QTBL Blok 1.4 1st Week

Which of the following correctly describes the organization of the autonomic nervous system?

• It controls voluntary muscle movements and skeletal reflexes.

• It is part of the central nervous system and regulates heart rate.
  

• It is divided into sympathetic, parasympathetic, and enteric systems.

• 1. It sends sensory signals from the body to the brain.

The resting membrane potential of a neuron is mainly maintained by:

• Equal distribution of Na⁺ and K⁺ ions across the membrane.

• The Na⁺/K⁺ ATPase pump actively transporting ions.

• Chloride ions entering the neuron to neutralize the charge.

• 1. Increased permeability of the membrane to sodium ions.

At rest, which of the following is true about the ionic environment of a neuron?

• Na⁺ concentration is higher inside the neuron than outside.
  

• K⁺ concentration is higher outside the neuron than inside.

• Negatively charged proteins are abundant inside the neuron.

• Cl⁻ ions are only found outside the neuron.

Which of the following correctly describes the repolarization phase of an action potential?

• Voltage-gated Na⁺ channels open, causing Na⁺ influx.

• K⁺ channels open, allowing K⁺ efflux from the cell.

• The Na⁺/K⁺ pump is inactivated during this phase.

• Membrane potential reaches +30 mV due to Na⁺ entry.

During the hyperpolarization phase of an action potential, which event occurs?

• Voltage-gated K⁺ channels remain open too long.

• Voltage-gated Na⁺ channels reopen for a second depolarization.

• The resting membrane potential is restored immediately.

• K⁺ and Na⁺ reach equilibrium across the membrane.

What triggers neurotransmitter release at the presynaptic terminal?

• Na⁺ entry into the presynaptic neuron.

• Action potential arrival and Ca²⁺ influx.
  

• Voltage-gated K⁺ channel activation.
  

• Chloride ion movement into the presynaptic neuron.

Which of the following occurs at the postsynaptic membrane after neurotransmitter binding?

• Voltage-gated ion channels open to propagate the signal.
  

• Ionotropic receptors open ion channels directly.
  

• Neurotransmitters are immediately degraded in the synaptic cleft.
  

• 1. The Na⁺/K⁺ pump maintains neurotransmitter activity.

What is a primary mechanism for terminating neurotransmitter activity in the synaptic cleft?

• Conversion of neurotransmitters into proteins by enzymes.

• Diffusion of neurotransmitters out of the synaptic cleft.

• Uptake of neurotransmitters by the postsynaptic neuron.

• 1. Blocking voltage-gated ion channels in the presynaptic membrane.