A1 Nervous system organisation

What are the two main components of the nervous system?

• Central and Autonomic Nervous Systems

• Central and Peripheral Nervous Systems

• Peripheral and Autonomic Nervous Systems

• Somatic and Autonomic Nervous Systems

Answer explanation

The nervous system is primarily divided into two main components: the Central Nervous System (CNS), which includes the brain and spinal cord, and the Peripheral Nervous System (PNS), which connects the CNS to the rest of the body.

Which type of cell makes up the myelin sheath in the peripheral nervous system?

• Schwann cells

• Astrocytes

• Oligodendrocytes

• Microglia

Answer explanation

Schwann cells are the type of cells that form the myelin sheath in the peripheral nervous system, providing insulation and support to nerve fibers, which enhances the speed of electrical signal transmission.

What is the primary difference between myelinated and unmyelinated neurons?

• Myelinated neurons have faster transmission speeds.

• Unmyelinated neurons have faster transmission speeds.

• Myelinated neurons are found only in the peripheral nervous system.

• Unmyelinated neurons are found only in the central nervous system.

Answer explanation

Myelinated neurons have a fatty sheath that insulates them, allowing for faster transmission of electrical signals compared to unmyelinated neurons, which lack this sheath and transmit signals more slowly.

What is saltatory conduction?

• The continuous conduction of action potentials along an unmyelinated axon.

• The jumping of action potentials from one node of Ranvier to the next in a myelinated axon.

• The transmission of action potentials across a synapse.

• The release of neurotransmitters into the synaptic cleft.

Answer explanation

Saltatory conduction refers to the process where action potentials jump from one node of Ranvier to the next in a myelinated axon, allowing for faster signal transmission compared to continuous conduction in unmyelinated axons.

Which neurotransmitter is primarily involved in the transmission at neuromuscular junctions?

• Dopamine

• Serotonin

• Acetylcholine

• GABA

Answer explanation

Acetylcholine is the neurotransmitter that facilitates communication between nerve cells and muscles at the neuromuscular junction, enabling muscle contraction. The other options do not play this role.

What is the role of receptor cells in the nervous system?

• To transmit action potentials to muscles.

• To detect stimuli and convert them into electrical signals.

• To release neurotransmitters into the synaptic cleft.

• To form the myelin sheath around neurons.

Answer explanation

Receptor cells play a crucial role in the nervous system by detecting stimuli from the environment and converting them into electrical signals, which are then transmitted to the brain for processing.

Which division of the autonomic nervous system is responsible for the 'fight or flight' response?

• Central nervous system

• Parasympathetic nervous system

• Sympathetic nervous system

• Somatic nervous system

Answer explanation

The 'fight or flight' response is primarily controlled by the sympathetic nervous system, which prepares the body to respond to stress or danger by increasing heart rate, dilating pupils, and redirecting blood flow to muscles.

Which neurotransmitter is commonly associated with the parasympathetic nervous system?

• Dopamine

• Norepinephrine

• Acetylcholine

• Serotonin

Answer explanation

Acetylcholine is the primary neurotransmitter of the parasympathetic nervous system, facilitating rest-and-digest functions. In contrast, dopamine, norepinephrine, and serotonin are associated with other systems.

What is the primary function of intermediate neurons?

• To transmit signals from sensory neurons to motor neurons.

• To detect external stimuli.

• To form the myelin sheath.

• To release hormones into the bloodstream.

Answer explanation

The primary function of intermediate neurons, or interneurons, is to transmit signals between sensory neurons and motor neurons, facilitating communication within the nervous system.

Which of the following is a characteristic of voluntary reflexes?

• They are controlled by the autonomic nervous system.

• They involve conscious control and decision-making.

• They occur without conscious thought.

• They are slower than non-voluntary reflexes.

Answer explanation

Voluntary reflexes involve conscious control and decision-making, distinguishing them from involuntary reflexes, which occur automatically without thought. This makes the correct choice the one that highlights conscious involvement.