Neurones

Question 1

Why is it essential to maintain a concentration gradient across the membrane

Answer 1

The concentration gradient will enable rapid movement of ions across the membrane when the ion channels open. Sodium ions can move in quickly and potassium ions can move out.

Question 2

What is different about the neurons in the generator region than elsewhere in the neurone

Answer 2

In the generator region the sodium ion channels are opened by the presence of acetylcholine; elsewhere they are charge-gated – opened by changes in potential across the membrane

Question 3

How does Saltatory conduction make the ap more rapid

Answer 3

Only a few ions need to move along the neurone to alter the charge at the next node. The ions can move along very quickly

Question 4

Role of the SEM in the pre-synaptic bulb

Answer 4

Smooth endoplasmic reticulum is where the acetylcholinesterase is synthesised and placed into vesicles

Question 5

Nicotine

Answer 5

The nicotine molecule has a shape that is similar to that of acetylcholine and complementary to that of the acetylcholine receptor site so it will fit into the site

Question 6

Difference between a cell signal and an ap

Answer 6

An action potential is a signal being carried along one cell. It is an electrical impulse. A cell signal is a message passed from one cell to another. It is a chemical signal.

Question 7

Summation

Answer 7

Summation is the combined effect of several small potentials. Small potentials combine together to produce a larger potential that may reach the threshold