Integrative Cell and Tissue Biology: The NEURON

Flashcards covering neuronal structure, ionic basis of membrane potentials, action potential mechanics, synaptic transmission, and long-term potentiation.

In 1778, Luigi Galvani discovered __________, demonstrating that electrical signals are used in biological systems.

bioelectricity

The __________ is the region of the neuron that contains the nucleus and is responsible for the majority of cellular maintenance.

soma

Signals are conducted away from the soma toward other cells via the __________.

axon

The specialized gap where a neuron communicates with another cell is called the __________.

synapse

According to Ohm's Law, the rate of movement of charged particles ($I$) is equal to the conductance ($g$) multiplied by the __________ ($V$).

potential

The __________ equation is used to calculate the electrical potential that exactly counter-balances the force of an ionic concentration gradient.

Nernst

At a temperature of $37\,^°C$, the equilibrium potential ($E_{ion}$) for potassium ($K^+$) in a typical neuron is __________.

$$-80\,mV$$

At a temperature of $37\,^°C$, the equilibrium potential ($E_{ion}$) for sodium ($Na^+$) in a typical neuron is __________.

$$62\,mV$$

The Na-K ATPase is a major ion pump that moves __________ ions out of the cell for every 2 $K^+$ ions moved in.

3 $Na^+$

The narrow extracellular gap between presynaptic and postsynaptic membranes is approximately __________ nm wide.

30-50

During physiological electrical signaling, an __________ current refers to the movement of positive ions into the cell, which causes depolarization.

inward

The "decision" to fire an action potential is made in the __________, where there is a high density of voltage-gated $Na^+$ channels.

axon initial segment

The threshold level for initiating an action potential in a typical neuron is approximately __________.

$$-40\,mV$$

The rapid rising phase of the action potential is caused by the opening of __________ channels.

voltage-gated $Na^+$

The toxin __________, found in puffer fish, acts as a potent blocker of voltage-gated $Na^+$ channels.

tetrodotoxin

In the Central Nervous System (CNS), myelin is produced by cells called __________.

oligodendrocytes

In the Peripheral Nervous System (PNS), myelin is produced by cells called __________.

Schwann cells

The regular breaks in myelin that allow for saltatory conduction of the nerve impulse are known as __________.

Nodes of Ranvier

Direct flow of electrical current between cells occurs at electrical synapses through protein ion channels called __________.

connexons

A chemical is classified as a neurotransmitter if it is synthesized __________, released in sufficient quantity, mimics natural effects when administered externally, and has an inactivation mechanism.

endogenously

The protein __________ in the vesicle membrane is thought to act as the sensor that triggers exocytosis when it binds to $Ca^{2+}$.

synaptotagmin

The physical basis of __________ release is the spontaneous release of a single synaptic vesicle, producing a miniature postsynaptic potential.

quantal

Ligand-gated ion channels also known as __________ receptors, produce fast electrical responses.

ionotropic

The __________ receptor is a glutamate-gated channel that is unique because its ion pore is blocked by magnesium ($Mg^{2+}$) at resting membrane potentials.

NMDA

__________ inhibition occurs when chloride ($Cl^-$) channels open, lowering membrane resistance and allowing current to leak out, even if the membrane potential does not change significantly.

Shunting

The summation of simultaneously active synapses at different locations on the dendritic tree is known as __________ summation.

spatial

The Hebbian model of synaptic plasticity is often summarized by the phrase: "Inputs that __________ together, wire together."

fire

A persistent, activity-dependent increase in synaptic responses induced by high-frequency stimulation is called __________.

Long term potentiation (LTP)

Induction of LTP at CA3-CA1 synapses in the hippocampus requires the influx of __________ through NMDA receptor channels.

$$Ca^{2+}$$

The maintenance of LTP for more than 3 hours requires the activation of genes and the synthesis of new __________.

proteins