Question

What are ganglia in the nervous system?

Answer 1

Hint: An organised ovoid cluster of neuron cell bodies, along with glial cells and connective tissues that is found outside the central nervous system is called a ganglion (pl. ganglia).

Complete answer:
Ganglia act as relay stations for nerve impulses outside the central nervous system, hence also called peripheral ganglia. They consist of both afferent and efferent neurons, that receive and send signals in and out of the ganglia. Based on their primary function, ganglia can be of two types:
-Sensory ganglia: contain cell bodies and axons of neurons responsible for sensory stimuli.
-Autonomic ganglia: forms relay stations for impulses travelling in Autonomic nerves from the CNS to target organs.
Dorsal root ganglion is one of the major sensory ganglia. It relays impulses coming from the peripheral like the skin towards the CNS, i.e. it is composed of afferent neurons. All the nerve cells of dorsal root ganglion are unipolar, which means only one process extends from the cell body and there is an absence of dendrites.
Cranial nerve ganglia are also sensory types of ganglia which are associated with cranial nerves instead of spinal nerves, as seen in dorsal root ganglia. These too are unipolar in shape.
Just like the autonomic nervous system, autonomic ganglia are of two main types; sympathetic ganglia and parasympathetic ganglia. Sympathetic ganglia relay the fight-or-flight response in case the neuron senses any stress or danger. These ganglia are present along the spinal cord on either side. Parasympathetic ganglia are relay stations associated with the parasympathetic nervous system. They are named terminal and intramural ganglia depending on their location with respect to the organ they innervate, i.e. if they lie close to or within the organ.

Note:
Sensory ganglia contain satellite cells, which are skeletal precursor cells. They are multipotent cells.
Neurons of autonomic ganglia are multipolar, i.e. they have extensions like dendrites protruding from the cell body.