Neural Transmission Flashcards
Quiz 2
Important Ions
K+ potassium
Na+ sodium
Cl - Chloride
Ca++ calcium
Microstructure of the nervous system
-Neuron is the primary cell within the nervous system
-Neuron is the main avenue for information transfer
-Behaviors occur through hundreds of thousands of neurons firing in synchrony along a serial and parallel pathway.
structures
- Dendrites
- Axon hillock
- Axon
- Nodes of Ranvier
- Soma
- Myelin Sheath
Cytoplasm
Within the cell (intracellular) Electrically conductive fluid
Cell membrane
Insulator
Outside of the cell (extracellular)
Salty solution, excellent electronic conduction
Neural Transmission
Part 1: The resting state of the neuron
Part 2: Axon potential
Part 3: Neural transmission between neurons and at the neuromuscular junctions
Resting State
The brain is always active, not actually resting examined when not responding to a stimulus.
Resting state steps
-Neurons are in a state of electro-chemical imbalance
There is an electro-chemical imbalance with more negative ions within the neuron than outside.
Resting state factors
Factors that contribute to the electro-chemical gradient:
-Sodium potassium pump: 3 Na++ ions move out of the cell to every 2 K+ ions pumped into the cell
-There are large negative proteins inside the cell
-The neuron is less permeable to Na+ (gated channels)
Chemical- equilibrium between sodium Na+ and K+
Electrical- Like charges repel
Chemical factor: K+ flows out of the cell to equalize levels of Na+ and K+
The flow of K+ ends because of the abundance of positive ions Na+ within the extracellular space.
Polarized
The intracellular space is 70 mV more negative than the extracellular space at the rest.
During resting state, the neuron is polarized
Action Potential
The action potential allows for transmission of a signal within the neuron
- A stimulus causes the neuron to reach a threshold level to activate (fire)
- An iconic current flow to the terminal end of the axon
Gated channels: an electrical, chemical, or physical stimulus can open gated channels
Stimulated
Na+ channels open and Na+ enters the cell, a passive ionic current signal spreads to the beginning of the axon.
Depolarization
Influx of Na+ = cell becomes less polarized
Action potential steps
If sufficient Na+ enters the cell and voltage reaches threshold in the region of the axon hillock, an action potential will occur. Na+ gate channels open, AP at one node of ranvier will cause AP at the next node.
Neurochemical transmission
Allows for information transfer between neurons
-Allows for information transfer between a neuron and a muscle (through cranial or spinal nerves)
-Neurochemicals (neurotransmitters) allow for this transfer.
-Neurochemicals create a circuit or network of information flow.
neurochemical transmission parts
Presynaptic neuron
Postsynaptic neuron
Synaptic cleft
Vesicles
Neurotransmitter
Neurochemical transmission steps
When the Ap reaches the terminal end bulb, it opens the membrane to Ca++
Ca++ enters the presynaptic neuron and stimulates the vesicles, which carry the neurotransmitter within the vesicle is released into the synaptic cleft.
Excitatory post synaptic potential
Na+
Action Potential
Inhibitory post synaptic potential
Cl -
Action potential unlikely
