Excitable Tissues

An INCREASE in the magnitude of the membrane potential of a neurone at rest is known as which of the following?

• hyperpolarisation

• a resting membrane potential

• depolarisation

• an action potential

• hypopolarisation

When the membrane potential of an excitable cell decreases in magnitude from the resting membrane potential (i.e. the inside of the cell becomes less negative) we refer to this type of movement as?

• hyperpolarisation

• repolarisation

• depolarisation

• hypopolarisation

• none of the above

Which of the following statements about depolarising graded potentials is FALSE?

• depolarising graded potentials are elicited by an excitatory stimulus

• depolarising graded potentials are fairly transient

• the size of the polarising graded potential is dependent upon the size of the stimulus

• depolarising graded potentials take the cell away from threshold

• none of these statements is false

The membrane potential of a typical excitable tissue cell at rest is usually around?

• +50mV

• -50mV

• 0mV

• +0.08V

• -0.08V

The hyperpolarising phase of the action potential is caused by?

• sodium channel inactivation

• slow opening of voltage-gated potassium channels

• slow-closing of voltage-gated potassium channels

• sodium channel activation

• voltage-gated sodium ions opening

Which of the following is primarily responsible for the repolarising phase of the action potential?

• the sodium/potassium exchange pump

• flow of sodium ions out of the cell

• flow of sodium ions into the cell

• flow of potassium ions into the cell

• flow of potassium ions out of the cell

The ion channels that are fundamentally responsible for the magnitude of the resting membrane potential are known as?

• voltage-gated K+ channels

• resting K+ channels

• stretch-gated K+ channels

• ligand-gated Na+ channels

• voltage-gated Na+ channels

Which of the following are classified as monovalent anions?

• sodium ions

• potassium ions

• chloride ions

• calcium ions

• none of these are monovalent anions

Which of the following statements about ion concentrations and excitable tissues is FALSE?

• the concentration of Na+ is higher in the extracellular fluid than the intercellular fluid

• the concentration of Ca2+ is lower in the intracellular fluid than the extracellular fluid

• the concentration of Cl- is higher in the extracellular fluid than the intercellular fluid

• the concentration of K+ is higher in the extracellular fluid than the intercellular fluid

• the concentration of Na+ is lower in the intracellular fluid than the extracellular fluid

Which of the following is/are features of voltage-gated ion channels?

  1. a gate whose opening is regulated by the membrane potential       

2. a molecular sensor that measures the membrane potential       

3. membrane-spanning proteins that act as conduits for ions

• 3 only

• 1 & 2 only

• 1, 2 & 3

• 1 only

• 1 & 3 only