Brain and cognition - Chapter 2

Neurons

Neurons

Signaling units that transmit information

Glial cells

Have several different functions (4 types):

Astrocytes, Oligodendrocytes, Microglial cells and Schwann cells

Astrocytes

Glial cell that surrounds neurons and are in contact with blood vessels. Can modulate neuron activity. In the central nervous system.

Oligondendrocyte

Form myelin around neurons in the central nervous system.

Microglial cells

Devour and remove damaged cells, in the central nervous system.

Schwann cells

Form myelin around neurons, in the peripheral nervous system.

Blood-brain barrier (BBB)

Barrier of Astrocytes which protects neurons in the brain from pathogens and drugs.

Myelin

Increases the speed of the information getting transported through a neuron.

Soma

Cell body (Not the nucleus)

Intracellulair fluid

The cytoplasm of the cell (salty, made up of ions)

Dendrites

Receive input from other neurons

Axon

Outputs a signal to other neurons via axon terminals.

Spines

Little knobs where neurons receive input from other neurons.

Synapses

Where the electrical signal is passed on from one cell to the next. Includes both the presynaptic and postsynaptic part.

Axon collaterals

Axons that branch together which allows them to transmit signals to more than one cell.

Presynaptic neuron

When output synapses are connected to other neurons.

Postsynaptic neuron

When the input synapses on dendrites connect to the other neuron.

Resting membrane potential

-70 mV across the neuronal membrane, when no signal is being sent.

Ion channels

Allows ions to pass through the membrane with the concentration (not against), passive transport

Ion pumps

Ion transport against gradients (low→ high), active transport (costs energy)

Permeability

Extent to which ions can pass through ion channels

Electrochemical equilibrium

Stable force/ position of electrochemical charge.

Electronic conduction

Ionic current that diminishes because of the distance from the site

K+

Potassium

Na+

Sodium

A-

Organic anions

Action potential

Rapid polarization and depolarization on the neuron’s output

Voltage-gated ion channel

Transmembrane ion channel that changes molecular conformation

Axon hillock

Specialized region of the neuronal soma where the axon emerges.

Spike-triggering zone

At the juncture of the soma and axon of the neuron, where voltage gated sodium channels are located. Which can be triggered to create an action potential.

Nodes of Ranvier

Gaps between myelin patches where action potential can be generated.

Equilibrium potential

Same amount of ions go in and out of the cell.

Refractory period

Period when the neuron is not able to generate an action potential.

Saltatory conduction