Lecture 10 (2/24) Flashcards Preview

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Flashcards in Lecture 10 (2/24) Deck (11):
1

Impulses

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

2

Ion

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.

3

Perturbation

When the natural setup of a cell is changed

4 Main disruptions can occur
Mechanical
Chemical
Temperature change
Electrical pulse

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)

4

Resting Potential

When a cell is completely unperturbed

When a cell is unperturbed the voltage is -70mV

5

Hyperpolarization

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

6

Depolarization

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

7

Action Potential

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.

8

Factors of Ion Flow

The ion concentration gradient

The density of ionic channels/pores

The size of ionic channels

9

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.

10

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

11

Size of Ionic Channels

The membrane channels that are there are gated - they aren't open forever

They are opened and closed by neurotransmitters

The gates are opened to allow some ions to pass through, but others aren't allowed.

The gate makes it difficult for negative ions inside the cell to move out because the channel isn't permeable to them