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.

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 go through water.

Hydrophobic

Opposite of hydrophilic

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.

Alpha helix

Spiral like configuration which occurs in the secondary structure of a protein.

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.

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.

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.

Voltmeter

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

Equilibrium potential

The electrical potential difference that balances an ionic concentration (Eion).

Nernst Equations

Used to calculate the equilibrium potential for any ion.

Sodium-potassium pump

An enzyme which breaks down ATP to get sodium out and potassium in (for the most part). If there is no pump there is no resting potential

Calcium pump

An enzyme which actively transports intracellular from the cytosol to the outside of the cell.

Goldman equation

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

Pore loop

The factor which contributes to the channel, only letting potassium in the pores.

Blood-brain barrier

Specialization in blood capillaries so that it limits the amount of potassium (and other substances in the blood) which mixed with the extracellular fluid at the brain.

charge of an atom

depends on the difference between the number of protons and electrons

Peptide bond

covalent bond between the amino group of 1 amino acid to the carboxyl group of another

4 molecular groups

hydrogen, amino, carboxyl, and variable (R)

Amino acid

have a central carbon atom covelantly bonded to bonded to one of the 4 molecular groups

Primary structure of a protein

chain of amino acids linked by a peptide bond

Secondary structure of a protein

coils into an alpha helix

Tertiary structure

complex 3d shape

quaternary structure

peptide chains bond together to form a larger molecule

Ion pump

enzymes that use the energy released by the breakdown of ATP to transport certain ions across the membrane

Neuronal membrane

electrically negative relative to the outside

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

Rate of ion movement across a membrane

rate proportional to the difference between the membrane potential and the equalibrium potential

Ionic driving force

difference between the real membrane potential (Vm) and the ionic equalibrium potential (Eion)

K concentration

on the inside of the membrane

Na and Ca concentration

on the outside of the membrane

Depolarization

membrane potential at a normal resting value to a less negative value

Depolarization

increasing extracellular K

Potassium spatial buffering

regulation of K by astrocytes

Voltage gradient

Electrolytes dissociate into ions in a solution and Ions with the same charge will repel each other

Impermeable membrane

nothing will get through

Selectively permeable channels

Select what ions are allowed to pass through the membrane

Selectively permeable membrane

Allows ions to move past according to their gradient

Electrochemical gradient

attracts ions based on charge

Sodium, Potassium, Chloride

responsible for electrical activity of neurons

Channel proteins

Cylindrical proteins that permit controlled exchange of ions across the membrane

Hyperpolarization

Will never lead to an action potential and silences a neurotransmitter

ATPase

an enzyme that breaks down ATP