Dendrites and Axons

Roll the dice!

Dendrites and Axons

Instructions

What do current clamp recordings measure?

Voltage

What are ion channels?

Ion channels are channels embedded into the membrane that allow for the movement of ions between the extracellular and intracellular space. They are ion specific and can be ligand gated, voltage gated, or mechano-sensitive channels

What is myelin and how does it affect signal transmission?

Myelin sheath is a layer of compacted plasma membrane that wraps and insulates the axon and speeds up signal transmission along the axon

What is Current?

Current is the movement of charged ions between the intracellular and extracellular spaces of a cell. The movement of ions is depends on their conductance through the membrane and electrochemical driving force

How does a neuron communicate with other neurons?

There are 3 big players: dendrites, axons, and axon terminals. dendrites receive signals from neighboring neurons. Axons transmit signals down the neuron to the axon terminal and then the signal moves across the synapse via neurotransmitters to other neuron dendrites or tissues.

What controls the electrochemical driving force?

The electrochemical driving force is the difference between the membrane potential and the ion equilibrium potential (Vdf = Vm − Veq.). The driving force is the net electromotive force that acts on the ion.

How are ion channels selective?

There is a selectivity filter formed from the arrangement of oxygen atoms at the top of the channel that are spaced to allow stable interaction with an ion. These interactions dehydrate the ion which allows the ion to enter the channel and then it gets rehydrated in a different part of the channel called the vestibule. This cannot be performed with ions of different sizes causing the channels to be ion specific.

What does the resting membrane potential depend on?

Resting membrane potential depends on equilibrium potentials of all ions weighted by their relative to their permeabilities and concentrations. It can be calculated using the Goldman-Hodgkin-Katz (GHK) equation

Box 55

What are action potentials?

Axon potentials are the generation and conduction of nerve impulses which spread from the axon hillock to the axon terminals due to changes in membrane voltage.

What do voltage clamp recordings measure?

Current

DENDRITES

AXONS

Axons

DENDRITES

If the player lands on a square where the dendrite starts, they go down to a lower square where the dendrite endingis located.

If the player falls on the bottom of an axon, they move up to the top square where the axon ends.

INSTRUCTIONS

Players start with an ion - which represents potassium, sodium, chloride, and calcium - in the initial square and take turns rolling the die. The ions move according to the numbering on the board, in ascending order. If, at the end of a move, a player lands on a square where an axon begins, they move up it to the square where it ends. If, on the other hand, they land on a square where a dendrite begins, they move down it to the square where the dendrite ends. If a player lands on a square that has a question on it, they must answer it correctly to move forward. If they pass a question during their move, they also must answer it correctly or they will end their turn on that square. The player who reaches the final square first is the winner.