Neuroscience Exploring the Brain: Chapter 3

Action potential

Nerve impulses specially made in the axonal membrane

Excitable membrane

Nerve and muscle cells that can process and use action potential.

Resting membrane potential

The difference in the electrical charges across the membrane.

Ions

Atoms or molecules that have a net charge. Carry charge to conduct electricity in the body

Polar covalent bonds

When two atoms bond by sharing electrons.

Ionic bonds

When one atom gives another it's electron (makes the other atom stable).

Spheres of hydration

Clouds of water which surrounds each ion.

Cations

Ions with a positive charge.

Anions

Ions with a negative charge.

Monovalent (1), Divalent (2), Trivalent (3), etc

The difference between the number of protons and electrons.

Hydrophilic

Substances that are "water-loving"/substances that can dissolve in water.

Hydrophobic

Opposite of hydrophilic

Phospholipids

the main chemical building blocks of cell membranes.

Enzymes

Acts as catalysts for chemical reactions in the neuron.

Cytoskeleton

Fibers that work to keep the shape of the cell.

Receptors

Things that react to neurotransmitters made up of protein.

Peptide Bonds

The bond which brings the amino acid of one to the carboxyl of another.

Polypeptides

Proteins made out a single chain of amino acid.

Primary structure

chain of amino acids linked by a peptide bond

Secondary structure

protein structure formed by folding and twisting of amino acid chain

Tertiary structure

protein structure is formed when the twists and folds of the secondary structure fold again to from a larger 3D structure

Quaternary structure

protein structure is a protein consisting of more than one folded amino acid chains

Subunit

Each of the polypeptides in the quaternary structure.

Ion channel

Requires 4-6 proteins to assemble to make the pore (pore=channel).

Ion selectivity

The different properties which ion channels have based on its diameter and the nature of the Residue group which are around the pore.

Gating

Only specific properties of specific ion can open the channel.

Ion pumps

Enzymes which helps with the transport of specific ions using ATP. ATP is the energy currency of cells.

Diffusion

The movement of something of net high concentration to net low concentration.

Concentration gradient

The difference in the concentration between the net high and the net low.

Electrical current

The movement of electrical charge.

Electrical potential

Force put on a charged particle (voltage) that reflects the difference in charge between the anode and cathode

Electrical conductance

The ability of an electrical charge to move from one point to another, represented by g, measured in siemens (s)

Electrical resistance

The inability of an electrical charge to move from one side to another, represented by R, measured in ohms, R=1/g

Ohm's law

I=gV ; amount of current flowing= product of conductance and potential difference

Membrane potential

The voltage across the membrane of a neuron at any moment (Vm).

Microelectrode

Thing glass tube which can go through the cell membrane with minimal damage and measure cell voltage

Voltmeter

Measures the difference in the electrical potential from inside and outside.

Equilibrium potential

The electrical potential difference that balances an ionic concentration (Eion). When diffusional and electrical forces are equal and opposite.

Ionic driving force

The difference between the real membrane potential, Vm, and the ionic equilibrium potential, Eion.

Nernst Equation

Used to calculate the equilibrium potential for any ion with the ionic concentrations inside and outside the cell

Sodium-potassium pump

Uses ATP to get sodium out and potassium in. If there is no pump there is no resting potential

Calcium pump

Actively transports intracellular Ca2+ from the cytosol to the outside of the cell.

Goldman equation

Formula for membrane potential which take into account the relative permeability of the membrane for different ions.

causes of large changes in membrane potential

small changes in ionic concentrations

Net differences in electrical charge

occurs on the inside and outside surfaces of the membrane

K concentration is more concentrated

on the inside of the cell

Na and Ca are more concentrated

on the outside of the cell

Depolarization

change in the membrane potential to a less negative value

Hyperpolarization

change in the membrane potential to a more negative value

Potassium spatial buffering

regulation of K by astrocytes

Blood-brain barrier

Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out

Impermeable membrane

nothing will get through

Selectively permeable channels

Only allows specific ions to pass through the membrane