learning objective week 6

What are the three factors that influence the movement of ions?

diffusion-movement of ions from higher concentration to lower concentration through random motion. voltage gradient- difference in charge between two regions that allow a flow of current if the two regions are connected. concentration gradient- allows substance to diffuse from an area of high conc to low conc

What is the resting membrane potential?

electrical charge across the cell membrane in the absence of stimulation; a store of potential energy produced by a greater negative charge on the intercellular side relative to the extracellular side

What kind of force(s) is(are) acting on A-, K+, Na+?

electrical gradient??

What are the two ways that the resting membrane potential can be changed?

hyperolarization and depolarization

Is a hyperpolarization making the inside of the cell more positive/negative? Is a depolarization making the inside of the cell more positive/negative?

hyperpolarization is making the outside more negative ?? depoloarization is making the inside more negative??

What ion(s) is(are) likely involved to cause a hyperpolarization?

hyperpoloarization is accomplished with an efflux of K+ ions

The pufferfish releases a toxin that interferes with what type of graded potential? What is the likely outcome of exposure to the pufferfish poison?

interferes with the electrical activity of nuerons. likely exposure- poision?

During resting potential, is the inside of the neuron positively or negatively charged?

intracellular side is more negative

How is the resting membrane potential maintained?

the cell membrane channels, gates, and pumps maintain the resting potential. K+ is free to leave and enter cell. Na+ channels are closed keeping Na+ out. Na+ K+ pumps out three Na+ for two K+

What is the name of positively charged ions?

cation

what is the concentration gradient?

differences in concentration of a substance among regions of a container that allow the substance to diffuse from an area of higher concentration to an area of lower concentration

What ion(s) is(are) likely involved to cause depolarization

sodium (Na+)

What types of ions are mainly involved in producing the resting potential?

sodium, potassium, chloride, and large protein molecules

2) What kinds of ions can be found in the intra- and extracellular fluid of neurons?

The major cation in extracellular fluids is sodium, and the major anion is chloride; in intracellular fluid the major cation is potassium, and the major anion is phosphate.

What are the two factors that act on the ions?

Diffusion, concentration gradient, and electrical gradient influence the movement of ions.

What is the name for the event when the resting membrane potential is changed?

action potential?

What is the name of negatively charged ions?

anion

Make sure you know why there are more K+ and A- inside and more Na+ outside?

because Na+ K+ pumps extrude Na+ from the intracellular fluid and inject K+ it is necessary to only have a few K+ ions outside the cell to maintain the negative charge outside the cell.

Where along the neuron does hyperpolarization/depolarization typically occur?

membrane??

Where did those ions move (into or out of the cell)?

moving in

where did those ions move (into or out of the cell)?

moving out??

Are these ions equally distributed across the intro/extracellular fluid?

no. more protein anions and potassium ions in the intracellular fluid, and more chloride and sodium in the extracellular fluid.

What influences the movement of ions in and out of a neuron?

the separation of charges across the membrane

depolarization

when the charge (polarity) of the membrane decreases

hyperpolarization

when the charge (polarity) of the membrane increases