Coordination

Which of the following is NOT characteristics of electrical impulse?

• Electrical impulse is an all or nothing event

• During refractory period, neuron is not sensitive to another stimulus

• Impulse transmission along the axon is slower than the one at synapse

• Speed of impulse conduction depends on diameter of axon and the presence or absence of myelin sheath

In myelinated axon of mammals, depolarisation only occurs at

• Nodes of Ranvier

• Schwann cells

• Myelin sheath

• Oligodendrocytes

Which of the following represents positive feedback mechanism?

• 1

• 2

• 3

• 4

In which phase, does both, voltage gated sodium and potassium ions channels, are closed?

• 1

• 3

• 4

• 5

Which statement best describes the resting state of a neuron?

• Neuron is polarised with more sodium ions outside the cell and more potassium ions inside the cell

• Neuron is propagating the action potential along its axon

• Neuron is repolarising as potassium ions diffuse out of the cell

• Neuron is restoring the ionic conditions utilising the sodium-potassium pump

An action potential is caused by an influx of __________ ions into the cell.

• Calcium

• Potassium

• Chloride

• Sodium

Once the action potential has traveled along the sarcolemma, what structure takes the action potential into the interior of the muscle fibre?

• Sarcoplasmic reticulum

• Transverse tubule

• Mitochondria

• Sarcoplasm

What is the role of calcium ions during a synaptic transmission?

• Generate action potential in postsynaptic membrane

• Bind to the receptor of ligand gated sodium ion channels and causes depolarisation of postsynaptic membrane

• Trigger the fusion of synaptic vesicles containing neurotransmitter to the presynaptic membrane

• Involve in the reuptake of neurotransmitter into the synaptic knob

What generates a nerve impulse on the postsynaptic membrane?

• Neurotransmitter being removed from the synaptic cleft

• Neurotransmitter binds to the receptor protein of the ligand gated ion channels

• Influx of sodium ions into the postsynaptic membrane through opened ligand gated ion channels

• Influx of calcium ion into the presynaptic membrane

What two molecules are necessary for muscle contraction to occur?

• Sodium and potassium ions

• Calcium and sodium ions

• Calcium ions and ATP

• ATP and acetylcholine