Flashcards in Lecture 10 (2/24) Deck (11):
Electrical and chemical signals by which nerves communicate
Communication begins as an electrical signal, gets converted into a chemical signal, and then back into an electrical signal
An item that carries one or more positive or negative charges.
Ions with the same charge repel each other and are attracted to ions of different charges.
There are more negative ions inside a cell and more positive ions outside a cell.
When the natural setup of a cell is changed
4 Main disruptions can occur
When perturbation occurs it results in the movement of ions either inside and/or outside the cell (ions can flow into or out of the cell)
When a cell is completely unperturbed
When a cell is unperturbed the voltage is -70mV
When a cell is perturbed and the negative ions outside the cell flow in, the positive ions outside the cell flow out, or both.
This makes the voltage of the cell become more negative
Hyperpolarization is inhibitory
When the cell is perturbed and the negative ions flow out of the cell, the positive ions flow into the cell, or both.
This makes the voltage of the cell more positive.
Depolaraization is excitatory
The reaction to the depolarization of a cell.
The cell's threshold is met and the cell reacts by firing its negative charge down the length of its axon
When the action potential reaches the cell terminal it causes the release of synaptic vesicles (aka neurotransmitters) into the synaptic cleft
The neurotransmitters are released due to the action potential and are then received by the postsynaptic membrane where they combine with special receptors.
When this happens that chemically mediated action allows the receiving cell to become permeable to the chemicals outside itself - the receiving cell's chemical composition can be changed by this, creating a cycle.
Factors of Ion Flow
The ion concentration gradient
The density of ionic channels/pores
The size of ionic channels
Ion Concentration Gradient
Ions tend to move from regions of high concentration to regions of low concentration
This movement is called diffusion
The higher/steeper the concentration gradient the easier/greater the flow down the concentration gradient.
Density of Ionic Channels/Pores
Ions move down the concentration gradient through specialized ionic pores
The movement is affected by the density of the channels - the more channels that there are the greater the flow