Nervous Coordination

In myelinated axon of mammals, depolarisation only occurs at

• Nodes of Ranvier

• Schwann cells

• Myelin sheath

• Oligodendrocytes

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

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

Which type of neuron transmits a signal from a sense organ to the central nervous system?

• sensory
• relay
• motor
• efector

Which type of neuron transmits a signal from the central nervous system to an effector such as a muscle?

• sensory
• motor
• relay
• dendrite

Which part of the nervous system is not involved in producing reflex actions?

• brain
• spinal cord
• receptors
• sensory

What part of the neuron receives incoming messages from other cells?

• nucleus

• cell body

• dendrites

• synaptic terminals

During which stage of this action potential do sodium ions (Na+) flow through the sodium channels from the outside of the membrane to the inside of the membrane?

• threshold

• depolarization

• repolarization

• refractory period