What are the two main types of cells in the nervous system?
A: Neurons and glia cells
B: Axons and dendrites
C: Neurons and synapses
D: Astrocytes and oligodendrocytes
Correct: Neurons and glia cells
The nervous system contains two fundamental cell types: neurons, which transmit electrical and chemical signals, and glia (or glial cells), which provide structural support, insulation, and metabolic assistance to neurons. While neurons are the primary signalling units, glia outnumber them and are equally essential for healthy brain function.
What are the three main structural parts of a neuron?
A: Nucleus, mitochondria, and synapse
B: Dendrites, cell body (soma), and axon
C: Myelin sheath, axon terminal, and nucleus
D: Dendritic tree, glia, and axon hillock
Correct: Dendrites, cell body (soma), and axon
A neuron's three main components are: (1) dendrites — branching extensions that receive incoming signals; (2) the cell body (soma) — which contains the nucleus, organelles, and integrates incoming signals; and (3) the axon — a long projection that carries the output signal (action potential) away from the cell body toward the next neuron or target tissue.
Match each neuron type to its primary function.
Neurons carry the most information in the nervous system — glia cells are mainly passive support structures.
Answer: False
While neurons are the primary signalling cells, glia are far from passive. Astrocytes regulate the chemical environment around synapses and participate in signal transmission. Oligodendrocytes (CNS) and Schwann cells (PNS) produce myelin sheaths that dramatically speed up neural conduction. Microglia act as the brain's immune system. Modern neuroscience has revealed that glia actively modulate neural circuits.
What is the blood-brain barrier, and what does it primarily consist of?
A: A membrane of neurons that filters toxins from cerebrospinal fluid
B: Tight junctions between specialised endothelial cells lining brain capillaries, supported by astrocytes
C: A layer of myelin surrounding the brainstem that blocks pathogens
D: Meningeal membranes that physically separate the brain from the bloodstream
Correct: Tight junctions between specialised endothelial cells lining brain capillaries, supported by astrocytes
The blood-brain barrier (BBB) is formed by specialised endothelial cells that line the capillaries of the brain. Unlike capillaries elsewhere, these cells are joined by very tight junctions that restrict the passage of most substances. Astrocyte end-feet wrap around these capillaries and contribute to barrier maintenance. Nutrients such as glucose and oxygen cross via specific transport proteins rather than passive diffusion.
What are neurotransmitters, and what are their two major classes?
A: Electrical signals; classified as excitatory and inhibitory voltages
B: Chemical messengers released at synapses; classified as small-molecule transmitters and neuropeptides
C: Hormones secreted by glia; classified as steroids and proteins
D: Ions that cross the cell membrane; classified as cations and anions
Correct: Chemical messengers released at synapses; classified as small-molecule transmitters and neuropeptides
Neurotransmitters are chemical messengers synthesised and released by neurons at the synapse to communicate with adjacent cells. The two major classes are: (1) small-molecule transmitters (e.g., glutamate, GABA, dopamine, serotonin, acetylcholine) — fast-acting and synthesised locally at the axon terminal; and (2) neuropeptides (e.g., endorphins, substance P) — larger molecules synthesised in the cell body, slower-acting, and often modulatory.
Match each pharmacological term to its correct definition.
The central nervous system (CNS) consists of which structures?
A: The brain, spinal cord, and peripheral nerves
B: The brain and spinal cord only
C: The autonomic nervous system and somatic nervous system
D: The cerebral cortex and limbic system
Correct: The brain and spinal cord only
The CNS comprises the brain and spinal cord — the two structures encased within bone (skull and vertebral column respectively) and bathed in cerebrospinal fluid (CSF). The peripheral nervous system (PNS) consists of all nervous tissue outside the CNS: cranial nerves, spinal nerves, autonomic ganglia, and sensory receptors. The PNS connects the CNS to the rest of the body.