Neuronal Types

Question 1

What are the four major classes?

Answer 1

Multipolar Neurons, Bipolar Neurons, Pseudounipolar Neurons, Unipolar Neurons

Question 2

Multipolar neurons

Answer 2

Common in the mammalian nervous system with many dendrites and one long axon. Examples include motor neurons, pyramidal cells of the hippocampus, and Purkinje cells of the cerebellum

Question 3

Bipolar neurons

Answer 3

Have an elongated cell body and two processes, with one ending in dendrites and the other reaching the CNS. Examples are sensory neurons for smell, sight, taste, hearing, and vestibular functions.

Question 4

Pseudounipolar neurons

Answer 4

Have one axon with two branches—one to the periphery and another to the CNS. Examples include sensory cells in the dorsal root ganglion and baroreceptor-sensitive cells.

Question 5

Unipolar neurons

Answer 5

Extremely rare in vertebrates, with only one neurite extending from the soma, and dendrites and axon arising from the same location.

Question 6

How do neurons differ not only in morphology but also in their molecular composition?

Answer 6

Neurons differ in their chemical transmitters, ion channel combinations, and electrical properties such as resting membrane potential, threshold, excitability, and firing pattern. The scientific community categorizes neurons based on their place in the brain, morphology, connections, expression of specific proteins, and contribution to neuronal network activity.

Question 7

What techniques are used to characterize neurons, and what aspects do they cover?

Answer 7

Various techniques are used to characterize neurons, including microscopy and cell reconstruction for morphology, immunohistochemistry and molecular biology for gene and protein expression, patch-clamp recording for electrophysiological properties, and field recording and behavioral experiments for involvement in neuronal networks and brain oscillatory rhythms.

Question 8

How are excitatory and inhibitory neurons classified based on neurotransmitter release?

Answer 8

Neurons are classified as excitatory (principal cells) or inhibitory (interneurons) based on the neurotransmitter they release. Excitatory neurons release glutamate, while inhibitory neurons release GABA (Gamma-Amino-Butyric-Acid) and glycine. Serotonin and endorphins are also inhibitory, and dopamine and acetylcholine can have inhibitory or excitatory effects depending on postsynaptic receptors.