The Nervous System Flashcards
What is included in the Central Nervous System?
Brain and spinal cord.
What is included in the Peripheral Nervous System?
Everything that isn’t the brain and spinal cord.
Contrast spatial and temporal summation of neurons.
Spatial summation occurs when the signals are received at the same time.
Temporal summation occurs when the signals are received one after another.
Describe the concentration of Na and K around/ inside the cell.
Sodium (Na) is highly concentrated outside the cell.
Potassium (K) is highly concentrated inside the cell.
What is the resting membrane potential for neurons?
-70mV, the number isn’t important but realize that it is negative compared to the outside. The membrane is much more permeable to potassium than it is to sodium. The K+ leaves the cell rapidly down its concentration gradient.
What does the Na/K do?
Pumps 3 Na out/ pumps 2 K in.
What two forces create the equilibrium for the resting membrane potential.
Primary dictated by the diffusion of potassium going out of the cell. Followed by the electrochemical equilibrium of potassium in and out of the cell.
Describe the process of depolarization and repolarization
- In Depolarization: when a signal stronger than the threshold is met, the voltage gated sodium channels open allowing sodium to flood into the cell causing it to be more positive.
- In repolarization: after a point, the voltage gated sodium channels close which allow the voltage gated potassium channels to open allowing the potassium ions to flood out of the cell- may cause hyperpolarization.
- Na/K pump seeks to balance back to resting membrane potential.
What does “all of nothing” mean?
The signal either allows for a signal or occur, or it doesn’t. This also means the amplitude of the action potential is the same for every signal. The frequency increases for increased signals.
Contrast absolute and relative refractory period
Absolute refractory occurs during de/repolarization.
Relative refractory occurs during hyperpolarization.
Describe what occurs at the synapse
- The action potential reaches the presynaptic axon terminal and opens voltage gated calcium channels.
- Calcium floods into the cell which activates the release of neurotransmitters
- The neurotransmitters are released into the synapse and bind to the post synaptic terminal.
- Secondary messenger system activates or inhibits a response.
What is the function of the microglia?
Macrophages of the nervous system. Fight infections.
What is the function of the ependymal cells?
Epithelial cells which circulate the CSP
What is the function of astrocytes?
Help support cells in the CNS.
What is the function of satellite cells?
Help support cells in the PNS.
Compare oligodendrocytes vs schwann cells.
oligodendrocytes produce myelin for CNS
schwann cells produce myelin for PSN.
What is saltatory conduction?
Rapid movement of action potential down the axon of the neuron.