The excitable cell

Question 1

Action Potentials

Answer 1

Fixed size, all or nothing signals, pass either way along an axon but tend to go one way, coded by frequency

Question 2

Graded potentials

Answer 2

Variable size, local signals, pass both ways along neuronal membrane, coded by size and vary according to strength of stimulus

Question 3

What is membrane potential at rest?

Answer 3

-65vm

Question 4

What is the distribution of ions in cell at rest?

Answer 4

there are more K+ ions inside the cell and more Na+ ions outside the cell

Question 5

What are the 2 physical forces controlling ion movement?

Answer 5

diffusion - molecules will move down a concentration gradient

electrical gradients - positive ions will move away from highly positive areas of charge to more negative areas.

Question 6

Na+/K+ pump

Answer 6

exchanges internal Na+ for external K+ against concentration gradient, requires ATP

Question 7

Ca2+ pumps

Answer 7

Transports Ca2+ out of neurones