or __;
Hyperpolarization | Depolarization
__ __ is needed because Na+–K+ pumps are only at the nodes.
Less Energy
Some __ __ form ion channels and transporters for charged molecules, such as __ __, __, and __ __
Membrane Proteins | Amino Acids | Glucose | Metabolic Products
There are more __ ions (and amino acids) inside the cell and more __ ions outside.
Negative | Positive
__ __ __ receive information from thousands of synaptic connections at any given instant
Neuron Receptor Areas
Embryonic stem cells that form the nervous system become two primary cell types
- Neurons transmit information in the form of electrical signaling
- Glial cells provide metabolic support, protection, and insulation for neurons
Neurons have three parts:
- Soma — cell body; contains nucleus and other organelles
- Dendrites — projections from soma that receive information
- Axon — extension conducts electrical signals from cell body to terminal buttons
In myelinated axons, regeneration of the action potential occurs only at __ __ __, breaks in the myelin sheath at which the action potentials are regenerated
Nodes of Ranvier
Provide support and insulation to axons in the central nervous system equivalent to the function performed by Schwann cells in the peripheral nervous system
Oligodendroglia
Ions such as __, __, __ and __ are needed for neuron function and can move only through ion channels
Potassium (K+) | Sodium (Na+) | Chloride (Cl–) | Calcium (Ca2+)
• Many cell membrane proteins are __, initial sites of action of neurotransmitters, hormones, and drugs
Receptors
The difference in electrical charge between inside and outside of cell
Resting Membrane Potential
The conduction seems to jump along the axon
Saltatory Conduction
Form Myelin sheaths in the peripheral nervous system (PNS), wrap only one axon, release growth factors, and promote regeneration of damaged axons. They myelinate peripheral nerves that serve muscles, organs, and glands.
Schwann Cells
Convert physical stimuli into electrical signals.
Sensory Neurons
The __ __ __ moves 3 Na+ to the outside for every 2 K+ moved to the inside, helping to keep the inside of the cell negative.
It requires energy for Ions to be pumped against their __ __
Sodium Potassium (Na+–K+) Pump | Concentration Gradient
Several small depolarizations can add up to larger changes in membrane potential
Summation
Dendrites and Dendritic Spines are constantly modified and can change shape rapidly in response to changes in __ __
Synaptic Transmission
Terminal buttons have __ __ containing __ __
Synaptic Vesicles | Neurotransmitter Chemicals
Threshold Membrane Potential for firing. Voltage-gated Na+ channels open, generating a rapid change in membrane potential.
–50 mV
Open when the electrical potential across the membrane is altered
Voltage-Gated Channels
At rest, inside of cell is more negative: __ millivolts (mV); it is __.
–70 | Polarized
